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Robust transmission of information despite the presence of variation is a fundamental problem in cellular functions. However, the capability and characteristics of information transmission in signaling pathways remain poorly understood. We describe robustness and compensation of information transmission of signaling pathways at the cell population level. We calculated the mutual information transmitted through signaling pathways for the growth factor-mediated gene expression. Growth factors appeared to carry only information sufficient for a binary decision. Information transmission was generally more robust than average signal intensity despite pharmacological perturbations, and compensation of information transmission occurred. Information transmission to the biological output of neurite extension appeared robust. Cells may use information entropy as information so that messages can be robustly transmitted despite variation in molecular activities among individual cells.

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Before the emergence of life, left-handed amino acids (L-enantiomers) were selected and right-handed amino acids (D-enantiomers) were eliminated on the primal earth. Nevertheless, with the progress of analytical methods, D-amino acids have recently been found in higher order living organisms in the form of free amino acids, peptides, and proteins. Free D-amino acids have numerous physiological functions. D-amino acids containing animal peptides are well known as opioid peptides. D-amino acids in protein are related to aging. In this review, we describe the D-amino acids that are present and function as D-amino acid biosystems in our bodies.

Halobacterium salinarium, a member of the extremely halophilic archaebacteria, contains a C50-carotenoid namely bacterioruberin. We have previously reported the high resistance of this organism against the lethal actions of DNA-damaging agents including ionizing radiation and ultraviolet light (UV). In this study, we have examined whether bacterioruberin and the highly concentrated salts in this bacterium play protective roles against the lethal actions of ionizing radiation, UV, hydrogen peroxide, and mitomycin-C (MMC). The colourless mutant of H. salinarium deficient in bacterioruberin was more sensitive than the red-pigmented wild-type to all tested DNA-damaging agents except MMC. Circular dichroism (CD) spectra of H. salinarium chromosomal DNA at various concentrations of KCl (0-3.5 M) were similar to that of B-DNA, indicating that no conformational changes occurred as a result of high salt concentrations. However, DNA strand-breaks induced by ionizing radiation were significantly reduced by the presence of either bacterioruberin or concentrated KCl, presumably due to scavenging of free radicals. These results suggest that bacterioruberin and intracellular KCl of H. salinarium protect this organism against the lethal effects of oxidative DNA-damaging agents.

Ghrelin is known as a potent orexigenic hormone through its action on the brain. In this study, we examined the effects of intracerebroventricular (icv) and iv injection of ghrelin on water intake, food intake, and urine volume in rats deprived of water for 24 h. Water intake that occurred after water deprivation was significantly inhibited by icv injection of ghrelin (0.1, 1, and 10 nmol/rat) in a dose-related manner, although food intake was stimulated by the hormone. The antidipsogenic effect was as potent as the orexigenic effect. Similarly, water intake was inhibited, whereas food intake was stimulated dose dependently after iv injection of ghrelin (0.1, 1, and 10 nmol/kg). The inhibition of drinking was comparable with, or even more potent than, atrial natriuretic peptide (ANP), an established antidipsogenic hormone, when administered icv, although the antidipsogenic effect lasted longer. ANP had no effect on food intake. Urine volume decreased dose relatedly after icv injection of ghrelin but not by ANP. Intravenous injection of ghrelin had no effect on urine volume. Because drinking usually occurs with feeding, food was withdrawn to remove the prandial drinking. Then the antidipsogenic effect of ghrelin became more potent than that of ANP and continued longer than when food was available. Expression of Fos was increased in the area postrema and the nucleus of the tractus solitarius by using immunohistochemistry after icv and iv injection of ghrelin. The present study convincingly showed that ghrelin is a potent antidisogenic peptide in rats.

SUMMARYPurpose: Autonomic consequences of seizures are common, but can be severe. We sought to define changes in autonomic activity from limbic cortical seizures and their impact on the heart. Methods: We studied kainic acid (KA)-induced seizures in urethane-anesthetized rats using peripheral nerve, blood pressure (BP), and ECG recordings and echocardiography. Results: Seizures were associated with massive increases in parasympathetic (vagus nerves) and sympathetic (cervical sympathetic ganglion >renal nerve >splanchnic nerve) activity. Seizureassociated activity increases were greater than activity changes induced by nitroprusside or phenylephrine (each producing BP changes of >50 mmHg). Increases in c-fos expression were found in both sympathetic and parasympathetic medullary regions (as well as hypothalamic areas). Baroreceptor reflex function (tested with nitroprusside and phenylephrine) was impaired during seizures. Finally, a significant fraction of the animals died and the mechanism of death was defined through ECG, BP, and echocardiographic measures to be profound cardiac dilatation and bradyarrhythmia leading to hypoperfusion of the brain and ultimately hypoperfusion of the heart. Cardiovascular changes occur within seconds (or less) of autonomic nerve activity changes and death by these mechanisms takes minutes. Discussion: We propose that the massive parasympathetic and sympathetic outflow that occurs during a seizure gets compounded by respiratory distress (driving both autonomic nervous system divisions in the same direction) causing mechanical dysfunction, slowing the heart, and hypoperfusing the brain. KEY WORDS: Autonomic nervous system, Limbic cortex, Cardiac arrhythmia, Cardiac dilatation.Seizure-induced autonomic dysfunction can have serious clinical consequences (Devinsky, 2004; Goodman et al., 2008). Focal simple partial seizures may produce flushing, sweating, and piloerection (Baumgartner et al., 2001), while complex partial seizures produce a broader spectrum of autonomic signs, including changes in heart rate and rhythm, blood pressure, gastrointestinal moti- (Wilder-Smith, 1992;Lathers et al., 1998;Locatelli et al., 1999;Nei et al., 2000;Baumgartner et al., 2001). Generalized tonic-clonic seizures may be associated with severe increases in blood pressure and changes in heart rate and conduction, such as complete nodal block (Schraeder & Lathers, 1989). In some individuals, however, seizures may trigger more ominous autonomic derangements such as marked bradycardia or asystole (Smith-Demps & Jagoda, 1998;Cheung & Hachinski, 2000;Mameli et al., 2001). The causes of death in epilepsy are suspected to involve cardiovascular or respiratory dysfunction provoked by seizures (Liedholm & Gudjonsson, 1992;Smith-Demps & Jagoda, 1998;Cheung & Hachinski, 2000;Langan, 2000;Mameli et al., 2001;Tinuper et al., 2001). 983 Autonomic Consequences of Limbic Seizures in RatsAnimal experimentation has replicated features of human epilepsy and autonomic dysfunction (reviewed in (Lathers & Schraeder, 2006))....