bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Caffeine Co‐Ingested with Carbohydrate or Fat on Metabolism and Performance in Endurance‐Trained Men
Authors: Jacobson Talia L. , Febbraio Mark A. , Arkinstall Melissa J. , Hawley John A.
Published: February 2003

We examined the effect of caffeine co‐ingested with either carbohydrate or fat on metabolism and performance in eight endurance‐trained subjects who performed a random order of four experimental trials consisting of 120 min of steady‐state ergometer cycling at 70% of maximal O2 uptake (SS) followed by a time trial in which subjects completed a set amount of work (7 kJ kg−1) as quickly as possible. One hour before SS subjects ingested either 2.6 g kg−1 carbohydrate (CHO); 2.6 g kg−1 CHO + 6 mg kg−1 caffeine (CHO + CAF); 1.2 g kg−1 fat with 2000 U I.V. heparin (FAT); or 1.2 g kg−1 fat with 2000 U I.V. heparin + 6 mg kg−1 caffeine (FAT + CAF). The rate of carbohydrate oxidation was higher (μmol kg−1 min−1: CHO, 243 ± 39 and CHO + CAF, 239 ± 30 vs. FAT, 196 ± 48 and FAT + CAF, 191 ± 55; P < 0.05, values are means ± S.D.) and the rate of fat oxidation lower (μmol kg−1 min−1: CHO, 19 ± 8 and CHO + CAF, 22 ± 7 vs. FAT, 35 ± 19 and FAT + CAF, 37 ± 17; P < 0.05) with carbohydrate than fat ingestion. Yet despite lower carbohydrate use with fat feeding, the time taken to complete the time trial was less after carbohydrate than after fat ingestion (min: CHO, 30.37 ± 7.42 and CHO + CAF, 29.12 ± 5.62 vs. FAT, 33.02 ± 8.50 and FAT + CAF, 32.78 ± 7.70; P < 0.05). We conclude that (1) caffeine co‐ingested with either carbohydrate or fat meals has no additive effect on substrate utilization or exercise performance and (2) carbohydrate ingestion before exercise improves subsequent time trial performance compared with fat ingestion.
Role of Nitric Oxide and Renal Nerves in the Renal Responses to Acute Volume Expansion in Anaesthetized Rats
Authors: Wongmekiat Orawan , Johns Edward J.
Published: February 2003

An investigation was undertaken into the potential role of nitric oxide (NO) and its interaction with renal sympathetic nerves in mediating renal responses to acute saline volume expansion (VE). Groups of anaesthetized Wistar rats with innervated and denervated kidneys were subjected to VE, 0.25% body wt min−1 for 40 min, in the presence and absence of nitric oxide synthase (NOS) inhibitors, NG‐nitro‐{fontsize L‐arginine‐methyl‐ester ({fontsize L‐NAME, non‐selective), aminoguanidine (AG, relatively selective for inducible NOS (iNOS)), and 7‐nitroindazole (7‐NI, relatively selective for neuronal NOS (nNOS)). Pretreatment with {fontsize L‐NAME or AG enhanced the cumulative sodium excretion (CuUNaV) after 40 min VE in the innervated kidneys by 27 and 23% (both P < 0.001), respectively, compared to the untreated control group, whereas they were without effect in the denervated kidneys. Cumulative urine flow (CuUV) after VE in {fontsize L‐NAME‐ and AG‐treated groups was enhanced in both kidneys, by some 17‐21% in the denervated (P < 0.01) and 37‐39% in the innervated kidneys (P < 0.001) by comparison with the corresponding untreated controls. 7‐NI had no effect on CuUV, but reduced CuUNaV in the denervated kidneys by 25% (P < 0.01) when compared to the control group. The results suggested that NO, possibly generated by endothelial NOS (eNOS) and iNOS, was a contributory factor in mediating the renal response to VE. There appeared to be a tonic inhibitory action of NO on water excretion which was renal nerve independent, whereas its impact on sodium handling appeared to be dependent upon a background level of renal nerve activity.
The Physiological Basis of Uterine Contractility: A Short Review
Authors: Wray S. , Kupittayanant S. , Shmygol A. , Smith R. D. , Burdyga T.
Published: February 2003

In this review we discuss our current understanding of the cellular basis of uterine contractility, highlighting those areas requiring further study. It is clear that the basic processes of excitation‐contraction coupling lie within the myometrial cell, and that these may be modified by agonists. Pacemaker acitivity, however, remains a mystery. The contribution of extracellular calcium entry to contraction is shown to be vital, whilst the role of the sarcoplasmic reticulum remains controversial. Much current experimental focus is on pathways controlling and regulating contraction, and we discuss sensitisation mechanisms and question their role in intact uterine preparations.
Feto‐Maternal Relationships in Goats During Heat and Cold Exposure
Authors: Faurie A. S. , Mitchell D. , Laburn H. P.
Published: February 2003

Maternal and fetal body temperatures were measured in five Boer goats, of mean mass 64 ± 8 kg, using temperature‐sensitive radiotelemeters implanted intra‐abdominally. Body temperatures were recorded every 5 min. Throughout the last month of gestation, fetal temperature was approximately 0.6 oC higher than that of the mother, in normal laboratory conditions (ambient air temperature: 21‐24 oC). This feto‐maternal temperature difference between the goat fetus and its mother is similar to that found in other mammals, including sheep. When the pregnant goats were subjected to short‐term heating and cooling, the difference between maternal and fetal body temperatures changed. Thus the mean difference between fetal and maternal body temperatures decreased from 0.4 to 0.2 oC during 2 h of heating, while it widened from 0.3 to 0.7 oC during 6 h of cooling. These data support the idea that the fetus is thermally protected from excursions of body temperature during changes in the mother's thermal environment. Reports of goat stock losses and abortions during cold spells in their natural habitats may be the result of more severe and/or prolonged cold exposures that not only adversely affect fetal or maternal body temperature, but also influence other aspects of metabolism.
EP1 and EP4 Receptors Mediate Exocytosis Evoked by Prostaglandin E2 in Guinea‐Pig Antral Mucous Cells
Authors: Ohnishi Atsuko , Shimamoto Chikao , Katsu Ken‐ichi , Ito Sigenori , Imai Yusuke , Nakahari Takashi
Published: February 2003

Effects of prostaglandin E2 (PGE2) on exocytosis of mucin were studied in mucous cells isolated from guinea‐pig antrum using video‐microscopy. Stimulation with PGE2 elicited a sustained increase in the frequency of exocytotic events in a dose‐dependent manner, which was under regulation by both Ca2+ and cAMP. Stimulation with a selective prostanoid EP4 receptor agonist (ONO‐AEI‐329, 10 μM), which activates cAMP signals, elicited a sustained increase in the frequency of exocytotic events (30% of that evoked by 1 μM PGE2). Stimulation with an EP1 agonist (17‐P‐T‐PGE2, 1 μM), which activates Ca2+ signals, increased the frequency of exocytotic events to a lesser extent (5% of that evoked by 1 μM PGE2), while addition of an EP1 antagonist (ONO‐8713, 10 μM) decreased the frequency of exocytotic events (approximately 40% of that evoked by 1 μM PGE2). However, addition of the EP1 agonist potentiated the frequency of exocytotic events evoked by the EP4 agonist or forskolin (which elevates cAMP levels) and increased the sensitivity of the exocytotic events to forskolin. These results suggest that the Ca2+ signal activated via the EP1 receptor potentiates the cAMP‐regulated exocytotic events activated via the EP4 receptor during PGE2 stimulation, by increasing the sensitivity of the exocytotic response to cAMP. In conclusion, exocytotic events in PGE2‐stimulated antral mucous cells were regulated by interactions between EP1 and EP4 receptors.
Effects of the Potassium Channel Blocker Barium on Sodium and Potassium Transport in the Rat Loop of Henle In Vivo
Authors: Walter S. J. , Shirley D. G. , Folkerd E. J. , Unwin R. J.
Published: February 2003

In vitro evidence suggests that the ‘recycling’ of K+ ions through luminal K+ channels in the thick ascending limb of the loop of Henle (TALH) is essential for the normal operation of the luminal Na+‐K+‐2Cl− co‐transporter. In the present study these channels were investigated in vivo by perfusing superficial loops of Henle in anaesthetised rats with and without the K+ channel blocker barium. Using a standard perfusate, intraluminal barium (5 mmol l−1) reduced sodium reabsorption (JNa) from 1887 ± 50 to 1319 ± 53 pmol min−1 (P < 0.001). When the experiment was repeated using a low‐Na+ perfusate, designed to inhibit reabsorption in the pars recta (the initial segment of the loop of Henle), a similar reduction in JNa was observed (from 698 ± 47 to 149 ± 23 pmol min−1, P < 0.001), strongly suggesting that the effect of barium is localised to the TALH. The magnitude of the reduction in JNa during blockade of K+ channels confirms the importance of K+ recycling in facilitating Na+ reabsorption in the TALH in vivo. However, the reduction in JNa was not associated with a fall in the K+ concentration of the fluid collected at the early distal tubule. When bumetanide, an inhibitor of the Na+‐K+‐2Cl− co‐transporter, was included in the low‐Na+ perfusate, net K+ secretion was observed. Addition of barium to this perfusate reduced, but did not abolish, the secretion, suggesting that bumetanide‐induced K+ secretion results partly from paracellular transport.
Renal Vascular Effects of Frusemide in the Rat: Influence of Salt Loading and the Role of Angiotensin II
Authors: Dobrowolski Leszek , Badzyńska Bozena , Grzelec‐Mojzesowicz Monika , Sadowski Janusz
Published: February 2003

We showed recently that post‐frusemide (furosemide) natriuresis was associated with a major depression of medullary circulation. In the present study, prior to administration of frusemide the tubular transport of NaCl was modified by loading the animals with 5% saline to elucidate a possible interrelation between the tubular and vascular effects of the drug. Moreover, a possible involvement of the renin‐angiotensin system was examined by pharmacological blockade using captopril, an inhibitor of angiotensin converting enzyme (1 mg kg−1, I.V.), or losartan, a selective inhibitor of angiotensin AT1 receptor (10 mg kg−1, I.V.). The effects of frusemide (0.25 mg kg−1 I.V., then the same dose given over 1 h) on renal medullary and cortical circulation (using laser‐Doppler flowmetry) and renal excretion of sodium (UNaV), water and total solutes were measured in anaesthetised rats. With no pre‐treatment, frusemide decreased the medullary flow (36.6 ± 6.0%) significantly more than the cortical flow (10.1 ± 1.0%; P < 0.001). The difference between the medulla and cortex was not significant in rats which showed high UNaV after hypertonic saline loading (2.0 ± 0.4 vs. 0.4 ± 0.1 μmol min−1 in non‐loaded rats): 21.1 ± 3.9% and 15.8 ± 1.5%, respectively. At very high UNaV (9.5 ± 1.1 μmol min−1) the post‐frusemide decrease in blood flow tended to be smaller in the medulla (7.6 ± 7.7%) than in the cortex (16.2 ± 2.6%). The fall in medullary blood flow was attenuated by pre‐treatment with captopril (22.0 ± 3.3%) and abolished by pre‐treatment with losartan (2.8 ± 11.8%). The decrease in cortical blood flow was not changed by hypertonic saline or angiotensin II blockers. The abolition of the post‐frusemide depression of medullary blood flow by previous salt loading confirms the proposed link between tubular transport status and vasoconstriction. A similar modification of the response by blockade of the renin‐angiotensin system suggests that the system is involved in the mechanism of medullary vasoconstriction.
Interaction Between Store‐Operated Non‐Selective Cation Channels and the Na+‐Ca2+ Exchanger During Secretion in the Rat Colon
Authors: Seip G. , Schultheiss G. , Kocks S. L. , Diener M.
Published: February 2003

The properties of capacitative Ca2+ influx were studied using the whole‐cell patch‐clamp technique in crypts isolated from rat distal colon. Store‐operated cation influx was evoked by increasing the intracellular buffering capacity for Ca2+ in the pipette solution; contamination by Cl− currents was reduced by the use of NMDG gluconate as the main electrolyte in the pipette solution. The permeability of the non‐selective cation conductance stimulated by store depletion had the following sequence for monovalent cations: Cs+ > Na+ ≥ Li+. The store‐operated conductance is permeable to Na+ and Ca2+, but in contrast to Na+, Ca2+ also exerts a (feedback) inhibition on its own influx. Other divalent cations shared this inhibitory action with the sequence: Ca2+ ≥ Mg2+ ≥ Ba2+ ≥ Sr2+. Fura‐2 experiments revealed that replacement of extracellular Na+ by NMDG+ induced an increase in the intracellular Ca2+ concentration, which was suppressed by the Na+‐Ca2+ exchange inhibitor, dichlorobenzamil, indicating the presence of a Na+‐Ca2+ exchanger within the colonic crypt cells. In Ussing chamber experiments dichlorobenzamil induced an increase in short‐circuit current (Isc) in the majority of tissues tested indicating that this exchanger acts as a Ca2+‐extruding transporter under physiological conditions. When Ca2+‐dependent anion secretion was stimulated by the acetylcholine analogue carbachol, dichlorobenzamil no longer evoked an increase in Isc, indicating that after stimulation of the store‐operated cation conductance the Na+‐Ca2+ exchanger is turned off. Therefore, it is concluded that the influx of Na+ across the non‐selective store‐operated cation conductance serves to reduce the driving force for Ca2+ extrusion via the Na+‐Ca2+ exchanger and thereby maintains the increase in the intracellular Ca2+ concentration during induction of secretion.
Inhibition of Neuronal Nitric Oxide Reduces Heart Rate Variability in the Anaesthetised Dog
Authors: Markos F. , Snow H. M. , Kidd C. , Conlon K.
Published: February 2003

In the vagally intact anaesthetised dog, we have investigated the role of nitric oxide (NO) on a normal sinus arrhythmia using an inhibitor of neuronally released NO, 1‐(2‐trifluoromethylphenyl) imidazole (TRIM). The mean and S.D. of the R‐R interval was used to describe mean heart rate and heart rate variability, respectively. TRIM (0.8 mg I.C.) injected into the sinus node artery increased the mean heart rate slightly but reduced heart rate variability 3‐fold from a control of 790 ± 124 ms (mean ± S.D.; n = 5) to 666 ± 36 ms (P < 0.01 Student's paired t test, n = 5). These results suggest that neuronally released NO may have a vagal facilitatory role in the maintenance of sinus arrhythmia in the normal heart.
EMG and Oxygen Uptake Responses During Slow and Fast Ramp Exercise in Humans
Authors: Scheuermann Barry W. , McConnell Joyce H. Tripse , Barstow Thomas J.
Published: February 2003

This study examined the relationship between muscle recruitment patterns using surface electromyography (EMG) and the excess O2 uptake (ExV̇O2) that accompanies slow (SR, 8 W min−1) but not fast (FR, 64 W min−1) ramp increases in work rate (WR) during exercise on a cycle ergometer. Nine subjects (2 females) participated in this study (25 ± 2 years, ± S.E.M.). EMG was obtained from the vastus lateralis and medialis and analysed in the time (root mean square, RMS) and frequency (median power frequency, MDPF) domain. Results for each muscle were averaged to provide an overall response and expressed relative to a maximal voluntary contraction (%MVC). ΔV̇O2/ΔWR was calculated for exercise below (S1) and above (S2) the lactate threshold (LT) using linear regression. The increase in RMS relative to the increase in WR for exercise below the LT (ΔRMS/ΔWR‐S1) was determined using linear regression. Due to non‐linearities in RMS above the LT, ΔRMS/ΔWR‐S2 is reported as the difference in RMS (ΔRMS) and the difference in WR (ΔWR) at end‐exercise and the LT. SR was associated with a higher (P < 0.05) ΔV̇O2/ΔWR (S1, 9.3 ± 0.3 ml min−1 W−1; S2, 12.5 ± 0.6 ml min−1 W−1) than FR (S1, 8.5 ± 0.4 ml min−1 W−1; S2, 7.9 ± 0.4 ml min−1 W−1) but a similar ΔRMS/ΔWR‐S1 (SR, 0.11 ± 0.01% W−1; FR, 0.10 ± 0.01% W−1). ExV̇O2 was greater (P < 0.05) in SR (3.6 ± 0.7 l) than FR (‐0.7 ± 0.4 l) but was not associated with a difference in either ΔRMS/ΔWR‐S2 (SR, 0.14 ± 0.01% W−1; FR, 15 ± 0.02% W−1) or MDPF (SR, 2.6 ± 5.9%; FR, ‐15.4 ± 4.5%). The close matching between power output and RMS during SR and FR suggests that the ExV̇O2 of heavy exercise is not associated with the recruitment of additional motor units since ExV̇O2 was observed during SR only. Compared to the progressive decrease in MDPF observed during FR, the MDPF remained relatively constant during SR suggesting that either (i) there was no appreciable recruitment of the less efficient type II muscle fibres, at least in addition to those recruited initially at the onset of exercise, or (ii) the decrease in MDPF associated with fatigue was offset by the addition of a higher frequency of type II fibres recruited to replace the fatigued motor units.
Pyeloureteral Motility and Ureteral Peristalsis: Essential Role of Sensory Nerves and Endogenous Prostaglandins
Authors: Lang Richard J. , Davidson Margret E. , Exintaris Betty
Published: February 2003

The cellular mechanisms that underlie the initiation and propagation of the peristaltic contractions, which transport urine from the kidney to the bladder for storage, remain little understood. Extracellular and intracellular microelectrode recordings have identified two populations of smooth muscle cells as well as a population of renal interstitial cells (RICs) that all display spontaneous electrical activity. By analogy with the heart it has been proposed that atypical smooth muscle cells, preferentially located in the very proximal regions of the renal pelvis, generate the essential pacemaker signal. These pacemaker potentials propagate to neighbouring typical smooth muscle cells or RICs to trigger action potential discharge. These action potentials then propagate distally to trigger other bundles of typical smooth muscle cells. The frequency of action potential discharge and contraction decreases as the relative number of RICs and atypical smooth muscle cells compared to typical smooth muscle cells decreases with distance from the renal fornix. It is clear that functional capsaicin‐sensitive sensory afferents and the endogenous release of both tachykinins and prostaglandins are essential in the maintenance of normal peristalsis, as well as in monitoring and responding to any chemical or mechanical stimulation. However, the cellular mechanisms underlying the action of these endogenously‐released agents remain to be elucidated.
Role of Mitochondria in Apoptosis
Authors: Gulbins Erich , Dreschers Stephan , Bock Jürgen
Published: February 2003

Apoptosis is an evolutionary‐conserved physiological mechanism to remove cells from an organism. Cellular apoptosis is mediated via an intracellular signalling programme that involves a variety of signalling molecules and cellular organelles including caspases, sphingomyelinases, Bcl‐2‐like proteins and proteins to cleave the DNA and mitochondria. Mitochondria contain several pro‐apoptotic molecules that activate cytosolic proteins to execute apoptosis, block anti‐apoptotic proteins in the cytosol and directly cleave nuclear DNA. Mitochondria trap these pro‐apoptotic proteins and physically separate pro‐apoptotic proteins from their cytoplasmic targets. Apoptosis is then initiated by the release of mitochondrial pro‐apoptotic proteins into the cytosol. This process seems to be regulated by Bcl‐2‐like proteins and several ion channels, in particular the permeability transition pore (PTP) that is activated by almost all pro‐apoptotic stimuli.
Possible Role of Cytoskeleton in Intracellular Arrangement and Regulation of Mitochondria
Authors: Appaix Florence , Kuznetsov Andrey V. , Usson Yves , Kay Laurence , Andrienko Tatiana , Olivares Jose , Kaambre Tuuli , Sikk Peeter , Margreiter Raimund , Saks Valdur
Published: February 2003

The origin of significant differences between the apparent affinities of heart mitochondrial respiration for exogenous ADP in isolated mitochondria in vitro and in permeabilized cardiomyocytes or skinned fibres in situ is critically analysed. All experimental data demonstrate the importance of structural factors of intracellular arrangement of mitochondria into functional complexes with myofibrils and sarcoplasmic reticulum in oxidative muscle cells and the control of outer mitochondrial membrane permeability. It has been shown that the high apparent Km for exogenous ADP (250‐350 µM) in permeabilized cells and in ghost cells (without myosin) and fibres (diameter 15‐20 µm) is independent of intrinsic MgATPase activity. However, the Km may be decreased significantly by a selective proteolytic treatment, which also destroys the regular arrangement of mitochondria between sarcomeres and increases the accessibility of endogenous ADP to the exogenous pyruvate kinase‐phosphoenolpyruvate system. The confocal microscopy was used to study the changes in intracellular distribution of mitochondria and localization of cytoskeletal proteins, such as desmin, tubulin and plectin in permeabilized cardiac cells during short proteolytic treatment. The results show the rapid collapse of microtubular and plectin networks but not of desmin localization under these conditions. These results point to the participation of cytoskeletal proteins in the intracellular organization and control of mitochondrial function in the cells in vivo, where mitochondria are incorporated into functional complexes with sarcomeres and sarcoplasmic reticulum.
Transcriptional Regulation of
xyn2
in
Hypocrea jecorina
Authors: Würleitner Elisabeth , Pera Licia , Wacenovsky Christian , Cziferszky Angela , Zeilinger Susanne , Kubicek Christian P. , Mach Robert L.
Published: February 2003

The xylanase system of the filamentous fungus
Hypocrea jecorina
(
Trichoderma reesei
) consists of two specific xylanases, Xyn1 and Xyn2, which are simultaneously expressed during growth on xylan but respond differentially to low-molecular-weight inducers. Using in vivo footprinting analysis of xylan-induced and noninduced mycelia, we detected two adjacent nucleotide sequences (5′-AGAA-3′ on the noncoding strand and 5′-GGGTAAATTGG-3′, referred to as the xylanase-activating element [XAE], on the coding strand, respectively) to bind proteins. Among these, binding to the AGAA-box is only observed under noninduced conditions, whereas binding to XAE is constitutive. Electrophoretic mobility shift assay with heterologously expressed components of the
H. jecorina
Hap2/3/5 protein complex and the cellulase regulator Ace2 suggests that these two transactivators form the protein complex binding to XAE.
H. jecorina
transformants, containing correspondingly mutated versions of the
xyn2
promoter fused to the
Aspergillus niger goxA
gene as a reporter, revealed that the elimination of protein binding to the AGAA-box resulted in a threefold increase in both basal and induced transcription, whereas elimination of Ace2 binding to its target in XAE completely eliminated transcription under both conditions. Destruction of the CCAAT-box by insertion of a point mutation prevents binding of the Hap2/3/5 complex in vitro and results in a slight increase in both basal and induced transcription. These data support a model of
xyn2
regulation based on the interplay of Hap2/3/5, Ace2 and the AGAA-box binding repressor.
Ssk1p Response Regulator Binding Surface on Histidine- Containing Phosphotransfer Protein Ypd1p
Authors: Porter Stace W. , Xu Qingping , West Ann H.
Published: February 2003

Ypd1p, a histidine-containing phosphotransfer protein, plays an important role in a branched His-Asp phosphorelay signal transduction pathway that regulates cellular responses to hyperosmotic stress in
Saccharomyces cerevisiae
. Ypd1p is required for phosphoryl group transfer from the membrane-bound Sln1p sensor histidine kinase to two downstream response regulator proteins, Ssk1p and Skn7p. To investigate the molecular basis for interaction of Ypd1p with these response regulator domains, we used an approach that coupled alanine-scanning mutagenesis of surface-exposed residues in Ypd1p with a yeast two-hybrid interaction screen. Mutated residues that adversely affected the interaction of Ypd1p with the C-terminal response regulator domain of Ssk1p were identified and found to cluster on or near the αA helix in Ypd1p. Our results, supported by analysis of a modeled complex, identify a binding site on Ypd1p for response regulators that is composed of a cluster of conserved hydrophobic residues surrounded by less conserved polar residues. We propose that molecular interactions involving Ypd1p are mediated primarily through hydrophobic contacts, whereas binding specificity and strength of interaction may be influenced by select polar side chain interactions.
Another Europe: remembering Habsburg Galicja
Authors: Bialasiewicz Luiza
Published: February 2003

The past ten years have brought about a profound reordering of the spatial imaginary of Europe. It is a reordering, however, that continues to this day, and the tracing (symbolic as well as institutional) of the future ‘Eastern’ confine of the common European space remains a highly contested - and politically salient - issue. This paper examines one alternative geographical imaginary seeking to narrate and negate this emergent confine and its binary division of the European space by drawing upon the memory of the multinational Austro-Hungarian empire. In particular, I look to the ways in which the Habsburg myth is being adopted and articulated within the context of the erstwhile Austrian province of Galicja - now torn between the states of Poland and the Ukraine and straddling the probable future border of the European Union. Through an analysis of the spatial imaginary of the imperial Galicja felix, the paper attempts to trace the ways in which the Habsburg ideal of a liminal space of multinational coexistence is being resurrected in the present day in order to subvert the (national and soon supranational) borderlines cutting through these territories’ heart - and to argue for their reconceptualization as a wholly European border-space.
Voyage of the ancestors
Authors: Lundberg Anita
Published: February 2003

The people of the subsistence whale-hunting village of Lamalera in Eastern Indonesia continue to hunt whales according to the traditions of the ancestors, and through this ritual practice the memory of the ancestors is brought to life. Similarly, in the retelling of the myth of the heroic origin voyage the ancestors are reawakened. This paper engages in a rereading of texts that seek to trace the Lamaleran origin myth back to its beginning. It suggests that even as we write about myths we are simultaneously originating our own stories through them. Thus, as academics journey via these myths back through the islands of the eastern archipelagos in search of origins - from Lamalera on the island of Lembata, to the land of Lepan Batan, through the province of Maluku and back to Sulawesi - the structure of this story acts to originate their own discourses. All such origin stories are involved in intricate relations of becoming through the very myths they desire to uncover.
White in all the wrong places: white rural poverty in the postbellum US South
Authors: Winders Jamie
Published: February 2003

Many examinations of whiteness have proceeded on an unacknowledged equation of whiteness with various forms of privilege. I suggest that when differences within whiteness are brought into consideration, a more nuanced engagement with such representations and constructions becomes possible. This argument I make through an analysis of post-Civil War travel accounts of the US South, to demonstrate how prising open the presumed links between a white identity and privilege allows movement beyond a whiteness-as-power framework. In this way, I show that a textual analysis which holds at arm’s length such assumptions facilitates a more engaged understanding of constructions of whiteness in the US South and elsewhere.
Respiratory patterns and oxygen consumption in singing zebra finches
Authors: Franz Michele , Goller Franz
Published: February 2003

Song production in birds is driven by temporally complex respiratory patterns. In zebra finches (Taeniopygia guttata), song consists of repetitions of a stereotyped sequence of distinct syllables (motif). Syllables correspond to distinct expiratory pulses, which alternate with short deep inspirations. We investigated the effect of the song motor pattern on respiration using a newly developed mask system to measure oxygen consumption while simultaneously monitoring subsyringeal air sac pressure. The metabolic cost of song is closely related to song duration (mean=85.7 μl O2 g-1 min-1 over pre-song levels) and confirms earlier estimates for this species. When motif duration is controlled for, there is only small interindividual variability in oxygen consumption per motif. The oxygen measurements were also used to evaluate various methods of estimating and reporting the metabolic cost. Up to 20s before song,respiratory activity and oxygen consumption increased. Shortly before and during the introductory notes of the song bout, respiration and oxygen consumption decreased markedly. In some individuals, significant hyperventilation occurred during song, causing almost complete apnea after the song. In three different birds, we measured tracheal airflow and air sac pressure during song. Birds with higher airflow during song relative to flow during quiet respiration had a more pronounced decrease in respiratory activity after the song bout. These results suggest that gas exchange continues in the lung during the song bout and that long expiratory pressure pulses of the song motif can lead to hyperventilation but that no oxygen debt resulted from song. This research allows a first assessment of respiratory constraints that may influence the evolution of song complexity.
Probability and amplitude of novelty responses as a function of the change in contrast of the reafferent image inG. carapo
Authors: Caputi A. A. , Aguilera P. A. , Castelló M. E.
Published: February 2003

Pulse electric fish evaluate successive electrosensory images generated by self-emitted electric discharges, creating a neural representation of the physical world. Intervals between discharges (system resolution) are controlled by a pacemaker nucleus under the influence of reafferent signals. Novel sensory stimuli cause transient accelerations of the pacemaker rate(novelty responses). This study describes quantitatively the effect of changes in contrast of reafferent electrosensory signals on the amplitude and probability of novelty responses. We found that: (i) alterations of a single image in an otherwise homogeneous series cause a novelty response; (ii) the amplitude of the elicited novelty response is a linear function of the logarithm of the change in image contrast; (iii) the parameters of this function, threshold and proportionality constant, allowed us to evaluate the transference function between change in stimulus amplitude and the amplitude of the novelty response; (iv) both parameters are independent of the baseline contrast; (v) the proportionality constant increases with the moving average of the contrast of hundreds of previous images. These findings suggest that the electrosensory system (i) calculates the difference between each reafferent electrosensory image and a neural representation of the past electrosensory input (`template'); (ii) creates the comparison template in which the relative contribution of every image decreases with the incorporation of successive images. We conclude that contrast discrimination in the electrosensory system of G. carapo obeys the general principle of appreciating any instantaneous input by the input's departure from a moving average of past images.
K+ transport in Malpighian tubules ofTenebrio molitorL.: a study of electrochemical gradients and basal K+uptake mechanisms
Authors: Wiehart U. I. M. , Nicolson S. W. , Van Kerkhove E.
Published: February 2003

Malpighian tubules of the mealworm Tenebrio molitor were isolated for intracellular measurement of basolateral (Vbl) and,indirectly, apical (Vap) membrane potentials. In control Ringer (50 mmol l-1 K+, 140 mmol l-1Na+), Vbl was 24mV, cell negative, and Vap was 48 mV, cell negative with reference to the lumen. Ion substitution experiments involving K+ and Na+indicated that both Vbl and Vap were sensitive to the bathing K+ concentration, with the change in Vap being 60-77% that of Vbl. A 10-fold drop in bath [K+] irreversibly decreased fluid secretion rates from 6.38±0.95 nl min-1 (mean ± S.E.M.) to 1.48±0.52 nl min-1 (N=8). In the presence of 6 mmol l-1 Ba2+, a blocker of basal K+ channels,fluid secretion rates reversibly decreased and the hyperpolarization of both Vbl and Vap seen in 50 mmol l-1 and 140 mmol l-1 K+ indicated a favourable electrochemical gradient for basal K+ entry. In 5 mmol l-1 K+, Ba2+ induced two different responses: Vbl either hyperpolarized by approximately 10 mV or depolarised by approximately 14mV, according to the electrochemical gradient for K+, which was either inward or outward in low bath[K+]. Rubidium, a `permeant' potassium substitute, caused a hyperpolarization of Vbl, indicating the specificity of K+ channels found in Tenebrio tubule cells. Other possible K+ uptake mechanisms located in the basolateral membrane were investigated. Blocking of the putative electroneutral Na+/K+/2Cl- cotransporter by 10 μmol l-1 bumetanide reversibly decreased fluid secretion rates, with no detectable change in membrane potentials. Ouabain (1 mmol l-1), an Na+/K+-ATPase inhibitor, irreversibly decreased fluid secretion rates but had no effect on electrical potential differences either in the absence or presence of Ba2+. The results implicate K+ channels, the Na+/K+/2Cl-contransporter and the Na+/K+-ATPase in basal K+ and fluid transport of Tenebrio tubule cells.
Skiing across the Greenland icecap: divergent effects on limb muscle adaptations and substrate oxidation
Authors: Helge Jørn W. , Lundby Carsten , Christensen Dirk L. , Langfort Jozef , Messonnier Laurent , Zacho Morten , Andersen Jesper L. , Saltin Bengt
Published: February 2003

This study investigates the adaptive response of the lower limb muscles and substrate oxidation during submaximal arm or leg exercise after a crossing of the Greenland icecap on cross-country skies. Before and after the 42-day expedition, four male subjects performed cycle ergometer and arm-cranking exercise on two separate days. On each occasion, the subjects exercised at two submaximal loads (arm exercise, 45 W and 100 W; leg exercise, 100 W and 200 W). In addition, peak oxygen uptake(V̇O2max) was determined for both leg and arm exercise. Before and after the crossing, a muscle biopsy was obtained from the vastus lateralis and the triceps brachii muscles prior to exercise (N=3). After the crossing, body mass decreased by 5.7±0.5 kg (in four of four subjects), whereas V̇O2max was unchanged in the arm (3.1±0.2 l min-1) and leg(4.0±0.1 l min-1). Before the crossing, respiratory exchange ratio (RER) values were 0.84±0.02 and 0.96±0.02 during submaximal arm exercise and 0.82±0.02 and 0.91±0.01 during submaximal leg exercise at the low and high workloads, respectively. After the crossing, RER was lower (in three of four subjects) during arm exercise(0.74±0.02 and 0.81±0.01) but was higher (in three of four subjects) during leg exercise (0.92±0.02 and 0.96±0.01) at the low and high workloads, respectively. Citrate synthase andβ-hydroxy-acyl-CoA-dehydrogenase activity was decreased by approximately 29% in vastus lateralis muscle and was unchanged in triceps brachii muscle. Fat oxidation during submaximal arm exercise was enhanced without a concomitant increase in the oxidative capacity of the triceps brachii muscle after the crossing. This contrasted with decreased fat oxidation during leg exercise, which occurred parallel to a decreased oxidative capacity in vastus lateralis muscle. Although the number of subjects is limited, these results imply that the adaptation pattern after long-term, prolonged, low-intensity,whole body exercise may vary dramatically among muscles.
Active NaCl absorption across posterior gills of hyperosmoregulatingChasmagnathus granulatus
Authors: Onken Horst , Tresguerres Martin , Luquet Carlos M.
Published: February 2003

Split lamellae of posterior gills of Chasmagnathus granulatusadapted to 2.5‰ salinity were mounted in a modified Ussing chamber. With NaCl-saline on both sides of the preparation a transepithelial voltage(Vte) of 4.1±0.5 mV (outside positive) was measured. After voltage-clamping, the negative short-circuit current(Isc) amounted to -142±21 μA cm-2 at a conductance (Gte) of 44±5 mS cm-2. Substitution of either chloride (by nitrate) or sodium (by choline) on both sides of split gill lamellae significantly reduced Isc (by 70-80%) and Gte (by 30-50%). External CsCl (but not BaCl2 or furosemide) inhibited the negative Isc without affecting Gte. Addition of ouabain, BaCl2 or diphenylamine-2-carboxylate to the internal bath inhibited Isc at unchanged Gte. Internal acetazolamide did not affect Isc or Gte across split gill lamellae. Unidirectional Na+ influx across isolated and perfused posterior gills, however, was reduced by internal acetazolamide by approximately 20% at constant Vte. The results suggest that posterior gills of hyperosmoregulating C. granulatus display a high conductance epithelium that actively absorbs NaCl in a coupled way by an electrogenic mechanism similar to that seen in the thick ascending limb of Henle's loop and, to a minor degree, by an electroneutral mechanism,presumably via apical Na+/H+- and Cl-/HCO3--antiports.
Fluid mechanics of slot-coating in photopolymer-based rapid composites manufacturing
Authors: Haberer M , Zak G , Park C B , Paraschivoiu M , Benhabib B
Published: February 2003

This paper describes the fluid mechanics of the slot-coating process in the context of rapid layered manufacturing. It has been conjectured that slot-coating would successfully address a number of common difficulties encountered in the formation of thin layers from a highly viscous fibre—photopolymer composite liquid. The objective of the present study was therefore the development of an engineering analysis tool to assist with the design of a slot-coating-based liquid layer formation mechanism for use as an integral part of a lithography-based rapid layered composite parts manufacturing (RLCM) system.

In addition to an analytical model, the paper presents a numerical model based on a volume-of-fluid (VOF) algorithm. This algorithm allows (a) solution of non-steady-state problems, (b) tracking of the free surface of the fluid undergoing large deformations and (c) easy modification of the model's domain to facilitate experimentation with coater geometry. Results from a set of simulated experiments establish a relationship between the liquid-coat height and several design and process parameters.

Physical examination of cross-sections of several test parts built on an RLCM prototype system in the authors’ laboratory confirmed the ability of the new coater design to form solid layers of good quality, as predicted by the numerical simulations.
Investigation of fully dense laser sintering of tool steel powder using a pulsed Nd: Yag (neodymium-doped yttrium aluminium garnet) laser
Authors: Su W-N , Erasenthiran P , Dickens P M
Published: February 2003

A 550W neodymium-doped yttrium aluminium garnet (Nd:YAG) pulsed laser was used in the solid freeform fabrication (SFF) process to form fully dense sintered parts. Tool steel powder was chosen due to its wide acceptance in the tool-making industry. Unlike many processes applying either thermoplastic binder or metals of low melting points in the powder mixture, this process enables a direct fusion of material to solid parts without a further post-processing step. This paper presents a methodology and the results of high-power laser sintering of tool steel powder. The investigation includes the effects of various process parameters on the fully dense laser sintering results on a single bead and single layer and the related scan strategy to build up solid cubes. This process could eventually produce pre-forms with complex material structures rather than finished tools or parts.
Effect of cigarette smoke on lipid peroxidation, antioxidant enzymes and NMDA receptor subunits 2A and 2B concentration in rat hippocampus
Authors: Delibas Namik , Ozcankaya Ramazan , Altuntas Irfan , Sutcu Recep
Published: February 2003

The effect of cigarette smoke on lipid peroxidation and antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase and on the concentration of N‐methyl‐d‐aspartate receptor (NMDAR) subunits 2A and 2B in the hippocampus of Sprague‐Dawley rats exposed to cigarette smoke for 2h/day for a period of 4 weeks was determined. It was observed that NMDAR 2A and 2B concentrations in the hippocampus were enhanced in the case of animals exposed to cigarette smoke, whereas lipid peroxidation and antioxidant enzyme activities did not show any change as compared to control animals. The results of our study suggest that cigarette smoke induces NMDAR 2A and 2B expression in the hippocampus, and that this is not due to an increased lipid peroxidation, because cigarette smoke has no effect on lipid peroxidation and antioxidant enzyme activities in the hippocampus. Copyright © 2002 John Wiley & Sons, Ltd.
Enantiomeric discrimination of pyrethroic acid esters on polysaccharide derived chiral stationary phases
Authors: Kim Byoung‐Hyoun , Lee Sang Uck , Kim Kun Tai , Lee Joo‐Young , Choi Nak Hee , Han Young‐Kyu , Ok Jong Hoa
Published: February 2003

Enantiomeric separation of pyrethroic acid methyl and ethyl esters was examined on cellulose‐based chiral stationary phases (CSPs): chiralcel OD (cellulose tris(3,5‐dimethylphenyl carbamate)) and chiralcel OF (cellulose tris(4‐chlorophenyl carbamate)). The good resolution of pyrethroic acid esters was achieved on chiralcel OD and OF. Separation factors ranged from 1.19–5.12 for Chiralcel OD and 1.00–1.59 for chiralcel OF. Hexane/2‐propanol (100:0.15, v/v %) was used as the eluent. The resolution capability of CSPs was greater chiralcel OD than chiralcel OF in the case of the pyrethroic acid esters. The flow rate was 0.8 ml/min and detection was set at 230 nm. The results of the chromatographic data and molecular mechanics suggest that steric effect was a major factor in the enantioseparation. Furthermore, the hydrogen bond between analytes and CSP played an important role in the chiral recognition. Chirality 15:276–283, 2003. © 2003 Wiley‐Liss, Inc.
Numerical simulations on fatigue destruction of ultra‐high molecular weight polyethylene using discrete element analyses
Authors: Shibata Nobuyuki , Tomita Naohide , Ikeuchi Ken
Published: February 2003

Ultra‐high molecular weight polyethylene (UHMWPE) is a heterogeneous material composed of a networked substructure of grain boundary and grain aggregation. A new numerical model based on the discrete element method (DEM) was proposed to examine microscopic defect formation and propagation in UHMWPE. Numerical simulations were carried out using this model under two types of loading condition: unidirectional repetitive compression (simple loading) and bidirectional repetitive compression (switched loading). Subsurface defects were initiated and propagated in the vicinity of grain boundaries under both loading conditions. The defect propagation behavior was especially sensitive to grain boundary allocation under switched loading. An increase in defects was more rapid under switched loading than under simple loading. These numerical results showed qualitatively good agreement with experimental ones. It is suggested that the newly developed numerical method based on the DEM is a promising method to investigate fatigue behavior of a heterogeneous material such as UHMWPE under complicated loading conditions. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 570–582, 2003
Distribution patterns of the membrane glycoprotein CD44 during the foreign‐body reaction to a degradable biomaterial in rats and mice
Authors: Bonnema Harmke , Popa Eliane R , van Timmeren Mirjan M. , van Wachem Pauline B. , de Leij Lou F. M. H. , van Luyn Marja J. A.
Published: February 2003

Although biomaterials have been used in the clinical setting for a long time, little is known of the molecular mechanisms underlying the foreign‐body reaction (FBR). A good understanding of these mechanisms is requisite for the controlled regulation of the FBR needed to prevent adverse tissue reactions and thus to improve the function of the biomaterial. Macrophages are essential in the inflammatory reaction in, as well as around, the implants, and they also are believed to initiate most of the adverse responses. Typically, during the FBR macrophages become activated and fuse into multinucleated giant cells (MnGCs). CD44, an integral membrane glycoprotein expressed on a broad spectrum of cell types, is involved in MnGC formation in vitro and in inflammation processes in general. In vivo it is not known whether CD44 is part of a specific protein machinery that enables macrophage fusion or whether it has additional functions in the FBR. In the present in vivo study, CD44 expression patterns were followed in rats and mice during the FBR to a degradable collagen type I biomaterial. We found that CD44 is upregulated on all migrating cells and on newly formed blood vessels at the onset of the FBR and that MnGCs, up to week 15 postimplantation, expressed CD44. Although no evidence was found that CD44 participates in macrophage fusion leading to multinucleation, it nevertheless may be an interesting target molecule for modulating the FBR in vivo, possibly by affecting cell activation, cell migration towards the biomaterial, vascularization, and MnGC formation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 64A: 502–508, 2003
Does digital rectal examination affect uroflowmetry measurements?
Authors: Aybek Zafer , Sinik Zafer , Oguzulgen İbrahim , Turan Tahir , Güler Gökhan , Tuncay Levent
Published: February 2003

Aims

To determine whether digital rectal examination (DRE) would affect uroflowmetry parameters and whether these findings were not due to the circaidan changes.

Methods

A total of 79 male patients (59 in study and 20 in control group) were included in this study. First uroflowmetry was done at 10:00 am just before the genitourinary physical examination in the study group. Second and third uroflowmetry was performed at the 6th and 24th hour after the first uroflowmetry. The same uroflowmetry tests were done in a control group without DRE. Voided volume and maximum and average flow rate parameters of uroflowmetry were interpreted in our study. The relationship among first, second, and third uroflowmetry parameters were determined in the study and control groups.

Results

There were statistically no difference between the mean first, or 6th‐ or 24th‐hour uroflowmetry parameters of the study and control groups (P > 0.05).

Conclusions

We could not find any effect of DRE on uroflowmetry parameters. Studies in a larger patient series would be appropriate for recommending DRE before or after uroflowmetry test. Neurourol. Urodynam. 22:138–141, 2003. © 2003 Wiley‐Liss, Inc.