Brainstem Cholinergic Modulation of Muscle Tone in Infant Rats

In week-old rats, lesions of the dorsolateral pontine tegmentum (DLPT) and nucleus pontis oralis (PnO) have opposing effects on nuchal muscle tone. Specifically, pups with DLPT lesions exhibit prolonged bouts of nuchal muscle atonia (indicative of sleep) and pups with PnO lesions exhibit prolonged bouts of high nuchal muscle tone (indicative of wakefulness). Here we test the hypothesis that nuchal muscle tone is modulated, at least in part, by cholinergically mediated interactions between these two regions. First, in unanesthetized pups, we found that chemical infusion of the cholinergic agonist carbachol (22 mM, 0.1 µL) within the DLPT produced high muscle tone. Next, chemical lesions of the nucleus pontis oralis (PnO) were used to produce a chronic state of high nuchal muscle tone, at which time the cholinergic antagonist scopolamine (10 mM, 0.1 µL) was infused into the DLPT. Scopolamine effectively decreased nuchal muscle tone, thus suggesting that lesions of the PnO increase muscle tone via cholinergic activation of the DLPT. Using 2-deoxyglucose (2-DG) autoradiography, metabolic activation throughout the DLPT was observed after PnO lesions. Finally, consistent with the hypothesis that PnO inactivation produces high muscle tone, infusion of the sodium channel blocker, lidocaine (2%), into the PnO of unanesthetized pups produced rapid increases in muscle tone. We conclude that, even early in infancy, the DLPT is critically involved in the regulation of muscle tone and behavioral state and that its activity is modulated by a cholinergic mechanism that is directly or indirectly controlled by the PnO

The Development of Sleep-Wake Rhythms and the Search for Elemental Circuits in the Infant Brain

Despite the predominance of sleep in early infancy, developmental science has yet to play a major role in shaping concepts and theories about sleep and its associated ultradian and circadian rhythms. Here we argue that developmental analyses help us to elucidate the relative contributions of the brainstem and forebrain to sleep-wake control and to dissect the neural components of sleep-wake rhythms. Developmental analysis also makes it clear that sleep-wake processes in infants are the foundation for those of adults. For example, the infant brainstem alone contains a fundamental sleep-wake circuit that is sufficient to produce transitions among wakefulness, quiet sleep, and active sleep. In addition, consistent with the requirements of a flip-flop model of sleep-wake processes, this brainstem circuit supports rapid transitions between states. Later in development, strengthening bidirectional interactions between the brainstem and forebrain contribute to the consolidation of sleep and wake bouts, the elaboration of sleep homeostatic processes, and the emergence of diurnal or nocturnal circadian rhythms. The developmental perspective promoted here critically constrains theories of sleep-wake control and provides a needed framework for the creation of fully realized computational models. Finally, with a better understanding of how this system is constructed developmentally, we will gain insight into the processes that govern its disintegration due to aging and disease

Role of Iron, Light, and Silicate in Controlling Algal Biomass in Subantarctic Waters SE of New Zealand

Phytoplankton processes in subantarctic (SA) waters southeast of New Zealand were studied during austral autumn and spring 1997. Chlorophyll a (0.2–0.3 μg L−1) and primary production (350–650 mg C m−2 d−1) were dominated by cells μm (cyanobacteria) in both seasons. The photochemical efficiency of photosystem II (Fυ/Fm) of cells was low (0.3), indicating physiological stress. Dissolved Fe (DFe) levels in surface waters were subnanomolar, and the molecular marker flavodoxin indicated that cells were iron stressed. In contrast, Subtropical Convergence (STC) and subtropical waters had higher algal biomass/production levels, particularly in spring. In these waters, DFe levels were \u3e1 nmol kg−1, there was little evidence of Fe-stressed algal populations, and Fυ/Fm approached 0.60 at the STC. In addition to these trends, waters of SA origin were occasionally observed within the STC and north of the STC, and thus survey data were interpreted with caution. In vitro Fe enrichment incubations in SA waters resulted in a switch from flavodoxin expression to that of ferredoxin, indicating the alleviation of Fe stress. In another 6-day experiment, iron-mediated increases in chlorophyll a (in particular, increases in large diatoms) were of similar magnitude to those observed in a concurrent Si/Fe enrichment; ambient silicate levels were 4 μM. A concurrent in vitro Fe enrichment, at irradiance levels comparable to the calculated mean levels experienced by cells in situ, resulted in relatively small increases (approximately twofold) in chlorophyll a. Thus, in spring, irradiance and Fe may both control diatom growth. In contrast, during summer, as mean irradiance increases and silicate levels decrease, Fe limitation, Fe/Si colimitation, or silicate limitation may determine diatom growth

Distinct Retinohypothalamic Innervation Patterns Predict the Developmental Emergence of Species-typical Circadian Phase Preference in Nocturnal Norway Rats and Diurnal Nile Grass Rats

How does the brain develop differently to support nocturnality in some mammals, but diurnality in others? To answer this question, one might look to the suprachiasmatic nucleus (SCN), which is entrained by light via the retinohypothalamic tract (RHT). However, because the SCN is more active during the day in all mammals studied thus far, it alone cannot determine circadian phase preference. In adult Norway rats (Rattus norvegicus), which are nocturnal, the RHT also projects to the ventral subparaventricular zone (vSPVZ), an adjacent region that expresses an in-phase pattern of SCN-vSPVZ neuronal activity. In contrast, in adult Nile grass rats (Arvicanthis niloticus), which are diurnal, an anti-phase pattern of SCN-vSPVZ neuronal activity is expressed. We hypothesized that these species differences result in part from a weak or absent RHT-to-vSPVZ projection in grass rats. Here, using a developmental comparative approach, we assessed species differences in behavior, hypothalamic activity, and RHT anatomy. We report that a robust retina-to-vSPVZ projection develops in Norway rats around the end of the second postnatal week when nocturnal wakefulness and the in-phase pattern of neuronal activity emerge. In grass rats, however, such a projection does not develop and the emergence of the anti-phase pattern during the second postnatal week is accompanied by increased diurnal wakefulness. When considered within the context of previously published reports on RHT projections in a variety of species, the current findings suggest that how and when the retina connects to the hypothalamus differentially shapes brain and behavior to produce animals that occupy opposing temporal niches

High throughput methodology for synthesis, screening, and optimization of solid state Lithium ion electrolytes

A study of the lithium ion conductor Li3xLa2/3–xTiO3 solid solution and the surrounding composition space was carried out using a high throughput physical vapor deposition system. An optimum total ionic conductivity value of 5.45 × 10–4 S cm–1 was obtained for the composition Li0.17La0.29Ti0.54 (Li3xLa2/3–xTiO3x = 0.11). This optimum value was calculated using an artificial neural network model based on the empirical data. Due to the large scale of the data set produced and the complexity of synthesis, informatics tools were required to analyze the data. Partition analysis was carried out to determine the synthetic parameters of importance and their threshold values. Multivariate curve resolution and principal component analysis were applied to the diffraction data set. This analysis enabled the construction of phase distribution diagrams, illustrating both the phases obtained and the compositional zones in which they occur. The synthetic technique presented has significant advantages over other thin film and bulk methodologies, in terms of both the compositional range covered and the nature of the materials produce

Tree Biomass and Carbon Storage in an Old Growth Forest in Southeastern Ohio

Recently there has been increased interest in determining the baseline levels of carbon storage in different ecosystems, because of greater concern over the issue of global climate change and increased atmospheric CO2 concentrations. With a better understanding of carbon sequestration in various ecosystems, we can use land in a more environment-conscious way, and negative human impacts on the earth can be decreased. Forest ecosystems are especially important, because they have an immense capacity to store carbon as compared to other ecosystems. The majority of carbon sequestered in forest ecosystems is contained in tree biomass, but there is also carbon contained in soil, leaf litter, and necromass. The primary objective of our experiment was to determine and compare the baseline amount of carbon sequestered in the biomass of different forest plots: old-growth versus young-growth and north-facing versus south-facing. We also compared these results to data that had been collected from the same plots in 2003. We found that for the most part, the amount of biomass had decreased; the only exception was the north-facing young-growth stand. This forest plot contained the most biomass, followed by the old-growth south-facing, then the young-growth south-facing, then the old-growth north-facing. We believe that the reason for the overall decrease in biomass was a large number of fallen trees

The Development of Day-night Differences in Sleep and Wakefulness in Norway Rats and the Effect of Bilateral Enucleation

The suprachiasmatic nucleus (SCN) exhibits circadian rhythmicity in fetal and infant rats, but little is known about the consequences of this rhythmicity for infant behavior. Here, in Experiment 1, we measured sleep and wakefulness in rats during the day and night in postnatal day (P)2, P8, P15 and P21 subjects. As early as P2, day-night differences in sleep-wake activity were detected. Nocturnal wakefulness began to emerge around P15 and was reliably expressed by P21. We hypothesized that the process of photic entrainment over the first postnatal week, which depends upon the development of connectivity between the retinohypothalamic tract (RHT) and the SCN, influences the later emergence of nocturnal wakefulness. To test this hypothesis, in Experiment 2 infant rats were enucleated bilaterally at P3 and P11, that is, before and after photic entrainment. Whereas pups enucleated at P11 and tested at P21 exhibited increased wakefulness at night, identical to sham controls, pups enucleated at P3 and tested at P21 exhibited the opposite pattern of increased wakefulness during the day. Pups tested at P28 and P35 exhibited this same pattern of increased daytime wakefulness. All together, these results suggest that prenatal and postnatal experience modulates the development of species-typical circadian sleep-wake patterns. Moreover, we suggest that visual system stimulation, via the RHT’s connections with the SCN, exerts an organizational influence on the developing circadian system and, consequently, contributes to the emergence of nocturnality in this species

Tissue Penetration of Meropenem in Patients Undergoing Gynecologic Surgery

The purpose of this study was to assess the tissue-penetrating ability of a new β-lactam antibiotic, meropenem, in 64 patients undergoing elective gynecologic surgery. Patients received a single 500-mg dose intravenously before surgery. Plasma and tissue concentrations of meropenem were highest at ∼1 hour, and good tissue penetration was seen in the variety of specimens evaluated. The median plasma concentration at ∼1 hour was 13.3 µg/mL. The median fluid and tissue concentrations at ∼1 hour were as follows: cervix, 8.5 µg/g; endometrium, 2.3 µg/g; fallopian tube, 1.9 µg/g; myometrium, 3.6 µg/g; ovary, 2.3 µg/g; and uterus, 2.3 µg/g. These tissue concentrations exceed the MICs of meropenem for 90% of typical pathogens associated with gynecologic infections. Meropenem readily penetrates gynecologic tissue. A single 500-mg dose provides adequate tissue concentrations for treatment of gynecologic infections caused by susceptible pathogen

Double-Blind, Multicenter, Prospective Randomized Study of Trospectomycin Vs. Clindamycin, Both With Aztreonam, in Non-Community Acquired Obstetric and Gynecologic Infections

Objective: The purpose of this study was to compare the clinical efficacy and safety of trospectomycin sulfate with that of clindamycin phosphate, both with aztreonam, for the treatment of obstetric and gynecologic infections