bluuebunny/crossref_metadata_2025 huggingface dataset:
Archaeology and Anthropology in Southeast Asia
Authors: Solheim Wilhelm G.
Published: April 2011

I agreed in the fall of 1979 to be the guest editor of a special issue of the Journal of Southeast Asian Studies on the state of the art of archaeology and anthropology in Southeast Asia. This special issue was to be published in March 1984 and I was to have the papers to the editor by the 15th of October 1983; plenty of time I thought. I first attempted to get two senior American anthropologists to be associate editors, one for Mainland Southeast Asia and one for Island Southeast Asia. This did not work out so in the fall of 1980 I started to organize authors for each country. By the summer of 1981 I had arranged authors for thirteen reports.
Archaeology in Peninsular Malaysia: Past, Present and Future
Authors: Taha Adi Haji
Published: April 2011

The Federation of Malaysia was formed in 1963, comprising the Malay Peninsula and the states of Sabah and Sarawak. In Peninsular Malaysia, archaeological activities including the protection of archaeological sites is under the jurisdiction of the Museums Department while the East Malaysian states have their own enactments and programmes covering this aspect of research. For this reason I restrict this paper to the archaeology of Peninsular Malaysia.
Positive topological entropy of Reeb flows on spherizations
Authors: MACARINI LEONARDO , SCHLENK FELIX
Published: April 2011

Let M be a closed manifold whose based loop space Ω (M) is “complicated”. Examples are rationally hyperbolic manifolds and manifolds whose fundamental group has exponential growth. Consider a hypersurface Σ in T*M which is fiberwise starshaped with respect to the origin. Choose a function H : T*M → ℝ such that Σ is a regular energy surface of H, and let ϕt be the restriction to Σ of the Hamiltonian flow of H.

Theorem 1. The topological entropy of ϕt is positive.

This result has been known for fiberwise convex Σ by work of Dinaburg, Gromov, Paternain, and Paternain–Petean on geodesic flows. We use the geometric idea and the Floer homological technique from [19], but in addition apply the sandwiching method. Theorem 1 can be reformulated as follows.

Theorem 1'. The topological entropy of any Reeb flow on the spherization SM of T*M is positive.

For q ∈ M abbreviate Σq = Σ ∩ Tq*M. The following corollary extends results of Morse and Gromov on the number of geodesics between two points.

Corollary 1. Given q ∈ M, for almost every q′ ∈ M the number of orbits of the flow ϕt from Σq to Σq′ grows exponentially in time.

In the lowest dimension, Theorem 1 yields the existence of many closed, orbits.

Corollary 2. Let M be a closed surface different from S2, ℝP2, the torus and the Klein bottle. Then ϕt carries a horseshoe. In particular, the number of geometrically distinct closed orbits grows exponentially in time.
The Poor of Noakhali: Danish Development Assistance Policy and Rural Development in Bangladesh
Authors: BRUNBECH PETER YDING
Published: April 2011

The Danish integrated rural development project in the Bangladeshi district of Noakhali (1978–92) was in many ways the largest aid project in the history of the Danish aid agency, DANIDA, and was intended to break new ground by reaching the poorest and weakest directly. Despite elaborate planning and a small army of Danish experts, however, the project failed to reach the targeted groups and would ultimately be viewed as a partial fiasco. By analysing the historical context of the project, this article will show how both the project and the problems it encountered were a by-product of the basic principles of the Danish aid policy developed in the 1960s and 1970s: the same factors that produced the high level of Danish aid spending and the will to embrace new agendas in development assistance such as the ‘basic-needs’ approach also created a number of problems with regard to the implementation of Danish policy on the ground.
Perspectives on Security in Twentieth-Century Europe and the World
Authors: LÜTHI BARBARA
Published: April 2011

Despite the present-day attraction of ‘security’ as an attention-grabbing word in politics and the public sphere, the study of security is a missing chapter in many state-of-the-art surveys of historical literature. Its central relevance for the modern statehood has been obvious for centuries in the European context. In Thomas Hobbes's mid-seventeenth-century Leviathan, written in the context of the devastating English civil war and previous religious wars, government was given the fundamental role in guaranteeing security. Over the course of the twentieth century, intellectuals have constantly debated Hobbes's ideas and concepts about security and societal peace. Especially after the second world war, security has found major attention in the fields of International Relations and its sub-discipline security studies. Security studies evolved during the nuclear age and were originally foremost about the study of the threat, use and control of military force, as one proponent of security studies, Stephen Walt, stated. They were mainly concerned with military strategy and giving policy advice to the military. Since the cold war, the study of security has come a long way. Most importantly, as Emma Rothschild has reminded us, during the past two decades or so, the concept was first extended downwards from states to individuals, upwards from the nation to the biosphere and horizontally from the military to the economic, social, political and environmental. It is the reflection of this dynamic change in theory, methodology and empirical research that connects most of the books under review in this article.
If You Want to Be a Good Fill-in-the-Blank Manager, Be a Good Plain-Vanilla Manager
Authors: Kelman Steven
Published: April 2011

This lecture was presented at the Annual Meeting of the American Political Science Association, Washington, DC, September 3, 2010.
The Political Scientist as a Blogger
Authors: Sides John
Published: April 2011

In November 2007, I helped found a blog, The Monkey Cage, with two of my colleagues, David Park and Lee Sigelman. This site joined a nascent political science blogosphere that is now composed of at least 80 blogs (Farrell and Sides 2010). The goals of The Monkey Cage are to publicize political science research and use this research to comment on current events. Although blogging is a promising way for scholars to promote their work to a larger audience, political scientists have been slow to take up this medium. To be sure, blogging is not without its challenges, particularly in terms of the time and energy needed to maintain a site. But blogging can also have its benefits by not only helping political science reach a broader audience, but also aiding individual scholars' research, teaching, and service goals.
Expect Confrontation, Not Compromise: The 112th House of Representatives Is Likely to Be the Most Conservative and Polarized House in the Modern Era
Authors: Abramowitz Alan I.
Published: April 2011

An examination of the results of the recent midterm elections indicates that the new House of Representatives will probably be the most conservative and ideologically polarized House since the end of World War II. Republicans will hold 242 seats after a net gain of 63 seats, constituting the largest Republican majority in the House of Representatives since the 80th Congress (1947–49), which also had 242 Republican members.
The 2010 Midterm Elections: Signs and Portents for the Decennial Redistricting
Authors: McDonald Michael P.
Published: April 2011

The 2010 midterm elections are consequential not only in terms of the candidates who were elected to office, but also in terms of the government policies that they will enact. High on the list of important policies is the decennial practice of drawing new redistricting plans for legislative offices. A new census reveals population shifts that will result in a reallocation of congressional seats among the states through apportionment and—following U.S. Supreme Court rulings in the 1960s—a re-balancing of congressional and state legislative district populations within states that aims to give fast-growing areas more representation and slow-growing areas less. Of course, much more than an innocuous administrative adjustment occurs during the process of redistricting. The individuals who draw districts are keenly aware that district lines may affect the fortunes of incumbents, political parties, and minority voters' candidates of choice.
Voter Turnout in the 2010 Congressional Midterm Elections
Authors: Panagopoulos Costas
Published: April 2011

Against the backdrop of the 2008 presidential election, a watershed event in terms of electoral participation, many speculated that renewed interest in voting would spill over into the 2010 cycle, resulting in a meaningful uptick in voter turnout in the midterm elections overall. Turnout was expected to be especially robust among Republicans eager to regain their numbers in 2010, capitalizing on Democratic withdrawal fueled by voters' frustration with President Obama, congressional Democrats, and the struggling economy. In 2008, an electorate energized around an historic contest and unprecedented levels of voter mobilization helped to drive more citizens to the polls on Election Day than ever before (Panagopoulos and Francia 2009). An estimated 131.1 million Americans voted for president, representing 61.6% of the eligible voting population (McDonald 2009). Voter turnout among eligible voters in 2008 was 1.5 percentage points higher than in 2004, when 122.3 million voters participated in the presidential election (Bergan et al. 2005). The 2008 election thus marked the third consecutive presidential election cycle in which voter turnout increased, reversing a trend of declining participation that began in the 1960s (McDonald 2009). In fact, national turnout in recent presidential elections has rivaled modern highs in the level of electoral participation that occurred in the 1950s and 1960s.
Democrats in Split-Outcome Districts and the 2010 Elections
Authors: Stonecash Jeffrey M.
Published: April 2011

The 2008 congressional elections produced a House in which 84 members came from split-outcome districts. Forty-nine Democrats won in districts that Barack Obama lost, and 35 Republicans won in districts that Obama won. To protect their majority, the Democrats needed to retain these 49 members. Given the party's 257 seats, these split members constituted the difference between being in the majority and the minority. The 49 Democrats faced the dilemma of whether to vote with their party, given that their district voted for the presidential candidate of the other party. The focus here is on these split Democrats: their electoral situation, their votes, and their fate in 2010.
The Normative Implications of Biological Research
Authors: Hatemi Peter K. , McDermott Rose
Published: April 2011

One of the concerns that has plagued research on the biological and genetic underpinnings of social behaviors and individual differences is the fear that such information can be used for ill. This fear rests on a foundation of good reason. Early abuses involving the use of selective phrenology and other purportedly “scientific” methods to establish moral hierarchies among races or between sexes have exerted profound and lasting damage on society, as well as affecting later attempts to more productively examine the biological bases of individual difference. And yet, many policies that have focused exclusively on social factors have created equal pain and suffering, although these approaches have rarely fostered as much discussion. However, despite these negative outcomes, biological research can also attack diseases, alleviate suffering, and dispel social myths that wrongfully assign blame to the victim or otherwise oversimplify behavior. Here, we argue for a similar positive valuation of such an approach in political and social research. We concentrate not on the ethics of conducting this research, but rather the ethical need for this research to be conducted.
Learning from Popular Culture: The “Politics” of Competitive Reality Television Programs
Authors: Dreyer David R.
Published: April 2011

Reality television programming has become a pervasive part of popular culture. Although such programming may seem to be mindless entertainment, it can serve as a tool to introduce political lessons in the classroom. This article examines how the concepts of alliance behavior and strategic voting can be explored by using the television program Survivor. An analysis reveals that contestants often behave strategically when forming alliances and voting, in ways that are similar to the strategic behavior of nation-states and individuals residing in democracies, respectively. This article does not suggest that reading political science texts should be replaced with viewing reality television, but rather that instructors can introduce abstract concepts to undergraduate students through popular culture. Such a technique can spark students' interest in politics and demonstrate the broad relevance of political concepts, leaving students with the desire to delve more deeply into the investigation of political phenomena.
Invisible Black Politics: An Analysis of Black Congressional Leadership from the Inside
Authors: Gamble Katrina L.
Published: April 2011

For most of American history, black Americans were excluded from the political process. Even after the passage of the Fifteenth Amendment, for decades, especially in the South, blacks were prevented from voting through various institutional tactics (e.g., poll taxes and literacy tests), violence, and intimidation. As a result, most political institutions through the mid-twentieth century had few or no black faces. With the passage of the 1965 Voting Rights Act, the Fifteenth Amendment was codified, and blacks began to vote and participate in the political process in unprecedented ways.
Tower of LondonversusReal Life Analogue Planning in Schizophrenia with Disorganization and Psychomotor Poverty Symptoms
Authors: Greenwood Kathryn E. , Wykes Til , Sigmundsson Thordur , Landau Sabine , Morris Robin G.
Published: April 2011

Neuropsychological models propose qualitatively distinct planning impairments in the psychomotor poverty and disorganization syndromes in schizophrenia. It was proposed that poor plan initiation in psychomotor poverty would lead to longer initial planning times, while poor plan execution in disorganization would lead to greater inefficiency. Participants with psychomotor poverty (n= 30) and disorganization (n= 29) symptoms were contrasted with healthy controls (n= 28) to elucidate distinct planning impairments. Planning was compared in the Tower of London taskversusreal life analogue performance in the form of a board-game style diary planning task. The specificity of planning impairments was investigated by controlling for current IQ. The disorganization group demonstrated inefficient planning across both tasks, with poor performance on the Tower of London but not on the real life analogue task remaining after intelligence levels were taken into account. Initial planning times did not differ between groups. Previous associations between poor planning and symptoms may have been driven by poor planning with disorganization symptoms and associated lower order impairments in executive function or the semantic system. Targeting these impairments in people with disorganization symptoms may lead to a greater chance of success in promoting generalization to the real world. (JINS, 2011,17, 474–484)
A Précis of Recent Advances in the Neuropsychology of Mild Cognitive Impairment(s) in Parkinson's Disease and a Proposal of Preliminary Research Criteria
Authors: Tröster Alexander I.
Published: April 2011

Cognitive changes of Parkinson's disease (PD) manifest earlier and are more heterogeneous than previously appreciated. Approximately one-third of patients have at least mild cognitive changes at PD diagnosis, and subtle changes might be appreciable among those at risk for PD. Executive dysfunction is the most common cognitive change, but other phenotypes exist. Pathobiologic and potential prognostic differences among cognitive phenotypes remain poorly understood. Progress in the neuropsychology, epidemiology and pathobiology of mild cognitive impairment (MCI) in PD is hampered by lack of diagnostic criteria. This study proposes preliminary research criteria for two categories of PD non-dementia cognitive impairment. (JINS, 2011,17, 393–406)
When voter loyalty fails: party performance and corruption in Bulgaria and Romania
Authors: Chiru Mihail , Gherghina Sergiu
Published: April 2011

This article identifies the determinants of party loyalty while making a distinction between government and opposition voters within an electoral cycle in the two most recent European Union members (Bulgaria and Romania). Both countries are characterized by the perception of widespread corruption and a general distrust of politicians that are likely to hinder the development of strong ties between citizens and parties. We test the explanatory potential of both traditional and revisionist theories of partisanship, suggesting that perceptions of corruption should be treated as equal to evaluations of actual performance. The statistical analysis of comparative study of electoral systems survey data emphasizes the salience of party performance evaluations for party loyalty. Corruption perceptions are significant predictors of loyalty in the Bulgarian case. Voters in both countries assess critically the performance of their preferred party whether it was part of the government or in opposition. A significant difference arises between government and opposition voters with regard to the predictive potential of identification conceptualized as closeness to a party.
The Motion Picture Mind-Reading Test
Authors: Wakabayashi Akio , Katsumata Asami
Published: April 2011

The Motion Picture Mind Reading (MPMR) Test is a novel naturalistic mind-reading task, designed to measure individual differences in a young adult population in Japan. Short scenes from TV films showing characters in social situations were presented to 128 university students; participants judged the mental state of a character in these films. The distribution of task performance (MPMR Test) of participants was approximately normal and its psychometric properties were found to be satisfactory. The MPMR Test scores correlated positively with those of the Eyes Test and also with scores on the empathy quotient (EQ); they correlated negatively with scores on the systemizing quotient (SQ). The MPMR Test provides a further method for assessing subtle individual differences in mind-reading ability in the general population.
Tectonic rotations and transcurrent deformation south of the Abancay deflection in the Andes of southern Peru
Authors: Roperch Pierrick , Carlotto Victor , Ruffet Gilles , Fornari Michel
Published: April 2011

We report new paleomagnetic results from 55 out of 76 sites sampled at different localities along a transect from Nazca to Cuzco where the general structures of the Peruvian Andes are strongly offset across the Abancay deflection. Nine new 39Ar/40Ar ages better constrain the timing of volcanism along the western edge of the Western Cordillera at the latitude of Nazca. A mean paleomagnetic result from 22 sites in the lower Miocene volcanics does not show significant rotation (R = −2.3° ± 7.7°) of the western margin of the Central Andean Plateau since the early Miocene. Within the Western Cordillera we sampled three structural blocks bounded to the north by the Abancay fault system. In the westernmost block, a large counterclockwise rotation (R = −65.0° ± 11.1°) is found in Mesozoic limestones and Paleocene‐Eocene red beds. Magnitude of rotation decreases toward the east from (R = −35.6° ± 12.8°) in the central block to (R = −4.5° ± 8.4°) south of the town of Cuzco. The anisotropy of magnetic susceptibility (AMS) recorded by the red beds sediments is the consequence of compaction and tectonic strain during the early stages of deformation. We show that the magnetic lineations were also rotated counterclockwise as the remanent magnetizations. The present study confirms results from the Peruvian fore arc, showing that rotations are not older than circa 40 Ma and likely not younger than circa 20 Ma. The spatial variation in the amount of counterclockwise rotation suggests a large component of shear along the Abancay deflection concomitant with a broad late Eocene–Oligocene oroclinal deformation in southern Peru.
Breaking the rules: bacteria that use several DNA polymerase IIIs
Authors: McHenry Charles S
Published: April 2011

Studies using Escherichia coli DNA polymerase (Pol) III as the prototype for bacterial DNA replication have suggested that—in contrast to eukaryotes—one replicase performs all of the main functions at the replication fork. However, recent studies have revealed that replication in other bacteria requires two forms of Pol III, one of which seems to extend RNA primers by only a few nucleotides before transferring the product to the other polymerase—an arrangement analogous to that in eukaryotes. Yet another group of bacteria encode a second Pol III (ImuC), which apparently replaces a Pol Y‐type polymerase (Pol V) that is required for induced mutagenesis in E. coli. A complete understanding of complex bacterial replicases will allow the simultaneous biochemical screening of all their components and, thus, the identification of new antibacterial compounds.
Effects of Human Aging on Patterns of Local Cerebral Glucose Utilization Determined by the [18F] Fluorodeoxyglucose Method
Authors: Kuhl David E. , Metter E. Jeffrey , Riege Walter H. , Phelps Michael E.
Published: April 2011

The [18F]fluorodeoxyglucose (FDG) scan method with positron emission computed tomography was used to determine patterns of local cerebral glucose utilization (LCMRglu) in 40 normal volunteer subjects aged 18 to 78 years. Throughout all the studies, each subject was quiet, without movement, with eyes open and ears unplugged, exposed only to ambient room light and sound. For the entire group, whole brain mean CMRglu was 26.1 ± 6.1 μmol 100 g−1 min−1 (mean ± SD, n = 40). At age 78, mean CMR glu was, on the average, 26% less than at age 18, an alteration of the same order as the variance among subjects at any age. The gradual decline of mean CMRglu with advancing age occurred at a faster rate than was reported for mean cerebral oxygen utilization, possibly due to increasingly altered pathways for glucose utilization, or to increasing oxidation of ketone bodies or other alternative substrates. Glucose utilization in the hemispheres was symmetrical and mean CMRglu of overall cortex, caudate, and thalamus was equal in individuals at all ages. The slopes of decline with age were similar when LCMRglu was averaged over zones corresponding to centrum semiovale, caudate, putamen, and frontal, temporal, parietal, occipital, and primary visual cortex. However, the metabolic ratio of superior frontal cortex to superior parietal cortex declined with age, possibly due to selective degeneration of superior frontal cortex or to differences between age groups in the sensory and cognitive response to the study. These results should be useful in distinguishing age from disease effects when the FDG scan method is used.
Evaluation of [123I]Isopropyliodoamphetamine as a Tracer for Local Cerebral Blood Flow Using Direct Autoradiographic Comparison
Authors: Lear James L. , Ackermann Robert F. , Kameyama Motonobu , Kuhl David E.
Published: April 2011

We investigated [123I]isopropyliodoamphetamine (IMP) for potential use in the autoradiographic determination of local cerebral blood flow (LCBF) in animals. The technique of direct autoradiographic comparison, derived from double radionuclide autoradiography, was used to compare the simultaneous uptakes of IMP and [14C]iodoantipyrine (IAP), a reference tracer, in awake and anesthetized rats. This new technique offers several advantages over the previously developed methods of comparing tracers, brain uptake index and first pass extraction ratio. These include the avoidance of disrupting normal cerebral blood–brain tracer exchange and the ability to compare uptakes at substructural levels, whereas the other methods are limited to larger areas. Mean values of LCBF obtained with IMP agreed closely with those using IAP, from 20 to 300 ml/100 g/min. Because IMP was found to have an extremely high effective brain:blood partition coefficient, approximately 25:1, a linear uptake tracer model could be used for IMP yielding more precise values than could IAP for LCBF values above 150. IMP was found to measure choroid plexus flows much more accurately than IAP, values being greater than 500 for IMP compared to approximately 200 for IAP. Because the mechanism of the extremely high partition coefficient of IMP is not yet defined, however, care must be used in measuring LCBF with IMP where the trapping mechanisms of normal vessels may be disrupted.
Effect of Acute Arterial Hypo- and Hypertension on Cerebrocortical NAD/NADH Redox State and Vascular Volume
Authors: Dóra Eörs , Kovách Arisztid G. B.
Published: April 2011

The effects of stepwise arterial hypotension (MABP: 80, 60, 40 mm Hg) and moderate arterial hypo- and hypertension (MABP: 80, 150–160 mm Hg) on cerebrocortical vascular volume and NAD/NADH redox state were studied in anaesthetized cats, The vascular volume and NADH fluorescence measurements were performed on closed skull preparations using a microscope fluororeflectometer. To determine the possible role of adrenergic alpha-receptors in the autoregulatory adjustment of cerebrocortical vascular volume, some of the animals were pretreated with intra-arterially infused phenoxybenzamine (1 mg/kg), It was found that longlasting stepwise arterial hypotension leads to a gradual increase in cerebrocortical vascular volume and NADH fluorescence, Though the cerebrocortical arteries dilatated considerably at 80 mm Hg, sustained for 30 min, the NAD/NADH redox state failed to be reoxidized but was shifted to a more reduced state. This finding suggests that some factor other than tissue hypoxia is responsible for the dilatation of cerebrocortical vessels during moderate arterial hypotension. When the arterial blood pressure was restored following stepwise arterial hypotension, the cerebrocortical vascular volume did not decrease and the NAD/NADH redox state remained reduced, showing that the autoregulatory capability of the vessels was lost and the tissue metabolism was irreversibly altered. During a 5-min duration of moderate arterial hypo- and hypertension, biphasic changes were obtained in cerebrocortical vascular volume while the NAD/NADH redox state was shifted to a more reduced and oxidized state. Since the dilatation and the constriction of the cerebrocortical vessels during arterial hypo- and hypertension lagged by 40–80 s behind the redox state alterations, it is suggested that the myogenic mechanism has a minor role in CBF autoregulation. Phenoxybenzamine (PBZ) dilatated the cerebrocortical vessels, indicating the existence of an active alpha-receptor-mediated vasoconstrictory tone. Since the extent of autoregulatory vascular volume changes was not affected by PBZ pretreatment, the involvement of adrenergic alpha-receptors in the autoregulation of CBF can be excluded, at least for cats.
Cholinergic Cerebral Vasodilatation in the Rabbit: Absence of Concomitant Metabolic Activation
Authors: Scremin Oscar U. , Sonnenschein Ralph R. , Rubinstein Eduardo H.
Published: April 2011

Cerebral blood flow (CBF) was estimated from measurements of internal carotid blood flow and sagittal sinus blood flow in mechanically ventilated rabbits under 70% N2O–30% O2. Intravenously administered physostigmine, a cholinesterase inhibitor, increased CBF under normocapnia and enhanced the cerebral vasodilatation of hypercapnia, but did not alter the cerebral metabolic rate of oxygen (CMRO2). The cerebrovascular effects of physostigmine were antagonized by atropine but not by dihydro-beta-erythroidine, a nicotinic blocker. Neostigmine, a quaternary cholinesterase inhibitor that does not cross the blood-brain barrier, showed no cerebrovascular effects, It is concluded that the cholinergic cerebral vasodilatation does not depend on cerebral metabolic activation, and that the cholinergic receptors involved are muscarinic and located beyond the blood-brain barrier.
A 31P Nuclear Magnetic Resonance in vivo Study of Cerebral Ischaemia in the Gerbil
Authors: Thulborn Keith R. , du Boulay George H. , Duchen Leo W. , Radda George
Published: April 2011

We have used the noninvasive method of 31phosphorus nuclear magnetic resonance (31P NMR) in vivo to follow changes in phosphorous metabolite concentrations and the intracellular pH in the right and left hemispheres and in the cerebellum of gerbil brains after the occlusion of the right carotid artery. Spatial resolution over the brain was possible using surface coils. Ligation, which is known to cause ischaemia in this species in the ipsilateral hemisphere, resulted in the diminution of phosphocreatine and adenine nucleotides and a decrease in tissue pH. Less acidification occurred in the contralateral hemisphere and in the cerebellum. The high-energy metabolite concentrations, phosphocreatine and adenosine triphosphate (ATP), declined in unison in the ischaemic region, in marked contrast to the sequence of events in skeletal muscle, in which phosphocreatine buffers against an immediate fall in ATP concentration. In a separate series of gerbils, 31P NMR spectra were followed for exactly 1 h after carotid ligation. The animals were then sacrificed and brain grey matter specific gravity was rapidly measured to assess the development of oedema. There was a clear correlation between abnormality of spectra and the presence of oedema. It cannot, however, be confidently asserted that a normal spectrum is never seen in oedematous gerbil brains. 31P NMR spectra specific gravity and histological changes shown by light microscopy have been correlated and show that useful signals are received from a depth of at least 4 mm or more from the 10-mm diameter coil.
Cerebral Oxygen Metabolism and Blood Flow in Human Cerebral Ischemic Infarction
Authors: Lenzi G. L. , Frackowiak R. S. J. , Jones T.
Published: April 2011

Fifteen patients with acute cerebral hemispheric infarcts have been studied with positron emission tomography and the oxygen-15 steady-state inhalation technique. Thirteen follow-up studies were also performed. The values of cerebral oxygen metabolism (CMRO2), cerebral blood flow (CBF), and oxygen extraction ratio (OER) have been calculated for the infarcted regions, their borders, the symmetrical regions in contralateral cerebral hemispheres, and the cerebellar hemispheres. This study demonstrates that in the completed stroke there are thresholds for regional CMRO2 and regional CBF below which the general clinical outcome of the patients is usually poor. The ischaemic lesions invariably produce an uncoupling between the greatly decreased metabolic demand and the less affected blood supply, with very frequent instances of relative hyperperfusion. Remote effects of the hemispheric infarcts have been demonstrated, such as crossed cerebellar diaschisis and contralateral transhemispheric depression. The level of consciousness correlates with oxygen uptake and blood flow both in the posterior fossa and in the contralateral cerebral hemispheres. The follow-up studies of individual patients underline the high variability of metabolism-to-flow balance during the acute phase of the illness, and stress the need for more studies focused on repeated assessments of homogeneous patient populations.
Does Endogenous Norepinephrine Regulate Potassium Homeostasis and Metabolism in Rat Cerebral Cortex?
Authors: Sick Thomas J. , Hertz Leif , LaManna Joseph C. , Rosenthal Myron , Flaggman Allan , Harik Sami I.
Published: April 2011

The role of endogenous cerebral norepinephrine (NE) as a modulator of transmembrane cation transport and energy metabolism was evaluated by monitoring extracellular potassium ion activity ([K+]o) in vivo and by measuring cortical Na+,K+-ATPase activity and oxygen consumption in vitro, Ipsilateral cortical NE was depleted by unilateral 6-hydroxydopamine (6-OHDA) lesions of the locus ceruleus (LC). The contralateral cortex was used for control measurements. NE depletion had no effect on resting levels of cortical [K+]o or on the rate of K+ removal from the extracellular space following direct cortical stimulation. There was also no effect of NE depletion on Na+,K+-ATPase activity in cortical homogenates nor on oxygen consumption of cortical slices over a wide range of K+ concentrations. These results indicate that central NE depletion does not influence movements of cortical K+ either directly through an influence on Na+,K+-ATPase activity or indirectly through effects on oxidative metabolism. It is probable, therefore, that previously described effects of NE on cortical oxidative metabolism are mediated through changes in cerebral perfusion and/or modification of substrate availability in vivo.
Pial Artery Diameter and Blood Flow Velocity during Sympathetic Stimulation in Cats
Authors: Busija David W. , Marcus Melvin L. , Heistad Donald D.
Published: April 2011

The effects of sympathetic stimulation on the cerebral circulation in cats are in dispute. One unexplained observation is that sympathetic nerve stimulation constricts pial arteries but does not decrease cerebral blood flow (CBF). To reconcile these findings, we studied effects of sympathetic nerves on cerebral vessels using a new method that permits virtually continuous measurement of pial artery diameter and blood flow velocity, and calculation of change in CBF. Change in CBF was calculated as the product of cross-sectional area (CSA) and blood flow velocity in a large pial artery. Pial artery diameter was measured with the cranial window method and CSA was calculated (πr2). Blood flow velocity was measured with a pulsed Doppler velocity meter. In 11 cats, CBF was measured during the control period and during electrical stimulation of sympathetic nerves. During stimulation, arterial diameter decreased 6 ± 1%, but CBF did not change because velocity increased 19 ± 5%. We also measured CBF with microspheres during control and after 60 s of sympathetic stimulation. Cerebral blood flow was 28 ± 3 ml/min/100 g during control and 26 ± 3 ml/min/100 g after 60 s of sympathetic stimulation (n = 5). It is likely that the increase in velocity during sympathetic stimulation was due to compensatory dilatation of downstream arteries.
Intracellular pH in the Brain following Transient Ischemia
Authors: Mabe Hideo , Blomqvist Photjanee , Siesjö Bo K.
Published: April 2011

The objective of the present study was to discover whether or not intracellular alkalosis develops in the brain in the recovery period following transient ischemia. Forebrain ischemia of 15-min duration was induced by four-vessel occlusion in rats, with recovery periods of 15, 60, and 180 min. Intracellular pH was derived both by the HCO3−–H2CO3 method and from the creatine kinase equilibrium. The ischemia was associated with energy failure and marked accumulation of lactic acid in the cerebral cortex. Recirculation brought about rapid rephosphorylation of adenine nucleotides and gradual normalization of lactic acid levels. After 15 min of recovery, the HCO3−–H2CO3 method indicated persisting acidosis, but the creatine kinase reaction did not. After 60 min, a shift of pH in the alkaline direction was demonstrated in both methods. This alkalosis had disappeared after 3 h of recovery. It is concluded that resumption of ATP production after ischemia is followed by a rapid rise in intracellular pH, which transiently increases above normal.
Transport of α-Aminoisobutyric Acid across Brain Capillary and Cellular Membranes
Authors: Blasberg Ronald G. , Fenstermacher Joseph D. , Patlak Clifford S.
Published: April 2011

The transport of α-aminoisobutyric acid (AIB), N-methyl-AIB (MeAIB), and diethylenetriaminepentaacetic acid (DTPA) from blood to brain was measured over different experimental periods in eight regions of the rat brain. Unidirectional transfer rate constants were determined from multiple-time/graphical and single-time analysis of the experimental data; values of 0,0018, 0,00057, and 0,000021 ml g−1 min−1, respectively, were obtained for the thalamus by graphical analysis, The initial distribution volume of AIB and MeAIB in brain tissue was several-fold greater than that of DTPA and the tissue plasma volume, and this difference was not accounted for by red blood cell uptake, This discrepancy could be due to rapid transport of AIB and MeAIB into brain endothelial cells in addition to the relatively rapid uptake by choroidal, meningeal, and ependymal associated tissues that was demonstrated by autoradiography. Thus, it may be misleading and erroneous to consider the blood–brain barrier (BBB) to be a simple, single-membrane structure when analyzing the blood–brain transfer data of solutes such as amino acids. The data from the ventriculocisternal perfusion experiments and previously published AIB uptake data in mouse brain slices were used to estimate the transfer rate constants across brain cell membranes. These studies indicated that the transport of AIB into brain cells was approximately 110 to 265 times greater than that across normal brain capillaries per unit mass of brain tissue, and that the BBB limits blood-to-brain cell transport of this amino acid. These observations (low rate of transport across normal brain capillaries and rapid concentrative uptake by brain cells) indicate that AIB is a good marker for measuring moderate to large increases in BBB permeability by experiments that require unidirectional flux of the tracer.
Importance of Vascular Responses in Determining Cortical Oxygenation during Recurrent Paroxysmal Events of Varying Duration and Frequency of Repetition
Authors: Kreisman Norman R. , Sick Thomas J. , Rosenthal Myron
Published: April 2011

Cerebral oxygenation initially increases and later decreases in rats subjected to experimental status epilepticus. In this study, we have compared cerebral oxygen supply and vascular changes during paroxysmal events of different durations and at different time intervals to test the hypothesis that oxygen insufficiency is associated more readily with paroxysmal events of greater intensity. Continuous measurements were made of local changes in cortical blood volume, redox levels of cytochrome a,a3, cortical Po2, and systemic arterial blood pressure during recurrent seizures induced by pentylenetetrazol or bicuculline. In contrast to expectations, systemic and cerebral vascular responses and associated increases in cerebral oxygenation were better maintained during long-duration ictal episodes than during short-duration ictal bursts, interictal spikes, or evoked potentials. Short-duration paroxysmal events were often accompanied by decreases in cerebral oxygenation, whereas long-duration events were still accompanied by increases in oxygenation. Ictal bursts occurring with short interburst intervals caused a more rapid failure of vascular responsiveness than those occurring at longer intervals. These relationships of intensity and frequency of repetition of seizures to changes in vascular responses indicate progressive dissociation of the normally tight couple between neuronal activity, energy demand, and cerebral blood flow during status epilepticus.
Effects of Kininase II Inhibitors on the Vasomotor Response to Bradykinin of Feline Intracranial and Extracranial Arteries in vitro and in situ
Authors: Wahl Michael , Young Alan R. , Edvinsson Lars , Wagner Franz
Published: April 2011

Bradykinin is known to effect a vasodilatation of feline cerebral arteries in situ and of both human and feline pial arteries in vitro. In order to demonstrate whether kininase II (localized within the vessel wall or in the surrounding tissue or fluid) influences the response to bradykinin, two different inhibitors of this bradykinin degradation enzyme were tested. Perivascular microapplication of potentiator C (10−10–10−4 M) or captopril (10−10–10−3 M) did not, by itself, change the diameter of feline pial arteries (87–305 μm) in situ. In a similar investigation, the dilating action of bradykinin (10−8–10−5 M) was not modified by the simultaneous application of potentiator C or captopril (10−5 M). Furthermore, the relaxing effect of bradykinin (10−10–10−4 M) on isolated feline middle cerebral arteries (preconstricted with 5-hydroxytryptamine or prostaglandin F2α) was not influenced by the presence of captopril (10−7 M). In contrast, when studied on isolated extracranial vessel segments (feline sublingual artery), bradykinin caused a concentration-dependent constriction of the artery. This constriction was completely reversed to dilatation in the presence of captopril (10−7 M). Moreover, the characteristic effect of kininase II inhibition was demonstrated in the isolated guinea pig ileum preparation. In this instance, bradykinin induced a concentration-dependent contraction that was enhanced by potentiator C or captopril. We conclude, therefore, that bradykinin exerts variable responses on vascular smooth muscle, depending on the species used, the muscle location and experimental conditions. Finally, the in situ and in vitro findings for pial and middle cerebral arteries demonstrate that kininase II does not modify the dilating effect of bradykinin under our experimental conditions.
Relationship between Calcium Accumulation and Recovery of Cat Brain after Prolonged Cerebral Ischemia
Authors: Hossmann K.-A. , Paschen W. , Csiba L.
Published: April 2011

The relationship between brain tissue calcium content and postischemic electrophysiological and metabolic recovery was investigated in 18 adult normothermic cats, 12 of which were submitted to 1 h of complete ischemia and 3 h of recirculation. Six animals served as controls. Functional recovery was estimated by recording the electrocorticogram (ECoG) and evoked potentials, and biochemical recovery by regional evaluation of ATP, glucose, and pH in intact brain sections. One group of animals was treated with the calcium antagonist flunarizine (0.1 mg/kg i. v., followed by continuous i. v. infusion of 0.1 mg/kg/h during the recirculation phase); another group did not receive this treatment. Evoked potentials in all six untreated animals (and in four also, spontaneous ECoG activity) returned after ischemia. In the animals with ECoG activity, biochemical recovery was homogeneous, as indicated by a return toward normal of regional tissue ATP and glucose content. In one animal without ECoG activity, several small regions were present in which energy metabolism was impaired. In regions with biochemical recovery, brain tissue calcium significantly increased by ∼35% (controls, 0.330 ± 0.045; ischemia, 0.447 ± 0.194 μg/mg protein; means ± SD). Changes were accompanied by a parallel increase in sodium (controls, 7.72 ± 1.92; ischemia, 10.50 ± 2.47 μg/mg protein), a slight decrease of potassium (controls, 29.52 ± 0.85; ischemia, 27.66 ± 2.30 μg/mg protein), and an increase of tissue pH (controls, 7.10 ± 0.096; ischemia, 7.307 ± 0.083). In regions without biochemical recovery, pH fell to 6.288 ± 0.157, and calcium content was 0.602 ± 0.235, sodium content 11.70 ± 4.60, and potassium content 23.00 ± 3.91 μg/mg protein. Treatment with the calcium antagonist flunarizine did not reduce tissue calcium content, nor did it improve functional or metabolic recovery after ischemia: three of six treated animals exhibited ECoG activity, one showed only evoked potentials, and two showed no recovery at all. It is concluded that postischemic accumulation of calcium in brain tissue cannot be prevented by the calcium antagonist flunarizine. However, the observed increase of calcium did not interfere with the early postischemic electrophysiological and biochemical recovery. Its pathophysiological importance, therefore, may be associated with more delayed postischemic disturbances.
Nerve Fibres Containing Gastrin-Releasing Peptide around Pial Vessels
Authors: Uddman Rolf , Edvinsson Lars , Owman Christer , Sundler Frank
Published: April 2011

Nerve fibres containing immunoreactive gastrin-releasing peptide (GRP) were demonstrated around pial blood vessels of cat, guinea pig, rat, and mouse. A sparse supply was found around spinal cord blood vessels, whereas the choroid plexus seemed to be devoid of GRP fibres. Sympathectomy did not affect the number or distribution of the GRP fibres. The administration of neither GRP nor its closely related analogue, bombesin, contracted or dilated feline pial arteries in vitro.
Correction for the Presence of Intravascular Oxygen-15 in the Steady-State Technique for Measuring Regional Oxygen Extraction Ratio in the Brain: 1. Description of the Method
Authors: Lammertsma Adriaan A. , Jones Terry
Published: April 2011

The oxygen-15 steady-state inhalation technique provides quantitative values of regional cerebral blood flow, fractional oxygen extraction, and oxygen utilisation. These last two, however, have been found to be higher than those reported using arteriovenous difference techniques. On theoretical grounds, this overestimation is due to the signal from nonextracted intravascular oxygen-15. In this paper, a method is presented to correct for this intravascular component utilising a measurement of regional cerebral blood volume. The statistical penalty imposed as a result of this correction is defined.
Correction for the Presence of Intravascular Oxygen-15 in the Steady-State Technique for Measuring Regional Oxygen Extraction Ratio in the Brain: 2. Results in Normal Subjects and Brain Tumour and Stroke Patients
Authors: Lammertsma Adriaan A. , Wise Richard J. S. , Heather Jon D. , Gibbs Jeremy M. , Leenders Klaus L. , Frackowiak Richard S. J. , Rhodes Christopher G. , Jones Terry
Published: April 2011

Values of regional cerebral oxygen extraction ratio and oxygen utilisation obtained with the oxygen-15 steady-state inhalation technique have been found to be overestimated due to the signal from intravascular oxygen-15. A previously described method to correct for this intravascular component has been applied to a series of studies on normal subjects, and on brain tumour and stroke patients. With this correction the regional cerebral oxygen extraction ratio in normals becomes comparable to the global values previously reported with arteriovenous sampling techniques. Within the lesions of brain tumour and stroke patients, the corrections have been found to be variable and often substantial. It is concluded that failure to apply this correction may result in major errors in the values for regional oxygen extraction ratio and oxygen utilisation. This is especially true when the regional blood flow and oxygen extraction ratio of a tissue is low and regional blood volume is high.