bluuebunny/crossref_metadata_2025 huggingface dataset:
Disturbances in Hormonal Profiles of Night Workers during Their Usual Sleep and Work Times
Authors: Weibel L. , Brandenberger G.
Published: May 2004

In a previous study, the authors reported that the 24-h rhythms of pituitary and adrenal hormones—that is, thyrotropin (TSH), prolactin (PRL), growth hormone, and cortisol—adapted only partially in a group of permanent night workers. However, the real impact of circadian rhythm alterations on the health and well-being of subjects is still unclear. In this study, the authors focus on an ergonomic field and address questions of adaptation of these hormones during the usual day sleep time (0700-1500 h) and during the usual night work time (2200-0600 h) in permanent night workers. Eleven night workers, working a night schedule for at least 2 years, submitted to a high-frequency blood sampling procedure (10 min) and to electroencephalographic recordings during sleep. The endocrine profiles of night workers were compared to those of day-active subjects studied during their usual sleep-wake schedule. During usual day sleep, despite an adapted sleep structure, cortisol levels among night workers were abnormally enhanced, whereas the TSH decreased in comparison to the plateau observed among day-active subjects. During usual work time, some hormonal disturbances persisted, in particular concerning cortisol and PRL (two hormones known to reflect the level of activation). Among night workers, the work time was associated with the quiescent period of cortisol secretion normally occurring during the first hours of sleep, and with a transient PRL increase. These results revealed altered hormonal profiles during the sleep time of night workers that do not result in an altered sleep pattern. The nocturnal work time, which requires a high level physical and mental performance, is associated with some endocrine alterations reflecting an eventual phase of hypovigilance.
Local Administration of Serotonin Agonists Blocks Light-Induced Phase Advances of the Circadian Activity Rhythm in the Hamster
Authors: Weber E. T. , Gannon R. L. , Rea M. A.
Published: May 2004

Circadian rhythms in mammals are synchronized to environmental light-dark cycles through a direct retinal projection to the suprachiasmatic nucleus (SCN), a circadian clock. This process is thought to be modulated by other afferents to the SCN, including a dense serotonergic projection from the midbrain raphe. Previous work from this laboratory demonstrated that a systemically administered 5-hydroxytry ptamine1A/7 (5-HT1A/7) agonist 8-hydroxy-2-(di- n-propylamino)tetralin (8-OH-DPAT) dose dependently attenuates light-induced phase shifts of the circadian activity rhythm of the Syrian hamster. In this study, we demonstrate that local injections (1-100 μM) of the 5-HT1A/7 agonists 8-OH-DPAT or 5-carboxamidotryptamine into the region of the SCN inhibit light-induced phase advances of the circadian wheel-running rhythm. In addition, the inhibitory effects of systemically administered 8-OH-DPAT were unaffected by either radiofrequency-induced lesions of the intergeniculate leaflet or 5,7-dihydroxytryptamine-induced lesions of serotonergic projections to the SCN. These findings support a modulatory role of serotonin in photic regulation of circadian phase through an action at the level of the SCN.
Choline Depletion, frq Mutations, and Temperature Compensation of the Circadian Rhythm in Neurospora crassa
Authors: Lakin-Thomas Patricia L.
Published: May 2004

In the fungus Neurospora crassa, the chol-1 mutation blocks the synthesis of the lipid phosphatidylcholine and also lengthens the period of the circadian rhythm of conidiation under conditions of choline depletion. The frq mutations, which have no known metabolic defect, affect both the period of the rhythm and temperature compensation. In this article, the chol-1 mutant strain has been further characterized with respect to its temperature compensation and its interactions with frq. Choline depletion of chol-1 abolishes good temperature compensation: Low temperatures lengthen the period under choline-depleted conditions, and low choline lengthens the period at any one temperature. Double-mutant strains carrying both chol-1 and one of a series of frq alleles demonstrate interactions between chol-1 and frq: On high choline, the periods of the double mutants are identical to the corresponding chol + strains, whereas on low choline all double mutants display very long periods (greater than 50 h). Short-period frq mutations shorten the long period on low choline, whereas long-period frq mutations have no effect. A null frq mutation in the chol-1 background is arrhythmic on high choline but is robustly rhythmic on low choline and has no effect on the long period. The interactions between frq and chol-1 are similar to the interactions between frq and cel, another lipid-deficient mutant. These results provide support for the hypothesis that membrane lipids may be involved in temperature compensation of the circadian rhythm. The possibility is discussed that the frq gene may not be required for circadian rhythmicity under some conditions and therefore may not be a central component of the circadian oscillator but rather a component of an input pathway.
Locking and Unlocking of Running Wheel Affects Circadian Period Stability Differently in Three Inbred Strains of Rats
Authors: Kohler Markus , Wollnik Franziska
Published: May 2004

Running-wheel access has been shown to shorten the circadian period length ([.tau]) of various mammalian species. Due to the close correlation between [.tau] and the level of activity, running wheel–induced changes of the activity level are thought to be responsible for the observed changes in [.tau]. In the present study, the influence of the running wheel on [.tau] and the activity level was examined in three inbred strains of rats (ACI, BH, LEW). Four animals of each strain had free access to their running wheels, while the wheels of the other 4 animals of each strain were mechanically locked. These conditions were changed twice, so that each animal encountered both kinds of changes, that is, from a locked to an unlocked running wheel and vice versa. During the whole study, overall activity was measured by infrared detectors. Running-wheel access resulted in a significant increase of overall activity in strains LEW and ACI. However, significant changes of [.tau] were observed only in LEW rats. These rats showed a significant shortening of [.tau] after the second change of the housing conditions regardless of whether the wheel was locked or unlocked. Consequently, no causal relationship was found between changes of [.tau] and running wheel–induced changes of overall activity. Instead, the results suggest that subtle environmental influences like locking or unlocking the running wheel affect [.tau] in a strain-dependent manner, whereas changes in the activity level are neither necessary nor sufficient to induce changes of [.tau].
Circadian Behavior and Plasticity of Light-Induced c-fos Expression in SCN of tau Mutant Hamsters
Authors: Shimomura Kazuhiro , Kornhauser Jon M. , Wisor Jonathan P. , Umezu Toyoshi , Yamazaki Shin , Ihara Naomi L. , Takahashi Joseph S. , Menaker Michael
Published: May 2004

In hamsters homozygous for the circadian clock mutation tau, the photic history dramatically affects the magnitude of light-induced circadian phase shifts. The maximum amplitude of phase shifts produced by 1-h light pulses presented at CT 14 was less than 2 h in animals that had been in DD for 2 days, whereas animals that had been kept in DD for 49 days could be shifted by more than 8 h. In this study, the authors compared the effect of previous light history on the amplitude of circadian phase shifts and on c- fos expression in the SCN of tau mutant hamsters. Although the maximum amplitude of behavioral phase shifts was drastically different between animals that had been held for either 2 or 49 days in DD, maximal fos induction was not significantly different in these two groups. However, photic thresholds for light-induced behavioral phase shifts, c- fos mRNA, and Fos immunoreactivity were closely correlated within both groups, and these thresholds were lower (more sensitive to light) after 49 than after 2 days in DD. The correlation between phase shifting and Fos induction thresholds, under conditions where both responses are dramatically altered by the previous light history, demonstrates an association between changes in circadian behavioral phase-shifting responses of tau mutant hamsters and plasticity of light-induced c- fos expression in SCN. However, because the maximum amplitudes of Fos induction and phase shifting were not correlated in animals that had been in DD for 2 days, we speculate that the level of c- fosexpression does not directly determine phase shift amplitude.
Characterization of the Circadian System of NGFI-A and NGFI-A/NGFI-B Deficient Mice
Authors: Kilduff T. S. , Vugrinic C. , Lee S. L. , Milbrandt J. D. , Mikkelsen J. D. , O'Hara B. F. , Heller H. C.
Published: May 2004

The genes NGFI-A (also known as EGR-1, zif/268, and Krox-24) and NGFI-B ( nur/77) have previously been shown to be induced in the SCN of rats and hamsters by photic stimulation during the subjective night. The purpose of this study is to determine whether these genes are also induced in the SCN of mice and, if so, to characterize the circadian system of animals in which either NGFI-A or both NGFI-A and NGFI-B were eliminated by homologous recombination. In wildtype mice, NGFI-A mRNA was found to be induced in the SCN as in other rodent species. Therefore, wheel-running activity was recorded from null mutants and wildtype controls under LD 12:12 and DD conditions. Mice of all three strains appeared to entrain normally to LD 12:12 and could re-entrain to both phase advances and phase delays of the light cycle. The response of the circadian pacemaker of all three genotypes to acute light pulses appeared to be normal. The retinal innervation of the SCN in NGFI-A-/- mice and the photic induction of Fos in the SCN of both NGFI-A-/- and NGFI-A-/-B-/- mice were indistinguishable from wildtype mice. These results indicate that induction of NGFI-A and NGFI-B is not required for photic entrainment or phase shifting of the mouse circadian system.
Alterations of per RNA in Noncoding Regions Affect Periodicity of Circadian Behavioral Rhythms
Authors: Chen Yifeng , Hunter-Ensor Melissa , Schotland Peter , Sehgal Amita
Published: May 2004

Circadian rhythms in Drosophila depend on a molecular feedback loop that includes products of the period ( per) and timeless ( tim) genes. RNA and protein products of both genes cycle with a circadian period and the proteins feedback to inhibit expression of their own mRNAs. While cyclic expression of PER protein appears to be necessary for rhythmic behavior, the function of per RNA cycling is somewhat controversial. Rhythmic transcription accounts, in part, for cycling of per RNA, but it is clear now that posttranscriptional mechanisms also contribute to the cyclic expression of both per RNA and protein. As posttranscriptional mechanisms, such as mRNA stability and translation, are frequently mediated by 3’ untranslated regions (UTR) of genes, the authors examined the role of this region of per in the regulation of circadian rhythms. Removal of most of per's 3’ UTR had a small effect on the function of a per transgene. However, replacement of per's 3’ UTR with corresponding sequences of the tubulin gene led to the rescue of behavioral rhythms in per01 flies with periods that were 3 h shorter than those generated by a wild-type per transgene. The hybrid RNA cycles, but the protein produced by it accumulates earlier in a day-night cycle than the PER protein produced by a control per transgene carrying its own 3’ UTR, perhaps because the tubulin sequences counteract the effect of destabilizing elements in the per RNA at earlier points in the circadian cycle. These data indicate that the appropriate regulation of per RNA expression, effected by transcriptional as well as posttranscriptional mechanisms, is critical for the determination of circadian period.
Day/Night Differences in the Stimulation of Adenylate Cyclase Activity by Calcium/Calmodulin in Chick Pineal Cell Cultures: Evidence for Circadian Regulation of Cyclic AMP
Authors: Nikaido Selene S. , Takahashi Joseph S.
Published: May 2004

In chick pineal cell culture, stimulation of adenylate cyclase with the diterpene forskolin was greater during the subjective night than during the subjective day. This rhythm of cyclic AMP (cAMP) stimulation mimicked the rhythm of unstimulated cAMP measured previously during LD cycles from flow-through culture. Direct measurement of adenylate cyclase activity in permeabilized cells revealed an adenylate cyclase activity activated by Ca2+/calmodulin during the night but not during the day. However, this difference in adenylate cyclase activity at twotimes of the circadian cycle is apparent only when permeabilized cells were prewashed with buffer containing GTP. When cAMP was measured from flow-through cultures maintained in continuous darkness to determine whether a circadian clock may regulate cAMP, a low-amplitude rhythm was measured. The circadian rhythm of cAMP was similar to the cAMP rhythm previously measured on LD cycles except that the rhythm in darkness had a lower amplitude. Similar to the suppression of melatonin, cAMP was suppressed by light presented during the middle of the night. LD differencesin nocturnal cAMP levels were abolished with dipyridamole, an inhibitor of cyclic GMP (cGMP) phosphodiesterase. These results suggest that the rhythm of cAMP in chick pineal cells involves the stimulation of adenylate cyclase by Ca2+/calmodulin during the night and a GTP-dependent suppression of adenylate cyclase activity during the day. The photic suppression of cAMP at night involves the activation of a dipyridamole-sensitive, cGMP phosphodiesterase.
Destruction of Serotonergic Neurons in the Median Raphe Nucleus Blocks Circadian Rhythm Phase Shifts to Triazolam but Not to Novel Wheel Access
Authors: Meyer-Bernstein Elizabeth L. , Morin Lawrence P.
Published: May 2004

Systematic treatment of hamsters with triazolam (TRZ) or novel wheel (NW) access will yield PRCs similar to those for neuropeptide Y. Both TRZ and NW access require an intact intergeniculate leaflet (IGL) to modulate circadian rhythm phase. It is commonly suggested that both stimulus types influence rhythm phase response via a mechanism associated with drug-induced or wheel access-associated locomotion. Furthermore, there have been suggestions that one or both of these stimulus conditions require an intact serotonergic system for modulation of rhythm phase. Thepresent study investigated these issues by making serotonin neuron-specific neurotoxic lesions of the median or dorsal raphe nuclei and evaluating phase response of the hamster circadian locomotor rhythm to TRZ treatment or NW access. The expected effect of TRZ injected at CT 6 h on the average phase advance was virtually eliminated by destruction of serotonin neurons in the median, but not the dorsal, raphe nucleus. No control or lesioned animal engaged in substantial wheel running in response to TRZ. By contrast, all median raphe-lesioned hamsters that engaged in substantial amounts of running when given access to a NW had phase shifts comparable to control or dorsal raphe-lesioned animals. The results demonstrate that serotonergic neurons in the median raphe nucleus contribute to the regulation of rhythm phase response to TRZ and that it is unlikely that these neurons are necessary for phase response to NW access. The data further suggest the presence of separate pathways mediating phase response to the two stimulus conditions. These pathways converge on the IGL, a nucleus afferent to the circadian clock, that is necessary for the expression of phase response to each stimulus type.
Melatonin Chimeras Alter Reproductive Development and Photorefractoriness in Siberian Hamsters
Authors: Prendergast Brian J. , Zucker Irving , Yellon Steven M. , Ringold Daniel A. , Gorman Michael R.
Published: May 2004

Nightly melatonin (MEL) durations > 8 h provoke gonadal regression and decreases in body mass, whereas signals < 7 h stimulate gonadal and somatic growth in male Siberian hamsters. The authors sought to determine the minimum frequency of short MEL signals sufficient to induce the long-day phenotype in several photoperiodic traits. D, L-propranolol (hereafter propranolol) injections shortened MEL signals on the night of treatment without altering MEL on the subsequent night; this permitted interpolation of short MEL signals at variable frequencies against a background of long MEL signals (chimeras). Hamsters kept in short days (10 h light/day, 10L) were injected with propranolol 6 h after dark onset for 28 consecutive weeks beginning at 30 days of age (Week 0) either every other day or once every 3, 6, or 9 days. Control animals were injected with saline or with propranolol during the light phase or were transferred to long days (16L) at Week 0. Hamsters in 16L underwent rapid gonadal development and increases in body mass and displayed summer pelage color, as did hamsters treated with propranolol every other day. Animals treated with propranolol less frequently than every other day uniformly maintained undeveloped gonads and winter-like body weights, but pelage color becameproportionately darker with increased frequency of propranolol treatments. The onset of spontaneous testicular development in 10L was unaffected by propranolol injections. After termination of injections at Week 28, testicular regression was not observed in most 10L animals that previously had undergone spontaneous testicular development; however, 40% of hamsters that had been injected with propranolol every 3rd night did manifest the winter phenotype after Week 28. In an alternating sequence, short MEL signals completely override long signals and induce the summer phenotype. Threshold frequencies differ for MEL stimulation of long-day pelage and gonadal phenotypes. The timing and development of refractoriness to MEL does not depend in any simple manner on the number of long MEL signals or on the accumulation of a reaction product produced by long, and depleted by short, MEL signals.
Photoentrainment in Mammals: A Role for Cryptochrome?
Authors: Lucas Robert J. , Foster Russell G.
Published: May 2004

There is growing evidence in support of the hypothesis that, in mammals, photoreceptive tasks are segregated into those associated with creating a detailed visual image of the environment and those involved in the photic regulation of temporal biology. The hypothesis that this segregation extends to the use of different photoreceptors remains unproven, but published reports from several mammalian species that circadian photoentrainment survives a degree of retinal degeneration sufficient to induce visual blindness suggest that this may be so. This has lead to speculation that mammals might employ a dedicated ‘circadian photoreceptor’ distinct from the rod and cone cells of the visual system. The location and nature of this putative circadian photoreceptor has become a matter of conjecture. The latest candidates to be put forward as potential circadian photopigments are the mammalian cryptochrome proteins (CRY1 and 2), putative vitamin-B2 based photopigments. To date, published experimental evidence falls short of a definitive demonstration that these proteins form the basis of circadian photoreception in mammals. Consequently, this review aims to assess their suitability for this task in light of what we know regarding the biology of the cyrptochromes and the nature of mammalian photoentrainment.
Circadian Rhythmicity of Vasopressin Levels in the Cerebrospinal Fluid of Suprachiasmatic Nucleus-Lesioned and Grafted Rats
Authors: van Esseveldt K. E. Lisette , van der Geest Ben A. M. , Duindam Hans , Rietveld Wop J. , Boer Gerard J.
Published: May 2004

Transplantation of the fetal suprachiasmatic nucleus (SCN) in arrhythmic SCN-lesioned rats can reinstate circadian drinking rhythms in 40% to 50% of the cases. In the current article, it was investigated whether the failure in the other rats could be due to the absence of a circadian rhythm in the grafted SCN, using a circadian vasopressin (VP) rhythm in the cerebrospinal fluid (CSF) as the indicator for a rhythmic SCN. CSF was sampled in continuous darkness from intact control rats and SCN-lesioned and grafted rats. VP could be detected in all samples, with concentrations of 15 to 30 pg/ml in the control rats and 5 to 15 pg/ml in the grafted rats. A circadian VP rhythm with a two-to threefold difference between peak and nadir values was found in all 7 control rats but in only 4 of 13 experimental rats, despite the presence of a VP-positive SCN in all grafts. A circadian VP rhythm was present in 2 drinking rhythm-recovered rats (6 of 13) and in 2 nonrecovery rats. Apparently, in these latter rats, the failure of the grafted SCN to restore a circadian drinking rhythm cannot be attributed to a lack of rhythmicity in the SCN itself. Thus, the presence of a rhythmic grafted SCN, as is deduced from a circadian CSF VP rhythm, appears not to be sufficient for restoration of a circadian drinking rhythm in SCN-lesioned arrhythmic rats.
Fos Expression within Vasopressin-Containing Neurons in the Suprachiasmatic Nucleus of Diurnal Rodents Compared to Nocturnal Rodents
Authors: Rose Sandra , Novak Colleen M. , Mahoney Megan M. , Nunez Antonio A. , Smale Laura
Published: May 2004

The underlying neural causes of the differences between nocturnal and diurnal animals with respect to their patterns of rhythmicity have not yet been identified. These differences could be due to differences in some subpopulation of neurons within the suprachiasmatic nucleus (SCN) or to differences in responsiveness to signals emanating from the SCN. The experiments described in this article were designed to address the former hypothesis by examining Fos expression within vasopressin (VP) neurons in the SCN of nocturnal and diurnal rodents. Earlier work has shown that within the SCN of the diurnal rodent Arvicanthis niloticus, approximately 30% of VP-immunoreactive (IR) neurons express Fos during the day, whereas Fos rarely is expressed in VP-IR neurons in the SCN of nocturnal rats. However, in earlier studies, rats were housed in constant darkness and pulsed with light, whereas Arvicanthis were housed in a light:dark (LD) cycle. To provide data from rats that would permit comparisons with A. niloticus, the first experiment examined VP/Fos double labeling in the SCN of rats housed in a 12:12 LD cycle and perfused 4 h into the light phase or 4 h into the dark phase. Fos was significantly elevated in the SCN of animals sacrificed during the light compared to the dark phase, but virtually no Fos at either time was found in VP-IR neurons, confirming that the SCN of rats and diurnal Arvicanthis are significantly different in this regard. The authors also evaluated the relationship between this aspect of SCN function and diurnality by examining Fos-IR and VP-IR in diurnal and nocturnal forms of Arvicanthis. In this species, most individuals exhibit diurnal wheel-running rhythms, but some exhibit a distinctly different and relatively nocturnal pattern. The authors have bred their laboratory colony for this trait and used animals with both patterns in this experiment. They examined Fos expression within VP-IR neurons in the SCN of both nocturnal and diurnal A. niloticus kept on a 12:12 LD cycle and perfused 4 h into the light phase or 4 h into the dark phase, and brains were processed for immunohistochemical identification of Fos and VP. Both the total number of Fos-IR cells and the proportion of VP-IR neurons containing Fos (20%) were higher during the day than during the night. Neither of these parameters differed between nocturnal and diurnal animals. The implications of these findings are discussed.
Pineal-Independent Regulation of Photo-Nonresponsiveness in the Siberian Hamster (Phodopus sungorus)
Authors: Prendergast Brian J. , Freeman David A.
Published: May 2004

The pineal hormone melatonin influences circadian rhythms and also mediates reproductive responses to photoperiod. The authors tested whether pinealectomy influences circadian oscillators responsible for induction of nonresponsiveness to short day lengths by preventing normal short-day patterns of circadian entrainment. Adult male Siberian hamsters were pinealectomized or sham operated, maintained in either 18 h light per day (18L) or 15L for 10 weeks, and then tested for responsiveness to 10L. Because pinealectomized hamsters do not show gonadal regression in short day lengths, responsiveness was assessed by measuring phase angle of entrainment and the length of the nightly activity period following transfer to 10L. The incidence of nonresponsiveness was significantly higher in 18L hamsters than in 15L hamsters but was unaffected by pineal status. Fully 88% of 18L hamsters failed to entrain to 10L in the normal short-day manner; the duration of nightly activity remained compressed, and the phase angle of entrainment was large and negative relative to lights off. The 15L hamsters entrained normally to 10L. Exposure to constant light after 10L treatment was equally effective in inducing arrhythmicity in pinealectomized and intact hamsters. Changes in the period of morning and evening circadian oscillators subsequent to 18L treatment did not predict circadian responsiveness to short photoperiod. Long-day induction of photo-nonresponsiveness, which prevents winter responses to short day lengths, occurs independently of pineal melatonin feedback on the circadian system.
Melatonin Suppression by Light in Humans Is Maximal When the Nasal Part of the Retina Is Illuminated
Authors: Visser E. Kathalijne , Beersma Domien G. M. , Daan Serge
Published: May 2004

This study investigated whether sensitivity of the nocturnal melatonin suppression response to light depends on the area of the retina exposed. The reason to suspect uneven spatial sensitivity distribution stems from animal work that revealed that retinal ganglion cells projecting to the suprachiasmatic nuclei (SCN) are unequally distributed in several species of mammals. Four distinct areas of the retinas of 8 volunteers were selectively exposed to 500 lux between 1:30 a.m. and 3:30 a.m. Saliva samples were taken before, during, and after light exposure in 1-h intervals. A significant difference in sensitivity was found between exposure of the lateral and nasal parts of the retinas, showing that melatonin suppression is maximal on exposure of the nasal part of the retina. The results imply that artificial manipulation of the circadian pacemaker to alleviate jet lag, to improve alertness in shift workers, and possibly to treat patients suffering from seasonal affective disorder should encompass light exposure of the nasal retina.
A Delayed Rectifier Current Is Modulated by the Circadian Pacemaker in Bulla
Authors: Michel Stephan , Manivannan Kandiah , Zaritsky Joshua J. , Block Gene D.
Published: May 2004

Basal retinal neurons of the marine mollusc Bulla gouldiana continue to express a circadian modulation of their membrane conductance for at least two cycles in cell culture. Voltage-dependent currents of these pacemaker cells were recorded using the whole-cell perforated patch-clamp technique to characterize outward currents and investigate their putative circadian modulation. Three components of the outward potassium current were identified. A transient outward current (IA) was activated after depolarization from holding potentials greater than –30 mV, inactivated with a time constant of 50 ms, and partially blocked by 4-aminopyridine (1-5 mM). A Ca2+-dependent potassium current (IK(Ca)) was activated by depolarization to potentials more positive than –10 mV and was blocked by removing Ca2+ from the bath or by applying the Ca2+ channel blockers Cd2+ (0.1-0.2 mM) and Ni2+ (1-5 mM). A sustained Ca2+-independent current component including the delayed rectifier current (IK) was recorded at potentials positive to –20 mV in the absence of extracellular Na+ and Ca2+ and was partially blocked by tetraethylammonium chloride (TEA, 30mM). Whole-cell currents recorded before and after the projected dawn and normalized to the cell capacitance revealed a circadian modulation of the delayed rectifier current (IK). However, the IA and IK(Ca) currents were not affected by the circadian pacemaker.
Aging Affects the Ocular Circadian Pacemaker of Aplysia californica
Authors: Sloan Mark A. , Levenson Jonathan , Tran Quang , Kerbeshian Marie , Block Gene D. , Eskin Arnold
Published: May 2004

The eye of Aplysia has been used to explore various aspects of circadian rhythms. The authors discovered that age has profound effects on the circadian rhythm of nerve impulses from the eye. With age, there was a significant decrease in the amplitude of the rhythm. The decrease appeared to be continuous over the life span of the animal and was observed both in vitro and in vivo. The free-running period and phase angle of the rhythm steadily increased with age, indicating that the pacemaker itself was affected by age. Rates of transcription and translation were significantly increased with age, suggesting that age-associated alterations of the pacemaker may occur through changes in macromolecular synthesis. Interestingly, eyes from some older (≥10 months) animals had “cloudy” lenses (cataracts). Highly damped or arrhythmic rhythms always were seen in eyes with cloudy lenses. Morphology of eyes with cloudy lenses indicated severe retinal degeneration. No such degeneration was observed in eyes with clear lenses that were used in the analysis of the rhythm with age.
The Effect of Multiple Pulses of Light on the Circadian Phase Response of the Rat
Authors: Stokes Mark A. , Kent Stephen , Armstrong Stuart Maxwell
Published: May 2004

Multiple pulses of light administered to humans have been reported to result in type 0 phase responses. These results suggest the underlying pacemaker to be nonsimple. At present, results with this type of protocol have only been reported for humans. Therefore, multiple pulses of light were administered to rats. Rats were exposed to one, two, three, or four pulses of light for 5 h (1000 lux) at successive 24-h intervals. Results did not suggest a type 0 phase response. Nonetheless, results with a second, third, or fourth light exposure were not fully predictable from a phase response curve derived from a single light pulse.
No Evidence for Extraocular Photoreceptors in the Circadian System of the Syrian Hamster
Authors: Yamazaki Shin , Goto Maki , Menaker Michael
Published: May 2004

Campbell and Murphy reported recently that3hof bright light (13,000 lux) exposure to the area behind the knee caused phase shifts of the circadian rhythms of both body temperature and saliva melatonin in humans. The authors tested the hypothesis that extraocular photoreception is also involved in the circadian system of the Syrian hamster. Hamsters were bilaterally enucleated (eyes removed), and their backs were shaved. Hamsters with stable free-running rhythms in constant darkness were exposed to direct sunlight for 1 or 3 hours during their subjective night. Intact (control) animals showed phase shifts as expected, but the locomotor activity of enucleated animals was unaffected by the exposure to sunlight. The authors also measured the pineal melatonin content after exposure to sunlight. Pineal melatonin content in intact animals declined markedly as expected, but no decline was observed in the enucleated hamsters. The authors conclude that extraocular phototransduction is not capable of shifting the phase of the hamster's locomotor activity rhythm or of suppressing pineal melatonin synthesis.
Daily Rhythm of Spontaneous Immediate-Early Gene Expression in the Rat Suprachiasmatic Nucleus
Authors: Guido Mario E. , de Guido Liliana B. , Goguen Donna , Robertson Harold A. , Rusak Benjamin
Published: May 2004

Nocturnal light induces the expression of various immediate-early genes (IEGs) in the suprachiasmatic nucleus (SCN), the primary pacemaker of the circadian system of mammals, and causes phase shifts of behavioral rhythms. In the hamster SCN, some IEGs show both sensitivity to light induction at night and a daily peak of spontaneous expression near dawn in different regions of the nucleus. To investigate whether both patterns of IEG expression are observed in the rat SCN, the authors studied the expression of NGFI-A, junB, c-fos, and fosBnear the time of subjective dawn in rats entrained to a light-dark 12:12 cycle and then maintained in constant total darkness for ~48 h. They found that there were two independent rhythms of expression for junB and c-fos mRNAs in the SCN: (1) a rhythm of photic sensitivity expressed throughout the night and (2) a spontaneous rhythm of expression triggered around dawn and persisting for at least 2 h into the day. By contrast, fosB and NGFI-A transcripts were expressed only after light exposure at night and did not exhibit significant levels of spontaneous expression in the absence of photic input. These observations demonstrate that the circadian clock gates expression of two independent rhythms related to IEG expression in the rat SCN. The rhythm of sensitivity to nocturnal light exposure is expressed more strongly in the ventral SCN and may be related to photic entrainment. The second rhythm is triggered spontaneously in darkness around subjective dawn and is expressed in more dorsal parts of the SCN.
Ventromedial Hypothalamic Mediation of Photoperiodic Gonadal Responses in Male Syrian Hamsters
Authors: Bae Helen H. , Mangels Robert A. , Cho Betty S. , Dark John , Yellon Steven M. , Zucker Irving
Published: May 2004

Short day lengths induce testicular regression in seasonally breeding Syrian hamsters. To test whether the ventromedial hypothalamus is necessary to maintain reproductive quiescence once testicular regression has been achieved, photoregressed male hamsters were subjected to lesions of the ventromedial hypothalamus (VMHx), pinealectomy (Pinx), or sham operation (Sham). VMHx hamsters underwent accelerated gonadal recrudescence compared to Pinx and Sham hamsters. Recovery of prolactin concentrations (PRL) to values characteristic of long-day hamsters was hastened in the VMHx animals compared to Sham hamsters. Concentrations of follicle stimulating hormone (FSH) increased prematurely in both the VMHx and Pinx animals, beginning a few weeks after surgery.By the time the gonads had undergone recrudescence and the hamsters were refractory to melatonin, PRL and FSH concentrations had returned to baseline long-day values in all groups; there was no evidence of hypersecretion of either hormone in any of the animals with lesions. Melatonin concentrations of VMHx hamsters did not differ from those of sham-operated animals, but because only a single determination was made, it remains possible that VMH damage altered the duration of nightly melatonin secretion. An intact VMH appears to be essential for the continued maintenance of reproductive suppression induced by exposure to short day lengths; these and earlier findings suggest that the VMH-dorsomedial hypothalamic complex mediates regression of the reproductive apparatus during decreasing day lengths of late summer and early autumn and also is necessary to sustain regression during the winter months.
Inhibition of U937 Cytokine Secretion by HIV-1 gp120 C4-Derived Peptide Constructs
Authors: Kirkley Janet E. , Robey Frank A.
Published: May 2004

Lipopolysaccharide (LPS) stimulation of the human promyelomonocytic cell line U937 results in interleukin 6 and interleukin 10 secretion. Modulation of cytokine secretion in response to LPS may be possible through binding of ligands to surface receptors. A peptomer, containing multiple repeat units of the CD4-binding C4 region of HIV-1 gp120, and the monomeric C4 peptide each were investigated for their ability to affect LPSinduced IL-6 and IL-10 secretion. The peptomer inhibited IL-6 and IL-10 secretion, while the monomer inhibited only IL-6 secretion. Larger CD4-binding proteins, specifically gp120 and Leu3A, a CD4-directed monoclonal antibody, had no effect on the LPS response. PMA differentiation to downregulate CD4 expression did not reverse the inhibitory effect of the peptomer or peptide, suggesting a CD4-independent effect. Bioactivity changed markedly with different constructs in the presence of IFN. with reversal or enhancement of the IL-10 response but not IL-6 production. These results suggest that truncation of a larger polypeptide may result in constructs with novel binding capabilities and bioactivities not seen in parent proteins.
Preliminary Experience With Nesiritide in the Pediatric Population
Authors: Marshall Julie , Berkenbosch John W. , Russo Pierantonio , Tobias Joseph D.
Published: May 2004

Nesiritide is a recombinant formulation of brain-type natriuretic factor. Preliminary experience in the adult population suggests that nesiritide may be an effective agent in the treatment of decompensated congestive heart failure. Given its physiologic effects, it may be an effective agent in the pediatric population; however, to date, there are no reports regarding its use in infants and children. The authors retrospectively review their experience with nesiritide in 5 pediatric patients. The cohort of 5 patients included a diverse population with 2 patients who were status postcardiothoracic surgery, 2 with adult respiratory distress syndrome, and 1 in the recovery phase from septic shock. Although no direct measurement of cardiac output was feasible as none of the patients had a pulmonary artery catheter, other indicators of increased cardiac output were noted. These included improved peripheral perfusion with warming of the extremities and improvement of peripheral pulses in all of the patients, increased venous saturation in 2 of the patients, and maintenance of or increased urine output despite weaning or discontinuation of diuretics. In 3 of the patients, nesiritide was started as the primary agent to provide a decrease in systemic vascular resistance and augment cardiac output, while in the other 2 patients, nesiritide was used when other vasoactive agents failed to provide the desired effect or resulted in adverse effects.
Pediatric Acute Hypoxemic Respiratory Failure: Management of Oxygenation
Authors: Prodhan Parthak , Noviski Natan
Published: May 2004

Acute hypoxemic respiratory failure (AHRF) is one of the hallmarks of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which are caused by an inflammatory process initiated by any of a number of potential systemic and/or pulmonary insults that result in heterogeneous disruption of the capillary-pithelial interface. In these critically sick patients, optimizing the management of oxygenation is crucial. Physicians managing pediatric patients with ALI or ARDS are faced with a complex array of options influencing oxygenation. Certain treatment strategies can influence clinical outcomes, such as a lung protective ventilation strategy that specifies a low tidal volume (6 mL/kg) and a plateau pressure limit (30 cm H2O). Other strategies such as different levels of positive end expiratory pressure, altered inspiration to expiration time ratios, recruitment maneuvers, prone positioning, and extraneous gases or drugs may also affect clinical outcomes. This article reviews state-of-the-art strategies on the management of oxygenation in acute hypoxemic respiratory failure in children.
Residents’ Attitudes toward Tourism Development: a Literature Review with Implications for Tourism Planning
Authors: Harrill Rich
Published: May 2004

Planners are increasingly turning to tourism as a viable economic development strategy, as many communities experience industrial restructuring. Consequently, many residents are exposed to tourism for the first time, whereas established destinations experience increasing volumes of tourists. Planners are now challenged with understanding how the public perceives tourism in order to gain local support for tourism projects and initiatives. By exploring the literature on resident attitudes toward tourism development, this article examines (1) resident attitudes toward tourism in relation to socioeconomic factors; (2) spatial factors; (3) economic dependency; (4) resident and community typologies; (5) measuring residents’ attitudes tourism development; and (6) theoretical perspectives such as community attachment, social exchange theory, and growth machine theory. This literature review provides planners with a basis for initiating citizen participation processes related to tourism issues and identifying groups of people concerned about, or opposed to, tourism planning and development in their communities.
Postmortem Inquiries and Trauma Responses in Paramedics and Firefighters
Authors: Regehr Cheryl , Hill John , Goldberg Gerald , Hughes Judy
Published: May 2004

Following a critical event resulting in loss of life, members of emergency service organizations are frequently required to participate in postmortem inquiries that seek to understand the cause of the tragedy and ensure that such an event does not occur again. Although researchers have become increasingly knowledgeable about the effects of critical events on rescue workers, to date, no studies have focused on the stress and trauma experienced as a result of having one's actions questioned in such a process. This study compares trauma responses in firefighters and paramedics who have been questioned in postmortem inquiries following a critical event in the work-place and those who have not. Involvement in a review was found to be associated with significantly higher traumatic stress and depression symptoms. Those involved in reviews were more likely to have taken mental health stress leave. In addition, both media coverage of the event and the review were significantly associated with depression scores.
Comparison of Six Models for Violent Romantic Relationships in College Men and Women
Authors: Hendy Helen M. , Weiner Kristen , Bakerofskie John , Eggen Doreen , Gustitus Cheryl , McLeod Kelli C.
Published: May 2004

Six types of parent and partner violence were compared as possible models for violence in the romantic relationships of 608 college students (164 men, 444 women). Participants used the Conflict Tactics Scale to report violence to and from the present partner, as well as violence from mother to father, father to mother, mother to participant, father to participant, and past partners to participant. Stepwise multiple regression revealed that violence to the present partner was explained by both partner and parent models of violence for men (R2 = .39) and women (R2 = .51), with violence from the present partner found to be the most powerful model. Violence received from the mother was the most powerful parental model for violence in the present romantic relationship, but for women it was associated with receiving violence, whereas for men it was associated with both receiving and inflicting violence.
Counseling Services for Battered Women
Authors: Howard April , Riger Stephanie , Campbell Rebecca , Wasco Sharon
Published: May 2004

Approximately 15% of married or cohabiting women and as many as 60% of battered women are raped at least once by their partners. This study compared community-based counseling outcomes of battered women with outcomes of women who were both raped and battered by their partners. Over time, both groups improved in wellbeing and coping. Although those both battered and raped progressed more in counseling, they had lower scores before and after counseling compared to women who were battered only. Implications for research and intervention are discussed.
Coercing Victim Participation in Domestic Violence Prosecutions
Authors: Ford David A.
Published: May 2004

The proliferation of coercive prosecution policies toward victims of domestic violence is premised on the notion that prosecution protects victims. However noble this criminal justice ideology, it is largely untested and may reflect an interest in defining prosecution for its practitioners rather than using prosecution on behalf of victims. This article examines recent coercive policies in light of both differing views on the prosecutorial role of victims and extant research evidence on the protective impact of mandatory prosecution.
The Role of the Bar Context and Social Behaviors on Women’s Risk for Aggression
Authors: Buddie Amy M. , Parks Kathleen A.
Published: May 2004

The present study is an initial examination of the extent to which the environmental characteristics of bars and social behaviors that women engage in when drinking in this setting are associated with bar-related aggression. As expected, several environ-mental characteristics (e.g., young patrons, pool playing) and social behaviors (e.g., alcohol consumption, leaving the bar with strangers) were associated with more severe bar-related aggression experienced by women during the past year. These results shed light on the significant problem of bar-related aggression against women and can potentially be used to develop prevention and educational programs.
Revictimization and Self-Harm in Females Who Experienced Childhood Sexual Abuse
Authors: Noll Jennie G. , Horowitz Lisa A. , Bonanno George A. , Trickett Penelope K. , Putnam Frank W.
Published: May 2004

Lifetime trauma histories were ascertained for females with confirmed histories of childhood sexual abuse and comparison females participating in a longitudinal, prospective study. Abused participants reported twice as many subsequent rapes or sexual assaults (p = .07), 1.6 times as many physical affronts including domestic violence (p = .01), almost four times as many incidences of self-inflicted harm (p = .002), and more than 20% more subsequent, significant lifetime traumas (p = .04) than did comparison participants. Sexual revictimization was positively correlated with posttraumatic stress disorder symptoms (PTSD), peritraumatic dissociation, and sexual preoccupation. Physical revictimization was positively correlated with PTSD symptoms, pathological dissociation, and sexually permissive attitudes. Self-harm was positively correlated with both peritraumatic and pathological dissociation. Competing theoretical explanations for revictimization and self-harm are discussed and evaluated.
PCL-R Psychopathy Predicts Disruptive Behavior Among Male Offenders in a Dutch Forensic Psychiatric Hospital
Authors: Hildebrand MartIn , De Ruiter Corine , Nijman Henk
Published: May 2004

In this study, the relationship between psychopathy, according to the Dutch language version of Hare’s Psychopathy Checklist-Revised (PCL-R), and various types of disruptive behavior during inpatient forensic psychiatric treatment is investigated. Ninety-two male participants were administered the PCL-R following admission to an inpatient forensic hospital. From daily hospital information bulletins, incidents of verbal abuse, verbal threat, physical violence, and violation of hospital rules were derived. Also, the number of seclusion episodes was recorded. As expected, significant correlations were found between PCL-R scores and verbal abuse, verbal threat, violation of rules, total number of incidents, and frequency of seclusion. Psychopaths (PCL-R 30) were significantly more often involved in incidents than nonpsychopaths. Multiple regression analyses revealed that the PCL-R Factor 2 score in particular contributed uniquely to the prediction of the total number of incidents. The findings are discussed in terms of their clinical implications.