bluuebunny/crossref_metadata_2025 huggingface dataset:
Altered metaplastic response ofwaved-2EGF receptor mutant mice to acute oxyntic atrophy
Authors: Ogawa Masako , Nomura Sachiyo , Varro Andrea , Wang Timothy C. , Goldenring James R.
Published: November 2005

Metaplastic cell lineages are putative precursors for the development of gastric adenocarcinoma. The loss of parietal cells (oxyntic atrophy) is the initiating step in the evolution of gastric fundic mucosal lineage changes including metaplasia and hyperplasia. However, the intrinsic mucosal factors that promote and modulate the emergence of metaplastic phenotypes remain obscure. Over the past several years, we have studied pharmacologically induced, reversible oxyntic atrophy in rodents treated with DMP-777, a drug that acts as a parietal cell secretory membrane protonophore. DMP-777 elicits a rapid loss of parietal cells followed by the emergence of foveolar hyperplasia and spasmolytic polypeptide (SP)-expressing metaplasia (SPEM). The objective of the present study was to provide further insights into the intrinsic mucosal factors regulating the emergence of SPEM in the setting of oxyntic atrophy. We therefore studied the effects of DMP-777 administration on both SP/trefoil factor (TFF)2-deficient mice, which lack SP/TFF2, a marker of SPEM, and waved-2 mice, which harbor a point mutation in the EGF receptor that attenuates its tyrosine kinase activity. As in wild-type mice, treatment with DMP-777 for 7 days did elicit SPEM in SP/TFF2-deficient mice. These results suggest that SP/TFF2 does not impact on the development of metaplasia after the induction of parietal cell loss. In contrast, waved-2 homozygous mice displayed accelerated SPEM development by 3 days of treatment with DMP-777. These findings indicate that attenuation of EGF receptor signaling in waved-2 mice does elicit a more rapid emergence of SPEM. The results support a role for EGF receptor ligands in the regulation of gastric metaplasia.
Opposite action ofS-adenosyl methionine and its metabolites on CYP2E1-mediated toxicity in pyrazole-induced rat hepatocytes and HepG2 E47 cells
Authors: Wu Defeng , Cederbaum Arthur I.
Published: November 2005

S-adenosyl-l-methionine (SAMe) is protective against a variety of hepatotoxins, including ethanol. The ability of SAMe to protect against cytochrome P-450 2E1 (CYP2E1)-dependent toxicity was studied in hepatocytes from pyrazole-treated rats and HepG2 E47 cells, both of which actively express CYP2E1. Toxicity was initiated by the addition of arachidonic acid (AA) or by depletion of glutathione after treatment with l-buthionine sulfoximine (BSO). In pyrazole hepatocytes, SAMe (0.25–1 mM) protected against AA but not BSO toxicity. SAMe elevated GSH levels, thus preventing the decline in GSH caused by AA, and SAMe prevented AA-induced lipid peroxidation. SAMe analogs such as methionine or S-adenosyl homocysteine, which elevate GSH, also protected against AA toxicity. 5′-Methylthioadenosine (MTA), which cannot produce GSH, did not protect. The toxicity of BSO was not prevented by SAMe and the analogs because GSH cannot be synthesized. In contrast, in E47 cells, SAMe and MTA but not methionine or S-adenosyl homocysteine potentiated AA and BSO toxicity. Antioxidants such as trolox or N-acetyl cysteine prevented this synergistic toxicity of SAMe plus AA or SAMe plus BSO, respectively. In pyrazole hepatocytes, SAMe prevented the decline in mitochondrial membrane potential produced by AA, whereas in E47 cells, SAMe potentiated the decline in mitochondrial membrane potential. In E47 cells, but not pyrazole hepatocytes, the combination of SAMe plus BSO lowered levels of the antioxidant transcription factor Nrf2. Because SAMe can be metabolized enzymatically or spontaneously to MTA, MTA may play a role in the potentiation of AA and BSO toxicity by SAMe, but the exact mechanisms require further investigation. In conclusion, contrasting effects of SAMe on CYP2E1 toxicity were observed in pyrazole hepatocytes and E47 cells. In hepatocytes, SAMe protects against CYP2E1 toxicity by a mechanism involving maintaining or elevating GSH levels.
Curcumin suppresses the expression of extracellular matrix genes in activated hepatic stellate cells by inhibiting gene expression of connective tissue growth factor
Authors: Zheng Shizhong , Chen Anping
Published: November 2005

Upon liver injury, quiescent hepatic stellate cells (HSCs), the most relevant cell type for hepatic fibrogenesis, become active and overproduce extracellular matrix (ECM). Connective tissue growth factor (CTGF) promotes ECM production. Overexpression of CTGF during hepatic fibrogenesis is induced by transforming growth factor (TGF)-β. We recently demonstrated that curcumin reduced cell growth and inhibited ECM gene expression in activated HSCs. Curcumin induced gene expression of peroxisome proliferator-activated receptor (PPAR)-γ and stimulated its activity in activated HSCs, which was required for curcumin to suppress ECM gene expression, including αI(I)-collagen. The underlying mechanisms remain largely unknown. The aim of this study was to elucidate the mechanisms by which curcumin suppresses αI(I)-collagen gene expression in activated HSCs. We hypothesize that inhibition of αI(I)-collagen gene expression in HSCs by curcumin is mediated by suppressing CTGF gene expression through attenuating oxidative stress and interrupting TGF-β signaling. The present report demonstrated that curcumin significantly reduced the abundance of CTGF in passaged HSCs and suppressed its gene expression. Exogenous CTGF dose dependently abrogated the inhibitory effect of curcumin. Activation of PPAR-γ by curcumin resulted in the interruption of TGF-β signaling by suppressing gene expression of TGF-β receptors, leading to inhibition of CTGF gene expression. The phytochemical showed its potent antioxidant property by significantly increasing the level of total glutathione (GSH) and the ratio of GSH to GSSG in activated HSCs. De novo synthesis of cellular GSH was a prerequisite for curcumin to interrupt TGF-β signaling and inhibited gene expression of CTGF and αI(I)-collagen in activated HSCs. Taken together, our results demonstrate that inhibition of αI(I)-collagen gene expression by curcumin in activated HSCs results from suppression of CTGF gene expression through increasing cellular GSH contents and interruption of TGF-β signaling. These results provide novel insights into the mechanisms underlying inhibition of HSC activation by curcumin.
Estimation of arterial and cardiopulmonary total peripheral resistance baroreflex gain values: validation by chronic arterial baroreceptor denervation
Authors: Mukkamala Ramakrishna , Kim Jong-Kyung , Li Ying , Sala-Mercado Javier , Hammond Robert L. , Scislo Tadeusz J. , O'Leary Donal S.
Published: November 2005

Feedback control of total peripheral resistance (TPR) by the arterial and cardiopulmonary baroreflex systems is an important mechanism for short-term blood pressure regulation. Existing methods for measuring this TPR baroreflex mechanism typically aim to quantify only the gain value of one baroreflex system as it operates in open-loop conditions. As a result, the normal, integrated functioning of the arterial and cardiopulmonary baroreflex control of TPR remains to be fully elucidated. To this end, the laboratory of Mukkamala et al. (Mukkamala R, Toska K, and Cohen RJ. Am J Physiol Heart Circ Physiol 284: H947–H959, 2003) previously proposed a potentially noninvasive technique for estimating the closed-loop (dimensionless) gain values of the arterial TPR baroreflex (GA) and the cardiopulmonary TPR baroreflex (GC) by mathematical analysis of the subtle, beat-to-beat fluctuations in arterial blood pressure, cardiac output, and stroke volume. Here, we review the technique with additional details and describe its experimental evaluation with respect to spontaneous hemodynamic variability measured from seven conscious dogs, before and after chronic arterial baroreceptor denervation. The technique was able to correctly predict the group-average changes in GA and GC that have previously been shown to occur following chronic arterial baroreceptor denervation. That is, reflex control by the arterial TPR baroreflex was virtually abolished (GA = −2.1 ± 0.6 to 0.3 ± 0.2; P < 0.05), while reflex control by the cardiopulmonary TPR baroreflex more than doubled (GC = −0.7 ± 0.4 to −1.8 ± 0.2; P < 0.05). With further successful experimental testing, the technique may ultimately be employed to advance the basic understanding of TPR baroreflex functioning in both humans and animals in health and disease.
Bleomycin initiates apoptosis of lung epithelial cells by ROS but not by Fas/FasL pathway
Authors: Wallach-Dayan Shulamit B. , Izbicki Gabriel , Cohen Pazit Y. , Gerstl-Golan Regina , Fine Alan , Breuer Raphael
Published: November 2005

Epithelial cells are considered to be a main target of bleomycin-induced lung injury, which leads to fibrosis in vivo. We studied the characteristics of in vitro bleomycin-induced apoptosis in a mouse lung epithelial (MLE) cell line. Bleomycin caused an increase of reactive oxygen species (ROS) resulting in oxidative stress, mitochondrial leakage, and apoptosis. These were associated with elevated caspase-8 and resultant caspase-9 activity and with upregulation of Fas expression. Glutathione and inhibitors of caspase-8 or caspase-9, but not of FasL, inhibited these effects, suggesting their dependence on ROS, caspase-8 and -9, in a Fas/FasL-independent pathway. However, postbleomycin-exposed MLE cells were more sensitive to Fas-mediated apoptosis. These results demonstrate that the initial bleomycin-induced oxidative stress causes a direct apoptotic effect in lung epithelial cells involving a regulatory role of caspase-8 on caspase-9. Fas represents an amplification mechanism, and not a direct trigger of bleomycin-induced epithelial cell apoptosis.
Age-associated decrease in contraction-induced activation of downstream targets of Akt/mTor signaling in skeletal muscle
Authors: Funai Katsuhiko , Parkington Jascha D. , Carambula Silvia , Fielding Roger A.
Published: November 2005

In this study, we investigated the effect of age on the association of eukaryotic initiation factor 4E (eIF4E) with eukaryotic initiation factor 4G (eIF4G), as well as the activity of its binding protein (4E-BP1) and the activity of glycogen synthase kinase-3 (GSK-3) after a single bout of rat hindlimb muscle contractile activity elicited by high-frequency electrical stimulation (HFES) of the sciatic nerve. Tibialis anterior (TA) and plantaris (Pla) muscles from adult (Y; 6 mo old) and aged (O; 30 mo old) Fischer 344 × Brown Norway rats were collected immediately or 6 h after HFES. eIF4E-eIF4G association was elevated at 6 h of recovery in TA (1.9 ± 0.2-fold, P < 0.05) and immediately and 6 h after exercise in Pla (2.1 ± 0.3- and 2.1 ± 0.7-fold, P < 0.05) in Y rats. No significant increase was observed in O rats. An increase in 4E-BP1 phosphorylation was observed only 6 h after HFES in TA (5.0 ± 2.0-fold, P < 0.05) in Y rats. Phosphorylation of GSK-3α was increased immediately and 6 h after contraction in TA (1.6 ± 0.3- and 4.1 ± 0.8-fold, P < 0.05) and Pla (1.7 ± 0.2- and 2.1 ± 0.4-fold, P < 0.05) in Y rats and remained unaffected in O rats. Phosphorylation of GSK-3β was observed only immediately after HFES in TA (1.5 ± 0.2-fold, P < 0.05) in Y rats. Overall, eIF4E-eIF4G association and phosphorylation of 4E-BP1 and GSK-3 are increased after HFES in adult, but not in aged, animals. These observations suggest that the anabolic response to muscle stimulation is attenuated with aging and may contribute to the limited capacity of hypertrophy in aged animals.
Na+-d-glucose cotransporter in the kidney ofSqualus acanthias: molecular identification and intrarenal distribution
Authors: Althoff Thorsten , Hentschel Hartmut , Luig Jutta , Schütz Hendrike , Kasch Myriam , Kinne Rolf K.-H.
Published: November 2005

Using primers against conserved regions of mammalian Na+-d-glucose cotransporters (SGLT), a cDNA was cloned from the kidney of spiny dogfish shark ( Squalus acanthias). On the basis of comparison of amino acid sequence, membrane topology, and putative glycosylation and phosphorylation sites, the cDNA could be shown to belong to the family of sglt genes. Indeed, Na+-dependent d-glucose uptake could be demonstrated after expression of the gene in Xenopus laevis oocytes. In a dendrogram, the SGLT from shark kidney has a high homology to the mammalian SGLT2. Computer analysis revealed that the elasmobranch protein is most similar to the mammalian proteins in the transmembrane regions and contains already all the amino acids identified to be functionally important, suggesting early conservation during evolution. Extramembraneous loops show larger variations. This holds especially for loop 13, which has been implied as a phlorizin-binding domain. Antibodies were generated and the intrarenal distribution of the SGLT was studied in cryosections. In parallel, the nephron segments were identified by lectins. Positive immunoreactions were found in the proximal tubule in the early parts PIa and PIb and the late segment PIIb. The large PIIa segment of the proximal tubule showed no reaction. In contrast to the mammalian kidney also the late distal tubule, the collecting tubule, and the collecting duct showed immunoreactivity. The molecular information confirms previous vesicle studies in which a low affinity SGLT with a low stoichiometry has been observed and supports the notion of a similarity of the shark kidney SGLT to the mammalian SGLT2. Despite its presence in the late parts of the nephron, the absence of SGLT in the major part of the proximal tubule, the relatively low affinity, and in particular the low stoichiometry might explain the lack of a Tmfor d-glucose in the shark kidney.
Challenging the sleep homeostat does not influence the thermoregulatory system in men: evidence from a nap vs. sleep-deprivation study
Authors: Kräuchi Kurt , Knoblauch Vera , Wirz-Justice Anna , Cajochen Christian
Published: November 2005

The purpose of our study was to understand the relationship between the components of the three-process model of sleepiness regulation (homeostatic, circadian, and sleep inertia) and the thermoregulatory system. This was achieved by comparing the impact of a 40-h sleep deprivation vs. a 40-h multiple nap paradigm (10 cycles with 150/75 min wakefulness/sleep episodes) on distal and proximal skin temperatures, core body temperature (CBT), melatonin secretion, subjective sleepiness, and nocturnal sleep EEG slow-wave activity in eight healthy young men in a “controlled posture” protocol. The main finding of the study was that accumulation of sleep pressure increased subjective sleepiness and slow-wave activity during the succeeding recovery night but did not influence the thermoregulatory system as measured by distal, proximal, and CBT. The circadian rhythm of sleepiness (and proximal temperature) was significantly correlated and phase locked with CBT, whereas distal temperature and melatonin secretion were phase advanced (by 113 ± 28 and 130 ± 30 min, respectively; both P < 0.005). This provides evidence for a primary role of distal vasodilatation in the circadian regulation of CBT and its relationship with sleepiness. Specific thermoregulatory changes occur at lights off and on. After lights off, skin temperatures increased and were most pronounced for distal; after lights on, the converse occurred. The decay in distal temperature (vasoconstriction) was significantly correlated with the disappearance of sleep inertia. These effects showed minor and nonsignificant circadian modulation. In summary, the thermoregulatory system seems to be independent of the sleep homeostat, but the circadian modulation of sleepiness and sleep inertia is clearly associated with thermoregulatory changes.
Cerebral blood flow during orthostasis: role of arterial CO2
Authors: Serrador J. M. , Hughson R. L. , Kowalchuk J. M. , Bondar R. L. , Gelb A. W.
Published: November 2005

Reductions in end-tidal Pco2(PetCO2) during upright posture have been suggested to be the result of hyperventilation and the cause of decreases in cerebral blood flow (CBF). The goal of this study was to determine whether decreases in PetCO2reflected decreases in arterial Pco2(PaCO2) and their relation to increases in alveolar ventilation (V̇a) and decreases in CBF. Fifteen healthy subjects (10 women and 5 men) were subjected to a 10-min head-up tilt (HUT) protocol. PaCO2, V̇a, and cerebral flow velocity (CFV) in the middle and anterior cerebral arteries were examined. In 12 subjects who completed the protocol, reductions in PetCO2and PaCO2(−1.7 ± 0.5 and −1.1 ± 0.4 mmHg, P < 0.05) during minute 1 of HUT were associated with a significant increase in V̇a (+0.7 ± 0.3 l/min, P < 0.05). However, further decreases in PaCO2(−0.5 ± 0.5 mmHg, P < 0.05), from minute 1 to the last minute of HUT, occurred even though V̇a did not change significantly (−0.2 ± 0.3 l/min, P = not significant). Similarly, CFV in the middle and anterior cerebral arteries decreased (−7 ± 2 and −8 ± 2%, P < 0.05) from minute 1 to the last minute of HUT, despite minimal changes in PaCO2. These data suggest that decreases in PetCO2and PaCO2during upright posture are not solely due to increased V̇a but could be due to ventilation-perfusion mismatch or a redistribution of CO2stores. Furthermore, the reduction in PaCO2did not fully explain the decrease in CFV throughout HUT. These data suggest that factors in addition to a reduction in PaCO2play a role in the CBF response to orthostatic stress.
Optimization of oxygen tolerance extension in rats by intermittent exposure
Authors: Clark J. M. , Lambertsen C. J. , Gelfand R. , Troxel A. B.
Published: November 2005

Optimization of oxygen tolerance extension by intermittent exposure was studied in groups of 20 rats exposed to systematically varied patterns of alternating oxygen and normoxic breathing periods at 4.0, 2.0, and 1.5 ATA. Oxygen periods of 20, 60, and 120 min were alternated with normoxic intervals that provided oxygen-to-normoxia ratios of 4:1, 2:1, 1:1, and 1:3. In general, median survival times had nearly linear relationships to increasing normoxic intervals with oxygen period held constant. Exceptions occurred at 4.0 and 2.0 ATA where a 5-min normoxic interval was too short for adequate recovery even with a 20-min oxygen period, and an oxygen period of 120 min was too long even with a normoxic interval of 30 min. These exceptions did not occur at 1.5 ATA. Survival time for many intermittent exposure patterns was equivalent to that for continuous exposure to an oxygen pressure definable as a time-weighted average of the alternating oxygen and normoxia periods. However, this predictive method underestimated the degree of protection achieved by several of the intermittent exposure patterns, especially those performed at 4.0 ATA. Results provided guidance for selection of intermittent exposure patterns for direct evaluation in humans breathing oxygen at 2.0 ATA. Definition of intermittent exposure patterns and conditions that produced prominent gains in oxygen tolerance can also facilitate the performance of future experiments designed to study potential mechanisms for oxygen tolerance extension by intermittent exposure. Heat shock and oxidation-specific stress proteins that are induced by exposure to oxidant injury are suggested for emphasis in such investigations.
Predicting human chronically paralyzed muscle force: a comparison of three mathematical models
Authors: Frey Law Laura A. , Shields Richard K.
Published: November 2005

Chronic spinal cord injury (SCI) induces detrimental musculoskeletal adaptations that adversely affect health status, ranging from muscle paralysis and skin ulcerations to osteoporosis. SCI rehabilitative efforts may increasingly focus on preserving the integrity of paralyzed extremities to maximize health quality using electrical stimulation for isometric training and/or functional activities. Subject-specific mathematical muscle models could prove valuable for predicting the forces necessary to achieve therapeutic loading conditions in individuals with paralyzed limbs. Although numerous muscle models are available, three modeling approaches were chosen that can accommodate a variety of stimulation input patterns. To our knowledge, no direct comparisons between models using paralyzed muscle have been reported. The three models include 1) a simple second-order linear model with three parameters and 2) two six-parameter nonlinear models (a second-order nonlinear model and a Hill-derived nonlinear model). Soleus muscle forces from four individuals with complete, chronic SCI were used to optimize each model's parameters (using an increasing and decreasing frequency ramp) and to assess the models' predictive accuracies for constant and variable (doublet) stimulation trains at 5, 10, and 20 Hz in each individual. Despite the large differences in modeling approaches, the mean predicted force errors differed only moderately (8–15 % error; P = 0.0042), suggesting physiological force can be adequately represented by multiple mathematical constructs. The two nonlinear models predicted specific force characteristics better than the linear model in nearly all stimulation conditions, with minimal differences between the two nonlinear models. Either nonlinear mathematical model can provide reasonable force estimates; individual application needs may dictate the preferred modeling strategy.
Spinal estrogen attenuates the exercise pressor reflex but has little effect on the expression of genes regulating neurotransmitters in the dorsal root ganglia
Authors: Schmitt Petra M. , Gohil Kishorchandra , Kaufman Marc P.
Published: November 2005

Previously, our laboratory showed that estrogen, topically applied to the spinal cord, attenuated the exercise pressor reflex in female cats (Schmitt PM and Kaufman MP. J Appl Physiol 95: 1418–1424, 2003; 98: 633–639, 2005). The attenuation was gender specific and was in part opioid dependent. Our finding that the μ- and δ-opioid antagonist naloxone was only able to partially restore estrogen’s attenuating effect on the pressor response to static contraction suggested that estrogen affected an additional pathway, involving the dorsal root ganglion (DRG). Estrogen has been described to stimulate transcription within 10 min of its application to the DRG, raising the possibility that rapid genomic effects on neurotransmitter production may have contributed to estrogen’s effect on the exercise pressor reflex. This prompted us to test the hypothesis that estrogen modulated the pressor response to static contraction by influencing gene expression of the neurotransmitters released by the thin-fiber muscle afferents that evoke the exercise pressor reflex. We confirmed in decerebrated female rats that topical application of estrogen (0.01 μg/ml) to the lumbosacral spinal cord attenuated the pressor response to static muscle contraction (from 10 ± 3 to 1 ± 1 mmHg; P < 0.05). DRG were then harvested postmortem, and changes in mRNA expression were analyzed. GeneChip analysis revealed that neither estrogen nor contraction alone changed the mRNA expression of substance P, the neurokinin-1 receptor, CGRP, NGF, the P2X3 receptor, GABAA and GABAB, the 5-HT3A and 5-HT3B receptor, N-methyl-d-aspartate and non- N-methyl-d-aspartate receptors, opioid receptors, and opioid-like receptor. Surprisingly, however, contraction stimulated the expression of neuropeptide Y in the DRG in the presence and absence of estrogen. We conclude that estrogen does not attenuate the exercise pressor reflex through a genomic effect in the DRG.
Effects of Oleic Acid on Distinct Populations of Neurons in the Hypothalamic Arcuate Nucleus Are Dependent on Extracellular Glucose Levels
Authors: Wang R. , Cruciani-Guglielmacci C. , Migrenne S. , Magnan C. , Cotero V. E. , Routh V. H.
Published: November 2005

Pharmacological manipulation of fatty acid metabolism in the hypothalamic arcuate nucleus (ARC) alters energy balance and glucose homeostasis. Thus, we tested the hypotheses that distinctive populations of ARC neurons are oleic acid (OA) sensors that exhibit a glucose dependency, independent of whether some of these OA sensors are also glucose-sensing neurons. We used patch-clamp recordings to investigate the effects of OA on ARC neurons in brain slices from 14- to 21-day-old Sprague–Dawley (SD) rats. Additionally, we recorded spontaneous discharge rate in ARC neurons in 8-wk-old fed and fasted SD rats in vivo. Patch-clamp studies showed that in 2.5 mM glucose 12 of 94 (13%) ARC neurons were excited by 2 μM OA (OA-excited or OAE neurons), whereas six of 94 (6%) were inhibited (OA-inhibited2.5or OAI2.5neurons). In contrast, in 0.1 mM glucose, OA inhibited six of 20 (30%) ARC neurons (OAI0.1neurons); none was excited. None of the OAI0.1neurons responded to OA in 2.5 mM glucose. Thus OAI2.5and OAI0.1neurons are distinct. Similarly, in seven of 20 fed rats (35%) the overall response was OAE-like, whereas in three of 20 (15%) it was OAI-like. In contrast, in fasted rats only OAI-like response were observed (three of 15; 20%). There was minimal overlap between OA-sensing neurons and glucose-sensing neurons. In conclusion, OA regulated three distinct subpopulations of ARC neurons in a glucose-dependent fashion. These data suggest that an interaction between glucose and fatty acids regulates OA sensing in ARC neurons.
Tonic and Phasic Respiratory Drives to Human Genioglossus Motoneurons During Breathing
Authors: Saboisky Julian P. , Butler Jane E. , Fogel Robert B. , Taylor Janet L. , Trinder John A. , White David P. , Gandevia Simon C.
Published: November 2005

A tongue muscle, the genioglossus (GG), is important in maintaining pharyngeal airway patency. Previous recordings of multiunit electromyogram (EMG) suggest it is activated during inspiration in humans with some tonic activity in expiration. We recorded from populations of single motor units in GG in seven subjects during quiet breathing when awake. Ultrasonography assisted electrode placement. The activity of single units was separated into six classes based on a step-wise analysis of the discharge pattern. Phasic and tonic activities were analyzed statistically with the coefficient of determination ( r2) between discharge frequency and lung volume. Of the 110 motor units, 29% discharged tonically without phasic respiratory modulation (firing rate ∼19 Hz). Further, 16% of units increased their discharge during expiration (expiratory phasic and expiratory tonic units). Only half the units increased their discharge during inspiration (inspiratory phasic and inspiratory tonic units). Units firing tonically with an inspiratory increase had significantly higher discharge rates than those units that only fired phasically (peak rates 25 vs. 16 Hz, respectively). Simultaneous recordings of two or three motor units showed neighboring units with differing respiratory and tonic drives. Our results provide a classification and the first quantitative measures of human GG motor-unit behavior and suggest this activity results from a complex interaction of inspiratory, expiratory, and tonic drives at the hypoglossal motor nucleus. The presence of different drives to GG implies that complex premotor networks can differentially engage human hypoglossal motoneurons during respiration. This is unlike the ordered recruitment of motor units in limb and axial muscles.
Control of the Subthalamic Innervation of Substantia Nigra Pars Reticulata by D1 and D2 Dopamine Receptors
Authors: Ibañez-Sandoval Osvaldo , Hernández Adán , Florán Benjamin , Galarraga Elvira , Tapia Dagoberto , Valdiosera Rene , Erlij David , Aceves Jorge , Bargas José
Published: November 2005

The effects of activating dopaminergic D1 and D2 class receptors of the subthalamic projections that innervate the pars reticulata of the subtantia nigra (SNr) were explored in slices of the rat brain using the whole cell patch-clamp technique. Excitatory postsynaptic currents (EPSCs) that could be blocked by 6-cyano-7-nitroquinoxalene-2,3-dione and d-(−)-2-amino-5-phosphonopentanoic acid were evoked onto reticulata GABAergic projection neurons by local field stimulation inside the subthalamic nucleus in the presence of bicuculline. Bath application of ( RS)-2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine hydrochloride (SKF-38393), a dopaminergic D1-class receptor agonist, increased evoked EPSCs by ∼30% whereas the D2-class receptor agonist, trans-(−)-4aR-4,4a,5,6,7,8,8a,9-octahydro-5-propyl-1H-pyrazolo(3,4-g)quinoline (quinpirole), reduced EPSCs by ∼25%. These apparently opposing actions were blocked by the specific D1- and D2-class receptor antagonists: R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetra-hydro-1H-3-benzazepinehydrochloride (SCH 23390) and S-(−)-5-anino-sulfonyl- N-[(1-ethyl-2-pyrrolidinyl)-methyl]-2-methoxybenzamide (sulpiride), respectively. Both effects were accompanied by changes in the paired-pulse ratio, indicative of a presynaptic site of action. The presynaptic location of dopamine receptors at the subthalamonigral projections was confirmed by mean-variance analysis. The effects of both SKF-38393 and quinpirole could be observed on terminals contacting the same postsynaptic neuron. Sulpiride and SCH 23390 enhanced and reduced the evoked EPSC, respectively, suggesting a constitutive receptor activation probably arising from endogenous dopamine. These data suggest that dopamine presynaptically modulates the subthalamic projection that targets GABAergic neurons of the SNr. Implications of this modulation for basal ganglia function are discussed.
Isolation of “Side Population” Progenitor Cells From Healthy Arteries of Adult Mice
Authors: Sainz Julie , Al Haj Zen Ayman , Caligiuri Giuseppina , Demerens Corinne , Urbain Dominique , Lemitre Mathilde , Lafont Antoine
Published: November 2005

Objective—

Circulating progenitors and stem cells have been reported to contribute to angiogenesis and arterial repair after injury. In the present study, we investigated whether the arterial wall could host permanently residing progenitor cells under physiological context.

Methods and Results—

Using the Hoechst-based flow cytometry method, we identified and isolated progenitor cells termed side population (SP) cells at a prevalence of 6.0±0.8% in the tunica media of adult mice aortas. Arterial SP cells expressed the ATP-binding cassette transporter subfamily G member 2, frequently present on SP cell surface, and displayed a Sca-1
+
c-kit
−/low
Lin
−
CD34
−/low
profile. They did not form myeloid or lymphoid hematopoietic colonies after plating in methylcellulose-based medium. Importantly, cultured SP cells were able to acquire the phenotype of endothelial cells (CD31, VE-cadherin, and von Willebrand factor expression) or of smooth muscle cells (α-smooth muscle actin, calponin, and smooth muscle myosin heavy chain expression), in presence of either vascular endothelial growth factor or transforming growth factor (TGF)-β1/PDGF-BB, respectively. Moreover, they generated vascular-like branching structures, composed of both VE-cadherin
+
cells and α-smooth muscle actin
+
cells on Matrigel.

Conclusions—

In this study, we provide the first evidence to our knowledge that in the adult mice, the normal arterial wall harbors SP cells with vascular progenitor properties.
Lesional Overexpression of Matrix Metalloproteinase-9 Promotes Intraplaque Hemorrhage in Advanced Lesions But Not at Earlier Stages of Atherogenesis
Authors: de Nooijer R. , Verkleij C.J.N. , von der Thüsen J.H. , Jukema J.W. , van der Wall E.E. , van Berkel Th. J.C. , Baker A.H. , Biessen E.A.L.
Published: November 2005

Background—

Matrix metalloproteinase-9 (MMP-9) is involved in atherosclerosis and elevated MMP-9 activity has been found in unstable plaques, suggesting a crucial role in plaque rupture. This study aims to assess the effect of MMP-9 on plaque stability in apolipoprotein E-deficient mice at different stages of plaque progression.

Methods and Results—

Atherosclerotic lesions were elicited in carotid arteries by perivascular collar placement. MMP-9 overexpression in intermediate or advanced plaques was effected by intraluminal incubation with an adenovirus (Ad.MMP-9). A subset was coincubated with Ad.TIMP-1. Mock virus served as a control. Plaques were analyzed histologically. In intermediate lesions, MMP-9 overexpression induced outward remodeling, as shown by a 30% increase in media size (
p
=0.03). In both intermediate and advanced lesions, prevalence of vulnerable plaque morphology tended to be increased. Half of MMP-9–treated lesions displayed intraplaque hemorrhage, whereas in controls and the Ad.MMP-9/Ad.TIMP-1 group this was 8% and 16%, respectively (
p
=0.007). Colocalization with neovessels may point to neo-angiogenesis as a source for intraplaque hemorrhage.

Conclusion—

These data show a differential effect of MMP-9 at various stages of plaque progression and suggest that lesion-targeted MMP-9 inhibition might be a valuable therapeutic modality in stabilizing advanced plaques, but not at earlier stages of lesion progression.
The Apolipoprotein B/AI Ratio and the Metabolic Syndrome Independently Predict Risk for Myocardial Infarction in Middle-Aged Men
Authors: Lind Lars , Vessby Bengt , Sundström Johan
Published: November 2005

Background—

Both the metabolic syndrome and an increased apolipoprotein B/AI (apoB/AI) ratio are powerful risk factors for cardiovascular events. We hypothesized that the apoB/AI ratio well-characterizes the dyslipidemia associated with insulin resistance and the metabolic syndrome and investigated those relations and if the apoB/AI ratio and the metabolic syndrome independently predicted subsequent myocardial infarction (MI).

Methods and Results—

A community-based sample of 1826 men aged 50 was investigated at baseline and again at age 70. ApoB/AI ratio and the metabolic syndrome (National Cholesterol Education Program definition) were evaluated, and the incidence of fatal and nonfatal MI was followed for a median of 26.8 years from the age 50 baseline. ApoB/AI ratio was significantly higher in men with versus without the metabolic syndrome (
P
<0.0001), and increased with the number of components defining the syndrome (
P
<0.0001). ApoB/AI ratio was inversely related to euglycemic insulin clamp glucose disposal rate at age 70 (
r
=−0.34,
P
<0.0001). During follow-up from age 50, 462 subjects developed an MI. An apoB/AI ratio>=0.9 (hazard ratio [HR], 1.48; 95% confidence interval [CI], 1.15 to 1.91) and presence of the metabolic syndrome (HR, 1.69; 95% CI, 1.30 to 2.21) at baseline were independent predictors for MI, adjusting for low-density lipoprotein cholesterol and smoking.

Conclusion—

The apoB/AI ratio was related to the metabolic syndrome, as well as to a direct measurement of insulin resistance. Despite this, the apoB/AI ratio and the metabolic syndrome were both independent long-term predictors of MI in a community-based sample of middle-aged men.
Vascular Function and Mild Renal Impairment in Stable Coronary Artery Disease
Authors: van der Harst Pim , Smilde Tom D.J. , Buikema Hendrik , Voors Adriaan A. , Navis Gerjan , van Veldhuisen Dirk J. , van Gilst Wiek H.
Published: November 2005

Objective—

In patients with coronary artery disease, the concomitant presence of renal function impairment is associated with decreased survival. We aimed to assess whether in coronary artery diseased patients renal function impairment is associated with systemic vascular function, functional parameters of the renin-angiotensin system, or inflammation as potential mediators for cardiovascular risk.

Methods and Results—

We studied 125 patients, 87% male, with a mean age of 62.2±8.2 years; 72% had 3-vessel disease, and mean renal function was 74±13 mL/min per 1.73 m
2
. Internal thoracic artery rings were sampled during coronary bypass surgery and used for in vitro vascular measurements. We could not establish an association between endothelium-dependent vasorelaxation (response to methacholine) and renal function. In addition, vascular response to potassium chloride, phenylephrine, and angiotensin II were not associated with renal function. Finally, serum angiotensin-converting enzyme (ACE) activity, usage of ACE inhibitors, C-reactive protein, and soluble intercellular adhesion molecule 1 were not related to renal function.

Conclusions—

In coronary artery disease patients, mild renal function impairment is not associated with systemic vasomotor responsiveness, inflammation, or functional systemic parameters of the renin-angiotensin system. The relation between systemic endothelial dysfunction and mild renal insufficiency might be more complicated than previously thought.
Importance of Junctional Adhesion Molecule-A for Neointimal Lesion Formation and Infiltration in Atherosclerosis-Prone Mice
Authors: Zernecke Alma , Liehn Elisa A. , Fraemohs Line , von Hundelshausen Philipp , Koenen Rory R. , Corada Monica , Dejana Elisabetta , Weber Christian
Published: November 2005

Objective—

Although junctional adhesion molecule-A (JAM-A) has recently been implicated in leukocyte recruitment on early atherosclerotic endothelium and after reperfusion injury, its role in neointima formation after arterial injury remains to be elucidated.

Methods and Results—

Here we show that the genetic deletion of JAM-A in apolipoprotein E–deficient (apoE
−/−
) mice significantly reduced neointimal hyperplasia after wire injury of carotid arteries without altering medial area. This was associated with a significant decrease in neointimal macrophage content, whereas the relative content of smooth muscle cells and endothelial recovery was unaltered in JAM-A
−/−
apoE
−/−
compared with JAM-A
+/+
apoE
−/−
lesions. In carotid arteries perfused ex vivo, deficiency in JAM-A significantly impaired the recruitment of monocytes 1 week, but not 1 day, after injury. These effects were paralleled by an attenuation of monocyte arrest and transmigration on activated JAM-A
−/−
apoE
−/−
versus JAM-A
+/+
apoE
−/−
endothelial cells under flow conditions in vitro. A mechanism underlying reduced recruitment was implied by findings that the luminal expression of the arrest chemokine RANTES in injured arteries and its endothelial deposition by activated platelets in vitro were diminished by JAM-A deficiency.

Conclusions—

Our data provide the first evidence to our knowledge for a crucial role of JAM-A in accelerated lesion formation and monocyte infiltration in atherosclerosis-prone mice.
c-Jun N-Terminal Kinases Mediate Reactivation of Akt and Cardiomyocyte Survival After Hypoxic Injury In Vitro and In Vivo
Authors: Shao Zhili , Bhattacharya Kausik , Hsich Eileen , Park Larry , Walters Brian , Germann Ursula , Wang Yow-Ming , Kyriakis John , Mohanlal Ramon , Kuida Keisuke , Namchuk Mark , Salituro Francesco , Yao Yung-mae , Hou Wei-min , Chen Xin , Aronovitz Mark , Tsichlis Philip N. , Bhattacharya Susmita , Force Thomas , Kilter Heiko
Published: November 2005

Akt is a central regulator of cardiomyocyte survival after ischemic injury in vitro and in vivo, but the mechanisms regulating Akt activity in the postischemic cardiomyocyte are not known. Furthermore, although much is known about the detrimental role that the c-Jun N-terminal kinases (JNKs) play in promoting death of cells exposed to various stresses, little is known of the molecular mechanisms by which JNK activation can be protective. We report that JNKs are necessary for the reactivation of Akt after ischemic injury. We identified Thr450 of Akt as a residue that is phosphorylated by JNKs, and the phosphorylation status of Thr450 regulates reactivation of Akt after hypoxia, apparently by priming Akt for subsequent phosphorylation by 3-phosphoinositide–dependent protein kinase. The reduction in Akt activity that is induced by JNK inhibition may have significant biological consequences, as we find that JNKs, acting via Akt, are critical determinants of survival in posthypoxic cardiomyocytes in culture. Furthermore, in contrast to selective p38–mitogen-activated protein kinase inhibition, which was cardioprotective in vivo, concurrent inhibition of both JNKs and p38–mitogen-activated protein kinases increased ischemia/reperfusion injury in the heart of the intact rat. These studies demonstrate that reactivation of Akt after resolution of hypoxia and ischemia is regulated by JNKs and suggest that this is likely a central mechanism of the myocyte protective effect of JNKs.
Cardiomyocyte Cell Cycle Activation Ameliorates Fibrosis in the Atrium
Authors: Nakajima Hidehiro , Nakajima Hisako O. , Dembowsky Klaus , Pasumarthi Kishore B.S. , Field Loren J.
Published: November 2005

MHC-TGFcys33ser transgenic mice have elevated levels of active transforming growth factor (TGF)-β1in the myocardium. Previous studies have shown that these animals develop atrial, but not ventricular, fibrosis. Here we show that atrial fibrosis was accompanied with cardiomyocyte apoptosis. Although similar levels of cardiomyocyte apoptosis were present in the right and left atria of MHC-TGFcys33ser hearts, the extent of fibrosis was more pronounced in the right atrium. Thus, additional factors influence the degree of atrial fibrosis in this model. Tritiated thymidine incorporation studies revealed cardiomyocyte cell cycle activity in left atrial cardiomyocytes, but not in right atrial cardiomyocytes. These observations suggested that cardiomyocyte cell cycle activation ameliorated the severity of atrial fibrosis. To directly test this hypothesis, MHC-TGFcys33ser mice were crossed with MHC-cycD2 mice (which have constitutive cardiomyocyte cell cycle activity in the right atrium). Mice inheriting both transgenes exhibited right atrial cardiomyocyte cell cycle activity and a concomitant reduction in the severity of right atrial fibrosis, despite the presence of a similar level of cardiomyocyte apoptosis as was observed in mice inheriting the MHC-TGFcys33ser transgene alone. These data support the notion that cardiomyocyte cell cycle induction can antagonize fibrosis in the myocardium.
Microtubules Modulate the Stiffness of Cardiomyocytes Against Shear Stress
Authors: Nishimura Satoshi , Nagai Shinya , Katoh Masayoshi , Yamashita Hiroshi , Saeki Yasutake , Okada Jun-ichi , Hisada Toshiaki , Nagai Ryozo , Sugiura Seiryo
Published: November 2005

Although microtubules are involved in various pathological conditions of the heart including hypertrophy and congestive heart failure, the mechanical role of microtubules in cardiomyocytes under such conditions is not well understood. In the present study, we measured multiple aspects of the mechanical properties of single cardiomyocytes, including tensile stiffness, transverse (indentation) stiffness, and shear stiffness in both transverse and longitudinal planes using carbon fiber–based systems and compared these parameters under control, microtubule depolymerized (colchicine treated), and microtubule hyperpolymerized (paclitaxel treated) conditions. From all of these measurements, we found that only the stiffness against shear in the longitudinal plane was modulated by the microtubule cytoskeleton. A simulation model of the myocyte in which microtubules serve as compression-resistant elements successfully reproduced the experimental results. In the complex strain field that living myocytes experience in the body, observed changes in shear stiffness may have a significant influence on the diastolic property of the diseased heart.
Diabetic Microangiopathy in Ischemic Limb Is a Disease of Disturbance of the Platelet-Derived Growth Factor-BB/Protein Kinase C Axis but Not of Impaired Expression of Angiogenic Factors
Authors: Tanii Mitsugu , Yonemitsu Yoshikazu , Fujii Takaaki , Shikada Yasunori , Kohno Ri-ichiro , Onimaru Mitsuho , Okano Shinji , Inoue Makoto , Hasegawa Mamoru , Onohara Toshihiro , Maehara Yoshihiko , Sueishi Katsuo
Published: November 2005

Diabetic foot is caused by microangiopathy and is suggested to be a result of impaired angiogenesis. Using a severe hindlimb ischemia model of streptozotocin-induced diabetic mice (STZ-DM), we show that diabetic foot is a disease solely of the disturbance of platelet-derived growth factor B-chain homodimer (PDGF-BB) expression but not responses of angiogenic factors. STZ-DM mice frequently lost their hindlimbs after induced ischemia, whereas non-DM mice did not. Screening of angiogenesis-related factors revealed that only the expression of PDGF-BB was impaired in the STZ-DM mice on baseline, as well as over a time course after limb ischemia. Supplementation of the PDGF-B gene resulted in the prevention of autoamputation, and, furthermore, a protein kinase C (PKC) inhibitor restored the PDGF-BB expression and also resulted in complete rescue of the limbs of the STZ-DM mice. Inhibition of overproduction of advanced-glycation end product resulted in dephosphorylation of PKC-α and restored expression of PDGF-BB irrespective of blood sugar and HbA1c, indicating that advanced-glycation end product is an essential regulator for PKC/PDGF-BB in diabetic state. These findings are clear evidence indicating that diabetic vascular complications are caused by impairment of the PKC/PDGF-B axis, but not by the impaired expression of angiogenic factors, and possibly imply the molecular target of diabetic foot.
Incidence and Trends of Stroke and Its Subtypes in China
Authors: Jiang Bin , Wang Wen-zhi , Chen Honglei , Hong Zhen , Yang Qi-dong , Wu Sheng-ping , Du Xiao-li , Bao Qiu-ju
Published: November 2005

Background and Purpose—

To examine the incidence and trends of stroke and its major subtypes during the 1990s in 3 cities in China.

Methods—

Stroke cases registered between 1991 to 2000 were initially identified through the stroke surveillance networks established in Beijing, Shanghai, and Changsha, and then confirmed by neurologists.

Results—

The age-standardized incidence rates per 100 000 person years of overall first-ever stroke were 135.0 (95% CI, 126.5 to 144.6) in Beijing, 76.1 (70.6 to 82.6) in Shanghai, and 150.0 (141.3 to 160.0) in Changsha during the 1990s. Incidence of ischemic stroke (IS) was highest in Beijing, followed by Changsha and Shanghai; for intracerebral hemorrhage (ICH), the highest rate was found in Changsha, followed by Beijing and Shanghai. The same order as ICH was also observed for subarachnoid hemorrhage. The age-adjusted incidence of overall stroke and ICH for individuals ≥55 years of age in our populations was generally higher than that from Western populations. During the 1990s, ICH incidence decreased significantly at a rate of 12.0% per year in Beijing, 4.4% in Shanghai, and 7.7% in Changsha; in contrast, except for Changsha, IS incidence increased in Beijing (5.0% per year) and Shanghai (7.7%).

Conclusions—

There is a geographic variation in the incidence of stroke and its subtypes among these 3 cities, but the incidence of overall and hemorrhagic stroke in China is generally higher than that in the Western countries. Interestingly, the decrease in ICH and increase in IS during the past decade may reflect some underlying changes of risk factors in Chinese populations.