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Paul Tompkins and Jordi Nomen discuss how to teach philosophy to children and adolescents, and examine the role that language and dialogue play in the development of critical thinking. Paul Tompkins i Jordi Nomem conversen sobre com ensenyar filosofia a nens i adolescents, i sobre el paper que juguen la llengua i el diàleg en el desenvolupament del pensament crític. Paul Tompkins y Jordi Nomem conversan sobre cómo enseñar filosofía a niños y adolescentes, y sobre el papel que juegan la lengua y el diaólogo en el desarrollo del pensamiento crítico.

Mild traumatic brain injury (mTBI) diagnoses have increased due to aggressive sports and blast-related injuries, but the cellular mechanisms and pathology underlying mTBI are not completely understood. Previous reports indicate that Nociceptin Orphanin/FQ (N/OFQ), an endogenous neuropeptide, contributes to post-injury ischemia following mechanical brain injury, yet its specific role in cerebral hypoxia, vestibulomotor function and injury marker expression following blast-induced TBI is not known. This study is the first to identify a direct association of N/OFQ and its N/OFQ peptide (NOP) receptor with TBI-induced changes following a single 80psi head blast exposure in male rats. N/OFQ and NOP receptor expression increased in brain tissue and plasma following TBI, concurrent with vestibular dysfunction but preceding hypoxia and appearance of injury markers compared to sham rats. A single post-blast treatment with the NOP receptor antagonist, SB-612111, transiently improved acute vestibulomotor performance. It also prevented increases in markers of TBI-induced hypoxia, pro-apoptotic proteins and injury seen 8-10days post-blast. This study reveals an apparent role for the N/OFQ-NOP receptor system in blast TBI and suggests potential therapeutic utility of NOP receptor antagonists for mTBI.

Groupers are vulnerable to fishing pressure largely because of their life‐history traits. The Pacific goliath grouper (PGG; Epinephelus quinquefasciatus), the largest reef fish inhabiting the tropical Eastern Pacific region, is suspected to be subject to high levels of exploitation, but scarce information exists on their population status and the species remains classed as Data Deficient according to the International Union for Conservation of Nature (IUCN) Red List. This study documents for the first time the threats to the PGG along the Colombian Pacific coast, where one of the few active fisheries for this species persists. Reconstructed landings of groupers and traditional ecological knowledge, gathered throughout several coastal villages, were used to obtain a historical and contemporary overview of the PGG status in Colombia. Over the past 20 years grouper landings in the Colombian Pacific have been around 200 tons per year. Landings of PGG have averaged ~35 tons per year and are now close to matching those of the historically most landed grouper on this coast, the rooster hind (Hyporthodus acanthistius). The current small‐scale fishery for PGG focuses on immature small individuals, with most taken from the extensive southern mangroves. Until recently fishers have captured PGG exclusively with handlines, but new fishing practices (spearfishing) and markets commanding higher prices for small individuals are increasing the extinction risk for the PGG. The exploitation of PGG in the Colombian Pacific may not be as severe as in other countries where severe population declines are suspected (e.g. Mexico). Low coastal human population density and the presence of relatively intact mangroves, essential habitat for juvenile fishes, contribute to the persistence of PGG populations throughout the Colombian Pacific. National and regional conservation and management measures should identify and protect mangrove nurseries and offshore spawning aggregation sites. Well‐enforced protected nurseries and spawning aggregation sites will then protect juvenile and adult PGG, improving the sustainability of this fishery.

Background There is an emerging consensus that clinicians should initiate a proactive "goals of care conversation" (GoCC) with patients whose serious illness is likely to involve decisions about life-sustaining treatments (LSTs) such as artificial nutrition, ventilator support, or cardiopulmonary resuscitation. This conversation is intended to elicit the patient's values, goals, and preferences as a basis for shared decisions about treatment planning. LST decisions are often postponed until the patient is within days or even hours of death and no longer able to make his or her goals and preferences known. Decisions then fall to surrogates who may be uncertain about what the patient would have wanted. Life-Sustaining Treatment Decisions Initiative (LSTDI) The Veterans Health Administration's Life-Sustaining Treatment Decisions Initiative (LSTDI) was designed to ensure that patients' goals, values, and preferences for LSTs are elicited, documented, and honored across the continuum of care. The LSTDI includes a coordinated set of evidence-based strategies that consists of enterprisewide practice standards for conducting, documenting, and supporting high-quality GoCCs; staff training to enhance proficiency in conducting, documenting, and supporting GoCCs; standardized, durable electronic health record tools for documenting GoCCs; monitoring and information technology tools to support implementation and improvement; a two-year multifacility demonstration project conducted to test and refine strategies and tools and to identify strong practices; and a program of study to evaluate the LSTDI and identify strategies critical to improving care for patients with serious illness. Conclusion The LSTDI moves beyond traditional advance care planning by addressing well-documented barriers to goal-concordant care for seriously ill patients.

Previous work has highlighted the critical role of macroalgal productivity and dynamics in supporting and structuring marine food webs. Spatio-temporal variability in macroalgae can alter coastal ecosystems, a relationship particularly visible along upwelling-influenced coastlines. As a result of its equatorial location and nutrient rich, upwelling-influenced waters, the Galápagos Archipelago in the East Pacific, hosts a productive and biodiverse marine ecosystem. Reports and collections of macroalgae date back to the Beagle voyage, and since then, more than three hundred species have been reported. However, their ecology and functional role in the ecosystem is not well understood. According to various disparate and in part anecdotal sources of information, abundant and diverse communities exist in the Western regions of the archipelago, the North is essentially barren, and in the central/South abundance and distribution is variable and less well defined. Both oceanographic conditions and herbivore influence have been theorized to cause this pattern. Extensive changes in macroalgal productivity and community composition have occurred during strong ENSO events, and subsequent declines in marine iguana (an endemic and iconic grazer) populations have been linked to these changes. Iguanas are only one species of a diverse and abundant group of marine grazers in the system, highlighting the potentially important role of macroalgal productivity in the marine food web. This review represents a first compilation and discussion of the available literature and presents topics for future research. Rev. Biol. Trop. 65 (1): 375-392. Epub 2017 March 01. ResumenTrabajos previos han destacado el papel fundamental de la productividad y dinámica de las macroalgas en el mantenimiento y estructuración de las cadenas alimentarias marinas. La variabilidad espacio temporal de las macroalgas puede alterar ecosistemas costeros, particularmente visibles a lo largo del perfil costero en zonas de proliferación. Como resultado de su ubicación ecuatorial y riqueza en nutrientes, además de eventos de proliferación, el Archipiélago de Galápagos en el Pacífico Oriental acoge un productivo y biodiverso ecosistema marino. Informes y recolección de macroalgas se remontan desde el viaje del Beagle, y desde entonces se han informado más de trescientas especies. No obstante, su función ecológica en el ecosistema no ha sido bien comprendida. Según diversas fuentes de información y en parte anecdóticas, existen abundantes y diversas comunidades de macroalgas en las regiones occidentales del archipiélago, el norte es sustancialmente estéril, y en el centro/sur la abundancia y distribución es variable y menos definida. Tanto las condiciones oceanográficas y la influencia de herbívoros han sido teorizadas para causar este patrón. Grandes cambios en la composición de la productividad y comunidad de macroalgas se han producido durante eventos ENOS fuertes y subsecuentemente han provocado la disminución de poblaciones de iguana marina (herbívoro endémico e icónico) y han sido vinculados a estos cambios. Las iguanas marinas son sólo una de las especies de un grupo diverso y abundante de herbívoros marinos en el sistema, destacando potencialmente el importante rol de la productividad de macroalgas en la cadena alimentaria marina. Esta revisión representa una primera recopilación y análisis de la literatura disponible y presenta temas para futuras investigaciones.

Panama ranks among the top 20 nations in the world for mangrove area, with 1328 km2 ([ 1 ][1]). The mangroves of Panama Bay, near Panama City, represent 20% of that total ([ 2 ][2]). They are recognized as the most important staging site for migratory birds in the Americas, and they support valuable

For a long time the goliath grouper was considered to be a single species distributed along both tropical coasts of the Americas (Eastern Pacific and Western Atlantic including the Caribbean). However, goliath groupers are now distinguished as being two different species and inhabiting the Caribbean and the Atlantic Ocean (Epinephelus itajara) as well as the Tropical Eastern Pacific (Epinephelus quinquefasciatus) (Craig et al., 2009). The Atlantic goliath grouper has been heavily exploited throughout its range. Heavy exploitation and severe population declines are also suspected in various distributional regions of E. quinquefasciatus (Mexican and Panamanian Pacific) (Craig, 2011; Erisman, 2013). Provided here is first time data on length–weight relationships (LWR) of E. quinquesfaciatus from specimens landed in different fishing ports on the Colombian Pacific coast.

Object. This study was conducted to evaluate peripheral nerve regeneration through a conduit composed of a bioresorbable material (LactoSorb). Methods. Sprague—Dawley rats weighing approximately 250 g were randomized into five groups. A 20-mm-long sciatic nerve gap was created, then it was bridged by a reverse nerve autograft (Group I), an empty silicone tube (Group II), a silicone tube containing a short (2-mm) interposed nerve segment (Group III), an empty LactoSorb conduit (Group IV), or a LactoSorb conduit containing a 2-mm interposed nerve segment (Group V). The intact sciatic nerve served as the control in each animal. At 16 weeks postoperatively, no nerve regeneration was observed through either the empty silicone tube or the empty LactoSorb conduit. There was regeneration in all animals receiving the reverse autograft as well as in all animals receiving the silicone or LactoSorb conduit containing the 2-mm interposed nerve segment. Effective regeneration was assessed based on histological, electrophysiological, and morphometric criteria. Conclusions. The results indicate that a conduit made of resorbable material will support sciatic nerve regeneration over a critical gap defect.

Object. Exogenous progesterone has been shown to reduce brain edema and ischemia-induced cell damage and to improve physiological and neurological function during the early stage of focal cerebral ischemia. In the present study, the authors assessed the neuroprotective potential of progesterone during the late stage of ischemia in a transient middle cerebral artery (MCA) occlusion model in the rat.Methods. Forty-eight male spontaneously hypertensive rats were randomly assigned to six groups. Progesterone was dissolved in dimethyl sulfoxide (DMSO). In four groups of rats, the dissolved progesterone (4 mg/kg or 8 mg/kg) was administered for 2 or 7 days after ischemia. In two control groups DMSO was administered for 2 or 7 days after ischemia. Occlusion of the MCA was induced by insertion of an intraluminal suture, and reperfusion was accomplished by withdrawal of the suture. Treatment was initiated on reperfusion, which followed 2 hours of MCA occlusion, and continued once a day. Lesion volume, neurological deficit, and body weight loss were measured 2 or 7 days after ischemia, depending on the animal group.Treatment with a high dose of progesterone (8 mg/kg) resulted in reductions in lesion size, neurological deficits, and body weight, compared with control rats.Conclusions. Administration of progesterone to male rats 2 hours after MCA occlusion reduces ischemic brain damage and improves neurological deficit even 7 days after ischemia.

Blast wave-induced traumatic injury from terrorist explosive devices can occur at any time in either military or civilian environments. To date, little work has focused on the central nervous system response to a non-penetrating blast injury. We have evaluated the effect of a single 80-psi blast-overpressure wave in a rat model. Histological and immunochemical studies showed an early inflammatory response, tissue damage and the initiation of apoptosis. With regard to inflammation, polymorphonuclear leukocytes and lymphocytes infiltrated brain parenchyma within 1 h post-blast. Glial-fibrillary protein, cyclo-oxygenase-2ir, interleukin-1β and tumor necrosis factor were present by 1 h and remained detectable at three weeks post-injury. High mobility group box-1 protein was detectable at three weeks. With regard to tissue damage, S100β and 4-hydroxynonenal were present at 1 h and remained detectable at three weeks. Amyloid precursor protein was detectable at three weeks. As for apoptosis, Cleaved Caspase-3 was detectable at three weeks. Morris water maze assessment of cognitive function showed that blast injured animals required significantly more time to reach the platform on day 1 of training and traveled a greater distance to get to the platform on days 1 and 2. Blast-injured animals showed a significant increase in swimming speed (p

Gliomas consist of up to 80% of malignant brain tumors that are invasive and typically resistant to radiotherapy and chemotherapy. Finding biomarkers to high-grade gliomas can enable better diagnosis and therapeutic intervention for this disease. We have identified ELTD1 as a biomarker for high-grade human gliomas. Here, we report our findings in vivo using anti-ELTD1 (at two different concentrations), Bevacizumab, and IgG antibodies on human G55 xenograft glioma models. Using MRI, we investigate tumor growth, perfusion, tumor blood flow, and microvessel density changes in mice. In addition, survival rates were measured. Mice were implanted with human G55 xenograft glioma cells and were left untreated, administered anti-ELTD1, (1 mg/kg or 2 mg/kg every 2-3 days) Bevacizumab (2 mg/kg every 2-3 days) or IgG (1 mg/kg every 2-3 days). MRI experiments were performed to assess tumor growth and calculate tumor volumes. In order to assess angiogenesis, representative histology slides were obtained and stained for blood vessels using CD34 antibody and microvessel density (MVD) was then calculated. Finally, cerebral blood flow rates from MR perfusion imaging was obtained as well as MR angiography to determine tumor blood volume from mice in each group. Our results show a significant decrease in tumor volumes and increase in percent survival for mice treated with 1 mg/kg and 2 mg/kg of ELTD1 antibody compared to untreated mice and IgG treated mice. Mice also had an increase in perfusion, decrease in tumor blood volume and decrease in MVD. Anti-ELTD1 antibody therapy reduced tumor volumes, prolonged life, and overall decreased angiogenesis in our mouse model. Anti-ELTD1 therapy may be an ideal anti-angiogenic treatment for high-grade gliomas. Citation Format: Jadith Ziegler, Nataliya Smith, Debra Saunders, Blake Evans, James D. Battiste, Michael Sughrue, Paul Tompkins, Jake Sutton, Megan Lerner, Patricia Coutinho de Souza, Kar-Ming Fung, Jonathan Wren, Rheal Towner. Eltd1 as an anti-angiogenic therapy against glioma tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3267.

Protecting military personnel from blast-induced traumatic brain injury (TBI) has been a tremendous challenge. TBI results in hypoxia and ischemia reperfusion injury to the brain. Nociceptin (Noc), an endogenous peptide, is upregulated within one hour of TBI, impairs cerebral reactivity and exacerbates TBI by activating proapoptotic cascades. Long term neuroprotection involves inhibition of NF-appaB (NFkB). We hypothesized that activation of NFkB by the elevated Noc following blast-induced TBI contributes to metabolic and cellular changes underlying the appearance of neuronal and cognitive defects. Our objective was to determine if ORL1 antagonists will be neuroprotective against NFkB activation in a blast-induced TBI rat model and in cultured neuronal cells. TBI was simulated by shock tube to the head or chest; both reduced cerebral glucose uptake, especially to the thalamus, hippocampus and cerebellum as determined by 18-F-FDG uptake and PET imaging. Brain blast (80 psi) significantly reduced vestibulomotor function as determined with rotarod. Brain tissue histology revealed that markers for apoptosis and reactive gliosis were significantly elevated in the cerebellum and Noc levels trended towards significance. Apoptotic and neuronal injury markers were also elevated in sensory and motor cortex, consistent with the blast and the behavioral deficits measured. Cognitive defects were assessed using Morris water maze (MWM). NFkB activation by Noc was demonstrated by an NFkB reporter gene assay in SH-SY5Y and NG108-15 neuroblastoma cells. Noc also stimulated NFkB binding to DNA that was specifically blocked by ORL1 antagonism, and Noc also activated RSK signaling cascades in both cell lines.

The LCROSS (Lunar Crater Observation and Sensing Satellite) project presented a number of challenges to the preparation for mission operations. A class D mission under NASA s risk tolerance scale, LCROSS was governed by a $79 million cost cap and a 29 month schedule from "authority to proceed" to flight readiness. LCROSS was NASA Ames Research Center s flagship mission in its return to spacecraft flight operations after many years of pursuing other strategic goals. As such, ARC needed to restore and update its mission support infrastructure, and in parallel, the LCROSS project had to newly define operational practices and to select and train a flight team combining experienced operators and staff from other arenas of ARC research. This paper describes the LCROSS flight team development process, which deeply involved team members in spacecraft and ground system design, implementation and test; leveraged collaborations with strategic partners; and conducted extensive testing and rehearsals that scaled in realism and complexity in coordination with ground system and spacecraft development. As a testament to the approach, LCROSS successfully met its full mission objectives, despite many in-flight challenges, with its impact on the lunar south pole on October 9, 2009.

As nations continue to explore space, the desire to reduce costs will continue to grow. As a method of cost reduction, transporting and/or use of launch system components as integral components of missions may become more commonplace in the future. There have been numerous scenarios written for using launch vehicle components (primarily space shuttle used external tanks) as part of flight missions or future habitats. Future studies for possible uses of launch vehicle upper stages might include asteroid diverter using gravity orbital perturbation, orbiting station component, raw material at an outpost, and kinetic impactor. The LCROSS (Lunar CRater Observation and Sensing Satellite) mission was conceived as a low-cost means of determining whether water exists at the polar regions of the moon. Manifested as a secondary payload with the LRO (Lunar Reconnaissance Orbiter) spacecraft aboard an Atlas V launch vehicle, LCROSS guided its spent Centaur Earth Departure Upper Stage (EDUS) into the lunar crater Cabeu's, as a kinetic impactor. This paper describes some of the challenges that the LCROSS project encountered in planning, designing, launching with and carrying the Centaur upper stage to the moon.

The LCROSS (Lunar CRater Observation and Sensing Satellite) mission was conceived as a low-cost means of determining the nature of hydrogen concentrated at the polar regions of the moon. Co-manifested for launch with LRO (Lunar Reconnaissance Orbiter), LCROSS guided its spent Centaur upper stage into the Cabeus crater as a kinetic impactor, and observed the impact flash and resulting debris plume for signs of water and other compounds from a Shepherding Spacecraft. Led by NASA Ames Research Center, LCROSS flight operations spanned 112 days, from June 18 through October 9, 2009. This paper summarizes the experiences from the LCROSS flight, highlights the challenges faced during the mission, and examines the reasons for its ultimate success.

The effect of 2 minutes of apnea during endotracheal intubation on intracranial pressure (ICP), compliance, and cerebral blood volume (CBV) was studied in 19 adult dogs during normo-, hypo-, and hypercapnia. The compliance was measured from the cisterna magna in response to an intrathecal bolus injection (pressure-volume index). CBV was monitored by radiolabeled red blood cell activity. These measurements were made before and after 2 minutes of apnea. At normocapnia (pCO2 of 35-40 mm Hg), a period of apnea resulted in an increase in ICP from 9.6 to 26.3 mm Hg, a decrease in compliance from 0.051 to 0.020 ml/mm Hg (60%), and an increase in CBV of 0.26 ml (9.6%). When the animals were hypocapnic (pCO2 of 24-28 mm Hg), ICP increased from 12.8 to 19.6 mm Hg, compliance fell from 0.041 to 0.029 ml/mm Hg(29%), and CBV increased 0.07 ml (3.1%). Hypercapnia (pCO2 of 50-58 mm Hg) before apnea resulted in an increase in ICP from 21.5 to 47.1 mm Hg, a decrease in compliance from 0.032 to 0.015 ml/mm Hg (52%), and an increase in CBV of 0.41 ml (13.4%). These results suggest that hyperventilation (hypocapnia) before intubation limits the adverse decrease in brain compliance and increase in ICP by reducing changes in cerebral blood volume.

The Atacama Desert of northern Chile may be the most lifeless place on Earth, yet where the desert meets the Pacific coastal range desiccation-tolerant micro-organisms are known to exist. The gradient of biodiversity and habitats in the Atacama’s subregions remain unexplored and are the focus of the Life in the Atacama project. To conduct this investigation, long traverses must be made across the desert with instruments for geologic and biologic measurements. In this paper we motivate the Life in the Atacama project from both astrobiologic and robotic perspectives. We focus on some of the research challenges we are facing to enable endurance navigation, resource cognizance, and long-term survivability. We conducted our first scientific investigation and technical experiments in Chile with the mobile robot Hyperion. We describe the experiments and the results of our analysis. These results give us insight into the design of an effective robotic astrobiologist and into the methods by which we will conduct scientific investigation in the next field season.

TEMPEST is a planner for long-range planetary navigation that bridges the gap between path planning and classical planning and scheduling. In addition to planning routes, our approach yields the timing and placement of actions to conserve and restore expendable resources and that abide by operational constraints. TEMPEST calls upon the incremental search engine (ISE) to enable heuristic path planning and efficient re-planning under global constraints, over a four dimensional state space. We describe our approach, then demonstrate how the planner operates in a simulated Mars science traverse. Following a brief summary of TEMPEST results from a recent rover field experiment, we evaluate our research progress and describe our current and future work.

Describes TEMPEST, a planner that enables a solar-powered rover to reason about path selection and event placement in terms of available solar energy and anticipated power draw. Unlike previous path planners, TEMPEST solves the coupled path, path timing and resource management problem. It combines information about mission objectives, operational constraints, the planetary environment and rover performance, and employs the Incremental Search Engine, a search algorithm that produces optimal paths through high-dimensional spaces. In July 2001, TEMPEST supported the Sun-Synchronous Navigation Field Experiment on Devon Island in the Canadian Arctic. The planner successfully selected time-sequenced, closed-circuit paths that enabled a solar-powered planetary rover prototype to traverse a multi-kilometer path over 24 hours with battery energy reserve. The field trial results motivate future work in mission re-planning, multiple resource constraint analysis and improved speed and memory performance. Our objective is to fulfill a need for resource-cognizant autonomy that is critical for future long-distance planetary surface missions.

Sun-synchronous exploration is accomplished by reasoning about sunlight: where the Sun is in the sky, where and when shadows will fall, and how much power can be obtained through various courses of action. In July 2001 a solar-powered rover, named Hyperion, completed two sun-synchronous exploration experiments in the Canadian high arctic (75/spl deg/N). Using knowledge of orbital mechanics, local terrain, and expected power consumption, Hyperion planned a sun-synchronous route to visit designated sites while obtaining the necessary solar power for continuous 24-hour operation. Hyperion executed its plan and returned to its starting location with batteries fully charged after traveling more than 6 kilometers in barren, Mars-analog terrain. We describe the concept of sun-synchronous exploration. We overview the design of the robot Hyperion and the software system that enables it to operate sun-synchronously. We then discuss results from analysis of our first experiment in sun-synchronous exploration and conclude with observations.

Object. The purpose of this study was to evaluate descriptive data obtained in patients who had received multimodality treatment with resection and gamma knife radiosurgery (GKS) for skull base tumors. Retrospective data were collected from 71 patients with skull base tumors who were treated from November 1996 to December 2000, all of whom underwent follow-up evaluation at 1 year or more. Methods. Data were collected from hospital charts and office records, including patient age, tumor type and location, number of tumors, maximum radiation dose, estimated radiation dose to the periphery, tumor volume, and percentage of patients with tumors smaller or the same size at follow-up evaluation. Conclusions. Of the 71 patients with 1 year or more of follow up, 93% had tumor either the same size or smaller and 34% of these patients had a smaller tumor size. It is concluded that: 1) GKS with multimodality treatment is effective for control of skull base tumors; 2) the radiosurgical team should consider the benefits of GKS for treatment of any skull base tumor to afford optimum patient management; and 3) neurosurgeons involved with the management of skull base tumors should either be trained and proficient in GKS or work closely with a colleague trained in the technique. This will ensure proper consideration of both options, resulting in overall improved patient treatment.

Object: The proper functioning of shunt valves in vivo is dependent on many factors, including the valve itself, the antisiphon device (if included), patency of inlet and outlet tubing and location of the valve. Two general categories of shunt valves are available today, the differential-pressure valve (with or without antisiphon device) and the flow-control valve. We have previously shown that the relationship between the position of the valve body and the inlet catheter tip can have profound effects on the outflow rate of differential pressure valves with antigravity devices. The current study was conducted to evaluate the importance of this relationship for the pressure/flow characteristics of the flow-control shunt valve. Methods: We bench-tested flow-control valves from two manufacturers in the system we devised for testing differential-pressure valves. Valves were connected to an "infinite" reservoir, and the starting head pressure was determined from product inserts. The inlet catheter tip was fixed at this position and the valve body was moved in relation to the inlet catheter tip. Outflow rates were determined gravimetrically for positions +4 to –8 cm relative to the inlet catheter tip. Conclusions: All flow-control valves utilized in this study showed nearly constant outflow rate as the valve body was moved incrementally with respect to the level of the inlet catheter tip. As previously tested, differential-pressure valves exhibit significant increases in outflow rate as the valve body is moved below the inlet catheter tip. The outflow rate for the flow-control shunt valves does not change over the range of effective head pressures used in this study.

Object: The proper functioning of shunt valves in vivo is dependent on many factors, including the valve itself, the anti-siphon device or ASD (if included), patency of inlet and outlet tubing, and location of the valve. One important, but sometimes overlooked, consideration in valve function is the valve location relative to the tip of the ventricular inlet catheter. As with any pressure measurement, the zero or reference position is an important concept. In the case of shunt valves, the position of the proximal inlet catheter tip is fixed and therefore serves as the reference point for all pressure measurements. This study was conducted to document the importance of this relationship for the pressure/flow characteristics of the shunt valve. Methods: We bench-tested differential pressure valves (with integral anti-gravity devices; AGDs) from three manufacturers. Valves were connected to an ”infinite” reservoir, and the starting head pressure for each was determined from product inserts. The inlet catheter tip was fixed at this position, and the valve body was moved in relation to the inlet catheter tip. Outflow rates were determined gravimetrically for positions varying between 4 cm above and 8 cm below the inlet catheter tip. Conclusions: All differential pressure valves utilized in this study that contained AGDs showed significant increases in outflow rate as the valve body was moved incrementally below the level of the inlet catheter tip. To allow functioning as a zero- hydrostatic pressure differential pressure valve, the AGD and the inlet catheter tip should be aligned at the same horizontal level.

Adult male rats (400+ grams) were used for all studies. Nembutal anesthesia was induced via intraperitoneal injection at 40mg/kg and maintained by IV infusion at 8mg/kg/hr. Induction for Halothane was via inhalation in a bell jar at 2.5% in an 80/20 mixture of breathing air/100% 02. Induction with Forane was likewise in a bell jar at 4% Forane in 100% 02. Maintenance for Halothane and Forane was at 1.5–2% in an 80/20 mix of breathing air/02. All animals were mechanically ventilated via tracheostomy. Following placement of femoral arterial and venous catheters, animals were placed in a head frame in the sphinx position. For measurement of ICP and determination of PVI’s, a 26 gauge needle was inserted into the cisternal space and connected to a Camino fiber optic pressure measuring system. Normocarbic conditions (pCO2 30–40 mmHg) were obtained using a respirator volume of 2.5 cc and a rate of 60/min. Hypercarbia (pCO2 > 40 mmHg) was achieved by lowering the respirator rate. After stabilization of blood gases and ICP, 10μl of liquid was injected through a side port via a Hamilton syringe for the PVI measurement.

This study evaluates regional cerebral perfusion flow and unidirectional glucose transport across the cerebral capillar in hydrocephalic rats. Perfusion flow and glucose influx were measured with 99mTc-ECD (Dupont Corp.) and 14C-(d)-Glucose, respectively. Perfusion flows for the control and hydrocephalic groups were 1.77ml/min per g and 1.53ml/min per g, respectively. The hydrocephalic perfusion flow was significantly lower than the control flow (P < .05). Maximal influx of glucose (Vmax) for the control group was 2.74 μm/min per g. The Vmax for the hydrocephalic group was 3.19 μm/min per g. Substrate concentration at half maximal transport (Km) was 8.02 mM for the controls and 11.5 mM for the hydrocephalies. There was no substantial difference between control and hydrocephalic groups for these kinetic parameters. These data suggest that reported changes in cerebral metabolism in hydrocephalus are due to derangements in utilization rather than to facilitated diffusion of glucose across the blood brain barrier.

The present study contrasted physiological response patterns occurring when subjects coped passively and actively with aversive stimuli. In one condition, 29 healthy young men were exposed to unpredictable noise (115BA) and shock (3.5 mA) with no means of control, and in the other they attempted to avoid the noise and shock with rapid keypresses. Both tasks were characterized by maximal uncertainty as to locus of presentation, chance of occurrence, and type of stimulus to occur next in sequence. Dependent variables included: reports of moods, reaction times, muscle tension, plasma concentrations of free fatty acids, cortisol and catecholamines, heart rate, blood pressures, systolic time intervals, cardiac output, systemic vascular resistance, and an index of myocardial contractility. Both experimental conditions produced significant neuroendocrine, lipid, and cardiovascular changes from baseline. The active avoidance procedure produced further increases in cardiac function which were related to control efforts as indexed by muscle tension and task performance. The results point toward the effects of effort in the face of uncertainty in determining the patterns of response to aversive stimulation.

Biochemical and physical parameters of cardiac hypertrophy accompanying hypertension were studied in water deprived versus non-deprived immature spontaneously hypertensive rats (SHR) and their normotensive progenitor strain, Wistar Kyoto (WKY). A 23.5 hour/day water deprivation schedule was maintained from 5 to 13 weeks of age in 23 SHR and 8 WKY rats to compare the non-deprived animals (16 SHR and 8 WKY controls). Water deprived SHR had lower left ventricular weight, lower total protein and hydroxyproline and the same total DNA as the non-deprived SHR. DNA concentration was higher in the deprived SHR than in the non-deprived SHR. No differences were found among the four groups in right ventricular weight or DNA concentration. Left to right ventricular weight ratio was significantly lower and left to right ventricular DNA concentration ratio significantly higher in the deprived SHR relative to non-deprived SHR. These data indicate that the water deprived SHR, which was less hypertensive than the non-deprived SHR, had less hypertrophy of their left ventricles. While water deprivation lowered mean arterial pressure in the WKY, also, there was no effect on left ventricular weight or biochemical indices of left ventricular cell size and cell number.

Mannitol therapy has been well documented to be effective in reducing elevated intracranial pressure (ICP) (Pollay et al. 1983, Wise and Chater 1962). This reduction in ICP is dependent on reversal of the blood/brain osmotic gradient. However it has been observed that too rapid an infusion rate may give rise to an early transient increase in ICP prior to a subsequent decrease (Ravussin et al. 1986, Roberts et al. 1987). This study was undertaken to evaluate the possible mechanism (s) by which this transient increase in ICP occurs.

The development of high blood pressure in young spontaneously hypertensive rats (SHR) is inhibited by operant conditioning motivated by chronic water deprivation. The present study showed that the inhibition of hypertension was not due to the operant conditioning,per se, but was a result of chronic water deprivation (23.5 hr schedule) imposed on the rats from five through 12 weeks of age. Blood pressures were measured directly using a carotid artery cannula and light enflurane anesthesia. The behaviorally conditioned SHR and the water-deprived SHR controls had equal blood pressures and were significantly less hypertensive than untreated or enriched environment SHR groups. The antihypertensive action of water deprivation was not detected by weekly indirect blood pressure measurements made in the awake state. Nonetheless, the chronicity of the deprivation-induced inhibition of hypertension was confirmed by a lesser degree of left ventricular hypertrophy in the deprived SHR relative to the nondeprived SHR. Our behavioral results again demonstrated hyperreactivity in the SHR relative to the Wistar Kyoto (WKY). This behavioral hyperreactivity in the SHR may explain the exaggerated increase in drinking in the deprived SHR groups when returned toad lib conditions. The data of this study and our previous work suggest that arousal differences between SHR and WKY strains are more reliably differentiated by fixed interval schedules of reinforcement than by a fixed ratio schedule. Hyperarousal may precede hypertension in the SHR, but it is undetermined whether hypertension can be found in the absence of hyperarousal in these rats.