bluuebunny/crossref_metadata_2025 huggingface dataset:
The Fas Receptor—1,4,5‐IP3 Cascade: A Potential Target for Treating Heart Failure and Arrhythmias
Authors: BINAH OFER , SHILKRUT MARK , YANIV GAL , LARISCH SARIT
Published: June 2004

Abstract: Activation of the Fas receptor in various cell types, including myocytes, triggers apoptotic as well as nonapoptotic effects. Recent studies suggest that Fas activation in the heart participates in the development of major pathologies such as myocarditis and ischemic/reperfusion insults, which are manifested by arrhythmias and mechanical dysfunction. To decipher the contribution of the Fas/FasL pathway to myocardial pathologies, we have investigated the functional consequences of Fas activation in normoxic and hypoxic ventricular myocytes. Our major findings were as follows. (1) Although Fas is constitutively expressed in ventricular myocytes, normoxic myocytes are resistant to Fas‐mediated apoptosis. In contrast, hypoxia predisposes myocytes to apoptosis induced by Fas activation. The underlying mechanism is a shift in the balance between proapoptotic proteins (including Fas) and antiapoptotic proteins toward the former. (2) In normoxic myocytes, Fas activation causes a wide range of functional disturbances, which include reduction in resting potential and action potential amplitude, prolonged action potential duration, development of delayed and early after‐depolarizations, occasionally culminating into arrhythmias, diastolic [Ca2+]i level increase, decreased Ito and increased ICa,L. (3) The above‐mentioned effects in normoxic myocytes (but not Fas‐mediated apoptosis in hypoxic myocytes) depend on the phospholipase C → 1,4,5‐IP3→ SR [Ca2+]i release cascade. (4) Inhibition of tyrosine kinases with genistein blocks both the apoptotic and nonapoptotic consequences of Fas activation in ventricular myocytes. Based on these studies we propose that tyrosine phosphorylation in ventricular myocytes can serve as a novel potential target for attenuating Fas‐mediated dysfunction in normoxic and hypoxic myocardium.
Dynamics of Blood Flow and Platelet Transport in Pathological Vessels
Authors: EINAV SHMUEL , BLUESTEIN DANNY
Published: June 2004

Abstract: Arterial disease, characterized by arterial occlusion (stenosis), is a leading cause of cardiovascular diseases and a major healthcare problem in the Western world. One of the main mechanisms leading to vessel occlusion is thrombus formation, which may be initiated by platelet activation. Shear rates and flow patterns (fluid dynamics factors) and concentration of coagulation factors and platelet agonists (biological factors) modulate platelet function and may lead to platelet activation and aggregation. Here, we examine the flow‐induced mechanisms leading to platelet activation in models of stenosed coronary vessels. Experimental and numerical methods were used to investigate and characterize the influence of the flow field on platelet activation. As it passes through pathological geometries characteristic of arterial stenosis, a platelet is exposed to varying levels of shear stress. The cumulative effect of the shear stress level and the duration of the platelet's exposure to it determine whether the platelet is brought beyond its activation threshold. Stress histories of individual platelets can be tracked within the flow field to locate the regions where activated platelets might be found and subsequently aggregate and/or adhere to the wall.
Novel Approaches to Reduce Restenosis
Authors: BEYAR RAFAEL
Published: June 2004

Abstract: Percutaneous coronary intervention (PCI) has become the major technique of revascularization and is replacing cardiac bypass surgery. PCI is typically performed today with a combination of balloon dilatation and stents, with some 80% of the procedures followed by stent implantation. After balloon dilatation, an acute recoil response can be responsible for some 30% immediate loss of the vessel lumen at the end of the procedure. Restenosis is the late loss (within 6–9 months) of the lumen of the artery due to vessel shrinkage (negative remodeling) and an intense proliferative response to the local injury. Stents reduce restenosis by 30% by preventing acute recoil and reducing long‐term negative arterial remodeling. Yet, long‐term pressure of the stent struts against the vessel wall stimulates an increased arterial proliferative response, which is the major cause for stent restenosis. Limiting the proliferative response by local radiation (brachytherapy) have reduced restenosis, at a cost of increased late thrombogenicity and delayed vessel healing. Drug‐eluting stents have shown extremely promising results in limiting restenosis. Rapamycin and paclitaxel are the major drugs in eluting stents in clinical use today, having reduced restenosis to less than 10%. Local cellular and genetic therapy approaches are currently at preclinical phases. The future of percutaneous revascularization remains bright and will enhance the effectiveness of PCI as the primary revascularization therapy for coronary artery disease.
Augmentation of Dilated Failing Left Ventricular Stroke Work by a Physiological Cardiac Assist Device
Authors: LANDESBERG AMIR , KONYUKHOV EUGENE , SHOFTI RONA , VAKNIN YUVAL , SHENHAV AVSHALOM , LIVSHITZ LEONID , LICHTENSTEIN OSCAR , LEVY CARMIT , BEYAR RAFAEL , SIDEMAN SAMUEL , ISRAEL OHANA , TER KEURS HENK E. D. J. , LANDESBERG GIORA
Published: June 2004

Abstract: A novel physiological cardiac assist device (PCAD), otherwise known as the LEVRAM assist device, which is synchronized with the heartbeat, was developed to assist the left ventricle (LV) in chronic heart failure (CHF). The PCAD utilizes a single cannula, which is inserted in less than 15 s through the apex of the beating LV by means of a specially designed device. Blood is withdrawn from the LV into the PCAD in diastole and is injected back to the LV, through the same cannula, during the systolic ejection phase, thereby augmenting stroke volume (SV) and stroke work (SW). CHF with dilated LV was induced in sheep by successive intracoronary injections of 100‐μm beads. The sheep (92.2 ± 25.9 kg, n= 5) developed stable CHF with increased LV end‐diastolic diameter (69.4 ± 3.3 mm) and end‐diastolic volume (LVEDV = 239 ± 32 mL), with severely reduced ejection fraction (23.8 ± 7.6%), as well as mild‐to‐moderate mitral regurgitation. The sheep were anesthetized, and the heart was exposed by left thoracotomy. Pressure was measured in the LV and aorta (Millar). The SV was measured by flow meters and the LV volume by sonocrystals. Assist was provided every 10 regular beats, and the assisted beats were compared with the preceding unassisted beats, at the same LVEDV. The PCAD displaced 13.6 ± 3.4 mL, less than 8% of LVEDV. Added SW was calculated from the assisted and control pressure‐volume loops. The efficiency, defined as an increase in SW divided by the mechanical work of the PCAD, was 85.4 ± 16.9%. We conclude that the PCAD, working with a small displaced blood volume in synchrony with the heartbeat, efficiently augments the SW of the dilated failing LV. The PCAD is suggested for use as a permanent implantable device in CHF.
The Computational Integrated Myocyte: A View into the Virtual Heart
Authors: BASSINGTHWAIGHTE JAMES B. , VINNAKOTA KALYAN C.
Published: June 2004

Abstract: The presentation outlines an integrative approach for developing a computational model of cardiomyocytes. A modular approach is proposed, and strategies of linking the modules (intermediary metabolism, electrophysiology, and mechanics) of the model are presented. A strong recommendation is given toward an integrated system approach backed by experimental validation.
Preface: Cardiac Engineering—Deciphering the Cardiome
Authors: SIDEMAN SAMUEL
Published: June 2004

Abstract: Two monumental phenomena have shaped science and medicine in the last century and practically changed the world we live in. The first relates to the intimate interaction between engineering science and medicine—for example, technology and cardiology. The second relates to the globalization of science, the proliferation of the internet, and the unprecedented international interaction and scientific cooperation in facing difficult multidisciplinary challenges. The beneficial combination of these two megaphenomena, accompanied by significant environmental and sanitary changes, has greatly improved the quality of life and increased longevity around the globe. This conference, and the volume issuing from it, aims to explore the application of new developments in the microworld of cells and genes to gain better insight into the structure and function of the cardiac system, and hence to lead to better therapeutic modalities This multinational gathering of outstanding scientists from the various fields of the cardiac sciences is a living testimonial to human ingenuity and the spirit of international cooperation.
Mitogenic Action of Calcium-Sensing Receptor on Rat Calvarial Osteoblasts
Authors: Chattopadhyay Naibedya , Yano Shozo , Tfelt-Hansen Jacob , Rooney Paul , Kanuparthi Deepthi , Bandyopadhyay Sanghamitra , Ren Xianghui , Terwilliger Ernest , Brown Edward M.
Published: June 2004

The parathyroid calcium-sensing receptor (CaR) plays a nonredundant role in systemic calcium homeostasis. In bone, Ca2+o, a major extracellular factor in the bone microenvironment during bone remodeling, could potentially serve as an extracellular first messenger, acting via the CaR, that stimulates the proliferation of preosteoblasts and their differentiation to osteoblasts (OBs). Primary digests of rat calvarial OBs express the CaR as assessed by RT-PCR, Northern, and Western blot analysis, and immunocolocalization of the CaR with the OB marker cbfa-1. Real-time PCR revealed a significant increase in CaR mRNA in 5- and 7-d cultures compared with 3-d cultures post harvesting. High Ca2+o did not affect the expression of CaR mRNA during this time but up-regulated cyclin D (D1, D2, and D3) genes, which are involved in transition from the G1 to the S phase of the cell cycle, as well as the early oncogenes, c-fos and early growth response-1; high Ca2+o did not, however, alter IGF-I expression, a mitogenic factor for OBs. The high Ca2+o-dependent increase in the proliferation of OBs was attenuated after transduction with a dominant-negative CaR (R185Q), confirming that the effect of high Ca2+o is CaR mediated. Stimulation of proliferation by the CaR involves the Jun-terminal kinase (JNK) pathway, as high Ca2+o stimulated the phosphorylation of JNK in a CaR-mediated manner, and the JNK inhibitor SP600125 abolished CaR-induced proliferation. Our data, therefore, show that the parathyroid/kidney CaR expressed in rat calvarial OBs exerts a mitogenic effect that involves activation of the JNK pathway and up-regulation of several mitogenic genes.
Relaxin Modifies Systemic Arterial Resistance and Compliance in Conscious, Nonpregnant Rats
Authors: Conrad Kirk P. , Debrah Dan O. , Novak Jackie , Danielson Lee A. , Shroff Sanjeev G.
Published: June 2004

Relaxin emanates from the corpus luteum of the ovary and circulates during pregnancy. Because the hormone is a potent renal vasodilator and mediates the renal vasodilation and hyperfiltration of pregnancy in conscious rats, we reasoned that it might also contribute to the broader cardiovascular changes of pregnancy. We began investigating this concept by testing whether relaxin can modify systemic arterial hemodynamics and load when chronically administered to nonpregnant rats. The major objectives of the present work were to determine whether relaxin administration to nonpregnant rats 1) modifies cardiac output (CO), systemic vascular resistance, and global arterial compliance (AC), and 2) regulates the passive mechanics of isolated arteries. To accomplish the first objective, we developed a conscious rat model for assessment of global AC. Passive mechanics of small renal arteries were assessed using a pressure arteriograph. Chronic administration of recombinant human relaxin by sc osmotic minipump to conscious, female, nonpregnant rats reduced the steady arterial load by decreasing systemic vascular resistance, increased CO, and reduced the pulsatile arterial load by increasing global AC as quantified by two indices—AC estimated from the diastolic decay of aortic pressure and CO and AC estimated by the ratio of stroke volume-to-pulse pressure. In another group of rats, relaxin administration also regulated the passive mechanics of small renal arteries, indicating that, in addition to reduction in vascular smooth muscle tone, modification of the vascular structure (e.g. extracellular matrix) contributes to the increase in global AC. These findings suggest a role for relaxin in the systemic hemodynamic changes of pregnancy, as well as novel therapeutic potential for relaxin in modifying arterial stiffness and cardiac afterload.
Local action of exogenous nitric oxide (NO) on the skin blood flow of rock pigeons (Columba livia) is affected by acclimation and skin site
Authors: Peltonen Liisa M. , Pyörnilä Ahti
Published: June 2004

We studied the blood flow over dorsal and abdominal, non-brooding patch skin of two groups of pigeons: one group was thermally acclimated to cold(winter-acclimatized, WAC) while the other group was acclimated to a mesic environment (thermally non-challenged, NOC). Two bilateral patches at the measurement sites were treated simultaneously with a gel containing sodium nitrate and ascorbic acid, to generate nitric oxide (NO), and a vehicle gel. Blood flow was measured by laser Doppler velocimetry. Changes induced by these treatments were calculated against basic blood flow values for the corresponding patch. The results showed that the basic blood flow over the abdominal skin patches at room temperature was higher than over the dorsal skin in both acclimation states, but comparison revealed a sustainably higher level of basic skin blood flow in the WAC pigeons. The local response to exogenous NO was non-uniform over the two skin areas measured, and a specific vasodilatory action on the abdominal microvessels was recorded in the NOC pigeons. Abdominal vasodilatation in the WAC pigeons seemed to involve other mechanisms as well as local NO-dependent ones, among which the role of cold-induced vasodilatation (CIVD) is discussed here. Interestingly, the dorsal skin seemed to be less responsive to the action of NO, irrespective of the acclimation state.

Our results show that acclimation state and skin site affect the action of exogenous NO on local skin blood flow, and we suggest that the differences reflect acclimation-induced changes in the vascularity of the skin and in its sensitivity to thermal stimuli and that the roles of the abdominal and dorsal skin are different with respect to environmental changes.
Cardiac plasticity in fishes: environmental influences and intraspecific differences
Authors: Gamperl A. Kurt , Farrell A. P.
Published: June 2004

Fish cardiac physiology and anatomy show a multiplicity of intraspecific modifications when exposed to prolonged changes in environmentally relevant parameters such as temperature, hypoxia and food availability, and when meeting the increased demands associated with training/increased activity and sexual maturation. Further, there is evidence that rearing fish under intensive aquaculture conditions significantly alters some, but not all,aspects of cardiac anatomy and physiology. This review focuses on the responses of cardiac physiology and anatomy to these challenges, highlighting where applicable, the importance of hyperplastic (i.e. the production of new cells) vs hypertrophic (the enlargement of existing cells) growth to the adaptive response of the heart. In addition, we summarize recent studies that have explored the relationship between the myocardial protection afforded by preconditioning and myocardial hypoxia tolerance. This latter research clearly demonstrates the capacity of the fish heart to adjust to short-term perturbations, and shows that it can be difficult to predict how short-term and long-term alterations in cardiac physiology will interact.
Basolateral ion transport mechanisms during fluid secretion byDrosophilaMalpighian tubules: Na+ recycling,Na+:K+:2Cl– cotransport and Cl– conductance
Authors: Ianowski Juan P. , O'Donnell Michael J.
Published: June 2004

Mechanisms of ion transport during primary urine formation by the Malpighian tubule of Drosophila melanogaster were analyzed through measurements of fluid secretion rate, transepithelial ion flux, basolateral membrane potential (Vbl) and intracellular activities of K+ (aKi) and Cl–(aCli). Calculation of the electrochemical potentials for both ions permitted assessment of the possible contributions of K+ channels, Na+:K+:2Cl–cotransport, and K+:Cl– cotransport, to net transepithelial ion secretion across the basolateral membrane. The data show that passive movement of both K+ and Cl– from cell to bath is favoured across the basolateral membrane, indicating that both ions are actively transported into the cell. Contributions of basolateral K+ channels or K+:Cl– cotransporters to net transepithelial ion secretion can be ruled out. After prior exposure of tubules to ouabain, subsequent addition of bumetanide reduced fluid secretion rate, K+ flux and Na+ flux, indicating a role for a Na+:K+:2Cl– cotransporter in fluid secretion. Addition of the K+ channel blocker Ba2+ had no effect on aKi or aCli. Addition of Ba2+ unmasked a basolateral Cl– conductance and the hyperpolarization of Vbl in response to Ba2+ was Cl–-dependent. A new model for fluid secretion proposes that K+ and Cl– cross the basolateral membrane through a Na+-driven Na+:K+:2Cl–cotransporter and that most of the Na+ that enters the cells is returned to the bath through the Na+/K+-ATPase.
Antennae on transmitters on penguins: balancing energy budgets on the high wire
Authors: Wilson Rory P. , Kreye Jan M. , Lucke Klaus , Urquhart Heather
Published: June 2004

The effect of externally mounted antennae on the energetics of penguins was studied by mounting various antennae on a transducer fixed to a model Magellanic penguin Spheniscus magellanicus to determine drag, run at speeds of up to 2 m s–1 in a swim canal. For rigid antennae set perpendicular to the water flow, measured drag increased with increasing swim speed. Increasing antenna length (for lengths between 100 and 200 mm) or diameter (for diameters between 1 and 4 mm) resulted in accelerating increased drag as a function of both antenna length and diameter. Where antennae were positioned at acute angles to the water flow, drag was markedly reduced, as was drag at higher speeds in flexible antennae. These results were incorporated in a model on the foraging energetics of free-living Magellanic penguins using data (on swim speeds, intervals between prey encounters, amount ingested per patch and dive durations) derived from previously published work and from a field study conducted on birds from a colony at Punta Norte,Argentina, using data loggers. The field work indicated that free-living birds have a foraging efficiency (net energy gain/net energy loss) of about 2.5. The model predicted that birds equipped with the largest rigid external antennae tested (200 mm × 3 mm diameter), set perpendicular to water flow,increased energy expenditure at normal swim speeds of 1.77 m s–1 by 79% and at prey capture speeds of 2.25 m s–1 by 147%, and ultimately led to a foraging efficiency that was about 5 times less than that of unequipped birds. Highly flexible antennae were shown to reduce this effect considerably. Deleterious antenna-induced effects are predicted to be particularly critical in penguins that have to travel fast to capture prey. Possible measures taken by the birds to increase foraging efficiency could include reduced travelling speed and selection of smaller prey types. Suggestions are made as to how antenna-induced drag might be minimized for future studies on marine diving animals.
Colourful orb-weaving spiders, Nephila pilipes, through a bee's eyes
Authors: Tso I-Min , Lin Chih-Wei , Yang En-Cheng
Published: June 2004

Many orb-weaving spiders in the tropics forage in open sites during the day and some of them have both bright and dark colourations. The conspicuous UV-reflective colour markings of these spiders have been reported to be attractive to visually oriented prey and thus could increase the spiders'foraging success. Using a combination of field and laboratory studies, we examine whether or not the body colouration of orb-weaving spiders exhibits optical properties that are attractive to insect prey from the viewpoint of insect visual physiology. We compared the prey interception rates and colour contrasts of the typical and melanic morphs of the giant wood spider, Nephila pilipes. Results of the field study showed that the typical morph caught significantly more insects than the melanic morph. Colour contrasts calculated from spectral reflectances of the background and body surface of spiders showed that the brightly coloured body parts of the typical morph exhibited rather high values, but those of the dark body parts were below the discrimination threshold. The differential colour contrasts of body parts generated a visual signal unlike that of a spider but rather like certain forms of food resources. On the other hand, the melanic morphs did not have bright colouration and the colour contrasts of every part of the body were significantly higher than the threshold, making the contour of spiders quite clear to bees.
Dopaminergic and serotonergic innervation of cockroach salivary glands:distribution and morphology of synapses and release sites
Authors: Baumann Otto , Kühnel Dana , Dames Petra , Walz Bernd
Published: June 2004

The paired salivary glands in the cockroach are composed of acini with ion-transporting peripheral P-cells and protein-secreting central C-cells, and a duct system for the modification of the primary saliva. Secretory activity is controlled by serotonergic and dopaminergic neurons, whose axons form a dense plexus on the glands. The spatial relationship of release sites for serotonin and dopamine to the various cell types was determined by anti-synapsin immunofluorescence confocal microscopy and electron microscopy. Every C-cell apparently has only serotonergic synapses on its surface. Serotonergic and dopaminergic fibres on the acini have their release zones at a distance of ∼0.5 μm from the P-cells. Nerves between acinar lobules may serve as neurohaemal organs and contain abundant dopaminergic and few serotonergic release sites. Some dopaminergic and serotonergic release sites reside in the duct epithelium, the former throughout the duct system, the latter only in segments next to acini. These findings are consistent with the view that C-cells respond exclusively to serotonin, P-cells to serotonin and dopamine, and most duct cells only to dopamine. Moreover, the data suggest that C-cells are stimulated by serotonin released close to their surface,whereas P-cells and most duct cells are exposed to serotonin/dopamine liberated at some distance.
Purification of a soluble glycoprotein from the uncalcified ecdysial cuticle of the blue crabCallinectes sapidusand its possible role in initial mineralization
Authors: Tweedie Elizabeth P. , Coblentz Francie E. , Shafer Thomas H.
Published: June 2004

A heavily glycosylated soluble protein was purified using a combination of lectin affinity and size exclusion chromatography from a soluble extract of uncalcified dorsal cuticle of blue crab Callinectes sapidus removed at ecdysis. Similarities in apparent molecular mass and carbohydrate composition suggest that this protein is the same species previously shown to disappear from soluble extracts coincidentally with the onset of mineral deposition in the newly exposed post-molt cuticle. The amino acid sequence of the N-terminal portion of the core polypeptide was determined and polyclonal antibodies were raised against both the purified glycoprotein and the peptide. Immunoblots of unfractionated soluble extracts taken at various times post-molt illustrated that the anti-peptide antibody recognized several polypeptides with electrophoretic mobilities that differ from the purified glycoprotein. These bands may be deglycosylation products which would not have been purified due to different lectin affinity or size. Immunohistochemical analysis indicated uniform protein distribution in the exocuticle at ecdysis,but decreased antibody binding at the interprismatic septa by 2 h post-molt. The location of the protein is therefore the negative image of the calcification pattern in the exocuticle and provides a spatial pattern to correlate with the previously reported temporal events. This strengthens the hypothesis that the glycoprotein under investigation is an inhibitor of calcite nucleation or of initial amorphous calcium carbonate accumulation.
Developmental allometry of pulmonary structure and function in the altricial Australian pelican Pelecanus conspicillatus
Authors: Seymour Roger S. , Runciman Sue , Baudinette Russell V. , Pearson James T.
Published: June 2004

Quantitative methods have been used to correlate maximal oxygen uptake with lung development in Australian pelicans. These birds produce the largest altricial neonates and become some of the largest birds capable of flight. During post-hatching growth to adults, body mass increases by two orders of magnitude (from 88 g to 8.8 kg). Oxygen consumption rates were measured at rest and during exposure to cold and during exercise. Then the lungs were quantitatively assessed using morphometric techniques. Allometric relationships between body mass (M) and gas exchange parameters(Y) were determined and evaluated by examining the exponents of the equation Y=aMb. This intraspecific study was compared to interspecific studies of adult birds reported in the literature. Total lung volume scales similarly in juvenile pelicans (b=1.05) as in adult birds (b=1.02). However, surface area of the blood–gas barrier greatly increases (b=1.25), and its harmonic mean thickness does not significantly change (b=0.02), in comparison to exponents from adult birds (b=0.86 and 0.07, respectively). As a result, the diffusing capacity of the blood–gas tissue barrier increases much more during development (b=1.23) than it does in adult birds of different sizes (b=0.79). It increases in parallel to maximal oxygen consumption rate (b=1.28), suggesting that the gas exchange system is either limited by lung development or possibly symmorphic. The capacity of the oxygen delivery system is theoretically sufficient for powered flight well in advance of the bird's need to use it.
Learning and memory inLymnaeaare negatively altered by acute low-level concentrations of hydrogen sulphide
Authors: Rosenegger David , Roth Sheldon , Lukowiak Ken
Published: June 2004

Hydrogen sulphide (H2S) is a common industrial pollutant as well as an endogenous neural transmitter/neural modulator. Experiments were performed on the pond snail Lymnaea stagnalis to determine the acute effects of low-level exposure to H2S (50–100 μmol l–1) on aerial respiratory behaviour, associative learning,and its subsequent consolidation into long-term memory (LTM). A 3-neuron network whose sufficiency and necessity have been demonstrated drives aerial respiratory behaviour in Lymnaea. In the presence of 100 μmol l–1 H2S the number of bouts of aerial respiration and the total breathing time were significantly increased compared to the control hypoxic situation, but were equivalent to those observed in snails that had been subjected to a `more intense hypoxic challenge'. In addition, at a concentration of 100 μmol l–1 H2S neither associative learning nor long-term memory (LTM) were observed. However, snails subjected to a `more intense hypoxic challenge' still had the capacity to learn and form LTM. These snails, in fact, showed statistically the best learning and memory performance of any group. While learning and memory were observed at 50 and 75 μmol l–1 H2S,respectively, they were statistically poorer than the learning and memory exhibited by snails in the standard hypoxia condition. Hence the ability to learn and form memory was compromised by H2S. Thus an invertebrate model system with a well-defined neural network can be used to study of the effects of H2S on the processes of learning and memory.
Adjustments of gastric pH, motility and temperature during long-term preservation of stomach contents in free-ranging incubating king penguins
Authors: Thouzeau C. , Peters G. , Le Bohec C. , Le Maho Y.
Published: June 2004

Male king penguins are able to store undigested food in their stomach for up to 3 weeks during their incubation fast, which evidently implies some modification of their digestive process. Using small electronic recorders, we studied the change in gastric pH, motility and temperature during the first week of food storage. The pH could be maintained at values as high as 6 throughout the incubation fast, a pH that is unfavourable for avian gastric proteinase activity. Gastric motility was never completely inhibited but could be markedly reduced. Stomach temperature was maintained at around 38°C. The fact that stomach temperature of incubating birds did not show a daily rhythmic fluctuation as seen in non-breeding birds could be due to temperature constraints on embryo development. Thus the present study demonstrates substantial adjustments of pH and gastric motility in incubating king penguins, which may contribute to the inhibition of digestive gastric processes.
The genes for the helix-loop-helix proteins Id6a, Id6b, Id1 and Id2 are specifically expressed in the ventral and dorsal domains of the fish developing somites
Authors: Rallière Cécile , Chauvigné François , Rescan Pierre-Yves
Published: June 2004

Muscle differentiation is inhibited by members of the Id family that block the transcriptional effect of myogenic bHLH regulators by forming inactive heterodimers with them. Also, Id proteins promote cell proliferation by interacting with key regulators of the cell cycle. In order to determine the role of Id-encoding genes during fish development and especially in early myogenesis, we examined the expression patterns of Id1, Id2 and two nonallelic Id6 (Id6a and Id6b)-encoding genes in developing trout embryos. These four Id paralogs were found to exhibit discrete expression in the developing nervous system and in the eye rudiment. During the segmentation process, Id6a, Id6b and Id1 were expressed in the tail bud, the paraxial mesoderm and the ventral and dorsal domains of neoformed somites. As the somite matured in a rostrocaudal progression, the labelling for Id1 transcripts rapidly faded whereas labelling for Id6 transcripts was found to persist until at least the completion of segmentation. By contrast, Id2 transcripts were visualised transiently only in dorsal domains of neoformed somites and strongly accumulated in the pronephros. The preferential localisation of Id6a, Id6b, Id1 and Id2 transcripts within ventral and/or dorsal extremes of the developing somites, suggests that these areas, which were the last ones to express muscle-specific genes, contain dividing cells involved in somite expansion.
Reduced juvenile hormone synthesis in mosquitoes with low teneral reserves reduces ovarian previtellogenic development in Aedes aegypti
Authors: Caroci Abrahim S. , Li Yiping , Noriega Fernando G.
Published: June 2004

We investigated the relationship among nutritional reserves,previtellogenic ovary development and juvenile hormone (JH) synthesis in Aedes aegypti female mosquitoes. By raising larvae under different nutritional regimes, two adult phenotypes (large and small females) were generated, which differed significantly in size at eclosion (measured by wing length). We measured the total amount of protein, lipids and glycogen in newly emerged (teneral) large and small females. Teneral reserves were significantly lower in small females. Maximum previtellogenic ovary development occurred only if enough teneral nutrients were present. Maximum previtellogenic ovary development was stimulated in small females with low teneral nutrients by topically applying a JH analog. The biosynthetic activity of Ae. aegypti corpora allata (CA) was studied in vitro using a radiochemical method. JH synthesis was significantly reduced in females emerged with low teneral reserves and stimulated by sugar feeding. These results establish that the CA synthesizes enough JH to activate ovary maturation only in the presence of large nutrient reserves.
Wing hair sensilla underlying aimed hindleg scratching of the locust
Authors: Page Keri L. , Matheson Thomas
Published: June 2004

The anatomy and physiology of exteroceptors on the surfaces of the wings have been described in many insects, but their roles in behaviour have been less well studied. They have often been assumed to have a role primarily in flight. We show that the wings of the locust Schistocerca gregariapossess at least three different hair types with characteristic patterns of distribution that determine the probability of eliciting targeted hindleg scratching behaviour.

The different hair types are defined by their morphology and innervation. The shortest hairs (14–46 μm) are basiconic receptors containing both chemosensory and mechanosensory afferents. They are distributed widely across the dorsal surfaces of the forewings; some are located on the ventral surfaces of the hindwings, but none are found on the ventral surfaces of the forewings or the dorsal surfaces of the hindwings. Medium length hairs (73–159μm) are found on all wing surfaces, but are restricted to the veins,principally the subcosta on the dorsal surface of the forewings. The longest hairs (316–511 μm) are found only on the postcubitus vein on the dorsal surfaces of the forewings, so that they form a pair of dorsal rows when the wings are folded at rest.

Touching the dorsal surface of a forewing can elicit aimed scratching movements of a hindleg, and we show that the probability of eliciting a scratch differs for different stimulus sites and for different start positions of the hind leg. The effectiveness of different stimulus sites can be correlated with the distribution of tactile hairs on the dorsal forewing surface. Touching the long hairs provides the strongest drive to elicit a scratch, and ablating them reduces the probability to almost zero. We conclude that input from forewing tactile hairs plays an important role in eliciting hindleg scratching and encodes the spatial location required for targeting.
Inventory Decisions in Dell's Supply Chain
Authors: Kapuscinski Roman , Zhang Rachel Q. , Carbonneau Paul , Moore Robert , Reeves Bill
Published: June 2004

The Tauber Manufacturing Institute (TMI) is a partnership between the engineering and business schools at the University of Michigan. In the summer of 1999, a TMI team spent 14 weeks at Dell Inc. in Austin, Texas, and developed an inventory model to identify inventory drivers and quantify target levels for inventory in the final stage of Dell's supply chain, the revolvers or supplier logistics centers (SLC). With the information and analysis provided by this model, Dell's regional materials organizations could tactically manage revolver inventory while Dell's worldwide commodity management could partner with suppliers in improvement projects to identify inventory drivers and to reduce inventory. Dell also initiated a pilot program for procurement of XDX (a disguised name for one of the major components of personal computers (PCs)) in the United States to institutionalize the model and promote partnership with suppliers. Based on the model predictions, Dell launched e-commerce and manufacturing initiatives with its suppliers to lower supply-chain-inventory costs by reducing revolver inventory by 40 percent. This reduction would raise the corresponding inventory turns by 67 percent. Net Present Value (NPV) calculations for XDX alone suggest $43 million in potential savings. To ensure project longevity, Dell formed the supply-chain-optimization team and charged it with incorporating the model into a strategic redesign of Dell's business practices and supervising improvement projects the model identified.
Schlumberger Optimizes Receiver Location for Automated Meter Reading
Authors: Gavirneni Srinagesh , Clark Lloyd , Pataki Gábor
Published: June 2004

In its efforts to provide automated meter-reading services to the utility industry, Schlumberger faces the problem of deploying receivers efficiently. In a geographic region, the problem is to install the minimum number of receivers on existing utility poles so that all wireless meters in that region can transmit their readings to at least one. Schlumberger first encountered this large-scale problem in a project it ran for Illinois Power. It found solving this problem manually very time consuming, and it had no ability to evaluate the robustness of the resulting solution. We proposed and implemented an optimization-based approach that reduced the duration and cost of implementations. In addition, we gave planners the ability to answer what-if questions.
Decision Rules for the Academy Awards Versus Those for Elections
Authors: Gehrlein William V. , Kher Hemant V.
Published: June 2004

Many researchers have evaluated various decision rules to determine how well they perform in selecting winners in elections. They have established criteria to measure how well these rules perform in selecting winners with the greatest mass appeal in general elections. We evaluate such decision rules on their performance in determining winners of awards for outstanding accomplishment. We examined the procedures the Academy of Motion Picture Arts and Sciences uses to choose nominees and winners for Academy Awards. We chose this example for two reasons. First, the academy uses several decision rules to select nominees and to select the winners from the lists of final nominees. Second, Academy Awards have an enormous impact on earnings and careers. We found that decision rules that can have negative effects in elections based on mass appeal can have positive aspects in determining winners of awards for outstanding accomplishment.
Metrics for Managing Online Procurement Auctions
Authors: Millet Ido , Parente Diane H. , Fizel John L. , Venkataraman Ray R.
Published: June 2004

Metrics can improve firms' ability to manage online procurement auctions. A key factor in business-to-business procurement auctions is supplier participation, which we modeled as a multistage process. We analyzed data collected from thousands of auctions conducted by a large multinational firm and found that different auction types lead to different participation and success dynamics. Typically, it is important to invite a sufficient number of suppliers and ensure that they accept the invitation and actually log into the auction. It is even more important to encourage active bidding and reduce the proportion of suppliers who log in but never bid.
The Slab-Design Problem in the Steel Industry
Authors: Dawande Milind , Kalagnanam Jayant , Lee Ho Soo , Reddy Chandra , Siegel Stuart , Trumbo Mark
Published: June 2004

Planners in the steel industry design a set of steel slabs to satisfy the order book subject to constraints on (1) achieving a total designed weight for each order using multiples of an order-specific production size range, (2) minimum and maximum sizes for each slab, and (3) feasible assignments of multiple orders to the same slab. We developed a heuristic solution based on matchings and bin packing that a large steel plant uses daily in mill operations.
Allocating Vendor Risks in the Hanford Waste Cleanup
Authors: Keisler J. M. , Buehring W. A. , McLaughlin P. D. , Robershotte M. A. , Whitfield R. G.
Published: June 2004

Organizations may view outsourcing as a way to manage risk. We developed a decision-analytic approach to determine which risks the buyer can share or shift to vendors and which ones it should bear. We found that allocating risks incorrectly could increase costs dramatically. Between 1995 and 1998, we used this approach to develop the request for proposals (RFP) for the US Department of Energy's (DOE's) privatization initiative for the Hanford tank waste remediation system (TWRS). In the model, we used an assessment protocol to predict how vendors would react to proposed risk allocations in terms of their actions and their pricing. We considered the impact of allocating each major risk to potential vendors, to the DOE, or to both and identified the risk allocation that would minimize the DOE's total cost—its direct payments to vendors plus the costs of any residual risks it accepted. Allocating inappropriate risks to the vendor would have increased costs because the vendor would add a large risk premium to its bids, while allocating inappropriate risks to the DOE also would have increased costs because the vendor would not take adequate risk-reduction measures. With the improved risk allocation, the RFPs resulted in bids that were acceptable to the DOE.
Endogenous Glucocorticoids Are Essential for Maintaining Prefrontal Cortical Cognitive Function
Authors: Mizoguchi Kazushige , Ishige Atsushi , Takeda Shuichi , Aburada Masaki , Tabira Takeshi
Published: June 2004

Glucocorticoid hormones are important in the maintenance of many brain functions. Although their receptors are distributed abundantly throughout the brain, including the prefrontal cortex (PFC), it is not clear how glucocorticoid functions, particularly with regard to cognitive processing in the PFC. There is evidence of PFC cognitive deficits such as working memory impairment in several stress-related neuropsychiatric disorders, including depression, schizophrenia, and Parkinson's disease. Disruption of the hypothalamo-pituitary-adrenal (HPA) system, which is characterized by attenuated glucocorticoid negative feedback, is also observed. In rats, chronic stress induces working memory impairment as a result of decreased dopaminergic transmission in the PFC. These chronically stressed rats also show HPA disruption; this is caused in part by a reduced glucocorticoid response in the PFC. These findings implicate reduced glucocorticoid actions in working memory impairment. In the present study, we examined the effects of the suppression of endogenous glucocorticoids by adrenalectomy (ADX) on working memory in rats and explored the involvement of PFC dopaminergic activities in memory. The ADX impaired working memory, decreased dopamine release, and upregulated D1receptors in the PFC. These dysfunctions were prevented by corticosterone replacement that reproduced normal physiological plasma levels, indicating that suppression of glucocorticoids causes these dysfunctions. Moreover, the ADX-induced working memory impairment was ameliorated by intra-PFC infusions of a D1receptor agonist, SKF 81297. Thus, suppression of glucocorticoids impaired working memory through a D1receptor-mediated hypodopaminergic mechanism in the PFC. This finding indicates that endogenous glucocorticoids are essential for maintaining PFC cognitive function and suggests that HPA disruption contributes to PFC cognitive deficits.
Brain Mechanisms for Inferring Deceit in the Actions of Others
Authors: Grèzes Julie , Frith Chris , Passingham Richard E.
Published: June 2004

During social interactions, it is important to judge accurately whether a person is honest or deceitful. We often use nonverbal cues to infer whether others are trying to deceive us. Using functional magnetic resonance imaging, we studied subjects watching videos of actors lifting a box and judged whether or not the actors were trying to deceive them concerning the real weight of the box. When the subjects judged the actions as reflecting deceptive intention, there was activation of the amygdala and rostral anterior cingulate cortex. These areas were not activated when subjects made judgements about the beliefs rather than the intentions of others. We suggest that these activations reflect the observers' judgements of social intentions toward themselves and might reflect an emotional response to being deceived.
The Role of the Central Nucleus of the Amygdala in Mediating Fear and Anxiety in the Primate
Authors: Kalin Ned H. , Shelton Steven E. , Davidson Richard J.
Published: June 2004

Numerous studies demonstrate that the rhesus monkey is an excellent species with which to investigate mechanisms underlying human emotion and psychopathology. To examine the role of the central nucleus of the amygdala (CeA) in mediating the behavioral and physiological responses associated with fear and anxiety, we used rhesus monkeys to assess the effects of excitotoxic lesions of the CeA. Behavioral and physiological responses of nine monkeys with bilateral CeA destruction (ranging from 46 to 98%) were compared with five animals with asymmetric lesions (42-86.5% destruction on the most affected side) and with 16 unoperated controls. Results suggest that similar to rodent species, the primate CeA plays a role in mediating fear- and anxiety-related behavioral and endocrine responses. Compared with controls and the asymmetric-lesion group, bilaterally lesioned monkeys displayed significantly less fear-related behavior when exposed to a snake and less freezing behavior when confronted by a human intruder. In addition, bilaterally lesioned monkeys had decreased levels of CSF corticotrophin-releasing factor (CRF), and both lesioned groups had decreased plasma ACTH concentrations. In contrast to these findings, patterns of asymmetric frontal brain electrical activity, as assessed by regional scalp EEG, did not significantly differ between control and lesioned monkeys. These findings suggest that in primates, the CeA is involved in mediating fear- and anxiety-related behavioral and pituitary-adrenal responses as well as in modulating brain CRF activity.
Excitotoxic Calcium Overload in a Subpopulation of Mitochondria Triggers Delayed Death in Hippocampal Neurons
Authors: Pivovarova Natalia B. , Nguyen Huy V. , Winters Christine A. , Brantner Christine A. , Smith Carolyn L. , Andrews S. Brian
Published: June 2004

In neurons, excitotoxic stimulation induces mitochondrial calcium overload and the release of pro-apoptotic proteins, which triggers delayed cell death. The precise mechanisms of apoptogen release, however, remain controversial. To characterize the linkage between mitochondrial calcium load and cell vulnerability, and to test the hypothesis that only a subpopulation of mitochondria damaged by calcium overload releases apoptogens, we have measured directly the concentrations of total Ca (free plus bound) in individual mitochondria and monitored in parallel structural changes and the subcellular localization of pro-apoptotic cytochromecafter NMDA overstimulation in cultured hippocampal neurons. Beyond transient elevation of cytosolic calcium and perturbation of Na+/K+homeostasis, NMDA stimulation induced dramatic, but mainly reversible, changes in mitochondria, including strong calcium elevation, membrane potential depolarization, and variable swelling. Elevation of matrix Ca in the approximately one-third of mitochondria that were strongly swollen, as well as the absence of swelling when Ca2+entry was abolished, indicate an essential role for Ca overload. Shortly after NMDA exposure, cytochromec, normally localized to mitochondria, became diffusely distributed in the cytoplasm, coincident with the appearance of severely swollen mitochondria with ruptured outer membranes; under these conditions, cytochromecwas retained in intact mitochondria, implying that it was released mainly from damaged mitochondria. Consistent with the role of mitochondrial Ca overload, carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone decreased Ca accumulation, prevented cytochromecrelease, and was neuroprotective. These results support a mechanism in which delayed excitotoxic death involves apoptogen release from a subpopulation of calcium-overloaded mitochondria, whereas other, undamaged mitochondria maintain normal function.