bluuebunny/crossref_metadata_2025 huggingface dataset:
TheC. elegansF-spondin family protein SPON-1 maintains cell adhesion in neural and non-neural tissues
Authors: Woo Wei-Meng , Berry Emily C. , Hudson Martin L. , Swale Ryann E. , Goncharov Alexandr , Chisholm Andrew D.
Published: July 2008

The F-spondin family of extracellular matrix proteins has been implicated in axon outgrowth, fasciculation and neuronal cell migration, as well as in the differentiation and proliferation of non-neuronal cells. In screens for mutants defective in C. elegans embryonic morphogenesis, we identified SPON-1, the only C. elegans member of the spondin family. SPON-1 is synthesized in body muscles and localizes to integrin-containing structures on body muscles and to other basement membranes. SPON-1 maintains strong attachments of muscles to epidermis; in the absence of SPON-1, muscles progressively detach from the epidermis, causing defective epidermal elongation. In animals with reduced integrin function, SPON-1 becomes dose dependent, suggesting that SPON-1 and integrins function in concert to promote the attachment of muscles to the basement membrane. Although spon-1mutants display largely normal neurite outgrowth, spon-1 synergizes with outgrowth defective mutants, revealing a cryptic role for SPON-1 in axon extension. In motoneurons, SPON-1 acts in axon guidance and fasciculation,whereas in interneurons SPON-1 maintains process position. Our results show that a spondin maintains cell-matrix adhesion in multiple tissues.
Hedgehog signaling is involved in development of the neocortex
Authors: Komada Munekazu , Saitsu Hirotomo , Kinboshi Masato , Miura Takashi , Shiota Kohei , Ishibashi Makoto
Published: July 2008

Sonic hedgehog (Shh) function is essential for patterning and cell fate specification, particularly in ventral regions of the central nervous system. It is also a crucial mitogen for cerebellar granule neuron precursors and is important in maintenance of the stem cell niche in the postnatal telencephalon. Although it has been reported that Shh is expressed in the developing dorsal telencephalon, functions of Shh in this region are unclear, and detailed characterization of Shh mRNA transcripts in situ has not been demonstrated. To clarify the roles of Shh signaling in dorsal pallium (neocortex primordium) development, we have knocked out the Shh and Smo genes specifically in the early developing dorsal telencephalon by using Emx1cre mice. The mutants showed a smaller dorsal telencephalon at E18.5, which was caused by cell cycle kinetics defects of the neural progenitor/stem cells. The cell cycle length of the progenitor/stem cells was prolonged, and the number of cycle-exiting cells and neurogenesis were decreased. Birth-date analysis revealed abnormal positioning of neurons in the mutants. The characteristics of the subventricular zone, ventricular zone and subplate cells were also affected. Weak immunoreactivity of Shh was detected in the dorsal telencephalon of wild types. Reduced Shh immunoreactivity in mutant dorsal telencephalons supports the above phenotypes. Our data indicate that Shh signaling plays an important role in development of the neocortex.
Hedgehog and Wingless stabilize but do not induce cell fate duringDrosophiladorsal embryonic epidermal patterning
Authors: Vincent Stephane , Perrimon Norbert , Axelrod Jeffrey D.
Published: July 2008

A fundamental concept in development is that secreted molecules such as Wingless (Wg) and Hedgehog (Hh) generate pattern by inducing cell fate. By following markers of cellular identity posterior to the Wg- and Hh-expressing cells in the Drosophila dorsal embryonic epidermis, we provide evidence that neither Wg nor Hh specifies the identity of the cell types they pattern. Rather, they maintain pre-existing cellular identities that are otherwise unstable and progress stepwise towards a default fate. Wg and Hh therefore generate pattern by inhibiting specific switches in cell identity,showing that the specification and the patterning of a given cell are uncoupled. Sequential binary decisions without induction of cell identity give rise to both the groove cells and their posterior neighbors. The combination of independent progression of cell identity and arrest of progression by signals facilitates accurate patterning of an extremely plastic developing epidermis.
The Ecdysone-inducible zinc-finger transcription factor Crol regulates Wg transcription and cell cycle progression inDrosophila
Authors: Mitchell Naomi , Cranna Nicola , Richardson Helena , Quinn Leonie
Published: July 2008

The steroid hormone Ecdysone is crucial for developmental cell death,proliferation and morphogenesis in Drosophila. Herein, we delineate a molecular pathway linking Ecdysone signalling to cell cycle regulation in the Drosophila developing wing. We present evidence that the Ecdysone-inducible zinc-finger transcription factor Crol provides a crucial link between the Ecdysone steroid hormone pathway and the Wingless (Wg)signalling pathway in Drosophila. We identified Crol as a strong enhancer of a wing phenotype generated by overexpression of the Wg-inducible cell cycle inhibitor Hfp. We demonstrate that Crol is required for cell cycle progression: crol mutant clones have reduced cell cycles and are removed by apoptosis, while upregulation of Crol overrides the Wg-mediated developmental cell cycle arrest in the zone of non-proliferating cells in the wing disc. Furthermore, we show that Crol acts to repress wgtranscription. We also show that overexpression of crol results in downregulation of Hfp, consistent with the identification of the crolmutant as a dominant enhancer of the Hfp overexpression phenotype. Taken together, our studies have revealed a novel mechanism for cell cycle regulation, whereby Crol links steroid hormone signals to Wg signalling and the regulation of crucial cell cycle targets.
Dap160/intersectin binds and activates aPKC to regulate cell polarity and cell cycle progression
Authors: Chabu Chiswili , Doe Chris Q.
Published: July 2008

The atypical protein kinase C (aPKC) is required for cell polarization of many cell types, and is upregulated in several human tumors. Despite its importance in cell polarity and growth control, relatively little is known about how aPKC activity is regulated. Here, we use a biochemical approach to identify Dynamin-associated protein 160 (Dap160; related to mammalian intersectin) as an aPKC-interacting protein in Drosophila. We show that Dap160 directly interacts with aPKC, stimulates aPKC activity in vitro and colocalizes with aPKC at the apical cortex of embryonic neuroblasts. In dap160 mutants, aPKC is delocalized from the neuroblast apical cortex and has reduced activity, based on its inability to displace known target proteins from the basal cortex. Both dap160 and aPKC mutants have fewer proliferating neuroblasts and a prolonged neuroblast cell cycle. We conclude that Dap160 positively regulates aPKC activity and localization to promote neuroblast cell polarity and cell cycle progression.
Synthesis of Rubrivivax gelatinosus Lipid A and Analogues for Investigation of the Structural Basis for Immunostimulating and Inhibitory Activities
Authors: Fukase Yoshiyuki , Fujimoto Yukari , Adachi Yo , Suda Yasuo , Kusumoto Shoichi , Fukase Koichi
Published: July 2008

To elucidate the structural requirements for the endotoxic and antagonistic activities of lipid A derivatives, we have focused on the effects of the acyl moieties and acidic groups at the 1- and 4′-positions in the present study. We have synthesized new analogues corresponding to Rubrivivax gelatinosus lipid A, which has a characteristic symmetrical distribution of its acyl groups on its two glucosamine residues with shorter acyl groups (decanoyl groups (C10) and lauryl groups (C12)) than Escherichia coli lipid A’s. Carboxymethyl (CM) analogues in which one of the phosphates was replaced with a CM group were also synthesized with a different distribution of acyl groups. Biological tests revealed that the acyl group distribution in the lipid A analogue, strongly affected its bioactivity. The synthetic Ru. gelatinosus type lipid A showed potent antagonistic activity against LPS, whereas its 1-O-carboxymethyl analogue showed weak endotoxic activity. These results demonstrate that when lipid A has shorter (C10 and C12) hexa-acyl groups, its bioactivity is more easily affected by small structural differences, such as differences in acidic groups or acyl group distribution, and that they can change bioactivity from endotoxic to agonistic or vice versa at this structural boundary for the bioactivity.
Geometrical and Kinetic Isotope Effects on R–H(D)···R Type Intramolecular Hydrogen Bonds (R = CH2, NH, and O) Using a Multi-Component Molecular Orbital Method
Authors: Kikuta Yoko , Ishimoto Takayoshi , Nagashima Umpei
Published: July 2008

We theoretically analyzed the geometrical isotope effect and kinetic isotope effect for R–H(D)···R type proton (deuteron) transfer on the intramolecular hydrogen bond of (Z)-1,3-pentadiene (R=CH2), 3-imino-1-propen-1-amine (R=NH), and malonaldehyde (R=O) by using Hartree–Fock (HF) and second-order Møller–Plesset (MP2) levels of a multi-component molecular orbital (MC_MO) method to treat the quantum effects of nuclei. As the protonic and deuteronic basis functions, our proposed exponent values of 24.1725 and 35.6214 for the single protonic and deuteronic Gaussian-type functions were employed, respectively. In the case of R=NH and O, the calculated R5–D6 and R1···D6 bond lengths are shorter and longer than those of the R5–H6 and R1···H6 bonds due to the anharmonicity of the potential. The charge densities around the deuteron for all R=CH2, NH, and O cases are larger than those around the proton because the deuteron is more localized than the proton. The ratio of rate constant (kaH⁄kaD) obtained by MP2 level theory of the MC_MO method is estimated as 10.16, which is in reasonable agreement with the experimental result (12.2). For the systematic analysis of the intramolecular proton (deuteron)-transfer reaction, we also estimated the kaH⁄kaD of R=NH and O.
Aromatic Conjugation Pathways in Porphyrins
Authors: Aihara Jun-ichi , Kimura Eiichi , Krygowski Tadeusz Marek
Published: July 2008

The π-current density induced in a polycyclic π-system is strongly dependent on molecular geometry, so that information on main aromatic pathways cannot be extracted straightforwardly from the π-current density. Using our graph theory of aromaticity and ring-current diamagnetism, we re-interpreted the π-current densities and aromatic stabilization energies of porphyrins consistently and found that main pathways of π-electron circulation along the macroscopic ring are not those of aromatic stabilization. Four five-site circuits instead proved to be the main origin of aromaticity in porphyrins. In general, currents are induced in all possible circuits in a π-system. Superposition of all these circuit currents gives rise to the apparent bifurcation of the π-current across each pyrrolic unit. Local π-currents induced in pyrrolic rings represent those induced in the corresponding five-site circuits.
Hydrogen Adsorption Properties of Lantern-Type Dinuclear M(BDC)(DABCO)1⁄2
Authors: Takei Tohru , Kawashima Jiro , Ii Takato , Maeda Akihiro , Hasegawa Mika , Kitagawa Tamami , Ohmura Tetsushi , Ichikawa Masao , Hosoe Mitsuya , Kanoya Izuru , Mori Wasuke
Published: July 2008

The hydrogen adsorption properties and uptake capacities of three-dimensional microporous materials of lantern-type dinuclear M(BDC)(DABCO)1⁄2 (M=CoII, CuII, and ZnII; BDC = 1,4-benzenedicarboxylate, DABCO = 1,4-diazabicyclo[2.2.2]octane; Co(BDC)(DABCO)1⁄2 (1), Cu(BDC)(DABCO)1⁄2 (2), Zn(BDC)(DABCO)1⁄2 (3)) were investigated at various temperatures of 77–333 K and pressures up to 10 MPa using a PCT automatic measuring system (Sievert-type apparatus). The results indicated that uptake to 4.11, 2.70, and 3.17 wt % of hydrogen can be stored on 1, 2, and 3, respectively, at 77 K. The amounts of hydrogen are adsorbed by all complexes at around room temperature (293 K) and high-pressures are much lower (<0.5 wt %). Adsorption isotherms at around room temperature show a linear uptake relationship; all of them follow the Henry’s law. By measuring nitrogen gas adsorption/desorption, all complexes exhibit approximately Type-I isotherms according to the IUPAC classification and possess BET surface areas in the range of 1165 (for 3) to 1595 m2 g−1 (for 1). Further, the thermal stability of all complexes is high, in the range of about 500 K (for 3) to 600 K (for 1). These complexes were synthesized and characterized by X-ray powder diffraction pattern, TG/DTA, FT-IR, surface area analysis, and hydrogen adsorption measurements.
Formation of 4-Hydroxy-3-(oxan-3-yl)coumarin from Photochemical Reaction between 4-Hydroxycoumarin and 3,4-Dihydro-2H-pyran and MO Analysis
Authors: Shimo Tetsuro , Sato Kenya , Wang Weidong , Obata Toru , Iwanaga Tetsuo , Shinmyozu Teruo , Somekawa Kenichi
Published: July 2008

Photochemical reaction of 4-hydroxycoumarin with 3,4-dihydro-2H-pyran gave 4-hydroxy-3-(oxan-3-yl)coumarin whose formation was explained by considering a hydrogen shift and successive keto–enol isomerization from a head–tail biradical intermediate (A). The reaction mechanism was confirmed by molecular orbital analysis to be induced by intermolecular hydrogen bonding between the 4-OH and pyran oxygen at the transition state.
The Alkylation of Naphthalene over One-Dimensional Twelve-Membered Ring Zeolites. The Influence of Zeolite Structure and Alkylating Agent on the Selectivity for Dialkylnaphthalenes
Authors: Sugi Yoshihiro , Maekawa Hiroyoshi , Naiki Hiroaki , Komura Kenichi , Kubota Yoshihiro
Published: July 2008

Alkylation, i.e., isopropylation, s-butylation, and t-butylation, of naphthalene (NP) was examined over one-dimensional twelve-membered (12-MR) zeolites: H-mordenite (MOR), SSZ-24 (AFI), SSZ-55 (ATS), and SSZ-42 (IFR) in order to elucidate how zeolite structure and alkylating agent play roles in the shape-selective catalysis. The β,β-selectivities (for β,β-dialkylnaphthalene (2,6- and 2,7-dialkylnaphthalenes, β,β-DAN)) and the 2,6-selectivities (for 2,6-DAN) were varied with the types of zeolite and of alkylating agent. MOR and AFI gave high β,β-selectivities by using alkylating agents, propene, 1-butene, and 2-methylpropene. However, the β,β-selectivities were changed over ATS and IFR at 250 °C: 40% for the isopropylation, 80% for the s-butylation, and almost 100% for the t-butylation. The 2,6-selectivities in the isopropylation were as high as 60% over MOR and 50% over AFI at 250 °C; however, they were less than 20% over ATS and IFR. The selectivities increased by using bulky alkylating agents over these one-dimensional zeolites: selective formation of 2,6-DAN occurred in the s-butylation and t-butylation. The different features among zeolites are explained by the zeolite channel and the bulkiness of alkylating agent. MOR and AFI with straight channels gave smaller reaction spaces than ATS and IFR with corrugated channels. Bulky alkylating agent also enhances the discrimination of the isomers, particularly between 2,6- and 2,7-DAN. The β,β- and 2,6-selectivities are synergetically governed by the zeolite channel and the bulkiness of alkylating agents.
Physical and Chemical Stability of Esomeprazole Sodium Solutions
Authors: Kupiec Thomas C , Aloumanis Vasileios , Ben Michel , Trissel Lawrence A , Chan Pak , Patterson Joe
Published: July 2008

Background

Esomeprazole sodium (Nexium IV, AstraZeneca) is the S-isomer of omeprazole and acts as a proton pump inhibitor gastric antisecretory agent indicated for the short-term treatment of gastroesophageal reflux disease in patients with a history of erosivo esophagitis. Currently, there is no information on the long-term stability of esomeprazole sodium in infusion solutions beyond 12 hours.

Objective

To evaluate the stability of esomeprazole sodium in 5% dextrose, 0,9% sodium chloride, and lactated Ringer's injection, at 2 concentrations, at room temperature and when refrigerated.

Methods

Triplicate samples of esomeprazole 0.4 and 0.8 mg/mL as the sodium salt were prepared in the solutions required. Stability evaluations were performed initially, over 2 days stored at 23 °C, and over 5 days stored at 4 °C. Physical stability was assessed using turbidimetric and particulate measurement, as well as visual observation. Chemical stability was evaluated by stability-indicating high-performance liquid chromatography.

Results:

The samples in all 3 infusion solutions were physically stable throughout the study. None of the samples had evidence of visible haze or particulates. Most samples developed a slight yellow discoloration within 24 hours, but this discoloration was not accompanied by an excessive loss of drug content. The esomeprazole sodium samples in all 3 infusion solutions exhibited less than 7% loss over 2 days at 23 °C and over 5 days at 4 °C.

Conclusions:

Esomeprazole 0.4 and 0.8 mg/mL as the sodium salt in the infusion solutions tested is chemically and physically stable for at least 2 days at room temperature and 5 days under refrigeration.
Tigecycline for the Treatment of Acinetobacter Infections: A Case Series
Authors: Gallagher Jason C , Rouse Heather M
Published: July 2008

Background

Acinetobacter infections resistant to multiple classes of antibiotics have become prevalent in many institutions. Tigecycline has in vitro activity against Acinetobacter spp. and has been suggested as a therapeutic option in these infections.

Objective

To describe the clinical and microbiologic outcomes of patients who received tigecycline for the treatment of infections caused by Acinetobacter spp. at our institution.

Methods

A retrospective review was conducted of the medical records of 29 sequential patients who received tigecycline for treatment of Acinetobacter infections. The outcomes assessed for efficacy were clinical improvement or cure and microbiologic cure in evaluable patients.

Results:

Patients received tigecycline a median of 30 days into hospitalization for a median of 11 days. Common indications were pneumonia (15 pts.), bacteremia (6), and urinary tract infection (3). Positive clinical outcomes (clinical cure or improvement) were seen in 8 (28%) of 29 patients. Of the 25 microbiologically evaluable patients, 11 (44%) had resolution of their cultures. Eleven patients had susceptibility testing performed, and the median minimum inhibitory concentration was 4 μg/mL (range 3–8).

Conclusions:

In this case series, most patients did not have clinically or microbiologically favorable outcomes with tigecycline therapy. No patient had an isolate that was fully susceptible to tigecycline. Data from more studies are needed before tigecycline can be recommended for the treatment of Acinetobacter infections.
How Criminal Organisations Work: Some Theoretical Perspectives
Authors: Gottschalk Petter
Published: July 2008

Organised crime has received increased attention in recent years and criminal organisations are involved in a wide range of crimes (Chawla & Pietschmann, 2005). To fight organised crime, there is a need to understand the organisations behind it and organisational theories may be helpful in this process. The purpose of this article is to apply well-known theories such as agency theory, alliance theory, network theory, resource-based theory and other organisational theories in order to shed light on criminal organisations.
Component-by-component construction of low-discrepancy point sets of small size
Authors: Doerr Benjamin , Gnewuch Michael , Kritzer Peter , Pillichshammer Friedrich
Published: July 2008

We investigate the problem of constructing small point sets with low star discrepancy in the s-dimensional unit cube. The size of the point set shall always be polynomial in the dimension s. Our particular focus is on extending the dimension of a given low-discrepancy point set.

This results in a deterministic algorithm that constructs N-point sets with small discrepancy in a component-by-component fashion. The algorithm also provides the exact star discrepancy of the output set. Its run-time considerably improves on the run-times of the currently known deterministic algorithms that generate low-discrepancy point sets of comparable quality.

We also study infinite sequences of points with infinitely many components such that all initial subsegments projected down to all finite dimensions have low discrepancy. To this end, we introduce the inverse of the star discrepancy of such a sequence, and derive upper bounds for it as well as for the star discrepancy of the projections of finite subsequences with explicitly given constants. In particular, we establish the existence of sequences whose inverse of the star discrepancy depends linearly on the dimension.
Generalized Becker–Döring equations modeling the time evolution of a process of preferential attachment with fitness
Authors: Guiaş Flavius
Published: July 2008

We introduce an infinite system of equations modeling the time evolution of the growth process of a network. The nodes are characterized by their degree k ∈ ℕ and a fitness parameter f ∈ [0, h]. Every new node which emerges becomes a fitness f′ according to a given distribution P and attaches to an existing node with fitness f and degree k at rate f Ak
, where Ak
are positive coefficients, growing sublinearly in k. If the parameter f takes only one value, the dynamics of this process can be described by a variant of the Becker–Döring equations, where the growth of the size of clusters of size k occurs only with increment 1. In contrast to the established Becker–Döring equations, the system considered here is nonconservative, since mass (i.e. links) is continuously added. Nevertheless, it has the property of linearity, which is a natural consequence of the process which is being modeled. The purpose of this paper is to construct a solution of the system based on a stochastic approximation algorithm, which allows also a numerical simulation in order to get insight into its qualitative behaviour. In particular we show analytically and numerically the property of Bose–Einstein condensation, which was observed in the literature on random graphs.
Sigma-algebra theorems
Authors: Halton John H.
Published: July 2008

In reviewing the foundations of probability, to establish the underpinnings of the Monte Carlo method, I found some basic results for which I could not find a simple, clear, and concise derivation in the literature. This paper is an attempt to present a sufficient collection of such results. The presentation is pitched at the level of Monte Carlo practitioners, rather than mathematical probabilists.
Novel immunocontraceptive targets in mammals: uterine secretions and the conceptus; a marsupial approach
Authors: Menkhorst E M , Cui S , Selwood L
Published: July 2008

We report the first immunocontraceptive trial in mammals using a uterine-secreted protein, the marsupial shell coat protein 4 (CP4). The marsupial shell coat, which surrounds the conceptus for 60–80% of gestation, is secreted by the uterine epithelium. Following immunization against glutathione S-transferase (GST)-CP4, the fertility of female common brushtail possums (n=6) was significantly reduced (P=0.000), and this reduction in fertility was positively correlated with the maximum GST-CP4 humoral immune response (P=0.025). Ultrastructural examination of the reproductive tract indicated that the cell-mediated immune response against GST-CP4 targeted the shell coat, the shell-free conceptus and the uterine glandular epithelium, thus preventing normal conceptus development and uterine secretion of shell coat proteins and nutrients. These results show that uterine-secreted proteins are promising immunocontraceptive targets, especially in pest mammal species, e.g. possum, rabbit and horse, that have uterine-secreted additions to embryonic coats, or that have late implantation requiring uterine nutrient provisioning from secretions.
Effects of Kaempferia parviflora extracts on reproductive parameters and spermatic blood flow in male rats
Authors: Chaturapanich G , Chaiyakul S , Verawatnapakul V , Pholpramool C
Published: July 2008

Krachaidum (KD, Kaempferia parviflora Wall. Ex. Baker), a native plant of Southeast Asia, is traditionally used to enhance male sexual function. However, only few scientific data in support of this anecdote have been reported. The present study investigated the effects of feeding three different extracts of KD (alcohol, hexane, and water extracts) for 3–5 weeks on the reproductive organs, the aphrodisiac activity, fertility, sperm motility, and blood flow to the testis of male rats. Sexual performances (mount latency, mount frequency, ejaculatory latency, post-ejaculatory latency) and sperm motility were assessed by a video camera and computer-assisted sperm analysis respectively, while blood flow to the testis was measured by a directional pulsed Doppler flowmeter. The results showed that all extracts of KD had virtually no effect on the reproductive organ weights even after 5 weeks. However, administration of the alcohol extract at a dose of 70 mg/kg body weight (BW)/day for 4 weeks significantly decreased mount and ejaculatory latencies when compared with the control. By contrast, hexane and water extracts had no influence on any sexual behavior parameters. All types of extracts of KD had no effect on fertility or sperm motility. On the other hand, alcohol extract produced a significant increase in blood flow to the testis without affecting the heart rate and mean arterial blood pressure. In a separate study, an acute effect of alcohol extract of KD on blood flow to the testis was investigated. Intravenous injection of KD at doses of 10, 20, and 40 mg/kg BW caused dose-dependent increases in blood flow to the testis. The results indicate that alcohol extract of KD had an aphrodisiac activity probably via a marked increase in blood flow to the testis.
A reappraisal of the factors involved in in vitro initiation of the acrosome reaction in chicken spermatozoa
Authors: Lemoine M , Grasseau I , Brillard J P , Blesbois E
Published: July 2008

Chicken spermatozoa may remain in the female oviduct for a prolonged period before induction of the acrosome reaction on contact with the inner perivitelline layer (IPVL). By contrast, the acrosome reaction may be induced very rapidly in vitro in the presence of IPVL and Ca2+. In the present study, we examined the extent to which the chicken acrosome reaction can be induced in media of various compositions in the presence or absence of IPVL and/or Ca2+ and other factors known to be efficient in mammals. We also compared the efficacy of perivitelline layer (PL) taken at various states of oocyte maturation in initiating the reaction. The acrosome reaction was induced in less than 5 min in the presence of Ca2+ and IPVL. Incubation of spermatozoa in different saline media (Beltsville poultry semen extender (BPSE); Dulbecco's modified eagle medium; NaCl-TES buffer) without IPVL showed a significant induction of acrosome reaction in BPSE supplemented with 5 mM Ca2+ and in the three media after supplementation with Ca2+ and Ca2+ ionophore A23187. By contrast, the acrosome reaction was never induced without Ca2+. BSA, NaHCO3, and progesterone did not stimulate the acrosome reaction. Ca2+ plus PL taken at various physiological states (follicle IPVL, ovulated IPVL, oviposited IPVL, and/or outer perivitelline layer) strongly stimulated the acrosome reaction, the latest states being the most efficient. Although PL induced the acrosome reaction in the presence of extracellular Ca2+, it was not possible to induce hyperactivation in chicken spermatozoa. Taken together, these results emphasize the central role of Ca2+ in the in vitro initiation of the acrosome reaction in chickens and show specific features of this induction in birds.
Channels for water efflux and influx involved in volume regulation of murine spermatozoa
Authors: Callies C , Cooper T G , Yeung C H
Published: July 2008

The nature of the membrane channels mediating water transport in murine spermatozoa adjusting to anisotonic conditions was investigated. The volume of spermatozoa subjected to physiologically relevant hypotonic conditions either simultaneously, or after isotonic pre-incubation, with putative water transport inhibitors was monitored. Experiments in which quinine prevented osmolyte efflux, and thus regulatory volume decrease (RVD), revealed whether water influx or efflux was being inhibited. There was no evidence that sodium-dependent solute transporters or facilitative glucose transporters were involved in water transport during RVD of murine spermatozoa since phloretin, cytochalasin B and phloridzin had no effect on volume regulation. However, there was evidence that Hg2+- and Ag+-sensitive channels were involved in water transport and the possibility that they include aquaporin 8 is discussed. Toxic effects of these heavy metals were ruled out by evidence that mitochondrial poisons had no such effect on volume regulation.
Economic freedom in terms of kinds of government actions: An empirical investigation
Authors: Kapás J. , Czeglédi P.
Published: July 2008

This paper evaluates the Economic Freedom of the World (EFW) Index on the basis of the Hayekian concept of freedom (Hayek 1960), more precisely on that of its conceptualisation in terms of the character of government actions developed in Kapás — Czeglédi (2007a). As a result of a detailed criticism, the components of the EFW index are regrouped in freedom-related, policy and other categories. Although the EFW index is not considered a good measure of economic freedom, its components and the index itself are used in empirical investigations. In these examinations the aim is to show that using freedom-related components of the EFW index (which is more in line with authors’ concept of economic freedom) instead of the index itself may lead to even more plausible propositions than those provided by the EFW index. The results provide support for this argument.
The moderator role of size in alliance-performance relationships
Authors: Agárdi I. , Bauer A.
Published: July 2008

Prior research suggests that alliances created between retailers provide numerous benefits for their members which result in higher retail performance. The paper investigates whether the size of a firm is a moderating variable and/or an alternative explanation in studying the effect of alliance membership on the retailer’s performance. An empirical study, based on a small-scale survey, was carried out among 99 small-and medium-sized retailers in Hungary. Not only the strength but also the form of the relationship between alliance membership, performance and firm size have been investigated. Findings of the research support that firm size changes the form of causal relationship between alliance and performance of a retailer. Size contributes substantially to the variation of retail performance and increases the impact of alliance membership on sales and profit growth of retailers.
Differential diagnosis of chest pain: point of view of a cardiologist and a rheumatologist
Authors: Siró Béla , Wórum Ferenc
Published: July 2008

A terápia utóbbi évtizedekben bekövetkezett rohamos fejlődése a klinikum minden területén szükségessé teszi a mihamarabbi bajmegállapítást, mivel döntően ettől függ a terápiával elérhető eredmény. Ez a cardio- és cerebrovascularis események esetében különösen igaz.
Célkitűzés:
Tekintettel arra, hogy a mellkasban életveszélyes cardiovascularis és az életet kevésbé veszélyeztető egyéb történések egyaránt fájdalmat okoznak, a szerzők – elsősorban saját tapasztalataik, továbbá az irodalmi adatok alapján – áttekintést adnak a mellkasi fájdalom differenciáldiagnosztikájáról.
Módszer:
A szerzők a mellkasi fájdalom veszélyességét, gyakoriságát és topográfiáját figyelembe vevő sorrendben és csoportosításban tárgyalják a különböző okokat.
Következtetés:
A korszerű diagnosztikai és terápiás lehetőségek birtokában sem nélkülözhető, sőt még inkább szükséges a mellkasi fájdalom mint tünet minél részletesebb elemzése.
The pulmonological manifestations of rheumatoid arthritis
Authors: Bernscherer György , Karabélyos Csaba , Tarján Zsolt
Published: July 2008

A szerzők összefoglaló közleményükben az irodalmi adatok figyelembevételével áttekintik a rheumatoid arthritis primer és szekunder pulmonalis szövődményeit. A rheumatoid arthritis gyógyszeres terápiájának pulmonológiai szövődményei közül kiemelik a betegségmódosító antireumatikus szereket, amelyek közül kitérnek a methotrexat indukálta tüdőgyógyászati kórképekre. A methotrexat szinte majdnem minden additív hatású kettős és hármas – O’Dell-séma – kombinációs terápiában szerepel, ezért is fontos e gyógyszer okozta pulmonalis szövődmények időben történő felismerése. A reumatológusok számára egyre nagyobb kihívást jelent a methotrexattal szemben rezisztens rheumatoid arthritis kezelése. A biológiai terápiás szerek citokinantagonistaként, TNF-α-blokkolás révén fejtik ki hatásukat, és a betegségmódosító antireumatikus szerekhez képest hatásosabban tudják fékezni a betegség progresszióját. Ezek a biológiai válaszmódosító szerek. Főbb képviselőik az infliximab, az adalimumab és az etanercept. A szerzők végül foglalkoznak a biológiai válaszmódosító szerek okozta szekunder pulmonalis szövődményekkel: a pulmonalis tuberculosissal, a bakteriális tracheobronchitisszel, a bakteriális pneumoniával, bronchiectasiával és pulmonalis oedemával, a rapid progresszív fibrotizáló alveolitisszel, valamint a coccidiomycosissal. Az Arizona, Kalifornia, Nevada területén élő, biológiai válaszmódosító szerekkel végzett terápiában részesülő rheumatoid arthritises betegek mintegy 3%-ánál várható a 15%-os halálozással járó pulmonalis és szisztémás gombafertőzés – coccidiomycosis – kialakulása. A gyakori földrengések következtében a talajból a légtérbe kerülő spórák betegítik meg a gyógyszeres terápia miatt immunszupprimált egyéneket. A szerzők felhívják a figyelmet, hogy az előbb említett endémiás, valamint egyéb földrengésaktív területre utazó, biológiai terápiában részesülő betegek potenciális fertőzésveszélynek vannak kitéve, amely miatt a betegek ez irányú tájékoztatása a kezelőorvos részéről elengedhetetlen. A biológiai válaszmódosító szerek újabb és újabb csoportjainak kipróbálása és felhasználása a közeljövőben várható rheumatoid arthritisben. Jelenleg a TNF-α-gátló kezelésre nem reagáló betegeknél lehetőség van a non-Hodgkin-lymphoma terápiájában használatos B-lymphocyta-gátló rituximab alkalmazására. Ez utóbbi citokin rheumatoid arthritisben történő felhasználása során észlelt pulmonalis szövődményeiről még nem rendelkezünk elegendő ismerettel. Napjaink antireumatikus terápiái a betegek életminőségének jelentős javulását eredményezik, miközben az egyre korszerűbb kezelési módok a pulmonalis szövődmények körét gyarapítják.
Etiology, diagnostics and therapy of hyponatremias
Authors: Laczi Ferenc
Published: July 2008

A tanulmány klinikusok számára foglalja össze a hyponatraemiák kóroktanát, diagnosztikáját és kezelését. A hyponatraemia a leggyakoribb elektrolit-rendellenesség. Az enyhe és mérsékelt fokú hyponatraemia a hospitalizált betegek 15–30%-ában, súlyosabb formája azok 1–4%-ában fordul elő. Patofiziológiai szempontból a hyponatraemiák két fő csoportja különböztethető meg: nem ozmotikus eredetű hypervasopressinaemiás hyponatraemiák (hypovolaemiás, hypervolaemiás, euvolaemiás) és nem hypervasopressinaemiás hyponatraemiák (pseudohyponatraemia, vízmérgezés, cerebrális sóvesztő szindróma). Az enyhe hyponatraemiás betegek sokszor tünetmentesek. A súlyos hyponatraemia az életet veszélyeztető központi idegrendszeri tüneteket okozhat. A hyponatraemiás állapotok kórismézése során figyelemmel vagyunk az extracelluláris folyadék térfogatára, a klinikai tünetekre, a hyponatraemia súlyosságára, kifejlődésének sebességére és tartamára. A hyponatraemia okainak felderítésekor az első feladat a nem hypervasopressinaemiás hyponatraemiák és a hypervasopressinaemiás hyponatraemiák elkülönítése a plazma ozmolalitásának, a vércukornak, a szérumlipidek és -fehérjék szintjének mérésével. A további differenciáldiagnosztikus ténykedést a vizelet ozmolalitásának, az extracelluláris folyadék térfogatának és a vizelet nátriumkoncentrációjának meghatározása segíti. Az euvolaemiás hyponatraemiák legfontosabb megjelenési formája a SIADH. A SIADH diagnózisát az egyéb kórismék kizárása biztosítja; itt kulcsadat, hogy a csökkent plazmaozmolalitáshoz (<275 mosmol/ttkg) viszonyítva a vizelet ozmolalitása (>100 mosmol/ttkg) aránytalanul nagy. Az akut (<48 óra), súlyos hyponatraemia (<120 mmol/l) intenzív terápiát igényel a normális ozmotikus viszonyok gyors helyreállításával. (A szérum nátriumemelkedésének sebessége óránként 1 mmol/l.) A krónikus (>48 óra), szimptómás hyponatraemia kezelése során a szérum nátriumszintjének gyors emelkedése demyelinisatiós szindrómát okozhat. (A szérum nátriumemelkedésének sebessége ne haladja meg az óránkénti 0,5 mmol/l-t!) A krónikus aszimptómás hyponatraemia (a hypovolaemia kivételével) kezelésében a hagyományos eljárásokat (folyadékbevitel-korlátozás, demeclocyclin, lítium, urea, furosemid + sóbevitel) a közeli jövőben a vazopresszinreceptor-antagonisták alkalmazása válthatja fel. A 2-es típusú vazopresszinreceptor-antagonista lixivaptan, tolvaptan és satavaptan, továbbá az 1A+2 típusú vazopresszinreceptor-antagonista conivaptan elektrolitvesztés nélkül növeli a vese vízkiválasztását és emeli a szérum nátriumszintjét.
A Roadmap for Coasters: Landscapes, Life Histories, and the Conservation of Brook Trout
Authors: Ridgway Mark S.
Published: July 2008

There is still much to do in developing informed policy on the issue of migratory (“coaster”) brook troutSalvelinus fontinalis. My purpose in this paper is to provide a summary of research from other programs that may be useful for understanding the dichotomy between coaster and stream‐resident brook trout. Great Lakes glacial history, population structure at the watershed level, landscape‐scale habitat patterns, the energetics of resident and migratory brook trout, and dichotomous movements of young of year all provide important context for coaster brook trout. I apply a new growth model to literature sources on brook trout life history to scope the potential range of coaster‐resident life histories. The results indicate that juvenile growth falls largely into two groups, depending on whether the adult prey field incorporates fish in the diet. Combining ideas on variation in the standard metabolic rate and habitat productivity with a new theory of food web structure from other authors leads to an interesting working hypothesis for coaster brook trout that builds on W. E. Ricker's original observations on brook trout diet over 75 years ago.
Genetic Population Structure among Source Populations for Coaster Brook Trout in Nipigon Bay, Lake Superior
Authors: D'Amelio Silvia , Wilson Chris
Published: July 2008

Populations of coaster brook trout Salvelinus fontinalis, a potadromous ecotype endemic to Lake Superior, have declined precipitously over the past 150 years. This study quantified the relatedness and genetic structure of remnant coaster and river‐resident brook trout within Nipigon Bay using microsatellite DNA markers. Individual assignment tests confirmed that coaster brook trout are a life history variant of brook trout derived from populations in tributary habitats, rather than a genetically distinct subspecies or evolutionarily significant unit. Furthermore, coasters appear to act as vectors for gene flow among riverine populations, providing genetic connectivity among allopatric tributaries. Molecular data indicated substantial gene flow among several below‐barrier populations, whereas other tributaries contained separate, largely discrete populations. Isolated above‐barrier populations showed the greatest interpopulation differentiation, with limited downstream gene flow observed within tributaries. The relative contributions of the sampled tributary populations to the coasters in Nipigon Bay were highly variable among rivers, indicating that management of source river populations will be critical for the effective conservation and restoration of coaster brook trout within Lake Superior.
Genetic Differentiation among Sympatric Migratory and Resident Life History Forms of Rainbow Trout in British Columbia
Authors: Heath Daniel D. , Bettles Corwyn M. , Jamieson Sara , Stasiak Iga , Docker Margaret F.
Published: July 2008

Rainbow trout Oncorhynchus mykiss in coastal areas of North America occur as two divergent migratory types: Steelhead that migrate to salt water and return to their natal river to spawn and resident rainbow trout that either do not migrate or migrate locally within the freshwater system. We extracted DNA from sympatrically occurring steelhead and rainbow trout collected from five major drainages in British Columbia. We used three types of genetic markers to test for differentiation within the sympatric population: Microsatellite DNA markers, gene intron polymorphisms (restriction fragment length polymorphisms [RFLPs] and fragment size polymorphisms), and major histocompatibility complex (MHC) exon polymorphisms (RFLPs). The migratory and resident forms were genetically differentiated in only one sympatric population based on microsatellite data, but no significant differentiation was found using the combined gene locus marker data. Overall, most of the observed allele variation at all marker types was attributable to among‐drainage variance, while migratory life history contributed a nonsignificant component based on hierarchical analysis of molecular variance. Interestingly, the migratory and resident forms were genetically differentiated in two different populations based on the gonadotropin and p53 intron polymorphisms, while no significant genetic differentiation was found between the two migratory types at any of the MHC exon or growth hormone intron‐length polymorphisms. Furthermore, the neighbor‐joining cluster dendrogram based on the microsatellite markers reflected geographic patterns, while the neighbor‐joining dendrogram using gene intron and MHC markers did not. Our data indicate that the migratory and resident life histories have probably evolved independently in different drainages in British Columbia. The disagreement between the results of the analyses using the microsatellite and gene locus markers probably reflects differences in selection, mutation, or both, acting at these two types of marker loci.
Effects of Winter Temperature and Flow on a Summer‐Fall Nursery Fish Assemblage in the Chesapeake Bay, Maryland
Authors: Wingate Rebecca L. , Secor David H.
Published: July 2008

In temperate estuaries, nearshore nursery fish assemblages are influenced by environmental conditions that are present during and prior to the period of juvenile fish occurrence. An intensively sampled site (Patuxent River estuary) in mesohaline Chesapeake Bay provided 9 years of data for relating previous and current environmental variables with juvenile fish assemblages. Canonical correspondence analysis identified temperature and flow from the previous winter (January‐March) and week and year of the assemblage sample as the most influential variables. In contrast, environmental variables at the time of sampling were not identified as important. High summer‐fall abundances of Atlantic silversides Menidia menidia, striped bass Morone saxatilis, white perch Morone americana, and Atlantic needlefish Strongylura marina were positively associated with low winter temperatures and high winter flows. High abundances of bluefish Pomatomus saltatrix, spot Leiostomus xanthurus, bay anchovy Anchoa mitchilli, and northern puffer Sphoeroides maculatus were associated with low winter flows and high winter temperatures. The mechanisms by which winter conditions affect the summer‐fall nursery fish assemblage were not directly addressed in this study, but winter conditions can affect subsequent spring and summer estuarine production, spawning and recruitment phenology, and distributions of juvenile fishes.
Effects of Severe Drought on Freshwater Mussel Assemblages
Authors: Haag Wendell R. , Warren Melvin L.
Published: July 2008

We examined changes in freshwater mussel abundance and species composition at eight sites in Alabama and Mississippi in response to a severe drought in 2000. Five small‐stream sites in Bankhead National Forest were heavily impacted by drought; one site dried almost completely, and four sites experienced total or near cessation of flow but retained water in their channels to a large extent. In contrast, three large‐stream sites retained flow and experienced only minor streambed exposure, primarily along the stream margins. In small streams, overall mussel density before and after the drought declined by 65‐83%, and the magnitude of the decline did not differ among streams regardless of whether the channel dried or remained wetted. IntroducedCorbicula fluminea(Asian clam) experienced near total mortality and declined to a greater extent than native unionids. The magnitude of decline was similar among unionid species, and the likelihood of surviving the drought was mostly a function of predrought abundance; differences in drought tolerance among species were not evident. Consequently, assemblage composition changed primarily because of the loss of rare species, resulting in drainagewide homogenization and convergence on a shrinking species pool. In contrast, we found no evidence for changes in the total abundance or composition of mussel assemblages in large streams that continued to flow during the drought. Our results show that mussels are highly sensitive to the secondary effects of drought—most likely the low levels of dissolved oxygen caused by low flow, warm temperatures, and high biological oxygen demand—in addition to the direct drying of their habitat. The postdrought abundances of some species in Bankhead National Forest may now be below the minimum necessary for successful reproduction. These populations, which are isolated by reservoirs, may be in a downward spiral from which they will have difficulty recovering in the absence of immigration.
Influence of Benthic Features and Fishing Pressure on Size and Distribution of Three Exploited Reef Fishes from the Southeastern United States
Authors: Kendall Matthew S. , Bauer Laurie J. , Jeffrey Christopher F. G.
Published: July 2008

Distribution, habitat preference, and size structure were examined for three commonly targeted bottom fishes (black sea bass Centropristis striata, gag Mycteroperca microlepis, and scamp M. phenax) in the southeastern United States. Fish communities and bottom characteristics of limestone ledges within Gray's Reef National Marine Sanctuary (located centrally along the southeastern continental shelf) were surveyed. Black sea bass occurred at 98% of the ledges and were evenly distributed throughout the sanctuary in much‐higher numbers than either gags or scamps, which were concentrated at only 11% of the ledges. Gag or scamp presence was most strongly related to height of ledge undercut, whereas abundance of black sea bass was best explained by percent cover of sessile biota. In addition, lower abundance of black sea bass occurred in the presence of either gags or scamps, which are generally larger than black sea bass. In all three species, an abrupt decline in abundance was observed for size‐classes above the size limit of the fishery. Also, modal size of gags or scamps was smaller and the percentage of fish exceeding the fishery size limit was lower in heavily fished areas than in less intensively fished areas.