Disease relevance of Periodicity

• Because mutations in HERG cause a form of long-QT syndrome, these properties of HERG channel function may be critical to the maintenance of normal cardiac rhythmicity [1].
• This study tested the hypothesis that acute hyperglycemia suppresses fed antral contractions and disrupts slow-wave rhythmicity via prostaglandin pathways [2].
• The periodicity of fluorescent alpha-actinin along stress fibers was wider in gerbil fibroma cells than it was in PtK2 cells [3].
• Cyanobacteria are the only prokaryotes known thus far possessing regulation of physiological functions with approximate daily periodicity, or circadian rhythms, that are controlled by a cluster of three genes, kaiA, kaiB, and kaiC [4].
• Incubation of the RNA with erythroleukemia K562 cytosolic extract results in deadenylation with distinct intermediates containing a periodicity of approximately 30 nucleotides, which is consistent with the binding of poly(A)-binding protein (PABP) monomers [5].

Psychiatry related information on Periodicity

• These include the localization of a gene for circadian periodicity in the mouse, gene knockouts of serotonin receptors, and the development of a transgenic model of Alzheimer's disease [6].
• In D. melanogaster, three allelic per mutations have been isolated which affect the periodicity of the circadian oscillators affecting both eclosion and locomotor activity [Konopka, R. & Benzer S. (1971) Proc. Natl. Acad. Sci. USA 68, 2112-2116] [7].
• We suggest that histamine, which participates in the control of vigilance, sleep, and wakefulness, as well as in the modulation of circadian rhythmicity, may play a role in the development of sleep disturbances in rats with PCA [8].
• Abnormal adrenocortical regulation has been reported in patients with endogenous depression, including excessive cortisol production with loss of circadian periodicity and decreased suppression by dexamethasone [9].
• Placebo had no effect on his cycles, amitriptyline lessened the amplitude of depression on "bad days" but did not effect the 48-hour periodicity, whereas lithium carbonate therapy terminated both affective symptoms and the cycle itself [10].

High impact information on Periodicity

• The double mutant has normal vision but is defective in mPer1 induction by light and lacks molecular and behavioral rhythmicity in constant darkness [11].
• The HAT activity of CLOCK is essential to rescue circadian rhythmicity and activation of clock genes in Clock mutant cells [12].
• These data demonstrate that CRY-mediated repression of the CLOCK/BMAL1 complex activity is required for maintenance of circadian rhythmicity and provide formal proof that transcriptional feedback is required for mammalian clock function [13].
• These results demonstrate that SCN hierarchical dominance can compensate for severe intrinsic genetic defects in peripheral clocks, but cannot induce rhythmicity in clock-defective tissues [14].
• The Clock mutation lengthens periodicity and reduces amplitude of circadian rhythms in mice [15].

Chemical compound and disease context of Periodicity

• Diurnal rhythmicity of saliva cortisol was flattened in both men and women with myotonic dystrophy, with significantly increased afternoon/evening levels (P < 0.013) [16].
• Females received T filled or empty Silastic capsules during days 15-30 of age and vaginal cyclicity, ovarian weight and appearance, lordosis and proceptive behaviors, mounting behavior, and the gonadotropin response to estrogen and progesterone were measured in adulthood [17].
• A patient with Cushing's disease due to a chromophobe adenoma was studied for 243 days before pituitary surgery and evidence for periodicity in cortisol steroid production was found with cycles occurring every 85.8 days (peak-to-peak length), associated with laboratory remissions and paradoxical response to dexamethasone [18].
• In chickens this rhythmicity results at least partly from the light sensitivity of the melatonin-producing and -secreting system [19].
• Effects of hyperprolactinemia on estrous cyclicity, serum luteinizing hormone, prolactin, estradiol, and progesterone concentrations, and catecholamine activity in microdissected brain areas [20].

Biological context of Periodicity

• Micrococcal nuclease digestion of nuclei cleaves telomeres with a uniform 157 bp periodicity, producing soluble particles that sediment in sucrose gradients exactly like oligonucleosomes [21].
• Much of the order and timing of the cell cycle events may involve the progressive activation of Cdc28 kinase activities associated with different cyclins, whose periodicity during the cycle is determined by both transcriptional and post-transcriptional controls [22].
• Here we show that inactivation of the mCry2 gene in mPer2 mutant mice restores circadian rhythmicity and normal clock gene expression patterns [23].
• RESULTS: Antral migrating motor complex periodicity and fasting and fed motility indices, not different in the groups under control conditions, decreased similarly in nonsmokers and smokers with nicotine [24].
• The periodicity of micrococcal nuclease-sensitive sites in the linker regions associated with histone H1 or H5 is 10.4 base pairs, suggesting that the spatial organization of the linker region in the higher-order structure of chromatin is similar to that in isolated nucleosomes [25].

Anatomical context of Periodicity

• We have identified and characterized c-hairy1, an avian homolog of the Drosophila segmentation gene, hairy. c-hairy1 is strongly expressed in the presomitic mesoderm, where its mRNA exhibits cyclic waves of expression whose temporal periodicity corresponds to the formation time of one somite (90 min) [26].
• Recent evidence in vertebrates suggests that the mammalian suprachiasmatic nucleus and the avian pineal gland contain clocks that affect the rhythmicity of indoleamine metabolism [27].
• GABA in the mammalian suprachiasmatic nucleus and its role in diurnal rhythmicity [28].
• The conceptus within the uterus, therefore, is believed to produce a substance or substances which directly or indirectly prolong the lifespan of the corpus luteum and prevent a return to ovarian cyclicity [29].
• In addition, similarities between the PAS-domain regions of molecules involved in light perception and circadian rhythmicity in several organisms suggest an evolutionary link between ancient photoreceptor proteins and more modern proteins required for circadian oscillation [30].

Associations of Periodicity with chemical compounds

• Abnormal circadian periodicity of plasma cortisol concentrations persisted [31].
• Here we show that loss of the PAS protein MOP3 (also known as BMAL1) in mice results in immediate and complete loss of circadian rhythmicity in constant darkness [32].
• This may be a consequence of functionally important, long-range amino acid or oligopeptide periodicities (for example, Asp x Ser or Glu x Ser corresponding to Hinf I sites) in the BRc protein product, in conjunction with preferential use of certain synonymous codons [33].
• Roles of circadian rhythmicity and sleep in human glucose regulation [34].
• The results suggest that melatonin is involved in the physiological control of circadian rhythmicity in sparrows [35].

Gene context of Periodicity

• The loss of Acf1 results in a decrease in the periodicity of nucleosome arrays as well as a shorter nucleosomal repeat length in bulk chromatin in embryos [36].
• Vasoactive intestinal polypeptide mediates circadian rhythmicity and synchrony in mammalian clock neurons [37].
• Critically, daily application of a VPAC(2) agonist restored rhythmicity and synchrony to VIP(-/-) SCN neurons, but not to Vipr2(-/-) neurons [37].
• The elimination of cyclin E during S and G(2) phases is impaired in Skp2(-/-) cells, resulting in loss of cyclin E periodicity [38].
• Utilizing yeast strains containing promoter mutations, we demonstrate that transcription of the HSP82 gene causes nucleosomes toward the 3'-end to become DNase I sensitive and 'split' into structures that exhibit a 'half-nucleosomal' cleavage periodicity [39].

Analytical, diagnostic and therapeutic context of Periodicity

• Electron microscopy of thin sections of the MAP2-saturated microtubules fixed in the presence of tannic acid demonstrates a striking axial periodicity of 32 +/- 8 nm [40].
• OBJECTIVE: Relationships between the apolipoprotein E epsilon4 allele and electroencephalographic (EEG) rhythmicity have been demonstrated in Alzheimer's disease (AD) patients but not in the preclinical stage prodromic to it, namely, mild cognitive impairment (MCI) [41].
• Here, we show that transplantation of mouse fetal SCN tissue into the hypothalamus restores free-running circadian behavioral rhythmicity in Clock mutant or mCry1/mCry2 double knockout mice [42].
• Serological tests indicated that HNF-1alpha was present in complexes throughout the day, while HNF-1beta binding exhibited circadian periodicity [43].
• Pulsatile characteristics of spontaneous growth hormone (GH) concentration profiles in boys evaluated by an ultrasensitive immunoradiometric assay: evidence for ultradian periodicity of GH secretion [44].

References