Enhanced circadian phase resetting in R192Q Cav2.1 calcium channel migraine mice.

Objective: Mammalian circadian rhythms are driven by the circadian pacemaker of the suprachiasmatic nucleus (SCN) and are synchronized to the external 24-hour light/dark cycle. After advance time zone transitions (eastbound jet lag), overt circadian rhythms require several days to adjust. The retarded adaptation may protect against acute imbalance of different brain systems.

Seasonal encoding by the circadian pacemaker of the SCN.

The circadian pacemaker of the suprachiasmatic nucleus (SCN) functions as a seasonal clock through its ability to encode day length [1-6]. To investigate the mechanism by which SCN neurons code for day length, we housed mice under long (LD 16:8) and short (LD 8:16) photoperiods. Electrophysiological recordings of multiunit activity (MUA) in the SCN of freely moving mice revealed broad activity profiles in long days and compressed activity profiles in short days.

The opioid fentanyl affects light input, electrical activity and Per gene expression in the hamster suprachiasmatic nuclei.

The suprachiasmatic nuclei (SCN) contain a major circadian pacemaker, which is regulated by photic and nonphotic stimuli. Although enkephalins are present in the SCN, their role in phase regulation of the pacemaker is largely unknown. The opioid agonist fentanyl, a homologue of morphine, is an addictive drug that induces phase shifts of circadian rhythms in hamsters.

A GABAergic mechanism is necessary for coupling dissociable ventral and dorsal regional oscillators within the circadian clock.

Background: Circadian rhythms in mammalian behavior, physiology, and biochemistry are controlled by the central clock of the suprachiasmatic nucleus (SCN). The clock is synchronized to environmental light-dark cycles via the retino-hypothalamic tract, which terminates predominantly in the ventral SCN of the rat. In order to understand synchronization of the clock to the external light-dark cycle, we performed ex vivo recordings of spontaneous impulse activity in SCN slices of the rat.

Light signalling in cryptochrome-deficient mice.

The mammalian master clock driving circadian rhythmicity in physiology, metabolism, and behaviour resides within the suprachiasmatic nuclei (SCN) of the anterior hypothalamus and is composed of intertwined negative and positive autoregulatory transcription-translation feedback loops. The Cryptochrome 1 and 2 gene products act in the negative feedback loop and are indispensable for molecular core oscillator function, as evident from the arrhythmic wheel running behaviour and absence of cyclic clock gene expression in mCry1/mCry2 double mutant mice in constant darkness. Recently, we have measured real-time multi-unit electrode activity recordings in hypothalamic slices from mCry-deficient mice kept in constant darkness and observed a complete lack of circadian oscillations in firing patterns.

Heterogeneity of rhythmic suprachiasmatic nucleus neurons: Implications for circadian waveform and photoperiodic encoding.

Circadian rhythms in neuronal ensemble, subpopulations, and single unit activity were recorded in the suprachiasmatic nuclei (SCN) of rat hypothalamic slices. Decomposition of the ensemble pattern revealed that neuronal subpopulations and single units within the SCN show surprisingly short periods of enhanced electrical activity of approximately 5 h and show maximal activity at different phases of the circadian cycle. The summed activity accounts for the neuronal ensemble pattern of the SCN, indicating that circadian waveform of electrical activity is a composed tissue property.

Dissociation between circadian Per1 and neuronal and behavioral rhythms following a shifted environmental cycle.

The suprachiasmatic nucleus (SCN) of the anterior hypothalamus contains a major circadian pacemaker that imposes or entrains rhythmicity on other structures by generating a circadian pattern in electrical activity. The identification of "clock genes" within the SCN and the ability to dynamically measure their rhythmicity by using transgenic animals open up new opportunities to study the relationship between molecular rhythmicity and other well-documented rhythms within the SCN. We investigated SCN circadian rhythms in Per1-luc bioluminescence, electrical activity in vitro and in vivo, as well as the behavioral activity of rats exposed to a 6-hr advance in the light-dark cycle followed by constant darkness.

Cryptochrome-deficient mice lack circadian electrical activity in the suprachiasmatic nuclei.

The mammalian master clock driving circadian rhythmicity in physiology and behavior resides within the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. Circadian rhythms are generated by a set of clock genes via intertwined negative and positive autoregulatory transcription-translation feedback loops. The Cryptochrome 1 and 2 genes are indispensable for molecular core oscillator function, as evident from the arrhythmic wheel-running behavior and lack of rhythmic clock gene expression in mCry1/mCry2 double-mutant mice in constant darkness.

Phase differences in electrical discharge rhythms between neuronal populations of the left and right suprachiasmatic nuclei.

The circadian pacemaker of the suprachiasmatic nuclei is a complex multioscillator system, which controls circadian and seasonal rhythmicity. A number of clock genes have been identified that play a key role in the generation of circadian rhythms. These clock genes are expressed in a circadian manner as has been shown in mice, rats and hamsters.

Membrane-controlled reagent-delivery systems--a new approach for the continuous production of reagent and standard solutions.

A new simple and robust system for the production of standard solutions, based on the mass-transfer of analytes through membranes, is described. The device consists of a cone-shaped reservoir vessel, filled with a concentrated solution of the analyte and separated from a liquid acceptor stream by a membrane. Mass-flow from donor to acceptor solution is controlled by the mass-transfer-affecting properties of the active membrane area, which is determined by the hole in a template (diameter 0.

Fentanyl, a upsilon-opioid receptor agonist, phase shifts the hamster circadian pacemaker.

The phase-shifting effects of the mu-opioid receptor agonist fentanyl on the circadian timing system were investigated in the hamster. Fentanyl injections during the mid-subjective day induced phase advances of the hamsters' wheel-running activity rhythm. The shifts were not accompanied by an increase in locomotor activity but instead a decrease of activity was often observed.

Functional absence of extraocular photoreception in hamster circadian rhythm entrainment.

The mammalian circadian pacemaker is entrainable by light via the retina. The putative role of extraocular light perception was investigated in blinded hamsters. These animals were shaved and exposed to a light-emitting pad for either 30 min or 3 h.

Light responsiveness of the suprachiasmatic nucleus: long-term multiunit and single-unit recordings in freely moving rats.

The suprachiasmatic nuclei (SCN) of the hypothalamus contain a pacemaker that generates circadian rhythms in many functions. Light is the most important stimulus that synchronizes the circadian pacemaker to the environmental cycle. In this paper we have characterized the baseline neuronal firing patterns of the SCN as well as their response to light in freely moving rats.

Electrophysiologic analysis of the actions of valproate on pyramidal neurons in the rat hippocampal slice.

Purpose: Studies in invertebrates and cultured mammalian neurons suggested that valproate (VPA) mediates its main antiepileptic effect by slowing the recovery from inactivation of voltage-dependent sodium channels. This predicts an effect on the refractory period of the action potential and, consequently, on the bursting behavior of neurons.

Methods: We investigated this prediction using intracellular and extracellular recording techniques in hippocampal slices prepared from adult rats.

Multiunit activity recordings in the suprachiasmatic nuclei: in vivo versus in vitro models.

The suprachiasmatic nuclei (SCN) of the hypothalamus continue to oscillate when they are isolated in a brain slice preparation. We recorded multiunit activity in the SCN of the rat both in vivo and in vitro to determine the circadian discharge pattern. The variability of the discharge pattern is larger and the amplitude of the rhythm is smaller in vivo than in vitro.

The effects of glutamate on membrane potential and discharge rate of suprachiasmatic neurons.

The suprachiasmatic nucleus (SCN) is a major pacemaker for circadian rhythms in mammals. Photic entrainment of the circadian pacemaker is mediated by the retinohypothalamic tract (RHT). Most likely, excitatory amino acids function as neurotransmitters in this pathway.

[Parvovirus B 19 infection and associated arthritis in children and adolescents].

The commonest clinical manifestation of an acute parvovirus B 19 infection is "infectious erythema (E.i.)".

Enhancement of recurrent inhibition by angular bundle kindling is retained in hippocampal slices.

Rats were kindled in the right angular bundle. EEG and monosynaptically evoked responses were monitored in the ipsilateral fascia dentata. Although every animal was kindled, Long Term Potentiation (LTP) of monosynaptic responses was observed only in part of the kindling sessions, suggesting that LTP is not required for kindling.

[Ventral intercorporal spondylodesis of the lumbar spine in segmental instability].

Ventral intercorporal spondylodesis or anterior interbody fusion was applied via the extraperitoneal route to the lumbar spine of 25 adult patients. The approach had in all cases been indicated for segmental instability in spondylolisthesis or degeneration of vertebral discs with low-back pain in the wake of surgery. Described are the surgical technique used as well as intra-operative and postoperative complications.

Spontaneous epileptiform discharges in hippocampal slices induced by 4-aminopyridine.

4-Aminopyridine (4-AP) induced 2 types of spontaneous field potentials (SFPs) in the hippocampal slice. Type I resembled spontaneous activity induced by other convulsants. They occurred at a rate of approximately 1 Hz, started in the CA2/CA3 region and spread at a velocity of 0.

Sodium-dependent sugar and amino acid transport in isolated goldfish intestinal epithelium: electrophysiological evidence against direct interactions at the carrier level.

The effects of mucosal application of monosaccharides and amino acids on transepithelial and membrane potentials in isolated goldfish intestinal epithelium were investigated. Isosmotic replacement of mucosal mannitol by sugars or L-amino acids resulted in a rapid depolarization of the mucosal membrane potential psi mc followed by a slow repolarization. Phlorizin inhibited the responses to sugar but not those to amino acids.