bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of serum flecainide trough levels in patients with tachyarrhythmia
Authors: Homma Masato , Kuga Keisuke , Doki Kosuke , Katori Kumi , Yamaguchi Iwao , Sugibayashi Kenji , Kohda Yukinao 
Published: December 2004

Abstract
The reported therapeutic range for trough flecainide concentration is 200–1000 ng mL−1. Severe adverse events, such as ventricular arrhythmias, have occurred occasionally in patients whose serum flecainide exceeded 1000 ng mL−1. However, the lower limit remains controversial. We have evaluated blood flecainide concentrations in patients with tachyarrhythmia who received the drug to control palpitation. We measured the flecainide trough levels and incidence and frequency of palpitation of 44 outpatients receiving oral flecainide (150–300 mg daily). Mean serum flecainide trough concentrations differed significantly between patients with (n = 14) and without (n = 30) palpitation (259.5 ± 85.2 vs 462.2 ± 197.7 ng mL−1, P &lt; 0.01). The frequency of palpitation decreased as the serum flecainide concentration increased. The incidence of palpitation was 65% at serum flecainide concentrations &lt; 300 ng mL−1 and 11% at ≥ 300 ng mL−1. QRS values were increased significantly in patients with serum flecainide ≥ 300 ng mL−1 compared with &lt; 300 ng mL−1 (0.110 ± 0.016s vs 0.093 ± 0.019s, P &lt; 0.05). We concluded that to control paroxysm in patients receiving flecainide for tachyarrhythmia serum flecainide concentrations should be maintained at ≥ 300 ng mL−1.
Aqueous garlic extract alleviates ischaemia-reperfusion-induced oxidative hepatic injury in rats
Authors: Şener Göksel , Sehirli özer , Ipçi Yeşim , Ercan Feriha , şirvanci Serap , Gedik Nursal , Yeĝen Berrak Ç 
Published: December 2004

Abstract
This study was designed to examine the effects of aqueous garlic extract (AGE) on hepatic ischaemia-reperfusion (I/R) injury in rats. For this purpose, Wistar albino rats were subjected to 45 min of hepatic ischaemia, followed by a 60-min reperfusion period. AGE (1 mL kg−1, i.p., corresponding to 500 mg kg−1) or saline was administered twice, 15 min before ischaemia and immediately before the reperfusion period. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined to assess liver functions. Liver tissues were taken for the determination of malondialdehyde (MDA) levels, an end product of lipid peroxidation; glutathione (GSH) levels, a key antioxidant; and myeloperoxidase (MPO) activity, as an indirect index of neutrophil infiltration. Hepatic collagen content, as a fibrosis marker, was also determined. Plasma ALT and AST activities were elevated in the I/R group as compared with the control group, while these increases were significantly decreased by AGE treatment. Hepatic GSH levels, significantly depressed by I/R, were elevated back to control levels in the AGE-treated I/R group. Increases in tissue MDA levels and MPO activity due to I/R injury were reduced back to control levels by AGE treatment. Similarly, increased hepatic collagen content in the I/R group was reduced to the control level with AGE treatment. Since AGE administration alleviated the I/R-induced injury of the liver and improved the hepatic structure and function, it seems likely that AGE, with its antioxidant and oxidant-scavenging properties, may be of potential therapeutic value in protecting the liver against oxidative injury due to ischaemia-reperfusion.
Low-frequency fatigue, post-tetanic potentiation and their interaction at different muscle lengths following eccentric exercise
Authors: Rijkelijkhuizen J. M. , de Ruiter C. J. , Huijing P. A. , de Haan A. 
Published: December 2004

SUMMARYLow-frequency fatigue (LFF) and post-tetanic potentiation (PTP) were quantified at different muscle lengths in rat medial gastrocnemius (GM)muscle. In situ experiments were performed on GM muscle-tendon complexes of anaesthetised (urethane, 1.5 g kg-1 i.p.) Wistar rats(N=8). Force-length characteristics were determined at maximal (200 Hz) and submaximal (60 Hz) stimulation. Data for submaximally stimulated muscle were obtained in a non-potentiated and in a potentiated condition. LFF was induced by a series of 40 eccentric contractions. Post-exercise (40-80 min), data for the force-length relationships were obtained once more. Whereas force loss at 200 Hz-stimulation was least at optimum muscle length, L0,200Hz, (17.0±1.4%, mean ± s.e.m.), force loss at 60 Hz-stimulation was maximal near L0,200Hz (55.1±4.3% at L0,200Hz-1 mm). When the muscle was potentiated, force loss at 60 Hz-stimulation was maximal at short muscle length: L0,200Hz-4 mm (53.5±3.8%). The extent of LFF,quantified by a decrease in the 60:200 Hz force ratio, varied with muscle length: LFF increased with decreasing muscle lengths when muscles were potentiated. However, in the non-potentiated condition, LFF was maximal at a length just below L0,200Hz; the 60:200 Hz force ratio had decreased to 54.6±5.9% of the pre-exercise ratio at L0,200Hz-1 mm. Compared with the non-potentiated condition, LFF was less pronounced in the potentiated condition. PTP counteracted LFF particularly at long muscle lengths. However, at short muscle lengths, LFF was still observed in potentiated muscles.
Stress signaling: coregulation of hemoglobin and male sex determination through a terpenoid signaling pathway in a crustacean
Authors: Rider Cynthia V. , Gorr Thomas A. , Olmstead Allen W. , Wasilak Beth A. , LeBlanc Gerald A. 
Published: December 2004

SUMMARY
Environmental signals can activate neuro-endocrine cascades that regulate various physiological processes. In the present study, we demonstrate that two responses to environmental stress signaling in the crustacean Daphnia magna - hemoglobin accumulation and male offspring production - are co-elevated by the crustacean terpenoid hormone methyl farnesoate and several synthetic analogs. Potency of the hormones with respect to the induction of both hemoglobin and male offspring was highly correlated, suggesting that both processes are regulated by the same terpenoid signaling pathway. Six clones of the D. pulex/pulicaria species complex that were previously characterized as unable to produce male offspring and five clones that were capable of producing males were evaluated for both hemoglobin induction and male offspring production in response to methyl farnesoate. Four of the five male-producing clones produced both hemoglobin and male offspring in response to the hormone. Five of the six non-male-producing clones produced neither hemoglobin nor males in response to the hormone. These results provide additional evidence that both physiological processes are regulated by the same signaling pathway. Furthermore, the results indicate that the non-male-producing clones are largely defective in some methyl farnesoate signaling component, downstream from methyl farnesoate synthesis but upstream from the genes regulated by the hormone. A likely candidate for the site of the defect is the methyl farnesoate receptor. As a consequence of this defect,non-male-producing clones have lost their responsiveness to environmental signals that are transduced by this endocrine pathway. This defect in signaling would be likely to enhance population growth in stable environments due to the elimination of males from the population, assuming that other processes critical to population growth are not also compromised by this defect.
Stretching of supercontracted fibers: a link between spinning and the variability of spider silk
Authors: Guinea G. V. , Elices M. , Pérez-Rigueiro J. , Plaza G. R. 
Published: December 2004

SUMMARY
The spinning of spider silk requires a combination of aqueous environment and stretching, and the aim of this work was to explore the role of stretching silk fibers in an aqueous environment and its effect on the tensile properties of spider silk. In particular, the sensitivity of the spider silk tensile behaviour to wet-stretching could be relevant in the search for a relationship between processing and the variability of the tensile properties. Based on this idea and working with MAS silk from Argiope trifasciata orb-web building spiders, we developed a novel procedure that permits modification of the tensile properties of spider silk: silk fibers were allowed to supercontract and subsequently stretched in water. The ratio between the length after stretching and the initial supercontracted length was used to control the process. Tensile tests performed in air, after drying,demonstrated that this simple procedure allows to predictable reproduction of the stress-strain curves of either naturally spun or forcibly silked fibers. These results suggest that the supercontracted state has a critical biological function during the spinning process of spider silk.
The interplay of cutaneous water loss, gas exchange and blood flow in the toad,Bufo woodhousei:adaptations in a terrestrially adapted amphibian
Authors: Burggren Warren W. , Vitalis Timothy Z. 
Published: December 2004

SUMMARYToads experiencing dehydrating conditions exhibit complex physiological and behavioral responses, some of which can potentially impact cutaneous gas exchange, an important component of total gas exchange. We measured the effect of dehydration on cutaneous gas exchange in the xeric-adapted toad Bufo woodhousei. First, two pharmacological agents were used to stimulate cutaneous blood flow - phentolamine (an α-blocker) and isoproterenol, aβ-stimulant and powerful cardio-accelerator - to determine a relationship between cutaneous blood flow and water loss. Both drugs increased heart rate and blood pressure, and caused visually evident extensive vasodilation of the skin. Untreated toads in a dry air stream took an average of 10.1±0.7 h to dehydrate to 80% body mass, while animals treated with isoproterenol and phentolamine requires only 7.2±0.8 h and 7.4±0.9 h,respectively. Rehydration, which was more rapid than dehydration, was similarly accelerated in pharmacologically treated toads.Cutaneous gas exchange(ṀO, ṀCO) and C18O diffusing capacity (DSkinC18O) were then examined in unanesthetized toads under different states of body hydration. Blood gases and hematocrit were measured separately but under identical conditions. In fully hydrated toads at 23-25°C, cutaneous gas exchange values were: ṀO =1.43±0.47 μmol g-1 h-1, ṀCO = 1.75±0.85μmol g-1 h-1, and the respiratory exchange ratio R =1.36±0.56 (N=6, mean + 1s.d.). DSkinC18O was 0.48±0.03 μmol g body mass-1 h-1 kPa. Following an enforced 20-25% loss of body water, DSkinC18O fell by nearly 50% to 0.28±0.09 μmol g-1 h-1 kPa. However, cutaneous ṀO, ṀCO and R were unchanged at 1.48±0.15 μmol g-1 h-1, 1.72±0.29μmol g-1 h-1 and 1.13±0.08 μmol g-1 h-1, respectively. Partial pressure of arterial(sciatic) oxygen, PaO2, normally about 12-13 kPa, remained unchanged by dehydration, but PaCO2 increased about 250% from 0.93±0.27 up to 2.27±0.93 kPa. The fall in DSkinC18O during dehydration presumably results at least in part from decreased cutaneous blood flow, possibly in an attempt to reduce the transcutaneous water loss that would otherwise result during dehydrating conditions. Concurrently, cutaneous ṀCO is maintained under dehyrdating conditions by a greatly increased PaCO2 diffusion gradient across the skin. Thus, Bufo woodhousei appears able to restrict cutaneous blood flow without compromising vital cutaneous CO2 loss.
Dendritic spike back propagation in the electrosensory lobe of Gnathonemus petersii
Authors: Gómez Leonel , Kanneworff Morten , Budelli Ruben , Grant Kirsty 
Published: December 2004

SUMMARY
Spike timing-dependent plasticity that follows anti-Hebbian rules has been demonstrated at synapses between parallel fibers and inhibitory interneurons known as medium ganglionic layer (MG) neurons in the cerebellum-like electrosensory lobe of mormyrid fish. This plasticity is expressed when presynaptic activation is associated with a characteristically broad,postsynaptic action potential, lasting 7-15 ms, occurring within a window of up to 60-80 ms following synaptic activation. Since the site of plastic change is presumably in the apical dendrites, it is important to know where, when and how this broad spike is generated and the manner in which such events propagate within the intrinsic network of the electrosensory lobe.
The electrosensory lobe has a strict layered organization that makes the preparation suitable for one dimension current source density analysis. Using this technique in an `in vitro' interface slice preparation, we found that following either parallel fiber stimulation or an orthogonal field stimulus, a sink appeared in the ganglionic layer and propagated into the molecular layer. Intracellular records from MG somata showed these stimuli evoked broad action potentials whose timing corresponds to this sink. TTX application in the deep fiber layer blocked the synaptically evoked ganglionic layer field potential and the `N3' wave of the outer molecular layer field potential simultaneously, while the molecular layer`N1' and `N2' waves corresponding to synaptic activation of the apical dendrites remained intact. These results confirm the hypothesis that the broad spikes of MG cells originate in the soma and propagate through the molecular layer in the apical dendritic tree, and suggest the possibility that this backpropagation may contribute to `boosting' of the synaptic response in distal apical dendrites in certain circumstances.
Tolerance of endolithic algae to elevated temperature and light in the coralMontipora monasteriatafrom the southern Great Barrier Reef
Authors: Fine Maoz , Meroz-Fine Efrat , Hoegh-Guldberg Ove 
Published: December 2004

SUMMARYPhotosynthetic endolithic algae and cyanobacteria live within the skeletons of many scleractinians. Under normal conditions, less than 5% of the photosynthetically active radiation (PAR) reaches the green endolithic algae because of the absorbance of light by the endosymbiotic dinoflagellates and the carbonate skeleton. When corals bleach (loose dinoflagellate symbionts),however, the tissue of the corals become highly transparent and photosynthetic microendoliths may be exposed to high levels of both thermal and solar stress. This study explores the consequence of these combined stresses on the phototrophic endoliths inhabiting the skeleton of Montipora monasteriata, growing at Heron Island, on the southern Great Barrier Reef. Endoliths that were exposed to sun after tissue removal were by far more susceptible to thermal photoinhibition and photo-damage than endoliths under coral tissue that contained high concentrations of brown dinoflagellate symbionts. While temperature or light alone did not result in decreased photosynthetic efficiency of the endoliths, combined thermal and solar stress caused a major decrease and delayed recovery. Endoliths protected under intact tissue recovered rapidly and photoacclimated soon after exposure to elevated sea temperatures. Endoliths under naturally occurring bleached tissue of M. monasteriata colonies (bleaching event in March 2004 at Heron Island) acclimated to increased irradiance as the brown symbionts disappeared. We suggest that two major factors determine the outcome of thermal bleaching to the endolith community. The first is the microhabitat and light levels under which a coral grows, and the second is the susceptibility of the coral-dinoflagellates symbiosis to thermal stress. More resistant corals may take longer to bleach allowing endoliths time to acclimate to a new light environment. This in turn may have implications for coral survival.
Scanning electron microscope and energy dispersive X-ray spectrometry studies on the material surface of extruded Polycel® ossicular prostheses
Authors: Jang Chul Ho , Wang Pa-Chun 
Published: December 2004

Background: The cause of ossicular prosthesis extrusion remains an issue of interest to many otologists. This study evaluated the change in material surfaces and chemical elements of extruded total ossicular replacement prostheses (TORPs) and partial ossicular replacement prostheses (PORPs).Methods: A total of nine extruded Polycel® ossicular prostheses (four TORPs, five PORPs) from nine patients was investigated using scanning electron microscope and energy dispersive X-ray spectrometry (EDX). Three prostheses (TORPs) obtained during revision surgery
for hearing restoration were used as control subjects for EDX study.Results: All subjects from the study group showed loss of fibrous capsule at both platform and shaft in the extruded prostheses. In comparison with the control group, the extruded prostheses had a lower level of carbon	element (Wilcoxon signed-rank test, p < 0.05).Conclusion: Loss of fibrous capsule and micro-degradation are probably two of the many factors that contribute to the extrusion of ossicular prostheses.
Post-transplant lymphoproliferative disorder presenting as epistaxis
Authors: Clarke Jonathan D. , Stock David , Singh Vijay 
Published: December 2004

An unusual case of epistaxis resulting from post-transplant lymphoproliferative disorder is described.A 30-year-old woman who had undergone renal transplantation 12 years previously presented with profuse, posterior, unilateral epistaxis. The initial findings, workup and treatment are presented. A post-nasal space (PNS) mass was detected and biopsy showed this to be an Epstein-Barrvirus-positive polymorphous B-cell post-transplant lymphoproliferative disorder. Computed tomography findings showed a polypoid lesion protruding from the sphenoethmoidal recess and filling
the left PNS.Post-transplant lymphoproliferative disorder is well known to involve tonsil tissue. Commonly, this is the first presentation of the disease in children. However, until now post-transplant lymphoproliferative disorder has not been described in the PNS or nasal cavity presenting
as epistaxis. We conclude that all transplant patients presenting with epistaxis should be followed up for an accurate examination of the PNS and nasal cavity after the acute episode.
Pharmacokinetics and Pharmacodynamics of Meropenem in Febrile Neutropenic Patients with Bacteremia
Authors: Ariano Robert E , Nyhlén Anna , Donnelly J Peter , Sitar Daniel S , Harding Godfrey KM , Zelenitsky Sheryl A 
Published: December 2004

BACKGROUND: Pharmacodynamic investigations with antimicrobials define the relationship between the infecting organism and achievable drug concentrations with clinical outcome. OBJECTIVE: To examine this relationship for meropenem in a population of patients who are at high risk of infection-related morbidity and mortality. METHODS: The study was a retrospective analysis of a multicenter, randomized, blinded clinical trial. A population-based predictive model was created using data from adults with febrile neutropenia and the nonparametric modeling program, NPEM. Patient age, body weight, and serum creatinine level were covariates in the model used to predict unbound concentrations for each patient. Pathogen susceptibility was estimated using product literature minimum inhibitory concentrations for effectiveness against 50% of microorganisms (MIC50) for specific organisms. The pharmacodynamic index of percent time above MIC (% T>MIC) was analyzed for its association with clinical outcome. RESULTS: A 2-compartment pharmacokinetic model using patient covariates of body weight and renal function best described the pharmacokinetics of meropenem in febrile neutropenic patients. Sixty patients with confirmed gram-positive or -negative bacteremia were studied. An average of 83% T>MIC was identified for the 42 clinical responders compared with 59% T>MIC for the 18 nonresponders (p = 0.04). An 80% clinical response rate was evident when the % T>MIC for meropenem exceeded 75% of the dosing interval (p = 0.01). CONCLUSIONS: To our knowledge, this is the first published report of a relationship between a pharmacodynamic index and clinical outcome in a febrile neutropenic population. Based on this relationship, dosing with intravenous meropenem 500 mg every 6 hours is predicted to be comparable to the currently recommended 1 g every 8 hours for serious infections. Our model provides further justification for a prospective clinical trial to evaluate a pharmacodynamically targeted meropenem dosing schedule as to its ability to improve clinical outcome in these patients.
Catalytic partial oxidation of methane in a high‐temperature reverse‐flow reactor
Authors: Neumann Dirk , Veser Götz 
Published: December 2004

AbstractThe production of hydrogen and synthesis gas (syngas) from methane is a key technology for the twenty‐first century. It is currently performed predominantly by steam reforming of methane. An alternative reaction route is the direct catalytic partial oxidation of methane (CPOM) at high‐temperature, short contact time conditions, which proceeds autothermally over noble metal catalysts. However, syngas yields are limited at autothermal operation by a complex interplay of total and partial oxidation reactions. We demonstrate that these limitations can be overcome through dynamic heat integration in a catalytic reverse‐flow reactor. The efficient heat integration in this reactor type leads to strongly increased syngas yields; that is, it effectively converts sensible heat into chemical energy. Furthermore, even shorter contact times can be achieved without yield losses, allowing for even more compact reactors or further increased reactor throughput. The combination of short contact time catalysis with dynamic heat integration therefore appears ideally suited for small‐scale and decentralized syngas and hydrogen production. © 2004 American Institute of Chemical Engineers AIChE J, 51: 210–223, 2005
Precipitation of CuS and ZnS in a bubble column reactor
Authors: Al‐Tarazi Mousa , Heesink A. Bert M. , Versteeg Geert F. , Azzam Mohammed O. J. , Azzam Khalid 
Published: December 2004

AbstractThis work presents an experimental study into the precipitation of CuS and ZnS in a semibatch‐wise operated bubble column. First the applied bubble column was characterized with respect to mass transfer phenomena. The influences of ionic strength and superficial gas velocity on volumetric mass transfer coefficient and gas holdup, respectively, were determined using both CO2 and H2S gas. Increasing the ionic strength was found to increase the gas holdup and volumetric mass‐transfer coefficient. Although the gas holdup with H2S was found to be higher than that with CO2 at the same ionic strength and superficial gas velocity, the measured volumetric mass transfer coefficient was for CO2 absorption. In the second part of the study the influences of the H2S gas concentration, initial metal concentration and gas pressure on the precipitation of ZnS and CuS were investigated. With increasing H2S concentration, the initial concentration or pressure of Zn ions yields a decrease in the average size of produced ZnS particles. No significant effects could be observed when producing CuS particles. This was probably a result of the surface activity of such particles, causing them to cluster and form agglomerates. The results are useful for scale‐up and design of similar types of precipitator. © 2004 American Institute of Chemical Engineers AIChE J, 51: 235–246, 2005