Search NEL Online

Clinical Trial 2005; 26(5): 493-498 PubMed PMID: 16264413 Citation  Keywords:  Adult, Circadian Rhythm:physiology, Humans, Light, Lighting, Male, Melatonin:blood, Middle Aged, Photic Stimulation, Pupil:physiology, Retina:physiology, Signal Transduction:physiology,.   

OBJECTIVES: Published data, both on nocturnal melatonin suppression in humans and on widely accepted retinal structure and function, suggest that spectral opponency plays a role in human circadian phototransduction. We directly test subadditivity, implied by spectral opponency, in human circadian phototransduction in response to nearly monochromatic and to polychromatic light.r />r /> METHODS: Adult male human subjects were exposed for 60 minutes to two intensities each of two lighting conditions, during nighttime experimental sessions. One condition consisted of light from mercury vapor lamps (450 and 1050 lx), and one condition consisted of light from these lamps filtered such that only the spectral line from this lamp at 436 nm was presented to subjects (7.5 and 15 lx).r />r /> RESULTS: Melatonin suppression from the filtered illumination at 436 nm alone was greater than mercury lamp illumination (containing energy at 436 nm in addition to other wavelengths), even when the sources exposed subjects' retinae to equal amounts of irradiance at 436 nm.r />r /> CONCLUSION: This direct test of subadditivity, together with evidence from neuroanatomy, supports the inference that spectral opponency is a fundamental characteristic of human circadian phototransduction....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 439-446 PubMed PMID: 16264412 Citation  Keywords:  Autistic Disorder:chemically induced, Autoimmune Diseases:chemically induced, Chelating Agents:therapeutic use, Child, Humans, Inflammation:chemically induced, Mercury:analysis, Mercury Poisoning:epidemiology,.   

: The causes of autism and neurodevelopmental disorders are unknown. Genetic and environmental risk factors seem to be involved. Because of an observed increase in autism in the last decades, which parallels cumulative mercury exposure, it was proposed that autism may be in part caused by mercury. We review the evidence for this proposal. Several epidemiological studies failed to find a correlation between mercury exposure through thimerosal, a preservative used in vaccines, and the risk of autism. Recently, it was found that autistic children had a higher mercury exposure during pregnancy due to maternal dental amalgam and thimerosal-containing immunoglobulin shots. It was hypothesized that children with autism have a decreased detoxification capacity due to genetic polymorphism. In vitro, mercury and thimerosal in levels found several days after vaccination inhibit methionine synthetase (MS) by 50%. Normal function of MS is crucial in biochemical steps necessary for brain development, attention and production of glutathione, an important antioxidative and detoxifying agent. Repetitive doses of thimerosal leads to neurobehavioral deteriorations in autoimmune susceptible mice, increased oxidative stress and decreased intracellular levels of glutathione in vitro. Subsequently, autistic children have significantly decreased level of reduced glutathione. Promising treatments of autism involve detoxification of mercury, and supplementation of deficient metabolites....

Read abstract  Full text PDF

Case Reports 2005; 26(5): 499-502 PubMed PMID: 16264411 Citation  Keywords:  Adrenal Insufficiency:complications, Adrenocorticotropic Hormone:deficiency, Adult, Autonomic Nervous System:physiopathology, Chromosomes, Human, Pair 12:genetics, Conjunctival Diseases:complications, Electroencephalography, Epilepsy:genetics, Hormone Rep.   

: Allgrove syndrome is a rare autosomal recessive disease with achalasia, alacrima, adrenocortical insufficiency, autonomic neuropathy and other neurological disturbances. A case of two brothers with Addison s disease from early childhood is presented. The younger brother with Addison disease died at the age of 5. The older brother was treated for adrenocortical insufficiency from the age 3, and then treated for achalasia and epilepsy from the age of 5. The patient is currently 26 years old and suffers from achalasia and adrenocortical insufficiency. He also suffers from alacrima, autonomic neuropathy, epilepsy and other damages of the central and peripheral nervous system. The clinical picture is typical for Allgrove or 4A syndrome, and the diagnosis was confirmed by means of molecular analysis of a new AAAS gene mutation....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 503-510 PubMed PMID: 16264410 Citation  Keywords:  Aging:physiology, Animals, Chickens:metabolism, Darkness, Female, Light, Male, Melatonin:metabolism, Organ Culture Techniques, Perfusion, Pineal Gland:metabolism, Temperature,.   

: The melatonin rhythm of cultured chicken pineal cells can be synchronized by cyclic environmental effects. Unlike the effects of light on the melatonin secretion, those of the temperature changes are much less known. Similarly, only a few data are available on the interactions between environmental illumination and periodic temperature changes and on the sensitivity of the pineal gland to temperature changes in different ages of animals. We monitored the effects of temperature on chicken pineals for several days in vitro, in a perifusion system under different illumination patterns. The effects of temperature on pineals from chicken of different age were also compared. The phase of the melatonin rhythm was controlled by periodic elevations of temperature under both constant darkness and continuous illumination. These results show that rhythmic changes of temperature prevent desynchronization induced by constant light. Following elevation of the temperature, the melatonin rhythm of pineals of young chickens (less, than 14 weeks old) was altered for 16 - 18 hours. Similar changes in melatonin rhythm were not found in older animals. It is concluded that the sensitivity for temperature changes of the pineal cells is varying with age....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 511-514 PubMed PMID: 16264409 Citation  Keywords:  Aging:physiology, Animals, Animals, Newborn, Cell Count, Colon:pathology, Hyperplasia, Male, Neurosecretory Systems:pathology, Paraffin Embedding, Pineal Gland:physiology, Rats, Rats, Wistar,.   

OBJECTIVES: The diffuse neuroendocrine system (DNES) participates in the systemic homeostasis and may work as a unified system with integrated functions but anatomically disperse. However, the mechanisms that are involved in the integration of the distant parts of the DNES are poorly known. This study is aimed on the effects of a pinealectomy on the population of the neuroendocrine cells (NECs) in the colon of rats.r />r /> METHODS: A group of seven newborn rats and one of adult rats were submitted to a pinealectomy. The animals were sacrificed after 15 days and 90 days, respectively. The control groups of adult and newborn rats were subjected to a 'sham surgery' and then sacrificed after similar periods of time. Paraffin-included sections of the colon samples were stained by the Churukian-Schenk method in order to selectively stain the NECs. The NEC index was estimated by the expression: iNEC = NECs population per crypt/Total cell population of the crypt. The results were expressed as median and absolute range, and the statistical significance was demonstrated by the Mann-Whitney (U) test.r />r /> RESULTS: The morphometric analysis showed a significant increase in the number of colonic NECs of the adult rats subjected to a pinealectomy when compared to the controls. No statistical difference was observed between the iNECs of the newborn groups of rats.r />r /> CONCLUSION: This finding suggests the existence of regulatory mechanisms that integrate distant parts of the DNES, by adapting the population of the endocrine cells after the ablation of an important component of the system. Further studies on the mechanisms involved in the integration of the DNES may be facilitated by the simple experimental model that we propose....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 515-520 PubMed PMID: 16264408 Citation  Keywords:  Adrenal Medulla:physiopathology, Adrenocorticotropic Hormone:blood, Animals, Cold Temperature, Corticosterone:blood, Epinephrine:blood, Luminescence, Male, Norepinephrine:blood, Pituitary-Adrenal System:physiopathology, Rats, Rats, Wistar, Restraint, Phys.   

OBJECTIVE: The effects of three different long-term (21 days) stresses: isolation(LTI), forced swimming (LTS) and isolation accompanied by forced swimming (LTI+LTS) on the level of plasma noradrenaline (NA), adrenaline (A), corticosterone (CORT) and adrenocorticotropic hormone (ACTH), both under basal conditions and in response to short-term immobilization and cold as heterotypic additional stressors, were compared.r />r /> METHODS: Plasma NA and A were assayed by the radioenzymatic method. Plasma CORT was measured using RIA kits. Plasma ACTH was determined by chemiluminescent method.r />r /> RESULTS: LTI produced a significant elevation of basal plasma CORT and ACTH, while basal plasma NA and A concentrations remained unchanged. Combination of long-term isolation and forced swimming, produced a significant elevation of basal plasma ACTH content only, while LTS did not influence the basal level of this hormone. When LTI rats were exposed to immobilization and cold, a significant elevation of plasma NA and A level was recorded. In LTS and LTI+LTS groups of rats exposed to immobilization or cold, increased plasma NA and A levels were observed, but this increase was lower in comparison with that found in LTI rats. No difference in plasma CORT content between the three long-term stressed groups of animals was observed, while plasma ACTH level was significantly more elevated in LTS and LTI+LTS than in LTI rats.r />r /> CONCLUSION: Based on these results, it may be concluded that LTI as a psychosocial stress represents a stronger stressor than LTS. Also, daily short-term (15 min, 21 days) swimming stress seems to attenuate the effect of long-term isolation on the activity of sympatho-adrenomedullary system....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 521-525 PubMed PMID: 16264407 Citation  Keywords:  Adult, Aged, Aging:physiology, Carcinoma, Papillary:genetics, Chromosomes:genetics, Genetic Markers, Humans, Loss of Heterozygosity:genetics, Microsatellite Repeats, Middle Aged, Protein-Tyrosine Kinases:genetics, RNA, Messenger:biosynthesis, Reverse Tran.   

OBJECTIVES: The aim of the study was to establish the LOH frequency of selected polymorphic markers in different histological types of thyroid tumors: 18 colloid goiters (CG), five follicular adenomas (FA), nine follicular carcinomas (FTC), 40 papillary carcinomas (PTC), and one anaplastic carcinoma (ATC). For PTC, tumors negative for RET/PTC rearrangements were preferred.r />r /> METHODS: LOH studies were performed using 14 highly polymorphic markers previously described as frequently lost in thyroid tumors.r />r /> RESULTS: In 20 cases (27%) the loss of at least one marker was found. No difference between the frequency of the LOH in FTC and PTC tumors was revealed (33% v. 33%). No differences between histopathological subtypes of PTC in LOH were found. Papillary thyroid carcinomas showed a tendency to higher LOH frequency from patients older than 45 years of age compared to younger ones (9/23 v. 4/17) although it was not statistically significant.r />r /> CONCLUSIONS: We conclude that papillary thyroid cancers, particularly those diagnosed in patients older than 45 years of age, do exhibit LOH at least with the same frequency as follicular cancers. This increased number of LOH events may contribute to the clinical aggressiveness of cancer in older patients....

Read abstract  Full text PDF

Journal Article 2005; 26(5): 526-532 PubMed PMID: 16264406 Citation  Keywords:  Animals, Astrocytes:drug effects, Blotting, Western, Cell Line, Estradiol:pharmacology, Estrogen Antagonists:pharmacology, Estrogen Receptor alpha:drug effects, Estrogen Receptor beta:drug effects, Gene Expression Regulation:drug effects, Ligands, Lucifer.   

OBJECTIVE: The mechanism through which estrogen exerts its neuroprotective and anti-neurodegenerative effects in the central nervous system is poorly understood. Human glial cells are implicated in the pathogenesis of Alzheimer's disease and have both alpha and beta estrogen receptors (ER). We developed a glial cell model for ER function using the N20.1 mouse oligodendroglial cell line to evaluate the response of ERalpha and ERbeta to estradiol (E2), a raloxifene analog LY117018 (LY) and 4-hydroxytamoxifen (4OHT).r />r /> DESIGN: We tested the ability of exogenous ER to activate transcription in response to ligands (100 nM) using the glial cell line N20.1 in a transient cotransfection assay with an ERalpha or ERbeta expression vector, an ERE-driven reporter and a Renilla luciferase transfection control.r />r /> RESULTS: Endogenous ER was not detected in the N20.1 cells by Western immunoblotting. E2 stimulated both ERalpha and ERbeta on both ERE- and AP-1 driven promoters. The transcription stimulation by E2 in the ERalpha and ERbeta through the AP-1driven promoter, though significant, was not of the same magnitude as the stimulation of the ERalpha through the ERE-driven promoter. 4OHT and LY did not show significant transcriptional activation of either the ERalpha or ERbeta, through either the ERE or AP-1 driven promoters. LY, at a 10-fold higher concentration than E2, showed a difference in its antagonist activity on the ERbeta through the AP-1 pathway when compared with the ERE- driven promoter, demonstrating not only promoter specificity, but also receptor specificity.r />r /> CONCLUSIONS: This is the first description of the activity of 4OHT and LY on estrogen receptors in glia....

Read abstract  Full text PDF