bluuebunny/crossref_metadata_2025_split huggingface dataset:
Block of potassium outward currents in the crayfish stretch receptor neurons by 4‐aminopyridine, tetraethylammonium chloride and some other chemical substances
Authors: PURALI N. , RYDQVIST B. 
Published: December 2008

The effects of 4‐aminopyridine (4‐AP) and tetraethylammonium (TEA) on the outward potassium currents in the rapidly and slowly adapting stretch receptor neurons (SRNs) of the crayfish (Pacifastacus leniusculus) were studied using a two micro‐electrode voltage‐clamp technique. The leakage current was not affected by either 4‐AP or TEA. External 4‐AP blocked the peak outward current in a dose‐dependent manner (1:1 stoichiometry) with an apparent dissociation constant (Kd) of 2.3 ± 0.2 mm (mean ± SEM) in the slowly and 1.4 ± 0.2 mm in the rapidly adapting SRN, the block being voltage dependent. External application of TEA resulted in a block of the steady state current enhancing the transient characteristics of the current response. The block appeared to deviate from a 1: 1 stoichiometry and the apparent Kd for TEA was 9.6 ± 3.4 mm with a cooperativity factor n= 0.43 ± 0.03 in the slowly adapting SRN and 34.5 ± 9.2 mm and 0.37 ± 0.03 respectively in the rapidly adapting SRN. Low Ca2+, apamin and charybdotoxin, which are known to block Ca2+‐dependent K‐currents, had no effects on the outward current as was also the case with catechol.It is concluded that the different effects of TEA and 4‐AP on the outward current in the two types of SRNs can be explained by the presence of at least two, probably heteromultimeric, channel populations having similar sensitivity to 4‐AP but different sensitivity to TEA. One channel has a high affinity (Kd= 0.8–1.6 mm) for TEA and the other a low affinity (Kd= 173–213 mm) for TEA. The low‐affinity channel seems to dominate in the slowly adapting SRN while both channels are equally common in the rapidly adapting SRN. Further, the present results do not support the existence of a macroscopic Ca2+‐dependent K+ current in the SRNs.
Polyamines in nerve terminals and secretory granules isolated from neurohypophyses
Authors: KRØIGAARD M. , THAMS P. , THORN N. A. 
Published: December 2008

In isolated nerve terminals from ox neurohypophyses the following concentrations of polyamines [pmol (μg protein)‐1 (mean ± SEM)] were found: spermine: 2.07 ± 0.14 (n = 3), spermidine: 0.22 ± 0.01 (n = 4), putrescine: 0.20 ± 0.01 (n = 4).In secretory granules isolated from the same tissue, the concentrations were: spermine: 0.57 ± 0.02 (n = 3), spermidine: 0.07 ± 0.04 (n = 3), putrescine: 0.13 ± 0.04 (n = 3).After incubation of isolated nerve terminals with the polyamines, they were taken up as a function of time and concentration, approaching saturation at high concentrations.The kinetic parameters of their synthesizing enzyme, ornithine decarboxylase, in ox neurohypophyseal nerve terminals (apparent Km 0.75 mm and Vmax 22.5 pmol mg protein‐1 h‐1) were comparable to those previously found in cerebral cortex of rats.When isolated, hemilobes from rat neurohypophyses were incubated in a medium which contained spermidine (5 mM), and were stimulated by 56 mrs K+, release of vasopressin was smaller than in control experiments. However, after removal of spermidine and after restimulation, 50 min after initial stimulation, the release was significantly elevated.It is suggested that polyamines may take part in modulation of vasopressin release.
Neuro‐effector characteristics of sweat glands in the human hand activated by irregular stimuli
Authors: KUNIMOTO M. , KIRNÖ K. , ELAM M. , KARLSSON T. , WALLIN B. G. 
Published: December 2008

Intraneural electrical stimulation of cutaneous fascicles in the median nerve was performed in 24 normal subjects and the effects on sweating within the innervation zone were monitored as changes of skin resistance and water vapour partial pressure (wvpp). The aims were: (1) to investigate the response variability between repeated stimulation sequences in the same skin site and between different sites and (2) to compare quantitative effects of regular and irregular stimulation on skin resistance and wvpp. Regional axillary anaesthesia of the brachial plexus eliminated spontaneous and reflex sympathetic activity.With repeated irregular stimulation sequences skin resistance responses from the same skin site varied only slightly between trials. Differences between response curves from two skin sites in the same subject or from different subjects were also small but significantly greater (P < 0.01) than differences between responses to repeated stimulation in the same site.Irregular stimulation with average frequencies of 0.49 Hz and 3.51 Hz gave greater resistance responses than if the same number of stimuli were delivered regularly (P < 0.01). The difference was most pronounced at 0.49 Hz.At an average frequency of 0.49 Hz the stimulation usually evoked no changes of wvpp whereas an average frequency of 3.51 Hz caused an increase of wvpp which was greater with irregular than with regular stimulation in all subjects.We conclude that: (1) sweat responses to sudomotor nerve traffic vary slightly due to local factors in the skin or the terminal nerve endings and (2) irregular sudomotor nerve traffic evokes more sweat than if the same impulses occur regularly.
Evidence for long‐term fluctuations in regional blood flow within the rabbit left ventricle
Authors: IVERSEN P.O. 
Published: December 2008

The regional distribution of coronary perfusion within the left ventricle is markedly heterogenous. The perfusion pattern is composed of both spatial and temporal variations in perfusion among single myocardial samples. Previous investigators have mostly studied short‐term (< 1 min) temporal variability. The aim of this study was to quantify long‐term fluctuations in perfusion to single samples within the rabbit left ventricle.Coronary perfusion was estimated from the deposition of microspheres in myocardial samples (range 32–96 mg). Two batches of microspheres were infused either simultaneously or sequentially over specified periods of time. The paired values for regional perfusion were compared and Kendalls correlation coefficient (T) calculated. The assumption being that the lower T, the higher degree of temporal perfusion variability was present.The T for paired values of regional myocardial perfusion based on two sequential infusions lasting either 10 s, 5, 10 or 30 min, averaged 0.40, 0.55, 0.80 and 0.80, respectively. No difference was detected between awake and anaesthetized animals. The T for two simultaneous infusions averaged 0.95 irrespective of the duration of the infusion, indicating negligible methodological error. The coefficient of variation for spatial perfusion heterogeneity ranged from 0.3 to 0.4 irrespective of the infusion duration.The findings suggest that regional coronary vasomotion is characterized by a wide range of cycle times, some of which have cycle times of more than 30‐min duration. Although part of the regional perfusion heterogeneity was due to long‐term fluctuations in perfusion, temporal variations with cycle times less than 5 and 10 min, respectively, were more prominent.
Pain‐induced inhibition of gastric motility is mediated by adrenergic and vagal non‐adrenergic reflexes in the rat
Authors: BOJÖ L. , CASSUTO J. , NELLGÅRD P. 
Published: December 2008

Painful stimuli have been shown to inhibit gastric motility in animal experiments and delay gastric emptying in humans. The aim of the present study was to investigate in detail mechanisms involved in pain‐induced gastric inhibition.Pain stimulation by exerting pressure on a testicle induced a prompt gastric relaxation which lasted throughout the period of stimulation. Pain‐induced gastric relaxation was significantly reduced by the selective α‐1 blocker, prazosin, and by the non‐selective β‐blocker, propranolol. Similarly pain‐induced inhibition of gastric tone was significantly reduced by bilateral cervical vagotomy. In contrast, gastric relaxation following pain stimulation was significantly potentiated by the selective adrenergic α‐2 blocker, yohimbine. Combined administration of prazosin and propranol followed by bilateral cervical vagotomy abolished gastric relaxation in response to pain stimulation.In conclusion, gastric relaxation in response to painful stimulation was found to be reflex‐mediated via sympathetic neurons acting on α‐1 and β receptors and possibly also via vagal non‐adrenergic fibres. Pain‐induced inhibition of gastric tone was significantly increased by yohimbine. It is suggested that yohimbine by blocking presynaptic inhibitory receptors on adrenergic neurons facilitates the release of noradrenaline in response to pain stimulation.
The role of purinergic neurotransmission in various cardiovascular reflexes
Authors: TARASOVA O. S. , RODIONOV I. M. 
Published: December 2008

In urethane‐anaesthetized rats the effects of α‐adrenoceptor antagonists and desensitization of P2‐purinoceptors with α,β‐methylene ATP on the pressor reflex responses were investigated. Pressor responses were elicited by electrical stimulation of the central end of the sciatic nerve, by asphyxia and by occlusion of the common carotid artery. Responses to sciatic nerve stimulation and to asphyxia, but not those to carotid artery occlusion were entirely suppressed by dihydroergotamine and phentolamine. Under the action of dihydroergotamine the sinocarotid reflex decreased by over 70% in 40% of the experiments. In 60% of experiments the response was only slightly reduced or even augmented, but it was entirely inhibited by subsequent desensitization with α,β‐methylene ATP.The magnitude of response to sciatic nerve stimulation was almost unaffected by α,β‐imethylene ATP, while the response to carotid occlusion was decreased by 40–50%. The recovery of purinoceptor sensitivity to α,β‐methylene ATP was accompanied by restoration of the sinocarotid reflex.It is suggested that purinergic neurotransmission plays a considerable role in the pressor sinocarotid reflex, while in the pressor response to stimulation of somatic afferents its role is negligible.
Local forearm and whole‐body respiratory quotient in humans after an oral glucose load: methodological problems
Authors: SIMONSEN L. , BÜLOW J. , MADSEN J. , HERMANSEN F. , ASTRUP A. 
Published: December 2008

The effects of an oral glucose load of 75 g on the local forearm and whole‐body energy thermogenesis were measured in normal subjects during the 4 h after the glucose intake. Simultaneous assessment of substrate metabolism in the forearm was performed.Energy expenditure (EE) increased after the glucose load and had not returned to baseline level at the end of the experiment. Whole‐body respiratory quotient (RQ) was, on average, 0.80 (SD 0.05) in the baseline condition and increased to a maximum of 0.91 (0.03) and then decreased to baseline level at the end of the experiment. The local forearm oxygen uptake increased 30 min after the glucose intake and remained elevated during the rest of the experiment. The carbon dioxide output from the forearm did not increase before 90 min after the glucose load. Consequently the local forearm RQ decreased significantly from a baseline value of 0.86 (0.17) to 0.63 (0.17) 30 min after the glucose load (P < 0.05). Ninety min after the glucose load RQ increased to a maximum level at 0.95 (0.22) and decreased then gradually to baseline level.The experiments emphasize several methodological problems in the measurement of local forearm RQ The whole‐body RQ and local forearm RQ are not significantly different in the fasting state. The finding of a decrease in local forearm RQ below 0.70 30 min after the glucose load probably indicates a non‐steady state in the carbon dioxide exchange. Thus, indirect calorimetry cannot be applied locally during short time periods.
Changes in the ovarian intermediate filament desmin during the luteal phase of the adult pseudopregnant rat
Authors: SELSTAM G. , NILSSON I. , MATTSSON M.‐O. 
Published: December 2008

The occurrence of the intermediate filament desmin in ovary and corpus luteum of pseudopregnant rats was studied using Western blot analysis and immunohisto‐chemistry. The luteal phase was induced by mating with vasectomized male rats and ovaries were studied after 6, 11 and 19 days. The findings from the Western blot analysis showed that desmin was present in the corpus luteum. Immunohistochemical localization of desmin showed two types of localization in the corpus luteum. The arteries around the corpus luteum, as well as arteries elsewhere in the ovary, had a high content of desmin in their muscle layer. Dispersed in the corpus luteum was an immunohistochemical staining of desmin that was localized mainly adjacent to the luteal cells. In the other part of the ovary a weak staining was registered in the theca layer, no staining in the granulosa layer and a streaky staining in the hilar region of the ovary.Desmin filaments are found in muscle cells of all types, including vascular smooth muscle cells. Probably, all desmin in the ovary is localized to smooth muscle cells with the possible exception of the corpus luteum where very few muscle cells have been identified. Localization to other vascular cells as endothelial is possible. In this study we found an increase in desmin content in the corpus luteum after day 6. If desmin is related to vascular resistance, our finding is consistent with the decrease in blood flow that occurs after day 6.
Thel‐arginine/nitric oxide pathway in the rabbit urethral lamina propria
Authors: ZYGMUNT P. K. E. , PERSSON K. , ALM P. , LARSSON B. , ANDERSSON K.‐E. 
Published: December 2008

A non‐adrenergic, non‐cholinergic (NANC)‐mediated relaxation has been demonstrated in the female rabbit urethral lamina propria, both in response to electrical stimulation and after administration of acetylcholine. The present study was performed to investigate if these relaxations are mediated via thel‐arginine/nitric oxide (NO) pathway. In the lamina propria of the female rabbit urethra, numerous NADPH diaphorase‐positive, fine varicose nerve fibres were observed both around arteries, in and around smooth muscle bundles, and in arterial endothelium. Since NADPH diaphorase histochemistry may be a marker of NO synthase‐containing neurons, this finding suggests the occurrence of NO synthase in this tissue. Isolated preparations of the rabbit urethral lamina propria, contracted by noradrenaline, produced frequency‐dependent NANC relaxations in response to electrical field stimulation, and concentration‐dependent NANC relaxations in response to acetylcholine. Electrically induced relaxations were possible to evoke even in preparations where acetylcholine‐induced relaxation was poor or absent. Pretreatment with the NO synthase inhibitor, NG‐nitro‐l‐arginine (l‐NOARG) reduced the maximum relaxation obtained at 30 Hz to 12% of the control response. NG‐nitro‐d‐arginine (d‐NOARG) had no effect. The effects ofl‐NOARG were antagonized by the addition ofl‐arginine. Acetylcholine relaxed noradrenaline‐precontracted strips by 36%; vasoactive intestinal polypeptide (VIP) reduced the contraction by 95%.l‐NOARG, but notd‐NOARG, abolished or reversed acetylcholine‐induced relaxations, but failed to reduce the relaxations produced by VIP.The results demonstrate the occurrence of NADPH diaphorase‐positive nerve fibres in the lamina propria of the female rabbit urethra. NANC‐mediated relaxations, sensitive to inhibition of NO synthase, were produced both by electrical stimulation and by acetylcholine. The fact that NANC nerve‐mediated relaxation was demonstrated also in preparations where no relaxant response to acetylcholine could be detected suggests that the NO which produces relaxation can be derived both from endothelium and from NANC nerves.
Sharing sovereignty for global regulation: The cases of fuel economy and online gambling
Authors: Mikler John 
Published: December 2008

AbstractGlobalization is sometimes taken as a synonym for market liberalization, because it is claimed that power has flowed from states to markets. Whether happening as a result of undeniable “forces” or some hegemonic consensus, many on both the left and right of politics agree that this is a reality. However, this article argues that states which share sovereignty with market actors are able to influence outcomes beyond their borders. The cases of fuel economy and online gambling regulations are used to illustrate the point. In the former case, Japanese and European industry‐driven regulations are being “exported” in the attributes of the products of their car industries. In the latter, UK market‐friendly regulations are likely to be “exported” to the European region and beyond because of industry support, and market liberalization principles embodied in European Union institutions. Both cases indicate that sharing sovereignty in the process of making and implementing national regulations produces opportunities for global regulation.
Immunohistochemistry is a more sensitive marker for the detection of myeloperoxidase in acute myeloid leukemia compared with flow cytometry and cytochemistry
Authors: SARAVANAN L. , JUNEJA S. 
Published: December 2008

SummaryMyeloperoxidase (MPO) is an unequivocal marker of myeloid differentiation which is routinely detected using cytochemistry (CC), flow cytometry (FC) and immunohistochemistry (IH). Several studies have compared the use of two of these methods, but to our knowledge none has compared all three techniques. We compared the performance of these three modalities in the detection of MPO in 158 cases of acute myeloid leukaemia (AML). Discrepancies were noted in a total of 28 cases. Of 110 cases in which all three modalities were performed, 23 cases showed discrepancies. CC was the least sensitive marker, being negative in 11 of 23 cases in the presence of positive IH and/or FC. IH was the most sensitive marker with only one case being negative in the presence of a positive result by FC and/or CC. The results highlight the necessity of employing more than one method in determining the presence of MPO and confirm the important role of IH in the diagnosis of AML particularly in cases where MPO is not detected by CC and FC.
Commissioning and quality assurance for intensity‐modulated radiotherapy with dynamic multileaf collimator: Experience of the Pontificia Universidad Católica de Chile
Authors: Venencia Carlos Daniel , Besa Pelayo 
Published: December 2008

The objective of this paper is to present our experience in the commissioning and quality assurance (QA) for intensity‐modulated radiotherapy (IMRT) using the dynamic multileaf collimator (dMLC), sliding window technique. The connectivity and operation between all IMRT chain components were checked on the Varian equipment. Then the following tests were performed: stability of leaf positioning and leaf speed, sensitivity to treatment interruptions (acceleration and deceleration), evaluation of standard field patterns, stability of dMLC output, segmental dose accuracy check, average leaf transmission, dosimetric leaf separation, effects of lateral disequilibrium between adjacent leaves in dose profiles, and multiple carriage field verification. Standard patterns were generated for verification: uniform field, pyramid, hole, wedge, peaks, and chair. Weekly QA protocol includes sweeping gap output, garden fence test (narrow bands, 2 mm wide, of exposure spaced at 2‐cm intervals), and segmental dose accuracy check. Monthly QA includes sweeping gap output at multiple gantry and collimator angles, sweeping gap off‐axis output, picket fence test (eight consecutive movements of a 5‐cm wide rectangular field spaced at 5‐cm intervals), stability of leaf speed and leaf motor current test (PWM test). Our patient QA procedure consists of an absolute dose measurement for all treatment fields in the treatment condition, analysis of actual leaf position versus planned leaf position (dynalog files) for each treatment field, film relative dose determination for each field, film relative dose determination for the plan (all treatment fields) in two axial planes, and patient positioning verification with orthogonal films. The tests performed showed acceptable results. After over one year of IMRT treatment, the routine QA machine checks confirmed the precision and stability of the IMRT system.PACS number: 87.53.Xd, 87.53.Dq, 87.53.Mr
A comparison of two commercial treatment‐planning systems for IMRT
Authors: Petric M. Peter , Clark Brenda G. , Robar James L. 
Published: December 2008

This study compared the clinical functionality of BrainSCAN (BrainLAB) and Helios (Eclipse, Varian) for intensity‐modulated radiation therapy (IMRT) treatment planning with the aim of identifying practical and technical issues. The study considered implementation and commissioning, dose optimization, and plan assessment. Both systems were commissioned for the same 6 MV photon beam equipped with a high‐resolution multileaf collimator (Varian Millennium 120 leaf). The software was applied to three test plans having identical imaging and contour data. Analysis considered 3D axial dose distributions, dose‐volume histograms, and monitor unit calculations. Each system requires somewhat different input data to characterize the beam prior to use, so the same data cannot be used for commissioning. In addition, whereas measured beam data was entered directly into Helios with minimal data processing, the BrainSCAN system required configured beam data to be sent to BrainLAB before clinical use. One key difference with respect to system commissioning was that BrainSCAN required high resolution data, which necessitated the use of detectors with small active volumes. This difference was found to impact on the ability of the systems to accurately calculate dose for highly modulated fields, with BrainSCAN being more successful than Helios. In terms of functionality, the BrainSCAN system uses a dynamically penalized likelihood inverse planning algorithm and calculates four plans at once with various relative weighting of the planning target and organ‐at‐risk volumes. Helios uses a gradient algorithm that allows the user to make changes to some of the input parameters during optimization. An analysis of the dosimetry output shows that, although the systems are different in many respects, they are each capable of producing substantially equivalent dose plans in terms of target coverage and normal tissue sparing.PACS number: 87.53.Tf
Intraoperative radiotherapy using a mobile electron LINAC: A retroperitoneal sarcoma case
Authors: Beddar A. Sam , Krishnan Sunil 
Published: December 2008

The advent of mobile LINACs for use in intraoperative radiation therapy (IORT) promises to make IORT more accessible than before and easier to deliver to patients undergoing surgery. Although mobile IORT systems have been available since 1999, few treatment centers currently use them. Here, we present the case of a typical patient undergoing IORT for retroperitoneal sarcoma to show how easy these mobile systems are to use and how adaptable they are within the operating room (OR) environment. We also discuss the roles and coordination of multidisciplinary team members during IORT and the feasibility of using mobile LINACs for IORT.PACS number(s):