bluuebunny/crossref_metadata_2025 huggingface dataset:
Self, Family and the State: Social Mythology in the Singapore Novel in English
Authors: Ann Koh Tai
Published: April 2011

Adopting an approach that situates texts in their historical, political and cultural contexts, this discussion suggests that a strictly literary estimate of Singapore novels in English is an unrewarding, debunking exercise which prevents a more appropriately serious consideration of the insights that can yield about class, contemporary values, issues and society in Singapore.
Political Tutelage in Rural Singapore: The Measurement and Analysis of the Cognitive Political Culture of some Chinese Farmers
Authors: Gibbons D. S. , Chee Chan Heng
Published: April 2011

Singapore is a new state without a long tradition of independent, democratic politics. The current political leadership is dedicated towards institutionalizing a political system which is both democratic and effective. Attainment of this goal will depend to a significant extent on the creation of citizens who are politically aware, who feel competent to participate in politics and who will participate through legitimate political channels to promote and protect their interests. In terms of contemporary political theory one of Singapore's immediate problems is the creation of a cognitive political culture which is congruent with a democratic and effective political structure. This article focuses on the content, creation and consequences of political awareness amongst farmers in rural Singapore.
Place-names in the Sitiawan Area, Perak
Authors: Chan K. E. , Cho C. H. , Khoo S. H.
Published: April 2011

An exercise in nomenclature can throw interesting light on the settlement history of an area. The location, site and situation of each of the place-names could in fact be incorporated into each place-name, which can thus authenticate, or can be authenticated by, a feature or features on the landscape. Place-names, when taken in the context of the geography of the area, can also commemorate events or personages, real or mythical, a locality being thus imbued with associations at once romantic. Coloured by romance, however, historical verisimilitude then is but an incidental consideration. Frequently, place-names just serve the mundane purpose of designation, the convenient presence of such features as trees, rocks, bays and others providing the root terms for the names. Even here though, it is possible to be adventurous and the rocks and stones and trees can be conceived fancifully, or even in the full force of belief, in terms of their semblances of animals shapes or of their magical properties. They can also be interpreted as petrifications of human forms (usually heroes or heroines, or ill-fated lovers) or as having historical pertinence in being touched by, or sat upon, or having sheltered some legendary or supernatural personalities.
Late Prehistoric and Early Historic Exchange Patterns in the Phimai Region, Thailand
Authors: Welch David J.
Published: April 2011

Based on archaeological evidence from the Phimai region and elsewhere in Northeast Thailand, late prehistoric exchange patterns, focused on local and regional centres of redistribution and perhaps markets, formed the foundation of the Khmer temple and market centred economy. Early regional exchange networks and the Khmer economic system into which they evolved were adaptive responses to the unpredictability of a monsoonal climate.
Archaeology and Anthropology in East Malaysia and Brunei
Authors: Sutlive Vinson H. , Chin Lucas , McCredie David
Published: April 2011

Dirges mark endings. And though it may seem strange to begin a report on archaeology and anthropology in East Malaysia and Brunei with a “dirge”, it is precisely the ritual form suited to set the tone for this review.
Thai-Japanese Relations at the Start of the Pacific War: New Insight into a Controversial Period
Authors: Swan William L.
Published: April 2011

Thailand's relations with Japan during the months surrounding the outbreak of the war in the Pacific are a topic of controversy in Thai historiography; and despite a growing number of studies which have endeavoured to explain, or at least shed light on, the rapid shift in Thai policy from neutrality on 8 December 1941 to an alliance and then declaration of war on the side of Japan by 25 January 1942, little progress or development in the debate has taken place over the decades since the war. This unsatisfactory situation has been largely due to the very limited knowledge available about the diplomatic activities that took place between Thailand and Japan during the period in question. The bulk of our information to date has come from records and recollections of Thais and Europeans involved in the events, and this has concentrated almost entirely on the activities and interplay of Thais and Europeans. The result has been to relegate Japan's presence in events of the period to some dimly perceived undertakings conducted by sinister characters who were nothing more than Thailand's enemies bent on absorbing that country into Japan's new East Asian order. The following article is an effort to redress this imbalance somewhat by directing attention toward Thai-Japanese relations. I have relied greatly on a number of dispatches that passed between Bangkok and Tokyo during the autumn of 1941. Some of the most important of these are available only from “Magic”, the files of intercepted and deciphered Japanese diplomatic messages accumulated by the United States government. The Japanese Foreign Ministry archive files on diplomatic correspondence with Thailand are extremely incomplete, and none of the messages I used from “Magic” are contained in the Japanese files.
Forty years in Aotearoa New Zealand: white identity, home and later life in an adopted country
Authors: GEORGE MOLLY , FITZGERALD RUTH P.
Published: April 2011

In this article we recount some of the memories, hopes and strategies of 22 older migrants who are ageing in their adopted country of Aotearoa New Zealand. Having arrived as young adults in the 20 years after World War II, most of the immigrants have lived on ‘foreign’ soil for twice as long as their brief sojourns of childhood and early adulthood in their country of origin. Arriving from a variety of backgrounds in 12 different countries, they can all be considered ‘white’ immigrants in relation to New Zealand's indigenous Māori population and other non-European immigrant groups such as those from Pacific Island Nations or Asia. Their lives encompass the experience of globalisation and transnationalism in communication technologies and inter-country migration. As they recount the meaning of living through these changes, these older folk discuss the delicacies of assimilation in post-World War II New Zealand and the interplay between the daily life of New Zealand as ‘home’ and the homeland asHeimat. Their stories argue against the assumption that decades of residence, particularly for white immigrants in a white-majority nation, imply an ‘assimilation’ of cultural identity. Instead, the stories evoke recognition of the negotiation of gain and loss which continues as they, and their contexts, change over time.
Piloting the development of a cost-effective evidence-informed clinical pathway: Managing hypertension in Jordanian primary care
Authors: Chalkidou Kalipso , Lord Joanne , Obeidat Nour A. , Alabbadi Ibriham A. , Stanley Adrian G. , Bader Rania , Momani Aiman , O'Mahony Rachel M. , Qatami Lara , Cutler Derek
Published: April 2011

Objectives: The UK's National Institute for Health and Clinical Excellence (NICE) and the Jordan office of the Medicines Transparency Alliance embarked on a pilot project to design an evidence-based guideline for cost-effective pharmacological treatment of essential hypertension in Jordan. The project's objectives were to directly address a major health problem for Jordan by producing a guideline; and to delineate the strengths and weaknesses of Jordan's healthcare process to allow similar future efforts to be planned more efficiently.

Methods: The pilot spanned a period of approximately 8 months. Activities were overseen by local technical and guideline development teams, as well as experts from NICE. NICE's hypertension guidelines and economic model were used as a starting point. Parameters in the economic model were adjusted according to input and feedback from local experts with regards to Jordanian physician and patient practices, resource costs, and quality of life estimates. The results of the economic model were integrated with the updated available clinical trial literature.

Results: The outputs of the economic model were used to inform recommendations, in the form of a clinical algorithm. A report of the process and the strengths and weaknesses observed was developed, and recommendations for improvements were made.

Conclusions: The pilot represented the start of what is intended to be a healthcare process change for the country of Jordan. Issues emerged which can inform strategies to ensure a more cohesive and comprehensive approach to the cost-effective use of appropriate drugs in managing chronic disease in Jordan and countries operating in a similarly resource-constrained environment. Furthermore, our pilot highlights how richer countries with relevant experience in evidence-informed healthcare policy making can assist others in strengthening their decision-making methods and processes.
A Forgotten Legacy of the Second World War: GI children in post-war Britain and Germany
Authors: LEE SABINE
Published: April 2011

Whether in war, occupation or peacekeeping, whenever foreign soldiers are in contact with the local population, and in particular with local women, some of these contacts are intimate. Between 1942 and 1945, US soldiers fathered more than 22,000 children in Britain, and during the first decade of post-war US presence in West Germany more than 37,000 children were fathered by American occupation soldiers. Many of these children were raised in their mothers’ families, not knowing about their biological roots and often suffering stigmatisation and discrimination. The question of how these children were treated is discussed in the context of wider social and political debates about national and individual identity. Furthermore, the effect on the children of living outside the normal boundaries of family and nation is discussed.
“Pracademics”: Mixing an Academic Career with Practical Politics
Authors: McDonald Michael P. , Mooney Christopher Z.
Published: April 2011

College professors are evaluated for promotion and tenure on the basis of their accomplishments in three areas: teaching, research, and service. All too often, however, service is considered the poor cousin of the trio. In political science in particular, we believe that this imbalance is detrimental to the individual scholar, our students, the discipline, and the general public. The goal of this symposium is to contribute to what we see as a nascent revitalization and rehabilitation of service—especially public service—as a respectable and integral part of a political science career. We encourage our colleagues to engage the political world more often, more directly, and more reflectively, and we encourage the profession—the APSA, our departments, and our colleagues—to value such engagement institutionally and through our social norms.
Generating Scholarship from Public Service: Media Outreach, Nonprofit Foundation Service, and Legal Expert Consulting
Authors: Smith Daniel A.
Published: April 2011

Most colleges and universities stipulate that public service is a requirement for tenure and promotion. Yet many political science faculty and their respective administrators pay only lip service to this “third leg” of a scholarly career, relying on teaching and research to shape most career decisions. This reality is particularly surprising in the context of the political science discipline, given that the nature of our scholarship provides many public service opportunities. However, the norms and pressures of academia in general are at play. Why, then, should political scientists engage in public service, much less become serious “pracademics”?
More than a Dime's Worth: Using State Party Platforms to Assess the Degree of American Party Polarization
Authors: Coffey Daniel J.
Published: April 2011

How polarized are American political parties? Recently, Kidd used an automated content analysis program to demonstrate that American party platforms reveal only minor policy differences. In contrast to his conclusions, this analysis produces three main findings. First, at the state level, state party platforms reveal considerable ideological differences between the parties. Second, differences in state public opinion do not account for these differences; rather, they are more closely correlated with activist opinions and increases in state party competition. Finally, the conflict is not simply ideological but applies to specific issues in the platforms. As such, American state parties are highly polarized on different measures. Automated content analysis programs clearly represent an important methodological advance in coding political texts, but the results here call attention to the importance of policy and agenda content in party platforms. Moreover, studies of American politics, particularly research focusing on parties and ideological polarization, need to take into account the diversity of agendas that is inherent in a federal party system.
Welfare Politics in Congress
Authors: Mead Lawrence M.
Published: April 2011

The stakes of political conflict involve contending values and issue definitions as well as policy. Welfare reform was the most important change in American domestic policy since civil rights. Its significance hinges crucially on how participants understood the issue, but existing research fails to resolve what their perceptions were. Most accounts suggest that welfare reform was an ideological contest concerning the proper scope of government, but there are other views. This study gauges the welfare agenda rigorously by coding speakers in congressional hearings on the basis of how they framed the issue and the position they took on it during the six chief episodes of welfare reform that occurred between 1962 and 1996. The reform efforts aroused four distinct divisions. Over time, positions moved rightward, but more important, the dominant issue changed: The ideological debate about government was overtaken by a more practical debate about how to manage welfare. This is the first study to track the substantive meaning of any issue in Congress over an extended period of time using hearing witnesses and a preset analytic scheme.
Philip J. Schlessinger
Authors: Weisberg Herbert F.
Published: April 2011

Dr. Philip J. Schlessinger died at age 96 on September 22, 2010. He had taught political science at Los Angeles City College (LACC) for more than 60 years.
Report of the Editors of the American Political Science Review, 2009–2010
Authors: Rogowski Ronald
Published: April 2011

We report here on the journal's operations during the year from July 1, 2009, to June 30, 2010.
Social Dominance Orientation
Authors: Perry Ryan , Sibley Chris G.
Published: April 2011

There has been considerable debate regarding the extent to which prejudice results from individual differences versus situational factors affecting self-categorization. We provide evidence for a stable baseline level of association between one individual difference index of prejudice proneness, that of social dominance orientation (SDO), and generalized racist attitudes. Consistent with an individual difference perspective, SDO retained a baseline level of association with racism across conditions invoking ethnic versus personal identity (N = 179 European/white undergraduates). Consistent with a self-categorization theory perspective, however, this association was heightened when ethnic (vs. personal) identity was made salient prior to (but not after) the assessment of SDO. Although the salience of different social identities moderated the association between SDO and prejudice, manipulating identity salience did not entirely remove or alter the direction of the effect. This supports our argument that there exists a baseline level or individual difference component of SDO that predicts prejudice and that cannot be accounted for by the manipulation of social identification as an individual versus a member of the ethnic majority in New Zealand.
The Georgia Tech millimeter‐wavelength measurement system and some applications to the study of planetary atmospheres
Authors: Devaraj Kiruthika , Steffes Paul G.
Published: April 2011

With the advent of new millimeter‐wavelength arrays such as the Atacama Large Millimeter Array capable of providing very precise maps of planetary emission, it becomes very critical to have an accurate knowledge of the millimeter‐wavelength properties of gases under those planetary conditions. A millimeter‐wavelength planetary atmospheric simulator and measurement system have been developed at the Georgia Tech Planetary Atmospheres Laboratory to accurately measure the propagation properties of gases under simulated planetary atmospheric conditions. The measurement system operates in the 2–4 millimeter‐wavelength range and withstands up to 3 bars of pressure. It currently operates in the 190–300 K temperature range, and with minor modifications can operate in the 300–550 K temperature range for measurements of certain highly millimeter‐wavelength‐opaque gases. The measurements from this system can be used for developing accurate models of the millimeter‐wavelength properties of gases under various planetary conditions which can then be used for retrieving the abundances of those gases through various remote sensing techniques.
Application of wavelet‐based denoising techniques to remote sensing very low frequency signals
Authors: Güzel Esat , Canyılmaz Murat , Türk Mustafa
Published: April 2011

In this paper, we apply wavelet‐based denoising techniques to experimental remote sensing very low frequency (VLF) signals obtained from the Holographic Array for Ionospheric/Lightning research system and the Elazig VLF receiver system. The wavelet‐based denoising techniques are tested by soft, hard, hyperbolic and nonnegative garrote wavelet thresholding with the threshold selection rule based on Stein's unbiased estimate of risk, the fixed form threshold, the mixed threshold selection rule and the minimax‐performance threshold selection rule. The aim of this study is to find out the direct (early/fast) and indirect (lightning‐induced electron precipitation) effects of lightning in noisy VLF transmitter signals without discomposing the nature of signal. The appropriate results are obtained by fixed form threshold selection rule with soft thresholding using Symlet wavelet family.
Water reform in the Murray‐Darling Basin
Authors: Connell Daniel , Grafton R. Quentin
Published: April 2011

In Australia's Murray‐Darling Basin the Australian and state governments are attempting to introduce a system of water management that will halt ongoing decline in environmental conditions and resource security and provide a robust foundation for managing climate change. This parallels similar efforts being undertaken in regions such as southern Africa, the southern United States, and Spain. Central to the project is the Australian government's Water Act 2007, which requires the preparation of a comprehensive basin plan expected to be finalized in 2011. This paper places recent and expected developments occurring as part of this process in their historical context and examines factors that could affect implementation. Significant challenges to the success of the basin plan include human resource constraints, legislative tensions within the Australian federal system, difficulties in coordinating the network of water‐related agencies in the six jurisdictions with responsibilities in the Murray‐Darling Basin, and social, economic, and environmental limitations that restrict policy implementation.
Ataxin‐1 and Brother of ataxin‐1 are components of the Notch signalling pathway
Authors: Tong Xin , Gui Hongxing , Jin Feng , Heck Bryan W , Lin Peihui , Ma Jianjie , Fondell Joseph D , Tsai Chih‐Cheng
Published: April 2011

Ataxin‐1 (ATXN1), a causative factor for spinocerebellar ataxia type 1 (SCA1), and the related Brother of ATXN1 (BOAT1) are human proteins involved in transcriptional repression. So far, little is known about which transcriptional pathways mediate the effects of ATXN1 and BOAT1. From our analyses of the properties of BOAT1 in Drosophila and of both proteins in mammalian cells, we report here that BOAT1 and ATXN1 are components of the Notch signalling pathway. In Drosophila, BOAT1 compromises the activities of Notch. In mammalian cells, both ATXN1 and BOAT1 bind to the promoter region of Hey1 and inhibit the transcriptional output of Notch through direct interactions with CBF1, a transcription factor that is crucial for the Notch pathway. Our results suggest that, in addition to their involvement in SCA1, ATXN1 and BOAT1 might participate in several Notch‐controlled developmental and pathological processes.
Columnar Alterations of NADH Fluorescence during Hypoxia-Ischemia in Immature Rat Brain
Authors: Welsh Frank A. , Vannucci Robert C. , Brierley James B.
Published: April 2011

Cerebral hypoxia-ischemia was produced in 7-day postnatal rats by unilateral carotid artery ligation combined with systemic hypoxia (8% O2). Levels of high energy phosphates, which were only slightly altered in the contralateral hemisphere, were nearly depleted in the ipsilateral hemisphere during the 3-h hypoxic insult. With hypoxia of between 1 and 3 hours' duration, columnar alterations of cortical NADH fluorescence occurred in the same location and regional pattern as did histologic damage demonstrated previously (Rice et al., 1981). In regions exhibiting columns of NADH fluorescence, there was no evidence of a columnar reduction of high energy phosphates as levels of ATP and phosphocreatine were nearly zero.

Recovery from 3 h of hypoxia was accompanied by partial and regionally heterogeneous restoration of ATP within the ipsilateral hemisphere. Columnar variations of NADH fluorescence were not detected in the recovery period; rather, regions with impaired restitution of high energy phosphates exhibited NADH fluorescence that was diminished diffusely compared to the contralateral hemisphere. The correlation between depressed NADH fluorescence and depleted ATP, present as cortical columns during hypoxia and as larger regions during recovery, suggests that decreased formation of NADH may be limiting the resynthesis of high energy phosphates.
Cerebral Blood Flow in Rats with Renal and Spontaneous Hypertension: Resetting of the Lower Limit of Autoregulation
Authors: Barry D. I. , Strandgaard S. , Graham D. I. , Braendstrup O. , Svendsen U. G. , Vorstrup S. , Hemmingsen R. , Bolwig T. G.
Published: April 2011

The effect of chronic hypertension on cerebral blood flow (CBF) was studied in anaesthetised rats. CBF was measured with the intracarotid 133Xe injection method. Rats with spontaneous and renal hypertension were compared with normotensive controls. The lower limit of autoregulation was determined during controlled haemorrhage. In the normotensive rats, CBF remained constant until mean arterial pressure (MAP) had decreased to the range of 50–69 mm Hg. Thereafter, CBF decreased with each further decrease in MAP. In both types of hypertensive rats, CBF remained constant until MAP had decreased to the range of 70–89 mm Hg. Thus, a 20-mm Hg shift of the lower limit of CBF autoregulation was found in both spontaneous and renal hypertensive rats. A neuropathological study revealed ischaemic brains lesions in half of the hypertensive rats following hypotension, whereas only a single lesion was found in one of six normotensive rats. No ischaemic brain lesions were found in a control study in which CBF was shown to be stable over a 2 1/2-h period. In conclusion, hypertensive rats showed a shift of the lower limit of CBF autoregulation as well as an increased susceptibility to ischaemic brain damage during hypotension. These findings presumably reflect hypertensive structural changes in the cerebral circulation.
Repeated Least Squares Analysis of Simulated Xenon Computed Tomographic Measurements of Regional Cerebral Blood Flow
Authors: Thaler H. T. , Baglivo J. A. , Lu H. C. , Rottenberg D. A.
Published: April 2011

Computer simulations were done as a feasibility study of xenon computed tomographic measurements of regional cerebral blood flow. Accuracy of initial least squares estimates of gray matter and white matter rate constants from a two-compartment model depended very little on the number and timing of scans, but did depend significantly on the enhancement-to-noise ratio as well as on the true values of the rate constants and gray/white ratio. Nonlinear least squares gives an optimal fit of the predicted wash-in-wash-out curve to the data rather than optimal estimates of the rate constants. A polynomial correction factor was obtained by regressing initial estimates on the true values used to generate the simulations. The correction factor substantially reduced error in the estimates and, in particular, eliminated large outliers.
Noninvasive Method of Estimating Human Newborn Regional Cerebral Blood Flow
Authors: Younkin D. P. , Reivich M. , Jaggi J. , Obrist W. , Delivoria-Papadopoulos M.
Published: April 2011

A noninvasive method of estimating regional cerebral blood flow (rCBF) in premature and full-term babies has been developed. Based on a modification of the xenon-133 inhalation rCBF technique, this method uses eight extracranial NaI scintillation detectors and an i. v. bolus injection of xenon-133 (∼0.5 mCi/kg). Arterial xenon concentration was estimated with an external chest detector. Cerebral blood flow was measured in 15 healthy, neurologically normal premature infants. Using Obrist's method of two-compartment analysis, normal values were calculated for flow in both compartments, relative weight and fractional flow in the first compartment (gray matter), initial slope of gray matter blood flow, mean cerebral blood flow, and initial slope index of mean cerebral blood flow. The application of this technique to newborns, its relative advantages, and its potential uses are discussed.
Graphical Evaluation of Blood-to-Brain Transfer Constants from Multiple-Time Uptake Data
Authors: Patlak Clifford S. , Blasberg Ronald G. , Fenstermacher Joseph D.
Published: April 2011

A theoretical model of blood–brain exchange is developed and a procedure is derived that can be used for graphing multiple-time tissue uptake data and determining whether a unidirectional transfer process was dominant during part or all of the experimental period. If the graph indicates unidirectionality of uptake, then an influx constant ( Ki) can be calculated. The model is general, assumes linear transfer kinetics, and consists of a blood–plasma compartment, a reversible tissue region with an arbitrary number of compartments, and one or more irreversible tissue regions. The solution of the equations for this model shows that a graph of the ratio of the total tissue solute concentration at the times of sampling to the plasma concentration at the respective times ( Cp) versus the ratio of the arterial plasma concentration–time integral to Cp should be drawn. If the data are consistent with this model, then this graph will yield a curve that eventually becomes linear, with a slope of Ki and an ordinate intercept less than or equal to the vascular plus steady-state space of the reversible tissue region.
Cerebral Blood Flow Studied by Xenon-133 Inhalation Technique in Parkinsonism: Loss of Hyperfrontal Pattern
Authors: Bès A. , Güell A. , Fabre N. , Dupui Ph. , Victor G. , Géraud G.
Published: April 2011

Cerebral blood flow (grey matter flow) in parkinsonism requires further investigation. The noninvasive method of 133Xe inhalation permits study of larger numbers of subjects than previously used invasive techniques such as the intracarotid 133Xe injection method. Measurements were made in this laboratory in 30 subjects having Parkinson's disease. Mean hemispheric blood flow (F1) values were 70.4 ± 9.3 ml/100 g/min, compared to 76.3 for a group of age-matched normal subjects, which is a decrease of −7.8%. The most striking difference was the loss of the “hyperfrontal distribution” in parkinsonism. The prefrontal F1 values were only 1.8% greater than the hemisphere grey matter flow, compared with 8.5% in controls of a similar age group.
Relationships between Extraction and Metabolism of Glucose, Blood Flow, and Tissue Blood Volume in Regions of Rat Brain
Authors: Cremer J. E. , Cunningham V. J. , Seville M. P.
Published: April 2011

Studies were made on the relationships between the rate of glucose metabolism, the transport of glucose between plasma and brain, cerebral blood flow, and blood content. Conscious control rats were compared with rats with intense tremors induced with cismethrin. The influence of plasma glucose concentration was studied by fasting some animals overnight prior to the induction of tremors. Mean plasma glucose was 8.83 m M in controls, 12.57 m M in fed rats with tremors, and 4.94 m M in rats fasted overnight prior to induction of tremors. Of 12 brain regions studied, nine showed an increased rate of glucose utilization in both fed and fasted trembling rats. Cerebellum had the highest percentage increase (200%). Rates of unidirectional glucose influx in fed trembling rats were significantly greater than those in controls in eight regions. In fasted animals, rates were the same as in controls, except in cerebellum, where it was 1.6 times higher. These high rates of glucose influx at low plasma glucose concentrations were indicative of a change in kinetic parameters of glucose transport. Unidirectional glucose influx rates were transformed to estimates of maximal transport rates ( Tmax), based on the Michaelis-Menten equation. Average plasma glucose concentrations in regional capillaries (c̄) were calculated and shown to be maintained at values close to arterial plasma glucose concentrations ( Ca), in all brain regions of each group. In trembling rats, Tmax for each brain region was higher than that in controls. In fasted rats with tremors, Tmax was higher in several brain regions than in fed rats. Tmax in cerebellum was 3.37, 4.71, and 7.89 μmol g−1 min−1 in control, fed trembling, and fasted trembling rats, respectively. Blood flow increased significantly in all regions in rats with tremors and was higher in fasted than in fed animals. There was only a weak correlation between blood flow and Tmax. Blood content of several regions increased in rats with tremors, and there was a strong correlation between Tmax and tissue blood volume. Results are consistent with localized regulatory links between blood flow, capillary surface area, and glucose transport in response to metabolic demand and hypoglycaemia. These involve changes in the linear velocity of blood through capillaries and in the extent of capillary recruitment.
Cholinergic Cerebral Vasodilatation: Lack of Involvement of Cranial Parasympathetic Nerves
Authors: Scremin Oscar U. , Sonnenschein Ralph R. , Rubinstein Eduardo H.
Published: April 2011

Cerebral blood flow (CBF) was estimated by measurement of internal carotid blood flow (ICBF) and sagittal sinus blood flow (SSBF) in mechanically ventilated rabbits under 70% N2O/30% O2. Electrical stimulation of cranial nerves III, VII, IX, or X, with stimulus parameters adequate to excite other visceromotor outflows of these nerves, failed to elicit change in CBF. Combined bilateral section of nerves VII, VIII, IX, X, and XI had no effect on the reactivity of CBF to CO2, nor did the sectioning of these nerves affect the increases in CBF induced by physostigmine. Division of the sinus and aortic nerves and of the vagi in the neck failed to change CO2 reactivity, even though normocapnic CBF was reduced. Pentobarbital blocked the increase in CBF produced by physostigmine, but had no effect on that produced by pilocarpine. The results indicate that cranial parasympathetic nerves do not contain cerebral vasodilator fibers, and that they are not the source of acetylcholine which is presumably involved in CBF regulation.
Why are Infant Gerbils More Resistant Than Adults to Cerebral Infarction after Carotid Ligation?
Authors: Matsuyama Tomohiro , Matsumoto Masayasu , Fujisawa Atsushi , Handa Nobuo , Tanaka Kenji , Yoneda Shotaro , Kimura Kazufumi , Abe Hiroshi
Published: April 2011

Younger gerbils have been found to be more resistant than adults to cerebral infarction after carotid ligation. In this study, the perfused cerebral area after bilateral common carotid occlusion was evaluated in infant, young, and adult Mongolian gerbils by the carbon black perfusion method to assess the existence and significance of collateral blood vessels between the vertebrobasilar and carotid circulations. Nineteen gerbils were divided into three groups (i.e., infant, young and adult gerbils aged 3–4, 5–7, and 10–17 weeks, respectively). After bilateral common carotid artery occlusion, carbon black was injected directly into the left ventricle by cardiac puncture through the closed thorax. In five of eight infant gerbils, the whole brain was perfused by carbon black, while in the remaining three, only the cerebellum and brainstem were stained well, and marked bilateral cerebral pallor was observed. On the other hand, carbon black did not perfuse the brain region supplied by the carotid arteries, both in young and adult gerbils (11 animals in total). These results suggest that infant gerbils might have a more highly developed network of collateral blood vessels between the vertebrobasilar and carotid circulations, and the existence of such a significant network might be the basis for the fact that infant gerbils are resistant to cerebral infarction following carotid ligation. We propose that gerbils should be used as a stroke model only when they are 5 weeks old or older.
Are the Vascular Effects of Naloxone Attributable to the Preservatives Methyl- and Propylparaben?
Authors: Brandt Lennart , Andersson Karl-Erik , Hindfelt Bengt , Ljunggren Bengt , Pickard John D.
Published: April 2011

In vitro, the Nalonee® preparation of naloxone caused a concentration-dependent relaxation of human pial cortical arteries contracted by potassium, noradrenaline, serotonin, prostaglandin F2α (PGF2α), and haemorrhagic cerebrospinal fluid, or inhibited contractions elicited by these agents. However, the preservatives in the Nalonee preparation, methyl- and propylparaben, had similar effects. Pure naloxone alone had no effect on potassium or PGF2α-induced contractions. It is suggested that the relaxant effects on vascular smooth muscle of Nalonee can be attributed to the alkylparabens rather than to naloxone. The pronounced relaxations induced by the alkylparabens had a rapid onset, and they were stable and could easily be cleared after rinsing.
Comparison of the Effects of Intravenous Papaverine Hydrochloride and Oral Pavabid HP Capsulets on Regional Cerebral Blood Flow in Normal Individuals
Authors: McHenry Lawrence C. , Stump David A. , Howard George , Novack Thomas T. , Bivins Don H. , Nelson Andrew O.
Published: April 2011

A single-blind study was conducted in 13 right-handed normal male subjects to compare the effects of oral and i.v. papaverine on regional cerebral blood flow (rCBF). Six xenon-133 inhalation rCBF measurements were performed on each subject; three tests—baseline, placebo, and drug evaluations—were carried out on each of two separate days. The oral and i.v. drugs were randomized for first-day administration. rCBF, measured as flow gray (FG), increased significantly (p ≤ 0.001) from baseline with both drug forms. Increases of 10.53% and 13.94% (left and right hemispheres, respectively) were demonstrated 90 min after a single 600-mg dose of oral papaverine. Increases of 5.09% and 8.69%, respectively, were recorded immediately after a single 100-mg dose of i. v. papaverine. FG also increased significantly (p ≤ 0.001) for both drug forms when compared to that of placebo. Placebo produced only a slight increase (not significant) with both the oral and i.v. groups. The data show that both oral and i.v. papaverine are equally effective in increasing rCBF in normal subjects.
Monoamine Oxidase Activity in Brain Microvessels Determined Using Natural and Artificial Substrates: Relevance to the Blood—Brain Barrier
Authors: Lasbennes F. , Sercombe R. , Seylaz J.
Published: April 2011

The possible contribution of cerebrovascular monoamine oxidase (MAO) to the blood–brain barrier to catecholamines was studied in isolated porcine and rat microvessels by determining its activity with various substrates. Michaelis-Menten kinetic constants, Km and Vmax, were determined using noradrenaline (NA) as substrate in a Tris medium. Km values were 0.25 ± 0.05 m M in control and 0.16 ± 0.09 m M in ultrasonically disintegrated (USD) preparations (difference not significant); Vmax in USD preparations (1.83 ± 0.20 n.atoms O2 min−1 mg protein−1) was slightly higher (p < 0.05) than in control preparations (1.35 ± 0.11 n.atoms O2 min−1 mg protein−1), suggesting a certain restriction by the plasma membrane of substrate access to the enzyme. This phenomenon was confirmed in a more physiological, ionic medium; the activity was then approximately doubled for 1 m M NA, whereas that for 1 m M β-phenylethylamine (β-PEA), a lipid-soluble substrate, tended to decrease with USD treatment. These results show that this highly active form of MAO is unlikely to be saturated by physiological concentrations of catecholamine. It can be estimated that, for a plasma concentration of NA of 1 μM, a facilitated diffusion accelerating the entry of the catecholamine into the cells by at least 15-fold would be necessary in order to exceed the catabolic capacity of MAO. It is concluded that circulating catecholamines are not likely to cross the endothelial barrier of cerebral microvessels intact, and that the small quantities of radioactivity detected in the parenchyma in measurements of the brain uptake index essentially represent metabolites due to MAO activity.
Measurement of Brain pH Using 11CO2 and Positron Emission Tomography
Authors: Buxton R. B. , Wechsler L. R. , Alpert N. M. , Ackerman R. H. , Elmaleh D. R. , Correia J. A.
Published: April 2011

We have examined the feasibility of measuring local brain pH in vivo with 11CO2 and positron emission tomography. In particular, we have addressed two objections that have been raised against this method: the assumed need to estimate local tissue Pco2 and the rapid fixation of 11C in tissue. From a reexamination of the basic theory, we argue that after administration of 11CO2 the time-dependent distribution of 11C between tissue and blood is independent of the distribution of CO2 already in the body, making it unnecessary to estimate local tissue Pco2. Assuming that the blood–brain barrier is impermeable to bicarbonate ions, there will be equal partial pressures of 11CO2 in blood and tissue at equilibrium. To overcome the problem of fixation in the tissue we have developed a kinetic model of the time-dependent distribution of 11C that accounts for regional variations in blood flow, CO2 extraction, pH, and rate of fixation. The values of the model parameters can be estimated from sequential measurements of tissue activity concentration during administration of 11CO2. Tissue pH can then be calculated from one of the parameter values, a measurement of arterial pH, and known constants. Numerical calculations based on the kinetic model with assumed values of the parameters were used to optimize the experimental design. The calculations show that problems with fixation are much less severe with continuous infusion of activity than with bolus administration. During infusion the tissue curve depends strongly on tissue pH but only weakly on the rate of fixation. With state of the art tomographic systems it should be possible to measure tissue pH with an error of about 0.04 pH units.
Effects of Naloxone on Canine Cerebral Vascular Smooth Muscle
Authors: Sasaki Tomio , Kassell Neal F. , Turner Donn M. , Maixner William , Torner James C. , Coester Hans C.
Published: April 2011

The pharmacological effects of naloxone on cerebral arterial smooth muscle in vitro were examined using canine basilar arterial strips. Naloxone exerted two different effects on canine basilar artery: (1) at a high concentration (3 × 10−4 M) it produced nonspecific vasodilation, and (2) at lower concentrations (3 × 10−7, 3 × 10−6, and 3 × 10−5 M) it inhibited the vasoconstrictor effects of norepinephrine without altering KCl-, serotonin-, or hemoglobin-induced constriction. Morphine (2 × 10−5 or 2 × 10−4 M) did not reverse the specific vasodilating effect of naloxone (3 × 10−5 M) on norepinephrine-induced constriction. Rather, morphine and naloxone together produced a greater vasodilating effect on norepinephrine-induced constriction than either agent alone. Naloxone (3 × 10−5 M) failed to alter either phenylephrine-induced constriction or clonidine-induced constriction. The vasodilating effect of naloxone (3 × 10−5 M) on 10−3 M norepinephrine-induced constriction was not reduced with 10−6 M propranolol. These results suggest that the vasodilating effect of naloxone on norepinephrine-induced constriction does not result from an antagonistic action on opiate receptors, direct inhibition of α-adrenoreceptors, or direct stimulation of β-adrenoreceptors in canine cerebral arterial smooth muscle. The vasodilating effect of naloxone on norepinephrine-induced constriction may influence the CBF changes following naloxone administration.
Neurologic Deficit and Cerebral ATP Depletion after Temporary Focal Ischemia in Cats
Authors: Sato M. , Paschen W. , Pawlik G. , Heiss W.-D.
Published: April 2011

Focal ischemia was induced in 23 cats by occluding the left middle cerebral artery for 2 h. The animals were then divided into groups for unforced reperfusion of variable duration ranging from 2 to 48 h. Neurological ratings were obtained during both ischemia and reperfusion. Following planned sacrifice the regional ATP content was assessed by means of a bioluminescence method showing spatial distribution and degree of ATP depletion. All the animals developed a neurologic deficit, with a median of 6 points on a disability scale of 0–10. After reopening of the middle cerebral artery, neurologic recovery was quite variable depending on the initial neurologic deficit (partial φ = 0.67, p1 < 0.05): Animals with mild initial functional impairment improved and those with severe neurologic disturbances either died early or developed a more severe neurologic deficit, irrespective of the duration of reperfusion. The degree of ATP depletion and the amount of brain tissue involved exhibited a significant correlation with the neurological outcome (τ = 0.50, p1 < 0.05), but they were even more closely related to the initial neurologic deficit (partial φ = 1.00, p1 < 0.001), suggesting an early definitive manifestation of deficiencies in regional energy metabolism.
Crossed Cerebellar Diaschisis in Ischemic Stroke: A Study of Regional Cerebral Blood Flow by 133Xe Inhalation and Single Photon Emission Computerized Tomography
Authors: Meneghetti G. , Vorstrup S. , Mickey B. , Lindewald H. , Lassen N. A.
Published: April 2011

Seventy measurements of CBF were performed in 12 stroke patients by 133Xe inhalation and a rapidly rotating single photon emission computerized tomograph. CBF was measured every other day during the acute phase and at 2- and 6-month follow-up visits. A persistent contralateral cerebellar blood flow depression was evident in five patients with severe hemispheric low flow areas, which correlated with large, hypodense lesions on the computerized tomographic scan. In a sixth patient with a small, deep infarct, a transient crossed cerebellar low flow was observed, while the clinical symptoms persisted. It is concluded from this serial study that crossed cerebellar diaschisis is a common finding in completed stroke. It is probably caused by disconnection of the corticopontine pathways, a disconnection that tends to persist. The phenomenon is in fact less variable than the stroke-related CBF changes in the infarcted hemisphere, in which a period of relative hyperemia is frequently seen.
Monoexponential Analysis of 133Xe Clearance Curves for Regional Cerebral Blood Flow Measurements
Authors: Ryding Erik
Published: April 2011

The theoretical properties of a monoexponential flow index, analogous to the one used earlier by other investigators for regional CBF (rCBF) measured after intraarterial injection, were investigated after the administration of 133Xe intraarterially, intravenously, and by inhalation under high and low flow conditions. The sensitivity of the flow index to changes in fast flow components or changes in the weight ratio between the fast and the slow flow compartments was found to be dependent on whichever part of the 133Xe clearance curve was used for the flow calculation and on the shape of the input function for 133Xe. Since biexponential analysis of the clearance curves includes a monoexponential approximation for each of the two components of the clearance curve corresponding to the high and the low flow “families” in the brain, the limitations of the monoexponential flow index observed are in principle also valid for the results of biexponential analysis of the clearance curves.
Multiple-Radionuclide Autoradiography in Evaluation of Cerebral Function
Authors: Lear James L. , Ackermann Robert , Kameyama Motonobu , Carson Richard , Phelps Michael
Published: April 2011

We have developed the mathematical model and experimental technique for quantitative simultaneous multiple-radionuclide autoradiography. The technique is an extension of previously described dual-tracer methods and offers the advantage of a general approach in which any two or more radionuclides with different half-lives can be used to measure multiple parameters of cerebral function. The model allows the selection of nuclide doses and exposure times to balance cross-contamination of the multiple images with nuclide requirements. The technique was validated with homogeneous tissue sections containing combinations of 123I, 124I, 131I, 18F, 99mTc, 68Ga, and 14C, and then used in qualitative and quantitative investigations of interrelationships of local cerebral blood flow, glucose metabolism, and protein synthesis in normal and several pathological conditions in rats.
Immunoreactive Glucagon in the Smooth Muscle Cells of the Rat Cerebral Artery: An Immunohistochemical Analysis
Authors: Matsuyama Tomohiro , Sadao Tomohiro , Matsumoto Masayasu , Mieno Masayuki , Yoneda Shotaro , Kimura Kazufumi , Hayashi Norio , Kamada Takenobu , Abe Hiroshi , Hayakawa Tõru , Tsubouchi Hirohito , Tohyama Masaya
Published: April 2011

The presence of immunoreactive glucagon (IRG) in smooth muscle of the cerebral arteries of rats was demonstrated immunohistochemically using two antisera against pancreatic glucagon, OAL-123 and Unger's 30K. Based on the results and on our previous radioimmunoassay and gel filtration study, the smooth muscle cells of the blood vessels may be one of the extrapancreatic sources of IRG in the plasma.
In vivo Time-Resolved Brain Phosphorus Nuclear Magnetic Resonance
Authors: Hilberman Mark , Subramanian V. Harihara , Haselgrove John , Cone John B. , Egan John W. , Gyulai Laszlo , Chance Britton
Published: April 2011

Methods used to obtain and quantify high-quality time-resolved dog brain phosphorus nuclear magnetic resonance (31P NMR) spectra are described. In eight animals the normoxic dog brain spectra showed 10% of total phosphorus in ATP, 14% in phosphocreatine (PCr), and 38% in brain phospholipids containing phosphodiesters. The chemical shift between PCr and inorganic phosphate, 5.09, corresponded to an intracellular brain pH of 7.2. During hypoxia, PCr declined to 0.5 ± 0.3 (n = 8) of starting levels, prior to any changes in brain ATP. Simultaneous recording of the EEG was obtained in two animals. During hypoxia, progressive PCr depletion was associated with progressive slowing of the EEG, which was essentially silent before significant changes occurred in brain ATP. Finally, the brain 31P NMR spectrum and pH were measured at 90-s intervals, and the sequential changes that followed respiratory arrest were monitored in one dog until high-energy phosphate depletion was complete.