bluuebunny/crossref_metadata_2025 huggingface dataset:
Age‐related changes of neuronal responsiveness to melatonin in the striatum of sham‐operated and pinealectomized rats
Authors: Castillo‐Romero José L. , Acuña‐Castroviejo Darto , Escames Germaine , Vives Francisco
Published: February 2007

Abstract: The age‐related changes and the acute effects of intravenous melatonin on the activity of striatal neurons of 1 ‐, 3‐, 6‐, 12‐, and 18‐month‐old sham‐operated and pinealectomized rats were investigated. There was a decline in responsiveness from 3‐ to 18‐months of age, although in sham‐pinealectomized rats the responses were similar at 12 and 18 months; in pinealectomized rats, the neuronal responses were quite stable at early ages. In all age groups of sham‐pinealectomized rats, neuronal firing decreased in most cells, and increased in only a small percentage of cells after intravenous melatonin injection (100 ng/kg). However, in pinealectomized rats, the injection of melatonin at the same doses significantly increased the firing rate of most neurons compared to that in sham‐operated animals at all age‐groups, while the number of neurons showing an inhibitory response decreased. These results indicate that melatonin may be involved in the modulation of the activity of striatal neurons and demonstrates an age‐dependent reduction in striatal sensitivity to melatonin. They also suggest that other compounds of pineal origin may modulate the activity of motor control centers.
(β‐Adrenergic receptor subtypes in human pineal gland
Authors: Little Karley Y. , Kirkman Jacob A. , Duncan Gary E.
Published: February 2007

Abstract: The secretion of melatonin by the pineal has been promoted as a direct monitor of adrenergic function in depressive illness. However, discrepant findings have been reported, possibly reflecting a complex adrenergic regulation of pineal output. In order to clarify the anatomical localization and relative density of β‐adrenergic receptors and their subtypes in human pineal, quantitative autoradiographic analysis was conducted of β‐adrenergic receptors in postmortem specimens using the high affinity radioligand 125I‐pindolol. Dense specific binding was found throughout the gland. β1,‐adrenergic receptors were more numerous, but β2‐receptors were present in an overlapping anatomical distribution with β1‐receptors.
Role of the pineal gland and melatonin in the development of autoimmune diabetes in non‐obese diabetic mice
Authors: Conti Ario , Maestroni Georges J.M.
Published: February 2007

Abstract: Earlier studies on the immunoregulatory role of the pineal gland and melatonin revealed that melatonin counteracts immunosuppression and thymus atrophy induced by stress or corticosteroid treatment. Moreover, melatonin protects mice injected with encephalitogenic virsuses, synergizes with interleukin‐2 (IL‐2) in cancer immunotherapy and rescues hematopoiesis from cancer chemotherapy toxicity. In regard to the mechanism of action, melatonin seems to act directly on CD4+ lymphocytes which release opioid peptides with immunoenhancing properties along with other cytokines. Because of these findings, we investigated the role of the pineal gland and melatonin in autoimmune diabetes mellitus type I using, as an experimental model, female non‐obese diabetic (NOD) mice. Mice were pinealectomized or treated chronically with melatonin (injected subcutaneously or administered via drinking water). This paper shows that neonatal pinealectomy accelerates the development of the disease in female NOD mice while exogenous melatonin protects the animals. This in spite of the fact that melatonin increased the production of insulin autoantibodies (IAA). We conclude that the pineal gland and melatonin influence the development of autoimmune diabetes although the mechanism of action that needs further investigation.
Nocturnal plasma melatonin concentrations in healthy volunteers: Effect of single doses of d‐fenfluramine, paroxetine, and ipsapirone
Authors: Nathan Pradeep J. , Norman Trevor R. , Burrows Graham D.
Published: February 2007

Abstract: The effect on nocturnal melatonin secretion of acute administration of the indirectly acting serotonin (5‐HT) receptor agonists d‐fenfluramine (30 mg) and paroxetine (20 mg) and a partial 5‐HT1A receptor agonist ipsapirone (20 mg) was investigated in healthy male volunteers and compared to a placebo condition. Each subject (n=8) received each drug on one occasion over a 4 week study period, with drug administration separated by 1 week. A randomized, counter‐balanced design was used. Drugs or placebo were administered at 2,000 hours in the light, and all blood samples were collected throughout the night in the dark at regular intervals until 0600 hours. Neither d‐fenfluramine, paroxetine, or ipsapirone following acute dosage had a statistically significant effect on nocturnal melatonin synthesis. The lack of effect seen with d‐fenfluramine, paroxetine, and ipsapirone may be due to limitations imposed by the dose requirements.
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, Copenhagen

Dopamine 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.

It 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.

Recently, 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.
Melatonin inhibits oxidative modification of human low‐density lipoprotein
Authors: Kelly Melissa R. , Loo George
Published: February 2007

ABSTRACT: An important property of melatonin is that it is a free‐radical scavenger or antioxidant. Since free radicals can induce oxidative modification of low‐density lipoprotein (LDL), a process believed to be involved in atherogenesis, we were prompted to evaluate the capacity of melatonin to prevent oxidative modification of LDL. To induce oxidation, human LDL (0.4 mg protein/ml) was incubated at 37°C with either 10 μM cupric chloride or 10 mM 2,2′‐azo‐bis‐(2‐amidinopropane) dihydrochloride (AAPH) for 3 hr or 24 hr, respectively. Several assays were then performed to unequivocally determine the extent of LDL oxidation. Compared to native LDL, oxidized LDL had increased agarose gel electrophoretic mobility and weaker immunoreactivity with a murine monoclonal antibody to human apolipoprotein B‐100. Measurement of thiobarbituric acid‐reactive substances (TBARS) revealed that native LDL contained 1.8 ± 0.6 nmoles TBARS/mg protein, whereas copper‐oxidized LDL contained 53 ± 4 nmoles TBARS/mg protein. However, when present during incubation, melatonin (0.125–4 mM) inhibited in a concentration‐dependent manner the increase in electrophoretic mobility, decrease in immunoreactivity of LDL, and increase in formation of TBARS caused by either copper or AAPH. In a fourth assay, phospholipid analysis of LDL was performed. Native LDL contained 420 ± 9 nmoles phosphatidylcholine (PC)/mg LDL protein and 30 ± 20 nmoles lysophosphatidylcholine (LysPC)/mg LDL protein. LDL incubated with copper had a decreased PC content (276 ± 48 nmoles PC/mg LDL protein) and increased LysPC content (76 ± 22 nmoles LysPC/mg LDL protein). But when present during the incubation of LDL with copper, melatonin attenuated in a concentration‐dependent manner the degradation of PC to LysPC. Therefore, we conclude that melatonin can inhibit oxidative modification of LDL in vitro.
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, Copenhagen

We 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, Copenhagen

In 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, Copenhagen

The 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.
Stimulatory effect of melatonin on the 5′‐monodeiodinase activity in the liver, kidney, and brown adipose tissue during the early neonatal period of the rabbit
Authors: Brzezińska‐Ślebodzińska Ewa , Ślebodziński Andrzej B. , Styczyńska Elżbieta
Published: February 2007

Abstract: The response of type I 5′‐monodeiodinase activity (5′‐MD) to a sc injection or oral administration of melatonin was studied in 3‐, 5‐, and 7‐day‐old rabbits. Melatonin‐treated animals showed higher activity of the type I 5′‐MD in the liver and kidney and of type II 5′‐MD in brown adipose tissue (BAT). This respond to melatonin treatment was age dependent. The stimulatory effect of melatonin on renal 5′‐MD activity was observed only in 3‐ and 5‐day‐old rabbits and in the liver and BAT during the first week of life. Oral melatonin administration tended to exert a more marked effect on enzyme activity than sc injection of the hormone. Changes in 5′‐MD activities were accompanied by an increase in serum iodothyronine (T4, T3, and rT3) concentrations. The T3 and rT3 increases may result from the deiodinating processes by the type I 5′‐MD and 5‐MD, respectively, whereas the rise in the serum T4 was probably due to the stimulatory effect of melatonin on the secretory activity of the thyroid gland itself. These results are the first description of the effects evoked by melatonin treatment during the early neonatal period in newborns of the altricial type.
Effects of two melatonin analogues, S‐20098 and S‐20928, on melatonin receptors in the pars tuberalis of the rat
Authors: Masson‐Pévet M. , Recio J. , Guerrero H. Y. , Mocaer E. , Delagrange Ph. , Guardiola‐Lemaitre B. , Pévet P.
Published: February 2007

Abstract: By using quantitative autoradiography, we studied the effects of two drugs related to melatonin on the 2‐ 125I‐melatonin binding in the pars tuberalis (PT) of rats. The drugs tested were two naphthalenic analogues of melatonin, S‐20098 (N‐[2‐(7‐methoxy‐l‐naphthyl) ethyl] acetamide), an agonist, and S‐20928 (N‐[2‐(l‐naphthyl) ethyl] cyclobutyl carboxamide), a putative antagonist. Melatonin (s.c. and i.p.), S‐20098 (s.c), and S‐20928 (i.p.) were injected 4 hr before sacrifice. Acute administration of both melatonin and S‐20098 decreased melatonin receptor density. In contrast, the putative antagonist S‐20928, at a low dose (1 mg/kg), was ineffective on melatonin receptors. It neither affected the 2‐ 125I‐melatonin specific binding observed in the control group nor did it prevent the decrease in binding induced by melatonin when injected 5 min before the hormone. At a high dose (10 mg/kg), S‐20928 totally blocked the effect of melatonin on melatonin receptor density and induced a decrease in binding capacity as melatonin did when injected alone. These results indicate that in the rat pars tuberalis, the melatonin agonist, S‐20098, is able to down‐regulate melatonin receptors, whereas S‐20928 seems to behave as a partial agonist.
Melatonin effects on sleep, mood, and cognition in elderly with mild cognitive impairment
Authors: Jean‐Louis Girardin , von Gizycki Hans , Zizi Ferdinand
Published: February 2007

Abstract: The effects of immediate‐release melatonin on circadian rest‐activity profiles, cognition, and mood were investigated in ten elderly individuals with self‐reported sleep‐wake disturbances. Melatonin (6 mg), administered 2 hr before habitual bedtime, enhanced the rest‐activity rhythm and improved sleep quality as observed in a reduction in sleep onset latency and in the number of transitions from sleep to wakefulness. However, total sleep time was not significantly increased nor was wake within sleep significantly reduced. The ability to remember previously learned items improved along with a significant reduction in depressed moods. No side effects or contraindications were reported by any of our participants during the 10 day trials. These data suggest that melatonin can safely improve some aspects of sleep, memory, and mood in the elderly in short‐term use.
The pineal and extra‐pineal origins of 5‐sulphatoxy N‐acetyl‐serotonin in humans
Authors: Di Wei‐Li , Djahanbakhch Ovrang , Kadva Aban , Street Cathy , Silman Robert
Published: February 2007

Abstract: In humans 6‐sulphatoxy melatonin (SaMT) is the principal metabolite of endogenous and exogenous melatonin. 5‐sulphatoxy N‐acetyl‐serotonin (SNAS) is a minor metabolite of exogenous melatonin, but it has not been established whether the levels of endogenous SNAS in plasma derives principally from endogenous melatonin. We have developed the first radioimmunoassay (RIA) for SNAS and used it (together with RIAs for melatonin and SaMT) to determine whether endogenous SNAS derives from endogenous melatonin or from platelet serotonin. Our results show a) the values of endogenous SNAS, unlike endogenous SaMT, increased with blood collection procedures that increased the values of serotonin, b) the values of endogenous SNAS in urine or in platelet‐poor plasma were approximately the same as those of endogenous SaMT, but, unlike SaMT, did not show a diurnal rhythm, and c) we confirmed that SNAS was a minor metabolite of orally ingested melatonin. Thus, our conclusion is that SNAS is a minor metabolite of exogenous melatonin, but is not a significant metabolite of endogenous melatonin. In all probability, endogenous SNAS is principally the metabolite of platelet serotonin.
Antioxidative effects of melatonin in Drosophila melanogaster: Antagonization of damage induced by the inhibition of catalase
Authors: Coto‐Montes Ana , Hardeland Rüdiger
Published: February 2007

Abstract: In Drosophila melanogaster strain Canton S, the catalase inhibitor 3‐amino‐1, 2, 4‐triazole was used to enhance oxidative stress from endogenous sources. This treatment was chosen as an alternative to direct administration of oxidants, which would cause damage and interact with melatonin already in the extracellular space before they reach the intracellular compartments. Male flies were kept in constant darkness and fed 1% sucrose as the only diet, with or without additions of melatonin (2 mM), inhibitor (100 mM), or combinations of both. After 20 or 24 hr, most of the animals exposed to 3‐amino‐1, 2, 4‐triazole only had died, whereas a large number of flies had survived the inhibitor treatment in the presence of melatonin. Protein carbonyl, an indicator of oxidative protein modification, and lipid peroxidation. as determined by the formation of malondialdehyde and 4‐hydroxyalkenal, were measured in flies treated for 20 hr. Melatonin alone did not substantially change these parameters, but prevented the increase in protein carbonyl caused by the catalase inhibitor. The effect of 3‐amino‐1, 2, 4‐triazole on lipid peroxidation was relatively minor, but a clear‐cut inhibition was found after simultaneous administration of melatonin. The preferential suppression of oxidative damage of proteins. as compared to lipids, indicates a particular protective role for melatonin in the aqueous phase of cellular compartments.
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

Heat 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

In 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

A 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

Heat 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

For 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.
MILK CONCENTRATION BY DIRECT CONTACT HEAT EXCHANGE
Authors: ZAIDA A. H. , SARMA S. C. , GROVER P. D. , HELDMAN D. R.
Published: February 2007

Milk was concentrated from 9% T.S. to 50% T.S. in batches by direct injection of hot air/nitrogen. the rates of evaporation were found satisfactory. Process was found energy efficient with thermal economy of 1.49 which approximates to that of a double effect evaporator. Inspite of high gas temperature (120 – 140°C) the bulk temperature of milk did not exceed 40°C which is advantageous from a nutritional view point. Lower processing temperature did not adversely affect the bacterial growth and it remained within permissible limit.
HYDRODYNAMICS and HEAT TRANSFER IN THIN FILM SCRAPED SURFACE HEAT EXCHANGERS — A REVIEW
Authors: ABICHANDANI H. , SARMA S. C. , HELDMAN D. R.
Published: February 2007

The available literature on hydrodynamics and heat transfer in thin film scraped surface heat exchangers was reviewed and arranged in concise form. the hydrodynamics covers fluid flow, residence time distribution, power consumption and film thickness. In heat transfer, sensible heating and evaporation aspects are explored. the constraints of various mathematical models are explained. the problems needing further investigation are also delineated.
A REVIEW of PARTICLE BEHAVIOR IN TUBE FLOW: APPLICATIONS to ASEPTIC PROCESSING1
Authors: SASTRY SUDHIR K. , ZURITZ CARLOS A.
Published: February 2007

The design of holding tubes for continuous sterilization of foods containing large particulates depends heavily on knowledge of pipe flow behavior of food suspensions. Although directly related literature is limited, a considerable body of potentially useful literature is available on solid‐liquid flows. This critical review discusses literature on solid‐liquid flow in tubes, including capsule flow, effects on bends, radial migration phenomena, particle‐particle interactions, modeling studies and other topics which may have a bearing on particle velocities in holding tubes.
HEAT TRANSFER IN THIN‐FILM WIPED‐SURFACE EVAPORATION of MODEL LIQUID FOODS
Authors: STANKIEWICZ KRZYSZTOF , RAO M. A.
Published: February 2007

Experimental product‐side heat transfer coefficients were studied in a laboratory scale thin‐film wiped‐surface (TFWS) evaporator under different rotational speeds, liquid flow rates and temperatures of the heating medium. Experiments were conducted with water, and 10, 30, and 45% sugar solutions in order to simulate the conditions during evaporation of fruit juices. Dimensionless correlations for heat transfer coefficient were established. It was shown that the “equivalent diameter” of the liquid bow wave formed in the front of wiper blade could be used as a characteristic dimension. Magnitudes of unstable and stable modes of evaporator performance were determined and different regimes related to the liquid flow were revealed.
COMPUTER SIMULATION of MICROBIAL GROWTH DURING FREEZING and FROZEN FOOD STORAGE
Authors: CASTELL‐PEREZ M. E. , HELDMAN D. R. , STEFFE J. F.
Published: February 2007

A computer simulation model was developed to predict the time for temperature equilibration as well as microbial growth within a food product during freezing and the equilibration to frozen storage conditions. Theoretical results indicate that freezing medium temperature, surface heat transfer coefficient and product size influence the equilibration time significantly. Storage conditions influenced the equilibration time during storage and significantly influenced the growth of microorganisms. Microbial growth is a function of the freezing time. Slow freezing of a food product from a high initial temperature and stored at a relatively high temperature can provide conditions for microbial growth as compared to very rapid freezing processes. the model is a useful tool for approximate indications of effects of freezing conditions on microbial growth within a food product.
PERFORMANCE of HEAT RECOVERY SYSTEM FOR A SPRAY DRYER
Authors: DONHOWE D.P. , AMUNDSON C.H. , HILL C.G.
Published: February 2007

A factorial experimental design was used to study the effect of exhaust heat recovery, air flow rate and outlet temperature on the energy consumption of a spray dryer. A commercial‐scale cocurrent flow dryer with pressure atomization was used to dry 15 wt% sodium sulfate solutions. the inlet air to the dryer was preheated by using a shell‐and‐tube heat exchanger to recover energy from the exhaust air. Heat recovery reduced the energy consumption of the dryer by 12–28%, with the largest reduction occurring at the high levels of air flow rate (13,000 kg/h) and outlet temperature (104°C). the energy consumption of the dryer was lowest when heat was recovered at the low air flow rate (6500 kg/h) and low outlet temperature (82°C).

No problems were encountered with fouling or cleaning of the heat exchanger. the total pressure drop across the heat exchanger varied from 0.05–0.2 kPa depending on the air flow rate. This additional flow restriction resulted in an estimated 8% decrease in air flow rate but had negligible effect on energy consumption. the warm‐up time and the space required by the heat recovery unit were insignificant factors for this dryer. the payback period of the heat recovery system was estimated as 4.1–5.4 years with a rate of return of 21–28%.
ON the DESIGN of TRIPLE CONCENTRIC‐TUBE HEAT EXCHANGERS1
Authors: ZURITZ CARLOS A.
Published: February 2007

A set of analytical equations for a triple‐tube heat exchanger was developed. They allow for independent computations of bulk (cross‐sectional area averaged) fluid temperatures at any axial location along the heat exchanger and are valid for parallel and counter flow configurations. the equations account for heat losses to the surroundings and are useful for design purposes. Mass flow rates, inlet fluid temperatures and heat transfer coefficients are input parameters required for temperature calculations. A simplified approximate equation for total rate of heat transfer, in terms of logarithmic mean temperature differences, was derived for well‐insulated heat exchangers and tested with the analytical equations. A case study is presented and the computational procedure is discussed. Results obtained with the simplified total rate of heat transfer equation were in excellent agreement with those obtained with the analytical equations. Simulations show that the creation of an annular region within the inner pipe increases the overall heat transfer efficiency and reduces the heat exchanger length requirement by almost 25%.
MICROFILTRATION of CHICKEN PROCESS WATERS FOR REUSE: PLANT STUDIES and PROJECTED OPERATING COSTS1
Authors: HART M. R. , HUXSOLL C. C. , TSAI L. S. , NG K. C. , KING A. D. , JONES C. C. , HALBROOK W. U.
Published: February 2007

Commercial scale ceramic microfilters were used in plant tests to determine flux rate and operating parameters for waters from a poultry scalder, a poultry chiller, and brine from a delicatessen products chiller, under commercial conditions. Filtration produced clear permeate from all waters. Microorganism counts were essentially reduced to zero in scalder and chiller water permeates, with BOD reduced by about 70% in scalder water permeate and about 60% in chiller water permeate. Flux rates were in the range of 224‐204 L/m2h for scalder water at 54°C and 114‐81 L/m2h for chiller water at ambient temperature. Test results were used to project nonlabor operating savings and/or costs resulting from the use of microfiltration to recondition and reuse bath overflow. For a processing rate of 140 birds/min and bath size of 37,850 L (10,000 gal), an annual savings of $21,000‐$26,000 were estimated for scalder water filtration, while annual costs of $65,000‐$84,000 were estimated for chiller water filtration. For a deli brine bath size of 1,170 L (300 gal), annual costs of about $700 were estimated. Retentate heating and electrical usage associated with centrifugal filter pumps were projected as predominant cost factors. Besides costs, other factors such as nonchemical control of microbial growth, water savings, and reduced discharge levels may also be important reasons for considering microfiltration.
QUALITY of ARTIFICIALLY DRIED LENTIL
Authors: TANG JUMING , SOKHANSANJ SHAHAB , SLINKARD A. E. , SOSULSKI FRANK
Published: February 2007

The effects of artificial drying on Laird lentil qualities such as breakage susceptibility, cooking quality, and seed germination were determined at three initial moisture levels, 16%, 18%, 20% wet basis and seven levels of drying temperature varying from 40°C to 80°C. Cooking quality was not affected by drying in the range of treatments used in this study. High initial Omoisture content and lengthy drying periods at temperatures above 40°C were associated with increased seed breakage. Seed germination was particularly sensitive to heat treatment at 80°C and extended drying time for high moisture samples.
LIQUID‐TO‐PARTICLE HEAT TRANSFER DURING CONTINUOUS TUBE FLOW: INFLUENCE of FLOW RATE and PARTICLE to TUBE DIAMETER RATIO1
Authors: SASTRY S. K. , LIMA M. , BRIM J. , BRUNN T. , HESKITT B. F.
Published: February 2007

Liquid‐to‐particle convective heat transfer coefficients were measured during continuous flow through tubes, using an experimental technique in which a thermocouple was moved at the same speed as the particle. Water was used as the carrier fluid and transducer particles were made hollow to approximate densities of real food particles. Results from over 250 experimental runs over a fluid Reynolds number range from 7300 to 43600, showed that the convective coefficient was increased significantly with increasing fluid flow rate and particle to tube diameter ratio. Convective coefficient values ranged from 688 to 3005 w/m20C depending on the experimental conditions. Dimensionless correlations obtained between the Nusselt number, particle Reynolds number, particle to tube diameter ratio, and the particle Froude number yielded R2 values ranging from 0.82 to 0.92 depending on the complexity of the relation.
POPULATION MODEL of BACTERIAL SPORES FOR VALIDATION of DYNAMIC THERMAL PROCESSES1
Authors: RODRIGUEZ A.C. , SMERAGE G.H. , TEIXEIRA A.A. , LINDSAY J.A. , BUSTA F.F.
Published: February 2007

Data are presented supporting a new model of spore populations during isothermal and dynamic lethal heat treatments. the model incorporates activation, injury, and preliminary inactivation of less‐resistant fractions as well as the usual predominant inactivation. Rate constants of those transformations were determined experimentally for Bacillus subtilis strain A and were found to vary with temperature according to Arrhenius equations. Model generated and experimental isothermal survivor curves compared well. Comparison of model and experimental survivor curves for this species in a time‐varying temperature regime showed the model to be a potentially good predictor of survivors during dynamic lethanl heat treatment. the new model could be particularly important in simulating sterilization and pasteurization processes, especially short duration UHT treatments, and microbiological validation of arbitrary, dynamic thermal processes.
EFFECT of STEAM/AIR MIXTURES ON THERMAL PROCESSING of an INDUCED CONVECTION‐HEATING PRODUCT (TOMATO CONCENTRATE) IN A STERITORT
Authors: DENISTON MARK F. , KIMBALL RICHARD N. , STOFOROS NIKOLAOS G. , PARKINSON KIM S.
Published: February 2007

The effect of reel speed, can size, and percent air during steam and steam/air processing in a Steritort on the heating rate of tomato concentrate (an induced convection‐heating product) was investigated. A Taylor expansion equation, relating Ball process times with the above three variables, considering first order, second order, and interaction effects, was presented. A correlation equation for the Nusselt number as a function of the Reynolds and Prandtl numbers, the can length over the diameter ratio, and the steam content was also presented. Percent reduction in process lethality increased with increasing can size and air content, and decreasing reel speed and target lethality. Increase in percent air in the steam/air mixture could be compensated by an increase of the rotational speed.
OPTIMUM STERILIZATION: A COMPARATIVE STUDY BETWEEN AVERAGE and SURFACE QUALITY
Authors: SILVA C.L.M. , OLIVEIRA F.A.R. , PEREIRA P.A.M. , HENDRICKX M.
Published: February 2007

Sterilization temperatures to maximize volume average or surface quality retention were calculated for one‐dimensional conduction heating foods as a function of (1) Food Properties, (2) Processing Conditions and (3) Processing Criteria. A target lethality at the least‐lethality point was used as a constraint, and optimal temperatures were qualitatively and quantitatively compared for equal design variables.

Average quality optimum conditions depend linearly on the inverse square of the Drefq‐value for the quality factor. These conditions do not vary linearly with all the other influential variables, opposite to what had been observed for surface quality. Optimum temperature for maximum average quality is always higher than the corresponding one for surface quality, but the difference is not constant. A systematic approach to the dependence of average quality optimal conditions on all the relevant parameters was carried out and quantitative relations were obtained. Optimum average quality retention is independent of surface heat transfer resistance.
ENZYMES IMMOBILIZED ON FORMED‐IN‐PLACE MEMBRANES FOR FOOD PROCESSING: PROCEDURES and PROPERTIES
Authors: WANG H. JEAN , THOMAS RONALD L. , SZANIAWSKI ANDRZEJ R. , SPENCER H. GARTH
Published: February 2007

The formation and properties of Formed‐In‐Place (FIP) membranes upon which enzymes had been immobilized were investigated to examine the potential of these reactive membranes in food processing applications. Enzymes were immobilized on two types of FIP membranes and their activities in appropriate fluids investigated. Flux was increased in the microfiltration of pectin solutions by immobilizing pectinase on titanium dioxide microfiltration membranes. A flux increase of 15% was obtained without permeate recycle and 112% with permeate recycle using a 0.1% solution of citrus pectin. Glucose production from dextrin was performed using glucoamylase (GA) immobilized on a zirconium hydrous oxide‐polyacrylate nanofiltration membrane. Optimum activity occurred at pH 4.0 and 50C for the immobilized GA. the dextrose equivalent (DE) value of the membrane permeate was approximately ten times higher than the product obtained with free GA during the same time interval.
PREDICTING the COOLING TIME FOR IRREGULAR SHAPED FOOD PRODUCTS
Authors: CARROLL NATALIE , MOHTAR RABI , SEGERLIND LARRY J.
Published: February 2007

A new method for calculating the cooling time for fresh fruits and vegetables and processed foods is presented. the method uses the truncated analytical solution of the governing partial differential equation to define a cooling curve with two parameters. One parameter is the lowest eigenvalue for the product. the second parameter is a constant multiplier similar to the one that occurs in the analytical solution. the lowest eigenvalue is evaluated using a finite element analysis. the multiplying constant is evaluated using a finite element solution in time. Cooling curves for a Rome apple and a Bartlett pear are presented and discussed.