Connections of the Mesencephalic Locomotor Region (MLR) in the Cat

The cat entopeduncular nucleus (EN), which is the main output of the basal ganglia, is known to project to the mesencephalic tegmentum. We have been able to elicit antidromic responses in single EN neurons from the region of the mesencephalic locomotor region (MLR), then transect (precollicular-postmamillary) the brainstem and elicit rhythmic movements of the limbs by stimulation of the same site in the same animal. Injections of the fluorescent dye 2,4 diamidino phenylindole 2 HCL (DAPI) into this area induces retrograde labeling of cell bodies in EN and motor cortex. Injections of a tritiated amino acid (leucine) into the motor cortex induce terminal labeling in the area of the MLR. These studies describe convergent projections from EN and motor cortex to the MLR. These connections may be involved in the sequencing and ordering of voluntary movements in which locomotion is necessary

Effects of Glutamate Receptor Agonists on the P13 Auditory Evoked Potential and Startle Response in the Rat

The P13 potential is the rodent equivalent of the P50 potential, which is an evoked response recorded at the vertex (Vx) 50 ms following an auditory stimulus in humans. Both the P13 and P50 potentials are only present during waking and rapid eye movement (REM) sleep, and are considered to be measures of level of arousal. The source of the P13 and P50 potentials appears to be the pedunculopontine nucleus (PPN), a brainstem nucleus with indirect ascending projections to the cortex through the intralaminar thalamus, mediating arousal, and descending inhibitory projections to the caudal pontine reticular formation (CPRF), which mediates the auditory startle response (SR). We tested the hypothesis that intracranial microinjection (ICM) of glutamate (GLU) or GLU receptor agonists will increase the activity of PPN neurons, resulting in an increased P13 potential response, and decreased SR due to inhibitory projections from the PPN to the CPRF, in freely moving animals. Cannulae were inserted into the PPN to inject neuroactive agents, screws were inserted into the Vx in order to record the P13 potential, and electrodes inserted into the dorsal nuchal muscle to record electromyograms and SR amplitude. Our results showed that ICM of GLU into the PPN dose-dependently increased the amplitude of the P13 potential and decreased the amplitude of the SR. Similarly, ICM of N-methyl-d-aspartic acid or kainate into the PPN increased the amplitude of the P13 potential. These findings indicate that glutamatergic input to the PPN plays a role in arousal control in vivo, and changes in glutamatergic input, or excitability of PPN neurons, could be implicated in a number of neuropsychiatric disorders with the common symptoms of hyperarousal and REM sleep dysregulation

Developmental Changes in Pedunculopontine Nucleus (PPN) Neurons

The developmental decrease in rapid-eye-movement (REM) sleep in man occurs between birth and after puberty. We hypothesize that if this decrease in REM sleep does not occur, lifelong increases in REM sleep drive may ensue. Such disorders are characterized by hypervigilance and sensory-gating deficits, such as are present in postpubertal onset disorders like schizophrenia, panic attacks (a form of anxiety disorder), and depression. The decrease in REM sleep in the rat occurs between 10 and 30 days of age. We studied changes in size and physiological properties of pedunculopontine nucleus (PPN) cells involved in the control of arousal, i.e., waking and REM sleep. During the largest decrease in REM sleep (12–21 days), cholinergic PPN neurons doubled in cell area, the hypertrophy peaking at 15–16 days, then decreasing in area by 20–21 days. Noncholinergic PPN cells did not change in area during this period. We confirmed the presence of two populations of PPN neurons based on action potential (AP) duration, with the proportion of short-AP-duration cells increasing and long AP duration decreasing between 12 and 21 days. Most cholinergic and noncholinergic cells had short AP durations. Afterhyperpolarization (AHP) duration became segregated into long and short AHP duration after 15 days. Cells with short AP duration also had short AHP duration. The proportion of PPN cells with Ih current increased gradually, peaking at 15 days, then decreased by 21 days. These changes in morphological and physiological properties are discussed in relation to the developmental decrease in REM sleep

Gamma band activity in the developing parafascicular nucleus

The parafascicular nucleus (Pf) receives cholinergic input from the pedunculopontine nucleus, part of the reticular activating system involved in waking and rapid eye movement (REM) sleep, and sends projections to the cortex. We tested the hypothesis that Pf neurons fire maximally at gamma band frequency (30–90 Hz), that this mechanism involves high-threshold voltage-dependent P/Q- and N-type calcium channels, and that this activity is enhanced by the cholinergic agonist carbachol (CAR). Patch-clamped 9- to 25-day-old rat Pf neurons (n = 299) manifested a firing frequency plateau at gamma band when maximally activated (31.5 ± 1.5 Hz) and showed gamma oscillations when voltage-clamped at holding potentials above −20 mV, and the frequency of the oscillations increased significantly with age (24.6 ± 3.8 vs. 51.6 ± 4.4 Hz, P < 0.001) but plateaued at gamma frequencies. Cells exposed to CAR showed significantly higher frequencies early in development compared with those without CAR (24.6 ± 3.8 vs. 41.7 ± 4.3 Hz, P < 0.001) but plateaued with age. The P/Q-type calcium channel blocker ω-agatoxin-IVA (ω-Aga) blocked gamma oscillations, whereas the N-type blocker ω-conotoxin-GVIA (ω-CgTx) only partially decreased the power spectrum amplitude of gamma oscillations. The blocking effect of ω-Aga on P/Q-type currents and ω-CgTx on N-type currents was consistent over age. We conclude that P/Q- and N-type calcium channels appear to mediate Pf gamma oscillations during development. We hypothesize that the cholinergic input to the Pf could activate these cells to oscillate at gamma frequency, and perhaps relay these rhythms to cortical areas, thus providing a stable high-frequency state for “nonspecific” thalamocortical processing.Fil: Kezunovic, Nebojsa. University Of Arkansas For Medical Sciences; Estados UnidosFil: Hyde, James. University Of Arkansas For Medical Sciences; Estados UnidosFil: Simon, Christen. University Of Arkansas For Medical Sciences; Estados UnidosFil: Urbano Suarez, Francisco Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Williams, D. Keith. University Of Arkansas For Medical Sciences; Estados UnidosFil: Garcia Rill, Edgar. University Of Arkansas For Medical Sciences; Estados Unido

Restoration of Frequency-Dependent Depression of the H-Reflex by Passive Exercise in Spinal Rats

Hyper-reflexia, measured as a decrease of low frequency-dependent depression of the H-reflex, is known to occur in both humans and animals after spinal cord injury (SCI). Previous studies have shown that passive exercise for 3 months could be used to restore low frequency-dependent depression of the H-reflex after SCI. To determine the effects of various periods of time on the ability of passive exercise to restore low frequency-dependent depression of the H-reflex. Spinal Cord Injury Mobilization Program of the Center for Translational Neuroscience, the research arm of the Jackson T Stephens Spine and Neuroscience Institute, Little Rock, AR, USA. Adult rats underwent complete spinal cord transection at the T10 level. The hindlimbs were passively exercised in different groups of rats for 1 h/day, 5 days/week for 15, 30, 45, 60, or 90 days, and low frequency-dependent depression of the H-reflex was tested. Statistically significant low frequency-dependent depression of the H-reflex was evident by 30 days of exercise, although numerical reductions were seen even at 15 days. There was a linear decrease in low frequency-dependent depression of the H-reflex with duration of passive exercise. Passive exercise can restore frequency-dependent depression of spinal reflexes in a time-dependent manner if used following complete spinal transection

Proteomic measures of gamma oscillations

Background: Gamma oscillations serve complex processes, and the first stage of their generation is the reticular activating system (RAS), which mediates the gamma-activity states of waking and paradoxical sleep. We studied whether the pedunculopontine nucleus (PPN), part of the RAS in which every cell manifests intrinsic gamma oscillations, undergoes changes resulting in distinctive protein expression. New method: We previously found that a histone deacetylation inhibitor, trichostatin A (TSA), acutely (30 min) blocked these oscillations. We developed a proteomic method for sampling stimulated and unstimulated PPN and determining protein expression in 1 mm punches of tissue from brain slices subjected to various treatments. Results: We compared brain slices exposed for 30 min to TSA (unstimulated), to the cholinergic agonist carbachol (CAR), known to induce PPN gamma oscillations, or exposed to both TSA + CAR. Comparison with existing methods: Label-free proteomics provides an unbiased and sensitive method to detect protein changes in the PPN. Our approach is superior to antibody-based methods that can lack specificity and can only be done for known targets. Proteomics methods like these have been leveraged to study molecular pathways in numerous systems and disease states. Conclusions: Significant protein changes were seen in two functions essential to the physiology of the PPN: cytoskeletal and intracellular [Ca2+] regulation proteins. TSA decreased, while CAR increased, and TSA + CAR had intermediate effects, on expression of these proteins. These results support the feasibility of the methods developed for determining proteomic changes in small samples of tissue participating in the most complex of brain processes.Fil: Byrum, Stephanie D.. Arkansas Children's Research Institute; Estados UnidosFil: Washam, Charity L.. Arkansas Children's Research Institute; Estados UnidosFil: Tackett, Alan J.. Arkansas Children's Research Institute; Estados UnidosFil: Garcia Rill, Edgar. University of Arkansas for Medical Sciences; Estados UnidosFil: Bisagno, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Urbano Suarez, Francisco Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Cholinergic modulation of the sleep state-dependent P13 midlatency auditory evoked potential in the rat

Abstract Injections into the pedunculopontine nucleus (PPN) of the cholinergic receptor agonist, carbachol (CAR), were found to reduce the amplitude of the vertex-recorded, sleep state-dependent P13 midlatency evoked potential in a dose-and time-dependent manner. This effect was blocked or reduced by pretreatment with the muscarinic receptor antagonist, scopolamine, injected into the PPN. © 2000 Elsevier Science B. V. All rights reserved. . The present characteristics of this potential in both species are (1) sleep study was conducted to determine if injections of a state-dependence (it is present during waking and paradoxcholinergic (muscarinic receptor) agonist into the region of ical sleep, but absent during slow wave sleep, i.e. during the PPN would affect the manifestation of the vertexstates of cortical EEG synchronization of high frequencies recorded P13 potential, and whether or not such an effect but absent during synchronization of low frequencies), skull. Guide cannulae were implanted stereotaxically 2 mm Cholinergic mesopontine neurons of the PPN are also dorsal to the PPN (A: 1.0, L: 1.9, H: 3.0

Defects in Chiral Columnar Phases: Tilt Grain Boundaries and Iterated Moire Maps

Biomolecules are often very long with a definite chirality. DNA, xanthan and poly-gamma-benzyl-glutamate (PBLG) can all form columnar crystalline phases. The chirality, however, competes with the tendency for crystalline order. For chiral polymers, there are two sorts of chirality: the first describes the usual cholesteric-like twist of the local director around a pitch axis, while the second favors the rotation of the local bond-orientational order and leads to a braiding of the polymers along an average direction. In the former case chirality can be manifested in a tilt grain boundary phase (TGB) analogous to the Renn-Lubensky phase of smectic-A liquid crystals. In the latter case we are led to a new "moire" state with twisted bond order. In the moire state polymers are simultaneously entangled, crystalline, and aligned, on average, in a common direction. In the moire state polymers are simultaneously entangled, crystalline, and aligned, on average, in a common direction. In this case the polymer trajectories in the plane perpendicular to their average direction are described by iterated moire maps of remarkable complexity, reminiscent of dynamical systems.Comment: plain TeX, (33 pages), 17 figures, some uufiled and included, the remaining available at ftp://ftp.sns.ias.edu/pub/kamien/ or by request to [email protected]

A randomized phase I study of the safety and immunogenicity of three ascending dose levels of a 3-antigen Staphylococcus aureus vaccine (SA3Ag) in healthy adults

Background: Staphylococcus aureus is a common cause of healthcare-acquired morbidity and mortalityand increased healthcare resource utilization. A prophylactic vaccine is being developed that may reducethis disease burden.Methods: Volunteers in good general health aged 50–85 (n = 312) and 18–24 (n = 96) years were random-ized to receive a single intramuscular dose of one of three dose levels of a non-adjuvanted, 3-antigen S.aureus vaccine (SA3Ag) or placebo. SA3Ag antigens included capsular polysaccharides 5 and 8 (CP5 andCP8), each conjugated to cross-reactive material 197 (CRM197), and recombinant clumping factor A (ClfA).Safety, tolerability, and immunogenicity were evaluated.Results: At day 29 post-vaccination, robust immune responses were observed in both age cohorts at allthree SA3Ag dose levels. In the primary analysis population, the 50- to 85-year age stratum, geometricmean-fold-rises in competitive Luminex® immunoassay antibody titers from baseline ranged from 29.2to 83.7 (CP5), 14.1 to 31.0 (CP8), and 37.1 to 42.9 (ClfA), all (P < 0.001) exceeding the pre-defined two-fold rise criteria. Similar rises in opsonophagocytic activity assay titers demonstrated functionality ofthe immune response. Most injection-site reactions were mild in severity and there were no substantial differences (SA3Ag vs. placebo) with regard to systemic or adverse events.Conclusions: In this study of healthy adults aged 50–85 and 18–24 years, SA3Ag elicited a rapid and robustimmune response and was well tolerated, with no notable safety concerns.Michael Nissen, Helen Marshall, Peter Richmond, Sepehr Shakib, Qin Jiang, David Cooper, Denise Rill, James Baber, Joseph Eiden, William Gruber, Kathrin U. Jansen, Emilio A. Emini, Annaliesa S. Anderson, Edward T. Zito, Douglas Girgent

Symmetries of Electrostatic Interaction between DNA Molecules

We study a model for pair interaction $U$ of DNA molecules generated by the discrete dipole moments of base-pairs and the charges of phosphate groups, and find noncommutative group of eighth order ${\cal S}$ of symmetries that leave $U$ invariant. We classify the minima using group ${\cal S}$ and employ numerical methods for finding them. The minima may correspond to several cholesteric phases, as well as phases formed by cross-like conformations of molecules at an angle close to $\rm{90}^{o}$, "snowflake phase". The results depend on the effective charge $Q$ of the phosphate group which can be modified by the polycations or the ions of metals. The snowflake phase could exist for $Q$ above the threshold $Q_C$. Below $Q_C$ there could be several cholesteric phases. Close to $Q_C$ the snowflake phase could change into the cholesteric one at constant distance between adjacent molecules.Comment: 13 pages, 4 figure