bluuebunny/crossref_metadata_2025 huggingface dataset:
Low‐Income Issues in Electricity Restructuring
Authors: OPPENHEIM JERROLD , MACGREGOR THEO
Published: May 2003

Lower prices. New technologies. More choices. These are benefits that competition through electric industry restructuring was supposed to bring customers. Thus far, results have been disappointing, and harmful to the most vulnerable–low‐income people. Restructuring is no longer under active consideration in any state that has not already enacted it. In several states, restructuring has been reversed. This article focuses on the few states that have retained electric industry restructuring, providing a menu of necessary protections, strategies for putting them into place, and supporting arguments to keep them there. However, low‐income protections are appropriate for anactment in all places because vulnerable low‐income families live in states with both restructured and traditional electricity regulation.
Complexity, Coupling, and the Future of European Integration
Authors: ZAHARIADIS NIKOLAOS
Published: May 2003

Why is there more integration in some areas of the European Union than others? Analyzing the dynamics of the integration process at the “normal politics” level, I specify two conditions, complexity and coupling, that make integration in Europe more likely in specific policy domains. Integration is more likely under conditions of low complexity and tight coupling. Using these two hypotheses, I probe tendencies toward more integration in four areas: competition policy, social policy, agriculture, and foreign and security policy. Integration need not be just a matter of conscious design or bargain, but also the perhaps unintended consequence of interaction between the various actors at the EU level. I conclude that European integration is segmented and that a more integrated Europe is necessarily a more expensive Europe.
The Making of Social Policy in Israel: The Perceived Influence of Members of the 13th Israeli Knesset
Authors: BEN‐ARIEH ASHER , DORON ABRAHAM
Published: May 2003

This article reports the findings of a study that explored possible connections between the perceived influence and the background variables of members of the 13th Israeli Knesset (MKs). The study involved extensive interviews with members of the 13th Israeli Knesset (1992–1996) and with a group of policy makers. It also drew on archival and quantitative data concerning the background variables and activities of the MKs. The article includes a short overview of the Israeli political system and of the 13th Israeli Knesset and its composition. The research methodology is described in the beginning of the article. The perceived influence of the MKs and their background variables are then the article. The perceived influence of the MKs and their background variables are then presented. Subsequently, possible correlations between the MKs’background variables and their influence are explored. The article ends with a discussion and a presentation of conclusions.
CANONICAL CURVES IN ℙ3
Authors: ROJAS JACQUELINE , VAINSENCHER ISRAEL
Published: May 2003

Let ${\rm Hilb}^{6t-3}(\mathbb{P}^3)$ be the Hilbert scheme of closed 1-dimensional subschemes of degree 6 and arithmetic genus 4 in $\mathbb{P}^3$. Let $H$ be the component of ${\rm Hilb}^{6t-3}(\mathbb{P}^3)$ whose generic point corresponds to a canonical curve, that is, a complete intersection of a quadric and a cubic surface in $\mathbb{P}^3$. Let $F$ be the vector space of linear forms in the variables $z_1, z_2, z_3, z_4$. Denote by $F_d$ the vector space of homogeneous forms of degree $d$. Set $X = \{(f_2,f_3)\}$ where $f_2 \in \mathbb{P}(F_2)$ is a quadric surface, and $f_3 \in \mathbb{P}(F_3/f_2 \cdot F)$ is a cubic modulo $f_2$. We have a rational map, $\sigma : X \cdots \rightarrow H$ defined by $(f_2,f_3) \mapsto f_2 \cap f_3$. It fails to be regular along the locus where $f_2$ and $f_3$ acquire a common linear component. Our main result gives an explicit resolution of the indeterminacies of $\sigma$ as well as of the singularities of $H$.

2000 Mathematical Subject Classification: 14C05, 14N05, 14N10, 14N15.
ABSOLUTE, RELATIVE, AND TATE COHOMOLOGY OF MODULES OF FINITE GORENSTEIN DIMENSION
Authors: AVRAMOV LUCHEZAR L. , MARTSINKOVSKY ALEX
Published: May 2003

We study finitely generated modules $M$ over a ring $R$, noetherian on both sides. If $M$ has finite Gorenstein dimension $\mbox{G-dim}_RM$ in the sense of Auslander and Bridger, then it determines two other cohomology theories besides the one given by the absolute cohomology functors ${\rm Ext}^n_R(M,\ )$. Relative cohomology functors ${\rm Ext}^n_{\mathcal G}(M,\ )$ are defined for all non-negative integers $n$; they treat the modules of Gorenstein dimension $0$ as projectives and vanish for $n > \mbox{G-dim}_RM$. Tate cohomology functors $\widehat{\rm Ext}^n_R(M,\ )$ are defined for all integers $n$; all groups $\widehat{\rm Ext}^n_R(M,N)$ vanish if $M$ or $N$ has finite projective dimension. Comparison morphisms

$\varepsilon_{\mathcal G}^n \colon {\rm Ext}^n_{\mathcal G}(M,\ ) \to {\rm Ext}^n_R(M,\ )$

and

$\varepsilon_R^n \colon {\rm Ext}^n_R(M,\ ) \to \widehat{\rm Ext}^n_R(M,\ )$

link these functors. We give a self-contained treatment of modules of finite G-dimension, establish basic properties of relative and Tate cohomology, and embed the comparison morphisms into a canonical long exact sequence

$0 \to {\rm Ext}^1_{\mathcal G}(M,\ ) \to \cdots \to {\rm Ext}^n_{\mathcal G}(M,\ ) \to {\rm Ext}^n_R(M,\ ) \to \widehat{\rm Ext}^n_R(M,\ ) \to {\rm Ext}^{n+1}_{\mathcal G}(M,\ ) \to \cdots$.

We show that these results provide efficient tools for computing old and new numerical invariants of modules over commutative local rings.

2000 Mathematical Subject Classification: 16E05, 13H10, 18G25.
COURBES ALGÉBRIQUES RÉELLES ET COURBES FLEXIBLES SUR LES SURFACES RÉGLÉES DE BASE [Copf ]P1
Authors: WELSCHINGER JEAN-YVES
Published: May 2003

A first aim of this paper is to answer, in the case of real ruled surfaces $X_l$ of base $\mathbb{C}P^1$, with $l \geq 2$, a question of V. A. Rokhlin: is it true that the equivariant isotopy class does not suffice to distinguish the connected components of the space of smooth real algebraic curves of $X_l$? A second aim is to prove that there exist in these surfaces some real schemes realized by real flexible curves but not by smooth real algebraic curves. These two results of real algebraic geometry are deduced from the following comparison theorem: when $m = l + 2k$, with $k > 0$, the discriminants of the surface $X_m$ are deduced from those of the surface $X_l$ via weighted homotheties. All these results are obtained from a study of a deformation of ruled surfaces.

The paper is written in French.

2000 Mathematical Subject Classification: 14H10, 14J26, 14P25.
IS WAVE PROPAGATION COMPUTABLE OR CAN WAVE COMPUTERS BEAT THE TURING MACHINE?
Authors: WEIHRAUCH KLAUS , ZHONG NING
Published: May 2003

According to the Church-Turing Thesis a number function is computable by the mathematically defined Turing machine if and only if it is computable by a physical machine. In 1983 Pour-El and Richards defined a three-dimensional wave $u(t,x)$ such that the amplitude $u(0,x)$ at time 0 is computable and the amplitude $u(1,x)$ at time 1 is continuous but not computable. Therefore, there might be some kind of wave computer beating the Turing machine. By applying the framework of Type 2 Theory of Effectivity (TTE), in this paper we analyze computability of wave propagation. In particular, we prove that the wave propagator is computable on continuously differentiable waves, where one derivative is lost, and on waves from Sobolev spaces. Finally, we explain why the Pour-El-Richards result probably does not help to design a wave computer which beats the Turing machine.

2000 Mathematical Subject Classification: 03D80, 03F60, 35L05, 68Q05.
C‐Type Inactivation Involves a Significant Decrease in the Intracellular Aqueous Pore Volume of Kv1.4 K+ Channels Expressed in Xenopus Oocytes
Authors: Jiang XueJun , Bett Glenna C. L. , Li XiaoYan , Bondarenko Vladimir E. , Rasmusson Randall L.
Published: May 2003

Channels are water‐filled membrane‐spanning proteins, which undergo conformational changes as they gate, i.e. open or close. These conformational changes affect both the shape of the channel and the volume of the water‐filled pore. We measured the changes in pore volume associated with activation, deactivation, C‐type inactivation and recovery in an N‐terminal‐deleted mutant of the Kv1.4 K+ channel (Kv1.4ΔN) expressed in Xenopus oocytes. We used giant‐patch and cut‐open oocyte voltage clamp techniques and applied solutes which are too large to enter the pore mouth to exert osmotic pressure and thus favour smaller pore volume conformations. Applied intracellular osmotic pressure (300 mm sucrose) sped inactivation (time constants (τinactivation): control, 0.66 ± 0.09 s; hyperosmotic solution, 0.29 ± 0.04 s; n= 5, P < 0.01), sped deactivation (τdeactivation: control, 18.8 ± 0.94 ms; hyperosmotic solution, 8.01 ± 1.92 ms; n= 5, P < 0.01), and slowed activation (τactivation: control, 1.04 ± 0.05 ms; hyperosmotic solution, 1.96 ± 0.31 ms; n= 5, P < 0.01). These effects were reversible and solute independent. We estimated the pore volume change on inactivation to be about 4500 Å3. Osmotic pressure had no effect when applied extracellularly. These data suggest that the intracellular side of the pore closes during C‐type inactivation and the volume change is similar to that associated with activation or deactivation. This is also similar to the pore volume estimated from the crystal structure of KcsA and MthK K+ channels. Intracellular osmotic pressure also strongly inhibited re‐opening currents associated with recovery from inactivation, which is consistent with a physical similarity between the C‐type inactivated and resting closed state.
Development of Synchronized Activity of Cranial Motor Neurons in the Segmented Embryonic Mouse Hindbrain
Authors: Gust J. , Wright J. J. , Pratt E. B. , Bosma M. M.
Published: May 2003

Spontaneous electrical activity synchronized among groups of related neurons is a widespread and important feature of central nervous system development. Among the many places from which spontaneous rhythmic activity has been recorded early in development are the cranial motor nerve roots that exit the hindbrain, the motor neuron pool that, at birth, will control the rhythmic motor patterns of swallow, feeding and the oral components of respiratory behaviour. Understanding the mechanism and significance of this hindbrain activity, however, has been hampered by the difficulty of identifying and recording from individual hindbrain motor neurons in living tissue. We have used retrograde labelling to identify living cranial branchiomeric motor neurons in the hindbrain, and [Ca2+]i imaging of such labelled cells to measure spontaneous activity simultaneously in groups of motor neuron somata. We find that branchiomeric motor neurons of the trigeminal and facial nerves generate spontaneous [Ca2+]i transients throughout the developmental period E9.5 to E11.5. During this two‐day period the activity changes from low‐frequency, long‐duration events that are tetrodotoxin insensitive and poorly coordinated among cells, to high‐frequency short‐duration events that are tetrodotoxin sensitive and tightly coordinated thoughout the motor neuron population. This early synchronization may be crucial for correct neuron‐target development.
ATP Triggers Intracellular Ca2+ Release in Type II Cells of the Rat Carotid Body
Authors: Xu Jianhua , Tse Frederick W. , Tse Amy
Published: May 2003

Using a Ca2+‐imaging technique, we studied the action of ATP on the intracellular Ca2+ concentration ([Ca2+]i) of fura‐2‐loaded mixtures of type I and type II cells dissociated from rat carotid bodies. ATP (100 μm) triggered a transient rise in [Ca2+]i in the spindle‐shaped type II (sustentacular) cells, but not the ovoid type I (glomus) cells. When challenged with ionomycin (1 μm), no amperometry signal could be detected from the ATP‐responsive type II cells, suggesting that these cells lacked catecholamine‐containing granules. In contrast, KCl depolarization triggered robust quantal catecholamine release from type I cells that were not responsive to ATP. In type II cells voltage clamped at −70 mV, the ATP‐induced [Ca2+]i rise was not accompanied by any current change, suggesting that P2X receptors are not involved. The ATP‐induced Ca2+ signal could be observed in the presence of Ni2+ (a blocker of voltage‐gated Ca2+ channels) or in the absence of extracellular Ca2+, indicating that Ca2+ release from intracellular stores was the dominant mechanism. The order of purinoreceptor agonist potency in triggering the [Ca2+]i rise was UTP > ATP > 2‐methylthioATP ≫α,β‐methyleneATP, implicating the involvement of P2Y2 receptors. In carotid body sections, immunofluorescence revealed localization of P2Y2 receptors on spindle‐shaped type II cells that partially enveloped ovoid type I cells. Since ATP is released from type I cells during hypoxia, we suggest that the ATP‐induced Ca2+ signal in type II cells can mediate paracrine interactions within the carotid bodies.
Dynamic Imaging of Somatosensory Cortical activity in the Rat Visualized by Flavoprotein Autofluorescence
Authors: Shibuki Katsuei , Hishida Ryuichi , Murakami Hiroatsu , Kudoh Masaharu , Kawaguchi Tadashi , Watanabe Masatoshi , Watanabe Shunsuke , Kouuchi Takeshi , Tanaka Ryuichi
Published: May 2003

We used autofluorescence of mitochondrial flavoproteins to image cortical neural activity in the rat. Green autofluorescence in blue light was examined in slices obtained from rat cerebral cortex. About half of the basal autofluorescence was modulated by the presence or absence of O2 or glucose in the medium. Repetitive electrical stimulation at 20 Hz for 1 s produced a localized fluorescence increase in the slices. The amplitude of the increase was 27 ± 2 % (mean ±s.d., n= 35). Tetrodotoxin or diphenyleneiodonium, an inhibitor of flavoproteins, blocked the autofluorescence responses. The autofluorescence responses were not observed in slices perfused with calcium‐, glucose‐ or O2‐free medium. In the primary somatosensory cortex of rats anaesthetized with urethane (1.5 g kg−1, i.p.), an activity‐dependent increase in autofluorescence of 20 ± 4 % (n= 6) was observed after electrical cortical stimulation at 100 Hz for 1 s, and an increase of 2.6 ± 0.5 % (n= 33) after vibratory skin stimulation at 50 Hz for 1 s applied to the plantar hindpaw. These responses were large enough to allow visualization of the neural activity without having to average a number of trials. The distribution of the fluorescence responses after electrical or vibratory skin stimulation was comparable to that of the cortical field potentials in the same rats. The fluorescence responses were followed by an increase in arterial blood flow. The former were resistant to an inhibitor of nitric oxide synthase, while the latter was inhibited. Thus, activity‐dependent changes in the autofluorescence of flavoproteins are useful for functional brain imaging in vivo.
Multifunctional Cells of Mouse Anterior Pituitary Reveal a Striking Sexual Dimorphism
Authors: Núñez Lucía , Villalobos Carlos , Senovilla Laura , García‐Sancho Javier
Published: May 2003

The existence of cells storing and secreting two different anterior pituitary (AP) hormones (polyhormonal cells) or responding to several hypothalamic releasing hormones (HRHs) (multiresponsive cells) has been reported previously. These multifunctional cells could be involved in paradoxical secretion (AP hormone secretion evoked by a non‐corresponding HRH) and transdifferentiation (phenotypic switch between mature cell types without cell division). Despite their putative physiological relevance, a comprehensive characterization of multifunctional AP cells is lacking. Here we combine calcium imaging (to assess responses to the four HRHs) and multiple sequential immunoassay of the six AP hormones in the same individual cells to perform a complete phenotypic characterization of mouse AP cells. Polyhormonal and multiresponsive cells were identified within all five AP cell types. They were scarce in the more abundant cell types, somatotropes and lactotropes, but quite frequent in corticotropes and gonadotropes. Cells with mixed phenotypes were the rule rather than the exception in thyrotropes, where 56–83 % of the cells stored two to five different hormones. Multifunctional AP cells were much more abundant in females than in males, indicating that the hormonal changes associated with the sexual cycle may promote transdifferentiation. As the phenotypic analysis was performed here after stimulation with HRHs, the fraction of polyhormonal cells might have been underestimated. With this limitation, the polyhormonal cells detected here responded to the HRHs less than the monohormonal ones, suggesting that they might contribute less than expected a priori to paradoxical secretion. Overall, our results reveal a striking sexual dimorphism, the female pituitary being much more plastic than the male pituitary.
Thin Filament Activation and Unloaded Shortening Velocity of Rabbit Skinned Muscle Fibres
Authors: Morris Carl A. , Tobacman Larry S. , Homsher Earl
Published: May 2003

The unloaded shortening velocity of skinned rabbit psoas muscle fibres is sensitive to [Ca2+]. To determine whether Ca2+ affects the unloaded shortening velocity via regulation of crossbridge kinetics or crossbridge number, the shortening velocity was measured following changes in either [Ca2+] or the number of active thin filament regulatory units. The native troponin C (TnC) was extracted and replaced with either cardiac TnC (cTnC) or a mixture of cTnC and an inactive mutant cardiac TnC (CBMII TnC). The unloaded shortening velocity of the cTnC‐replaced fibres was determined at various values of [Ca2+] and compared with different cTnC:CBMII TnC ratios at a saturating [Ca2+]. If Ca2+ regulates the unloaded shortening velocity via kinetic modulation, differences in the velocity‐tension relationship between the cTnC fibres and the cTnC:CBMII TnC fibres would be apparent. Alternatively, Ca2+ control of the number of active crossbridges would yield similar velocity‐tension relationships when comparing the cTnC and cTnC:CBMII TnC fibres. The results show a decline in the unloaded shortening velocity that is determined by the relative tension, defined as the level of thin filament activation, rather than the [Ca2+]. Furthermore, at lower levels of relative tension, the reduction in unloaded shortening is not the result of changes in any cooperative effects of myosin on Ca2+ binding to the thin filament. Rather, it may be related to a decrease in crossbridge‐induced activation of the thin filament at the level of the individual regulatory unit. In summary, the results suggest that Ca2+ regulates the unloaded shortening velocity in skinned fibres by reducing the number of crossbridges able to productively bind to the thin filament without affecting any inherent property of the myosin.
Baroreflex‐Mediated Changes in Cardiac Output and Vascular Conductance in Response to Alterations in Carotid Sinus Pressure during Exercise in Humans
Authors: Ogoh Shigehiko , Fadel Paul J. , Nissen Peter , Jans Øeivind , Selmer Christian , Secher Niels H. , Raven Peter B.
Published: May 2003

We sought to quantify the contribution of cardiac output (Q) and total vascular conductance (TVC) to carotid baroreflex (CBR)‐mediated changes in mean arterial pressure (MAP) during mild to heavy exercise. CBR function was determined in eight subjects (25 ± 1 years) at rest and during three cycle exercise trials at heart rates (HRs) of 90, 120 and 150 beats min−1 performed in random order. Acute changes in carotid sinus transmural pressure were evoked using 5 s pulses of neck pressure (NP) and neck suction (NS) from +40 to −80 Torr (+5.33 to −10.67 kPa). Beat‐to‐beat changes in HR and MAP were recorded throughout. In addition, stroke volume (SV) was estimated using the Modelflow method, which incorporates a non‐linear, three‐element model of the aortic input impedance to compute an aortic flow waveform from the arterial pressure wave. The application of NP and NS did not cause any significant changes in SV either at rest or during exercise. Thus, CBR‐mediated alterations in Q were solely due to reflex changes in HR. In fact, a decrease in the carotid‐HR response range from 26 ± 7 beats min−1 at rest to 7 ± 1 beats min−1 during heavy exercise (P= 0.001) reduced the contribution of Q to the CBR‐mediated change in MAP. More importantly, at the time of the peak MAP response, the contribution of TVC to the CBR‐mediated change in MAP was increased from 74 ± 14 % at rest to 118 ± 6 % (P= 0.017) during heavy exercise. Collectively, these findings indicate that alterations in vasomotion are the primary means by which the CBR regulates blood pressure during mild to heavy exercise.
Neuropeptide Y and Peptide YY Inhibit Excitatory Synaptic Transmission in the Rat Dorsal Motor Nucleus of the Vagus
Authors: Browning Kirsteen N. , Travagli R. Alberto
Published: May 2003

Pancreatic polypeptides (PPs) such as neuropeptide Y (NPY) and peptide YY (PYY) exert profound, vagally mediated effects on gastrointestinal (GI) motility and secretion. Whole‐cell patch clamp recordings were made from brainstem slices containing identified GI‐projecting rat dorsal motor nucleus of the vagus (DMV) neurons to determine the mechanism of action of PPs. Electrical stimulation of nucleus tractus solitarii (NTS) induced excitatory postsynaptic currents (EPSCs) that were reduced in a concentration‐dependent manner by NPY and PYY (both at 0.1–300 nm) in 65 % of the neurons. An increase in the paired‐pulse ratio without changes in the postsynaptic membrane input resistance or EPSC rise and decay time suggested that the effects of PPs on EPSCs were due to actions at presynaptic receptors. The Y1 and Y2 receptor selective agonists [Leu31,Pro34]NPY and NPY(3–36) (both at 100 nm) mimicked the inhibition of NPY and PYY on the EPSC amplitude. The effects of 100 nm NPY, but not PYY, were antagonized partially by the Y1 receptor selective antagonist BIBP3226 (0.1 μm). In addition, the inhibition of the EPSC amplitude induced by NPY, but not PYY, was attenuated partially by pretreatment with the α2 adrenoceptor antagonist yohimbine (10 μm), and occluded partially by the α2 adrenoceptor agonist UK14,304 (10 μm) as well as by pretreatment with reserpine. Pretreatment with a combination of BIBP3226 and yohimbine almost completely antagonized the NPY‐mediated effects on EPSCs. Contrary to the inhibition of EPSCs, perfusion with PPs had no effect on the amplitude of inhibitory postsynaptic currents (IPSCs) and a minimal effect on a minority of DMV neurons. Differences in the receptor subtypes utilized and in the mechanism of action of NPY and PYY may indicate functional differences in their roles within the circuitry of the dorsal vagal complex (DVC).
Stimulation of Sodium Pump Restores Membrane Potential to Neurons Excited by Glutamate in Zebrafish Distal Retina
Authors: Nelson Ralph , Bender Anna M. , Connaughton Victoria P.
Published: May 2003

Glutamate either depolarizes or hyperpolarizes retinal neurons. Those are the initial and primary effects. Using a voltage probe (oxonol, DiBaC4 (5)) to study dissociated zebrafish retinal neurons, we find a secondary, longer‐term effect: a post‐excitatory restoration of membrane potential, termed after‐hyperpolarization (AHP). AHP occurs only in neurons that are depolarized by glutamate and typically peaks about 5 min after glutamate application. AHP is seen in dissociated horizontal cells (HCs) and hyperpolarizing, or OFF type, bipolar cells (HBCs). These cells commonly respond with only an AHP component. AHP never occurs in depolarizing, or ON type, bipolar cells (DBCs), which are cell types hyperpolarized by glutamate. AHP is blocked by 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX). It is evoked by kainate, AMPA and the AMPA‐selective agonist (S)‐5‐fluorowillardiine, but not by NMDA, d‐aspartate, the kainate‐selective agonist SYM 2081 or by dl‐2‐amino‐4‐phosphonobutyric acid (dl‐AP4). Cells with exclusively AHP responses are tonically depolarized. Resting potentials can be restored by nifedipine, suggesting a tonic, depolarizing action of L‐type Ca2+ channels. However AHP is not blocked by nifedipine and is insensitive to [Cl−]o. AHP is blocked by Li+o substitution for Na+o and by ouabain. A mechanism is proposed in which Na+ entering through ionotropic AMPA channels stimulates Na+,K+‐ATPase, which, by electrogenic action, restores membrane potential, generating the AHP response. Patterns of ATPase immunoreactivity support localization in the outer plexiform layer (OPL) as cone pedicles, HCs and BCs were positively labelled. Labelling was weaker in the inner plexiform layer (IPL) than in nuclear layers, though two IPL bands of immunoreactive BC terminals could be discerned, one in sublamina a and the other in sublamina b. Persistent stimulation of distal retina by photoreceptor glutamate may induce increased expression and activity of Na+,K+‐ATPase, with a consequent impact on distal glutamate responses.
Phosphorylation‐Induced Modulation of pNBC1 Function: Distinct Roles for the Amino‐ and Carboxy‐Termini
Authors: Gross E. , Fedotoff O. , Pushkin A. , Abuladze N. , Newman D. , Kurtz I.
Published: May 2003

The human NBC1 (SLC4A4) gene encodes the electrogenic sodium bicarbonate cotransporters kNBC1 and pNBC1, which are highly expressed in the kidney and pancreas, respectively. The HCO3−:Na+ stoichiometry of these cotransporters is an important determinant of the direction of ion flux. Recently we showed in a mouse proximal tubule (mPCT) cell line expressing kNBC1, that 8‐Br‐cAMP shifts the stoichiometry of the cotransporter from 3:1 to 2:1 via protein kinase A (PKA)‐dependent phosphorylation of Ser982. pNBC1 has the identical carboxy‐terminal consensus phosphorylation PKA site (KKGS1026), and an additional site in its amino‐terminus (KRKT49). In this study we determined the potential role of these sites in regulating the function of pNBC1. The results demonstrated that in mPCT cells expressing pNBC1, PKA‐dependent phosphorylation of Ser1026 following 8‐Br‐cAMP treatment shifted the stoichiometry from 3:1 to 2:1. The effect was electrostatic in nature as replacing Ser1026 with Asp resulted in a similar stoichiometry shift. In addition to shifting the stoichiometry, 8‐Br‐cAMP caused a significant increase in the 4,4′‐dinitrostilbene‐2,2′‐disulfonic acid (DNDS)‐sensitive basolateral membrane conductance (GDS) of cells expressing pNBC1, but not kNBC1. Although, the effect did not involve phosphorylation of Thr49, which was endogenously phosphorylated, replacing this residue with Asp or Ala abolished the 8‐Br‐cAMP‐induced increase in GDS. In the mPEC pancreatic duct cell line, where endogenous pNBC1 functions with a HCO3−:Na+ stoichiometry of 2:1, 8‐Br‐cAMP increased GDS by ∼90 % without altering the stoichiometry or inducing phosphorylation of the cotransporter. The results demonstrate that phosphorylation of Ser1026 mediates the cAMP‐dependent shift in the stoichiometry of pNBC1, whereas Thr49 plays an essential role in the cAMP‐induced increase in GDS.
Reduced Nephron Number in Adult Sheep, Hypertensive as a Result of Prenatal Glucocorticoid Treatment
Authors: Wintour E. M. , Moritz K. M. , Johnson K. , Ricardo S. , Samuel C. S. , Dodic M.
Published: May 2003

There is some evidence, mainly from rodent studies, that any factor which alters the final total number of nephrons formed, during nephrogenesis, will result in hypertension in adult life. Sheep, programmed to become hypertensive by exposure to synthetic glucocorticoid (dexamethasone, 0.48 mg h−1, for 48 h) early in development (∼27 days of gestation), were killed at 7 years of age, and had nephron counting performed by unbiased stereology. Mean arterial pressure was 83 ± 4 mmHg in the dexamethasone (DEX) group (n= 5), and 73 ± 5 in the control (CON; n= 7; P < 0.05). The total nephron number, in the right kidney (249 070 ± 14 331; n= 5) was significantly lower (P < 0.01) than that of controls (402 787 ± 30 458; n= 7). Mean glomerular volume was larger in the DEX than the CON group (P < 0.01), but there was no significant difference in the sclerosis index between the two groups. Low nephron number was associated with grossly enlarged and dilated proximal tubules and greater accumulation of collagen type I and type III in the tubular interstitium and periadventitia of the renal cortical vessels. These data suggest that the hypertensive programming effect of glucocorticoid treatment, early in kidney development, results, at least in part, from impaired nephrogenesis.
Failure of Systemic Hypoxia to Blunt α‐Adrenergic Vasoconstriction in the Human Forearm
Authors: Dinenno Frank A. , Joyner Michael J. , Halliwill John R.
Published: May 2003

Systemic hypoxia in humans evokes forearm vasodilatation despite significant reflex increases in sympathetic vasoconstrictor nerve activity and noradrenaline spillover. We sought to determine whether post‐junctional α‐adrenergic vasoconstrictor responsiveness to endogenous noradrenaline release is blunted during systemic hypoxia. To do so, we conducted a two‐part study in healthy young adults. In protocol 1, we measured forearm blood flow (FBF; venous occlusion plethysmography) and calculated the vascular conductance (FVC) responses to brachial artery infusions of two doses of tyramine (evokes endogenous noradrenaline release) in 10 adults during normoxia and mild systemic hypoxia (85 % O2 saturation; pulse oximetry of the earlobe). Systemic hypoxia evoked significant forearm vasodilatation as indicated by the increases in FBF and FVC (∼20–23 %; P < 0.05). The low and high doses of tyramine evoked significant reductions in FVC (vasoconstriction) that were similar in magnitude during normoxia (−29 ± 3 and −53 ± 4 %) and mild hypoxia (−35 ± 4 and −58 ± 3 %; P= 0.33). In protocol 2, forearm vasoconstrictor responses to the high dose of tyramine were determined in eight young adults during normoxia and during graded levels of systemic hypoxia (85, 80 and 75 % O2 saturation). The reductions in FVC were similar during normoxia (−59 ± 2 %) and the three levels of hypoxia (85 % O2 saturation, −64 ± 3 %; 80 % O2 saturation, −62 ± 1 %; 75 % O2 saturation, −61 ± 3 %; P= 0.37). In both protocols, the tyramine‐induced increases in deep venous noradrenaline concentrations were similar during normoxia and all levels of hypoxia. Our results demonstrate that post‐junctional α‐adrenergic receptor vasoconstrictor responsiveness to endogenous noradrenaline release is not blunted during mild‐to‐moderate systemic hypoxia in healthy humans.
Enhanced GABAA Receptor‐Mediated Activity Following Activation of NMDA Receptors in Cajal‐Retzius Cells in the Developing Mouse Neocortex
Authors: Chan Chun‐Hung , Yeh Hermes H.
Published: May 2003

Cajal‐Retzius (CR) cells are among the earliest generated population of neurons in the developing neocortex and have been implicated in regulating cortical lamination. In rodents, CR cells are transient, being present only up to 2–3 weeks after birth. Although previous electrophysiological studies have demonstrated the presence of NMDA and GABAA receptors in CR cells, little is known about the functional properties of these receptors. Using whole‐cell patch‐clamp techniques in neocortical slices, we confirmed the presence of D‐aminophosphonovaleric acid (APV)‐ and ifenprodil‐sensitive NMDA receptors, and found that the functional expression of this receptor subtype is strain specific. The NMDA‐induced response was consistently accompanied by overriding current transients that were blocked by APV and ifenprodil. In addition, bicuculline readily abolished these transients without affecting the NMDA‐induced current response. The generation of these overriding current transients was dependent upon intracellular Ca2+ and was prevented by dialysis with the high‐affinity Ca2+‐chelator BAPTA. Overall, this study uncovered a synergistic interaction between these receptors, whereby activation of NMDA receptors leads to enhanced GABAA receptor‐mediated activity through a Ca2+‐dependent mechanism.
Effects of Plasma Adrenaline on Hormone‐Sensitive Lipase at Rest and during Moderate Exercise in Human Skeletal Muscle
Authors: Watt Matthew J. , Stellingwerff Trent , Heigenhauser George J. F. , Spriet Lawrence L.
Published: May 2003

We investigated the effect of increased plasma adrenaline on hormone‐sensitive lipase (HSL) activity and extracellular regulated kinase (ERK) 1/2 phosphorylation during exercise. Seven untrained men rested for 20 min and exercised for 10 min at 60 % peak pulmonary oxygen uptake on three occasions: with adrenaline infusion throughout rest and exercise (ADR), with no adrenaline infusion (CON) and with adrenaline infusion commencing after 3 min of exercise (EX+ADR). Muscle samples were obtained at rest before (Pre, −20 min) and after (0 min) infusion, and at 3 and 10 min of cycling. Exogenous adrenaline infusion increased (P < 0.05) plasma adrenaline at rest during ADR, which resulted in greater HSL activity (Pre, 2.14 ± 0.10 mmol min−1 (kg dry matter (dm))−1; 0 min, 2.74 ± 0.20 mmol min−1 (kg dm)−1). Subsequent exercise had no effect on HSL activity. During exercise in CON, HSL activity was increased (P < 0.05) above rest at 3 min but was not increased further by 10 min. The infusion of exogenous adrenaline at 3 min of exercise in EX+ADR resulted in a marked elevation in plasma adrenaline levels (3 min, 0.57 ± 0.12 nM; 10 min, 10.08 ± 0.84 nM) and increased HSL activity by 25 %. HSL activity at 10 min was greater (P < 0.05) in EX+ADR compared with CON. There were no changes between trials in the plasma concentrations of insulin and free fatty acids (FFA) and the muscle contents of free AMP, all putative regulators of HSL activity. ERK1/2 phosphorylation increased at 3 min in CON and EX+ADR. Because HSL activity did not increase during exercise when adrenaline was infused prior to exercise (ADR) and because HSL activity increased when adrenaline was infused during exercise (EX+ADR), we conclude that (1) high adrenaline levels can stimulate HSL activity regardless of the metabolic milieu and (2) large increases in adrenaline during exercise, independent of changes in other putative regulators, are able to further stimulate the contraction‐induced increase in HSL activity. The results also demonstrate that increased ERK 1/2 phosphorylation coincides with elevated HSL activity, indicating that ERK 1/2 may mediate the contraction‐induced increase in HSL activity early in exercise.
Characterization of a Novel Coronavirus Associated with Severe Acute Respiratory Syndrome
Authors: Rota Paul A. , Oberste M. Steven , Monroe Stephan S. , Nix W. Allan , Campagnoli Ray , Icenogle Joseph P. , Peñaranda Silvia , Bankamp Bettina , Maher Kaija , Chen Min-hsin , Tong Suxiong , Tamin Azaibi , Lowe Luis , Frace Michael , DeRisi Joseph L. , Chen Qi , Wang David , Erdman Dean D. , Peret Teresa C. T. , Burns Cara , Ksiazek Thomas G. , Rollin Pierre E. , Sanchez Anthony , Liffick Stephanie , Holloway Brian , Limor Josef , McCaustland Karen , Olsen-Rasmussen Melissa , Fouchier Ron , Günther Stephan , Osterhaus Albert D. M. E. , Drosten Christian , Pallansch Mark A. , Anderson Larry J. , Bellini William J.
Published: May 2003

In March 2003, a novel coronavirus (SARS-CoV) was discovered in association with cases of severe acute respiratorysyndrome (SARS). The sequence of the complete genome of SARS-CoV was determined, and the initial characterization of the viral genome is presented in this report. The genome of SARS-CoV is 29,727 nucleotides in length and has 11 open reading frames, and its genome organization is similar to that of other coronaviruses. Phylogenetic analyses and sequence comparisons showed that SARS-CoV is not closelyrelated to anyof the previouslycharacterized coronaviruses.
The Genome Sequence of the SARS-Associated Coronavirus
Authors: Marra Marco A. , Jones Steven J. M. , Astell Caroline R. , Holt Robert A. , Brooks-Wilson Angela , Butterfield Yaron S. N. , Khattra Jaswinder , Asano Jennifer K. , Barber Sarah A. , Chan Susanna Y. , Cloutier Alison , Coughlin Shaun M. , Freeman Doug , Girn Noreen , Griffith Obi L. , Leach Stephen R. , Mayo Michael , McDonald Helen , Montgomery Stephen B. , Pandoh Pawan K. , Petrescu Anca S. , Robertson A. Gordon , Schein Jacqueline E. , Siddiqui Asim , Smailus Duane E. , Stott Jeff M. , Yang George S. , Plummer Francis , Andonov Anton , Artsob Harvey , Bastien Nathalie , Bernard Kathy , Booth Timothy F. , Bowness Donnie , Czub Martin , Drebot Michael , Fernando Lisa , Flick Ramon , Garbutt Michael , Gray Michael , Grolla Allen , Jones Steven , Feldmann Heinz , Meyers Adrienne , Kabani Amin , Li Yan , Normand Susan , Stroher Ute , Tipples Graham A. , Tyler Shaun , Vogrig Robert , Ward Diane , Watson Brynn , Brunham Robert C. , Krajden Mel , Petric Martin , Skowronski Danuta M. , Upton Chris , Roper Rachel L.
Published: May 2003

We sequenced the 29,751-base genome of the severe acute respiratory syndrome (SARS)âassociated coronavirus known as the Tor2 isolate. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses, including two human coronaviruses, HCoV-OC43 and HCoV-229E. Phylogenetic analysis of the predicted viral proteins indicates that the virus does not closely resemble any of the three previously known groups of coronaviruses. The genome sequence will aid in the diagnosis of SARS virus infection in humans and potential animal hosts (using polymerase chain reaction and immunological tests), in the development of antivirals (including neutralizing antibodies), and in the identification of putative epitopes for vaccine development.
Quantitative Detection of Methanotrophs in Soil by Novel
pmoA
-Targeted Real-Time PCR Assays
Authors: Kolb Steffen , Knief Claudia , Stubner Stephan , Conrad Ralf
Published: May 2003

Methane oxidation in soils is mostly accomplished by methanotrophic bacteria. Little is known about the abundance of methanotrophs in soils, since quantification by cultivation and microscopic techniques is cumbersome. Comparison of 16S ribosomal DNA and
pmoA
(α subunit of the particulate methane monooxygenase) phylogenetic trees showed good correlation and revealed five distinct groups of methanotrophs within the α and γ subclasses of
Proteobacteria
: the
Methylococcus
group, the
Methylobacter/Methylosarcina
group, the
Methylosinus
group, the
Methylocapsa
group, and the forest clones group (a cluster of
pmoA
sequences retrieved from forest soils). We developed quantitative real-time PCR assays with SybrGreen for each of these five groups and for all methanotrophic bacteria by targeting the
pmoA
gene. Detection limits were between 10
1
and 10
2
target molecules per reaction for all assays. Real-time PCR analysis of soil samples spiked with cells of
Methylococcus capsulatus
,
Methylomicrobium album
, and
Methylosinus trichosporium
recovered almost all the added bacteria. Only the
Methylosinus
-specific assay recovered only 20% of added cells, possibly due to a lower lysis efficiency of type II methanotrophs. Analysis of the methanotrophic community structure in a flooded rice field soil showed (5.0 ± 1.4) × 10
6
pmoA
molecules g
−1
for all methanotrophs. The
Methylosinus
group was predominant (2.7 × 10
6
± 1.1 × 10
6
target molecules g
−1
). In addition, bacteria of the
Methylobacter/Methylosarcina
group were abundant (2.0 × 10
6
± 0.9 × 10
6
target molecules g of soil
−1
). On the other hand,
pmoA
affiliated with the forest clones and the
Methylocapsa
group was below the detection limit of 1.9 × 10
4
target molecules g of soil
−1
. Our results showed that
pmoA
-targeted real-time PCR allowed fast and sensitive quantification of the five major groups of methanotrophs in soil. This approach will thus be useful for quantitative analysis of the community structure of methanotrophs in nature.
Clade-Specific 16S Ribosomal DNA Oligonucleotides Reveal the Predominance of a Single Marine
Synechococcus
Clade throughout a Stratified Water Column in the Red Sea
Authors: Fuller Nicholas J. , Marie Dominique , Partensky Frédéric , Vaulot Daniel , Post Anton F. , Scanlan David J.
Published: May 2003

Phylogenetic relationships among members of the marine
Synechococcus
genus were determined following sequencing of the 16S ribosomal DNA (rDNA) from 31 novel cultured isolates from the Red Sea and several other oceanic environments. This revealed a large genetic diversity within the marine
Synechococcus
cluster consistent with earlier work but also identified three novel clades not previously recognized. Phylogenetic analyses showed one clade, containing halotolerant isolates lacking phycoerythrin (PE) and including strains capable, or not, of utilizing nitrate as the sole N source, which clustered within the MC-A (
Synechococcus
subcluster 5.1) lineage. Two copies of the 16S rRNA gene are present in marine
Synechococcus
genomes, and cloning and sequencing of these copies from
Synechococcus
sp. strain WH 7803 and genomic information from
Synechococcus
sp. strain WH 8102 reveal these to be identical. Based on the 16S rDNA sequence information, clade-specific oligonucleotides for the marine
Synechococcus
genus were designed and their specificity was optimized. Using dot blot hybridization technology, these probes were used to determine the in situ community structure of marine
Synechococcus
populations in the Red Sea at the time of a
Synechococcus
maximum during April 1999. A predominance of genotypes representative of a single clade was found, and these genotypes were common among strains isolated into culture. Conversely, strains lacking PE, which were also relatively easily isolated into culture, represented only a minor component of the
Synechococcus
population. Genotypes corresponding to well-studied laboratory strains also appeared to be poorly represented in this stratified water column in the Red Sea.
Concentration and Prevalence of
Escherichia coli
O157 in Cattle Feces at Slaughter
Authors: Omisakin F. , MacRae M. , Ogden I. D. , Strachan N. J. C.
Published: May 2003

The concentration and prevalence of
Escherichia coli
O157 in cattle feces at the time of slaughter was studied over a 9-week period from May to July 2002. Fecal samples (
n
= 589) were collected from the rectums of slaughtered cattle, and the animal-level prevalence rate was estimated to be 7.5% (95% confidence interval [CI], 5.4 to 9.6%) while the group prevalence was 40.4% (95% CI, 27.7 to 53.2%). Of the 44 infected animals detected, 9% were high shedders that contained
E. coli
O157 at concentrations of >10
4
CFU g
−1
. These 9% represented >96% of the total
E. coli
O157 produced by all animals tested. All isolates possessed the
vt
2
gene, 39 had the
eaeA
gene, and a further five had the
vt
1
gene also. The presence of high-shedding animals at the abattoir increases the potential risk of meat contamination during the slaughtering process and stresses the need for correctly implemented hazard analysis and critical control point procedures.
Prokaryotic Metabolic Activity and Community Structure in Antarctic Continental Shelf Sediments
Authors: Bowman J. P. , McCammon S. A. , Gibson J. A. E. , Robertson L. , Nichols P. D.
Published: May 2003

The prokaryote community activity and structural characteristics within marine sediment sampled across a continental shelf area located off eastern Antarctica (66°S, 143°E; depth range, 709 to 964 m) were studied. Correlations were found between microbial biomass and aminopeptidase and chitinase rates, which were used as proxies for microbial activity. Biomass and activity were maximal within the 0- to 3-cm depth range and declined rapidly with sediment depths below 5 cm. Most-probable-number counting using a dilute carbohydrate-containing medium recovered 1.7 to 3.8% of the sediment total bacterial count, with mostly facultatively anaerobic psychrophiles cultured. The median optimal growth temperature for the sediment isolates was 15°C. Many of the isolates identified belonged to genera characteristic of deep-sea habitats, although most appear to be novel species. Phospholipid fatty acid (PLFA) and isoprenoid glycerol dialkyl glycerol tetraether analyses indicated that the samples contained lipid components typical of marine sediments, with profiles varying little between samples at the same depth; however, significant differences in PLFA profiles were found between depths of 0 to 1 cm and 13 to 15 cm, reflecting the presence of a different microbial community. Denaturing gradient gel electrophoresis (DGGE) analysis of amplified bacterial 16S rRNA genes revealed that between samples and across sediment core depths of 1 to 4 cm, the community structure appeared homogenous; however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. Sequencing of DGGE bands and rRNA probe hybridization analysis revealed that the major community members belonged to delta proteobacteria, putative sulfide oxidizers of the gamma proteobacteria,
Flavobacteria
,
Planctomycetales
, and
Archaea
. rRNA hybridization analyses also indicated that these groups were present at similar levels in the top layer across the shelf region.
Biodiversity, Community Structural Shifts, and Biogeography of Prokaryotes within Antarctic Continental Shelf Sediment
Authors: Bowman John P. , McCuaig Robert D.
Published: May 2003

16S ribosomal DNA (rDNA) clone library analysis was conducted to assess prokaryotic diversity and community structural changes within a surficial sediment core obtained from an Antarctic continental shelf area (depth, 761 m) within the Mertz Glacier Polynya (MGP) region. Libraries were created from three separate horizons of the core (0- to 0.4-cm, 1.5- to 2.5-cm, and 20- to 21-cm depth positions). The results indicated that at the oxic sediment surface (depth, 0 to 0.4 cm) the microbial community appeared to be dominated by a small subset of potentially
r
-strategist (fast-growing, opportunistic) species, resulting in a lower-than-expected species richness of 442 operational taxonomic units (OTUs). At a depth of 1.5 to 2.5 cm, the species richness (1,128 OTUs) was much higher, with the community dominated by numerous gamma and delta proteobacterial phylotypes. At a depth of 20 to 21 cm, a clear decline in species richness (541 OTUs) occurred, accompanied by a larger number of more phylogenetically divergent phylotypes and a decline in the predominance of
Proteobacteria
. Based on rRNA and clonal abundance as well as sequence comparisons, syntrophic cycling of oxidized and reduced sulfur compounds appeared to be the dominant process in surficial MGP sediment, as phylotype groups putatively linked to these processes made up a large proportion of clones throughout the core. Between 18 and 65% of 16S rDNA phylotypes detected in a wide range of coastal and open ocean sediments possessed high levels of sequence similarity (>95%) with the MGP sediment phylotypes, indicating that many sediment prokaryote phylotype groups defined in this study are ubiquitous in marine sediment.
Virus Succession Observed during an
Emiliania huxleyi
Bloom
Authors: Schroeder Declan C. , Oke Joanne , Hall Matthew , Malin Gillian , Wilson William H.
Published: May 2003

Denaturing gradient gel electrophoresis was used as a molecular tool to determine the diversity and to monitor population dynamics of viruses that infect the globally important coccolithophorid
Emiliania huxleyi
. We exploited variations in the major capsid protein gene from
E. huxleyi
-specific viruses to monitor their genetic diversity during an
E. huxleyi
bloom in a mesocosm experiment off western Norway. We reveal that, despite the presence of several virus genotypes at the start of an
E. huxleyi
bloom, only a few virus genotypes eventually go on to kill the bloom.