bluuebunny/crossref_metadata_2025 huggingface dataset:
Silver‐Bearing and Associated Minerals in El Zancudo Deposit, Antioquia, Colombia
Authors: Gallego Hernández Alba Nury , Akasaka Masahide
Published: November 2007

The occurrence and the chemical compositions of ore minerals (especially the silver‐bearing minerals) and fluid inclusions of the El Zancudo mine in Colombia were investigated in order to analyze the genetic processes of the ore minerals and to examine the genesis of the deposit. The El Zancudo mine is a silver–gold deposit located in the western flank of the Central Cordillera in Antioquia Department. It consists mainly of banded ore veins hosted in greenschist and lesser disseminated ore in porphyritic rocks. The ore deposit is associated with extensive hydrothermally altered zones. The ores from the banded veins contain sphalerite, pyrite, arsenopyrite, galena, Ag‐bearing sulfosalts, Pb‐Sb sulfosalts, and minor chalcopyrite, electrum, and native silver. Electrum is included within sphalerite, pyrite, and arsenopyrite, and is also partially surrounded by pyrite, arsenopyrite, sphalerite, and tetrahedrite. Native silver is present in minor amounts as small grains in contact with Ag‐rich sulfosalts. Silver‐bearing sulfosalts are argentian tetrahedrite–freibergite solid solution, andorite, miargyrite, diaphorite, and owyheeite. Pb‐Sb sulfosalts are bournonite, jamesonite, and boulangerite. Two main crystallization stages are recognized, based on textural relations and mineral assemblages. The first‐stage assemblage includes sphalerite, pyrite, arsenopyrite, galena and electrum. The second stage is divided into two sub‐stages. The first sub‐stage commenced with the deposition and growth of sphalerite, pyrite, and arsenopyrite. These minerals are characterized by compositional growth banding, and seem to have crystallized continuously until the end of the second sub‐stage. Tetrahedrite, Pb‐Cu sulfosalts, Ag‐Sb sulfosalt, and Pb‐Ag‐Sb sulfosalts crystallized from the final part of the first sub‐stage and during the whole second sub‐stage. However, one Pb‐Ag‐Sb sulfosalt, diaphorite, was formed by a retrograde reaction between galena and miargyrite. The minimum and maximum genetic temperatures estimated from the FeS content of sphalerite coexisting with pyrite and the silver content of electrum are 300°C and 420°C, respectively. These estimated genetic temperatures are similar to, but slightly higher than the homogenization temperatures (235–350°C) of primary fluid inclusions in quartz. The presence of muscovite in the altered host rocks and gangue suggest that the pH of the hydrothermal solutions was close to neutral. Most of the sulfosalts in this deposit have previously been attributed as the products of epithermal mineralization. However, El Zancudo can be classified as a xenothermal deposit, in view of the low pressure and high temperature genetic conditions identified in the present study, based on the mineralogy of sulfosalts and the homogenization temperatures of the fluid inclusions.
Types, Characteristics, and Geodynamic Settings of Mesozoic Epithermal Gold Deposits in Eastern China
Authors: Mao Jingwen , Li Xiaofeng , White Noel C. , Zhao Caisheng , Zhang Zuoheng , Wang Yitian , Hu Huabin
Published: November 2007

Mesozoic epithermal gold deposits in eastern China are divided into calc‐alkaline and alkaline magma‐related gold deposits, and are also grouped as low‐sulfidation, intermediate‐sulfidation and high‐sulfidation types, of which the first two predominate. These gold deposits are distributed in the Tianshan–Yinshan–Great Xing’anling Variscan fold belt of North China craton, Qinling‐Dabie Indo‐Sinian fold belt of Yangtze craton, and South China fold belt or Cathaysian block, from north to south along the eastern China continent. Most of the epithermal gold orebodies are hosted either in volcanic rocks or their related granitoids, and volcanic breccia pipes. These orebodies are mainly associated with adularia–chalcedony–sericite, and alunite–kaolinite–quartz alteration. These orebodies formed in four mineralization pulses at 175, 145–135, 127–115, and 110–94 Ma. The first three pulses correspond to the post‐collision period between the North China and Yangtze cratons, an extension period during late‐stage rotation of the principal compressional stress from N‐S to E‐W, and a dramatic thinning period of the lithosphere, respectively. The last mineralizing pulse was the result of another extension in South China. Although the mineralizing pulses occurred at different times, they all occurred in extensional settings and were accompanied by crust and the mantle interaction.
Epithermal Gold‐Silver Mineralization of the Asachinskoe Deposit in South Kamchatka, Russia
Authors: Takahashi Ryohei , Matsueda Hiroharu , Okrugin Victor M. , Ono Shuji
Published: November 2007

The Asachinskoe epithermal Au‐Ag deposit is a representative low‐sulfidation type of deposit in Kamchatka, Russia. In the Asachinskoe deposit there are approximately 40 mineralized veins mainly hosted by dacite–andesite stock intrusions of Miocene–Pliocene age. The veins are emplaced in tensional cracks with a north orientation. Wall‐rock alteration at the bonanza level (170–200 m a.s.l.) consists of the mineral assemblage of quartz, pyrite, albite, illite and trace amounts of smectite. Mineralized veins are well banded with quartz, adularia and minor illite. Mineralization stages in the main zone are divided into stages I–IV. Stage I is relatively barren quartz–adularia association formed at 4.7 ± 0.2 Ma (K‐Ar age). Stage II consists of abundant illite, Cu‐bearing cryptomelane and other manganese oxides and hydroxides, electrum, argentite, quartz, adularia and minor rhodochrosite and calcite. Stage III, the main stage of gold mineralization (4.5–4.4 ± 0.1–3.1 ± 0.1 Ma, K‐Ar age), consists of a large amount of electrum, naumannite and Se‐bearing polybasite with quartz–adularia association. Stage IV is characterized by hydrothermal breccia, where electrum, tetrahedrite and secondary covellite occur with quartz, adularia and illite. The concentration of Au+Ag in ores has a positive correlation with the content of K2O + Al2O3, which is controlled by the presence of adularia and minor illite, and both Hg and Au also have positive correlations with the light rare‐earth elements. Fluid inclusion studies indicate a salinity of 1.0–2.6 wt% NaCl equivalent for the whole deposit, and ore‐forming temperatures are estimated as approximately 160–190°C in stage III of the present 218 m a.s.l. and 170–180°C in stage IV of 200 m a.s.l. The depth of ore formation is estimated to be 90–400 m from the paleo‐water table for stage IV of 200 m a.s.l., if a hydrostatic condition is assumed. An increase of salinity (>CNaCl≈ 0.2 wt%) and decrease of temperature (>T ≈ 30°C) within a 115‐m vertical interval for the ascending hydrothermal solution is calculated, which is interpreted as due to steam loss during fluid boiling. Ranges of selenium and sulfur fugacities are estimated to be logfSe2 = −17 to −14.5 and logfS2 = −15 to −12 for the ore‐forming solution that was responsible for Au‐Ag‐Se precipitation in stage III of 200 m a.s.l. Separation of Se from S‐Se complex in the solution and its partition into selenides could be due to a relatively oxidizing condition. The precipitation of Au‐Ag‐Se was caused by boiling in stage III, and the precipitation of Au‐Ag‐Cu was caused by sudden decompression and boiling in stage IV.
Characteristics of Publicly Insured Children with High Dental Expenses
Authors: Churchill Shervin S. , Williams Bryan J. , Villareale Nanci L.
Published: November 2007

Background: Dental coverage is provided for all children with Medicaid in Washington State. The goal of this study was to illuminate the characteristics of a sample of Medicaid‐enrolled children with high dental expenses.

Methods: Dental care utilization data for a 33‐month period were obtained from Washington State's Medicaid database. For children, 0 to 6 years, these data were linked with a parent survey addressing oral health behaviors, knowledge, family history of caries, snacking patterns, and access to dental care. Children with dental expenses of $1,000 or more were classified as the “high‐expense” group. Risk factors for the high‐expense group were evaluated using multiple logistic regression.

Results: 345 children had at least one dental procedure including preventive and diagnostic care. Among these, 30 children (9 percent) incurred 64 percent of total dental expenses for the entire group. Parent perception of lack of dental coverage was associated with incurring high dental expenses. Children of Asian or Pacific Islander heritage were at disproportionately high risk compared to White children. Age of child and family history of caries were also associated with increased risk for high expenses.

Conclusions: Not all low‐income children on Medicaid are at high risk for caries. A combination of factors, including family history of caries and parent's perception of lack of dental insurance coverage, can potentially increase a child's likelihood for high‐expense dental treatment. This study highlighted a small group of children with disproportionately high dental expenses. For some, earlier knowledge of coverage may have resulted in more timely access to preventive and diagnostic care, reducing the subsequent need for expensive restorative treatment.
The influence of insects and hummingbirds on the geographical variation of the flower phenotype in Mimulus luteus
Authors: Medel Rodrigo , Valiente Angela , Botto‐Mahan Carezza , Carvallo Gastón , Pérez Fernanda , Pohl Nélida , Navarro Luis
Published: November 2007

We describe the geographical variation of corolla and nectar guide size in seven populations of Mimulus luteus (Phrymaceae) in central Chile, and examine whether flower phenotypes associate with taxonomic composition and flower visit patterns of pollinators across populations. Flowers showed higher variation in nectar guide size than corolla size. Mean corolla size increased with the proportion of bees and decreased with the proportion of lepidopterans in the pollinator assemblages. Nectar guide size increased with the proportion of hummingbirds in the pollinator assemblages. When the frequency of flower visits rather than taxonomic composition was considered, the results revealed similar patterns. Because these traits previously have been described as targets of bee‐ and hummingbird‐mediated selection in M. luteus, our results have implications for understanding the processes that determine flower diversification in Chilean Mimulus. Although we cannot rule out ecological sorting as an explanation for the geographical association between pollinators and flower phenotypes, changes in the prevalence and importance of bees and hummingbirds across populations appear to account, at least in part, for the flower phenotypic variation across populations. The extent to which insect and hummingbird pollination in M. luteus produces pollinator‐mediated divergence among populations needs to be examined in future studies.
Growth and Pigment Production on
d
-Tryptophan Medium by
Cryptococcus gattii
,
Cryptococcus neoformans
, and
Candida albicans
Authors: Chaskes Stuart , Frases Susana , Cammer Michael , Gerfen Gary , Casadevall Arturo
Published: November 2007

Given the increasing prevalence of cryptococcosis caused by
Cryptococcus gattii
(serotypes B and C) strains, there is a need for rapid and reliable tests that discriminate
C. gattii
from
Cryptococcus neoformans
(serotypes A, D, and AD). Seventy-two
C. neoformans
strains, sixty-seven
C. gattii
strains, and five
Candida albicans
strains were analyzed for their ability to grow and produce pigment on minimal
d
-tryptophan
d
-proline (m-DTDP) medium, on yeast carbon base
d
-tryptophan
d
-proline (YCB-DTDP) medium, and on fructose
d
-tryptophan glycine (m-FDTG) medium. Of the
C. gattii
and
C. neoformans
isolates, 94% and 0% grew on m-DTDP agar, respectively, and 98% and 0% grew in YCB-DTDP medium, respectively.
C. gattii
produced large amounts of brown intracellular pigment(s) on m-DTDP agar and smaller amounts of yellow-brown (amber) extracellular pigment(s).
C. albicans
grew on both media and produced a pink photoactivated pigment on m-DTDP agar.
C. gattii
produced large amounts of brown intracellular pigments on the differential medium m-FDTG, whereas
C. neoformans
produced smaller amounts of the brown pigments and
C. albicans
produced a pink pigment. The pigments produced by
C. gattii
from
d
-tryptophan were distinct and were not related to melanin formation from 3,4-dihydroxyphenylalanine. Thin-layer chromatography of the methanol-extracted
C. gattii
cells detected four different pigments, including brown (two types), yellow, and pink-purple compounds. We conclude that tryptophan-derived pigments are not melanins and that growth on m-DTDP or YCB-DTDP agar can be used to rapidly differentiate
C. gattii
from
C. neoformans
.
Vitamin D status in apparently healthy adults in Kashmir Valley of Indian subcontinent
Authors: Zargar A H , Ahmad S , Masoodi S R , Wani A I , Bashir M I , Laway B A , Shah Z A
Published: November 2007

Background

The worldwide prevalence of vitamin D deficiency is reported to be high.

Objectives

To assess the vitamin D status in apparently healthy adults in Kashmir valley by measuring serum 25-hydroxyvitamin D (25 (OH) D).

Methods

92 healthy natives (64 men and 28 non-pregnant/non-lactating women, aged 18–40 years), residing in Kashmir for at least last 5 years and not having any suggestion of systemic disease, were selected for this study. The samples were collected throughout the year in both summer and winter months. Vitamin D deficiency was defined as a serum 25 (OH) D concentration of <50 nmol/l and graded as mild (25–50 nmol/l), moderate (12.5–25 nmol/l) and severe (<12.5 nmol/l).

Results

Body mass index, total energy intake, and other nutritional parameters were comparable among subjects in different groups. Overall 76 (83%) of the subjects studied had vitamin D deficiency—25%, 33%, and 25% had mild, moderate, and severe deficiency, respectively. 49 of the 64 males and all but 1 of the 28 females were vitamin D deficient. The prevalence of vitamin D deficiency ranged from 69.6% in the employed group to 100% in the household group. Vitamin D deficiency was equally prevalent in subjects from rural and urban areas. Serum calcium and phosphorus values were comparable in subjects with and without vitamin D deficiency, while daily intake and urinary excretion of calcium were significantly lower in the former. Vitamin D deficient subjects had a significantly lower mean weekly exposure to sunlight.

Conclusions

In spite of abundant sunlight, healthy individuals in Kashmir valley are vitamin D deficient, particularly women. Serum 25 (OH) D concentrations are significantly related to sun exposure.
Flexible working: policies are supportive but culture and finances are not
Authors: Goodyear Helen M , Lynch Finola
Published: November 2007

There is now an inverse correlation between the number of women entering medicine and the availability of flexible working
CONNECTIVITY INDUCED SYNCHRONIZATION IN CORTICAL NEURONAL NETWORKS
Authors: JIA L. C. , HAN C. R. , LAI PIK-YIN , CHAN C. K.
Published: November 2007

Synchronization of cortical neural cultures is studied as a function of the effective network connectivity in the phenomenon of synchronized firing(SF). The synchronized bursting frequency (during SF) of the network is found to be much slower than the characteristic time scale of a neuron and increases with the network connectivity. The synchronized bursting frequency f is characterized by a critical age (tc) as: [Formula: see text]. Furthermore, tc is found to scale with the cell plating density ρ as tc ~ ρ−β with β ≃ 0.44 ± 0.08. Although some aspects of the observed SF is similar to the array enhanced synchronization, detailed comparison of measured spike statistics from synchronized and non-synchronized cultures suggests that the nature of synchronization during SF is different from that of the array-enhanced synchronization. In particular, electrophysiological measurements using double patch technique revel that even though the bursting frequencies are synchronized, the intra-burst spikes are not.
INHOMOGENEOUS D-WAVE SUPERCONDUCTIVITY
Authors: SU W. P.
Published: November 2007

To understand several peculiar features of d-wave superconductors such as the cuprates, we have studied a two-dimensional tight-binding (extended Hubbard) model in which the electrons interact with a potential which is attractive at nearest neighbor distance and repulsive elsewhere. Such a model is designed to produce d-wave superconductivity. It also yields antiferromagnetism and phase separation. In the two-phase region, due to vanishing compressibility the system can be easily rendered inhomogeneous by weak perturbations. Thus inhomogeneous superconductivity is a likely consequence of d-wave pairing. In addition to inhomogeneity the model also reproduces a phase diagram strikingly similar to the one observed in the cuprates. As such it throws some light on the nature of the pseudogap state.
NEGATIVE PHASE VELOCITY IN NONLINEAR OSCILLATORY SYSTEMS — MECHANISM AND PARAMETER DISTRIBUTIONS
Authors: CAO ZHOUJIAN , LI PENGFEI , ZHANG HONG , HU GANG
Published: November 2007

Waves propagating inwardly to the wave source are called antiwaves which have negative phase velocity. In this paper the phenomenon of negative phase velocity in oscillatory systems is studied on the basis of periodically paced complex Ginzbug-Laundau equation (CGLE). We figure out a clear physical picture on the negative phase velocity of these pacing induced waves. This picture tells us that the competition between the frequency ωout of the pacing induced waves with the natural frequency ω0 of the oscillatory medium is the key point responsible for the emergence of negative phase velocity and the corresponding antiwaves. ωoutω0 > 0 and |ωout| < |ω0| are the criterions for the waves with negative phase velocity. This criterion is general for one and high dimensional CGLE and for general oscillatory models. Our understanding of antiwaves predicts that no antispirals and waves with negative phase velocity can be observed in excitable media.
QUANTUM MONTE CARLO STUDY ON RANDOM BOND MIXED-SPIN CHAIN
Authors: FAN HONGWEI , XU ZHAOXIN , YING HEPING
Published: November 2007

The effects of bond randomness on the quantum mixed-spin chain 1-1-1/2-1/2 are investigated by a quantum Monte Carlo study. We find that around the critical point of original pure system, quantum Griffiths phases appears, and its region is enlarged with increasing of bond randomness. Moreover, the critical behavior of the original quantum critical point has been changed by the randomness.
FINITE-SIZE SCALING OF THE CORRELATION LENGTH IN ANISOTROPIC SYSTEMS
Authors: CHEN X. S. , ZHANG H. Y.
Published: November 2007

The finite-size scaling functions of thermodynamic functions in anisotropic systems have been shown to be dependent on the spatial anisotropy [X.S. Chen and V. Dohm, Phys. Rev. E 70, 056136 (2004)]. Here we extend this study to the correlation length ξ‖ of the anisotropic O (n) symmetric φ4 model in an Ld−1 × ∞ cylindric geometry with periodic boundary conditions. We calculate the exact finite-size scaling function of correlation length ξ‖ for T ≥ Tc in 2 < d < 4 dimensions and in the limit n → ∞. The finite-size scaling function of ξ‖ is dependent on a normalized symmetric (d − 1) × (d − 1) matrix defined by the anisotropy matrix of anisotropic systems.
SPINOR BEC IN THE LARGE-N LIMIT
Authors: LI ZHIBING , BAO CHENGGUANG
Published: November 2007

The superfine structure of Bose-Einstein condensate of alkali atoms due to the spin coupling have been investigated in the mean field approximation. In the limit of large number of atoms, we obtained the analytical solution for the fully condensed states and the states with one-atom excited. It was found that the energy of the one-atom excited state could be smaller than the energy of the fully condensed state, even two states have similar total spin.
THE LÜDERS POSTULATE AND THE DISTINGUISHABILITY OF OBSERVABLES
Authors: MEISTER BERNHARD K.
Published: November 2007

The Lüders postulate is reviewed and implications for the distinguishability of observables are discussed. As an example the distinguishability of two similar spin-[Formula: see text] particle observables is described and implementation issues are briefly analyzed.
Molecular Ordering and Phase Behavior of Surfactants at Water-Oil Interfaces as Probed by X-Ray Surface Scattering
Authors: Schlossman Mark L. , Tikhonov Aleksey M.
Published: November 2007

Surfactants have their primary utility, both scientific and industrial, at the liquid-liquid interface. We review recent X-ray surface scattering experiments that probe the molecular ordering and phase behavior of surfactants at the water-oil interface. The presence of the oil modifies the interfacial ordering in a manner that cannot be understood simply from analogies with studies of Langmuir monolayers of surfactants at the water-vapor interface or from the traditional view that the solvent is fully mixed with the interfacial surfactants. These studies explored the role of chain flexibility and head group interactions on the ordering of long-chain alkanols and alkanoic acids. Small changes in the surfactant may produce large changes in the interfacial ordering. The interfacial monolayer can be spatially homogeneous or inhomogeneous. Investigators have observed interfacial phase transitions as a function of temperature between homogenous phases, as well as between homogeneous and inhomogeneous phases. Finally, varying the solvent chain length can alter the fundamental character of the phase transitions and lead to the formation of multilayer interfacial structures.
Calcium Cycling and Signaling in Cardiac Myocytes
Authors: Bers Donald M.
Published: November 2007

Calcium (Ca) is a universal intracellular second messenger. In muscle, Ca is best known for its role in contractile activation. However, in recent years the critical role of Ca in other myocyte processes has become increasingly clear. This review focuses on Ca signaling in cardiac myocytes as pertaining to electrophysiology (including action potentials and arrhythmias), excitation-contraction coupling, modulation of contractile function, energy supply-demand balance (including mitochondrial function), cell death, and transcription regulation. Importantly, although such diverse Ca-dependent regulations occur simultaneously in a cell, the cell can distinguish distinct signals by local Ca or protein complexes and differential Ca signal integration.
The Role of Kisspeptins and GPR54 in the Neuroendocrine Regulation of Reproduction
Authors: Popa Simina M. , Clifton Donald K. , Steiner Robert A.
Published: November 2007

Neurons that produce gonadotropin-releasing hormone (GnRH) reside in the basal forebrain and drive reproductive function in mammals. Understanding the circuitry that regulates GnRH neurons is fundamental to comprehending the neuroendocrine control of puberty and reproduction in the adult. This review focuses on a family of neuropeptides encoded by the Kiss1 gene, the kisspeptins, and their cognate receptor, GPR54, which have been implicated in the regulation of GnRH secretion. Kisspeptins are potent secretagogues for GnRH, and the Kiss1 gene is a target for regulation by gonadal steroids (e.g., estradiol and testosterone), metabolic factors (e.g., leptin), photoperiod, and season. Kiss1 neurons in the arcuate nucleus may regulate the negative feedback effect of gonadal steroids on GnRH and gonadotropin secretion in both sexes. The expression of Kiss1 in the anteroventral periventricular nucleus (AVPV) is sexually dimorphic, and Kiss1 neurons in the AVPV may participate in the generation of the preovulatory GnRH/luteinizing hormone (LH) surge in the female rodent. Kiss1 neurons have emerged as primary transducers of internal and environmental cues to regulate the neuroendocrine reproductive axis.
The Relationships Between Mass Media, Public Opinion, and Foreign Policy: Toward a Theoretical Synthesis
Authors: Baum Matthew A. , Potter Philip B.K.
Published: November 2007

Democracy requires that citizens' opinions play some role in shaping policy outcomes, including in foreign policy. Yet, although the literature on public opinion and foreign policy has made great progress in recent decades, scholars have reached no consensus concerning what the public thinks, or thinks about, with respect to foreign policy; how it comes to hold those opinions; or whether those opinions influence (or even should influence) foreign policy. In this article, we first review the extensive gains in scholarly knowledge in the area of public opinion and foreign policy over the past several decades, emphasizing relatively recent work. We then suggest a framework, based on the concept of market equilibrium, aimed at synthesizing the disparate research programs that constitute the literature on public opinion and foreign policy. To do so, in addition to considering the relationship between leaders and the public, we incorporate a third strategic actor, the mass media, which we believe plays a critical role alongside citizens and elites in shaping the public's attitudes about, and influence on, foreign policy. Our goal is to clarify the multifaceted relationships between these actors and foreign policy outcomes.
What the Ancient Greeks Can Tell Us About Democracy
Authors: Ober Josiah
Published: November 2007

The question of what the ancient Greeks can tell us about democracy can be answered by reference to three fields that have traditionally been pursued with little reference to one another: ancient history, classical political theory, and political science. These fields have been coming into more fruitful contact over the past 20 years, as evidenced by a spate of interdisciplinary work. Historians, political theorists, and political scientists interested in classical Greek democracy are increasingly capable of leveraging results across disciplinary lines. As a result, the classical Greek experience has more to tell us about the origins and definition of democracy, and about the relationships between participatory democracy and formal institutions, rhetoric, civic identity, political values, political criticism, war, economy, culture, and religion.
Importance of changes in gastric emptying for postprandial plasma glucose fluxes in healthy humans
Authors: Woerle H.-J. , Albrecht M. , Linke R. , Zschau S. , Neumann C. , Nicolaus M. , Gerich J. , Göke B. , Schirra J.
Published: October 2007

Objective: Regulation of postprandial (pp) plasma glucose excursions is complex. Insulin and glucagon are thought to play the predominant role. Nevertheless, only 50% of the variation in pp plasma glucose excursions is explained by variations by the latter. Theoretically, gastric emptying (GE) should be another important factor. However, its impact on pp glucose homeostasis is unknown. Research Design and Methods: We examined the consequences of pramlintide-induced delay in GE on pp glycemia and glucose fluxes, determined isotopically. GE was recorded by scintigraphy. Fourteen healthy subjects (8 men, 6 women; age 40 ± 3 yr, body mass index 27.8 ± 1.1 kg/m2) ate a mixed meal, and 30 μg of pramlintide (PRAM) or placebo (PBO) were injected subcutaneously. Results: At 60 min, greater proportions of the initial gastric contents remained in the stomach (PBO vs. PRAM). Thereafter, GE slopes paralleled until 240 min. Fifty percent retention times were lower when PBO was given ( P < 0.001). GE was greater from 240 min to the end of the PRAM experiments, so that only slightly greater proportions of the meal remained in the stomach at 330 min. Reductions of GE lowered pp glucose (7.5 ± 0.3 vs. 6.0 ± 0.2 mmol/l, P < 0.001), even though plasma insulin was lower with PRAM (164 ± 13 vs. 138 ± 13 pmol/ml, both P < 0.01). Reduction in total glucose appearance ( P < 0.001) was due to reduced meal-derived glucose appearance (10.2 ± 0.5 vs. 7.0 ± 0.4 μmol·kg−1·min−1, P < 0.001). Endogenous glucose appearance was greater with PRAM ( P < 0.001). Splanchnic glucose uptake was greater with PRAM (26.5 ± 1.6 vs. 32.5 ± 2.1%, P = 0.014). Conclusions: These data support the concept that GE is an important physiological regulator of pp glucose homeostasis in humans.
NPY Y1 receptor antagonist prevents NPY-induced torporlike hypothermia in cold-acclimated Siberian hamsters
Authors: Dark John , Pelz Kimberly M.
Published: November 2007

Siberian hamsters ( Phodopus sungorus) undergo bouts of daily torpor during which body temperature decreases by as much as 20°C and provides a significant savings in energy expenditure. Natural torpor in this species is normally triggered by winterlike photoperiods and low ambient temperatures. Intracerebroventricular injection of neuropeptide Y (NPY) reliably induces torporlike hypothermia that resembles natural torpor. NPY-induced torporlike hypothermia is also produced by intracerebroventricular injections of an NPY Y1 receptor agonist but not by injections of an NPY Y5 receptor agonist. In this research, groups of cold-acclimated Siberian hamsters were either coinjected with a Y1 receptor antagonist (1229U91) and NPY or were coinjected with a Y5 receptor antagonist ( CGP71683 ) and NPY in counterbalanced designs. Paired vehicle + NPY induced torporlike hypothermia in 92% of the hamsters, whereas coinjection of Y1 antagonist + NPY induced torporlike hypothermia in 4% of the hamsters. In contrast, paired injections of vehicle + NPY and Y5 antagonist + NPY induced torporlike hypothermia in 100% and 91% of the hamsters, respectively. Although Y5 antagonist treatment alone had no effect on body temperature, Y1 antagonist injections produced hyperthermia compared with controls. Both Y1 antagonist and Y5 antagonist injections significantly reduced food ingestion 24 h after treatment. We conclude that activation of NPY 1 receptors is both sufficient and necessary for NPY-induced torporlike hypothermia.
Epigenetic differences between male and female bovine blastocysts produced in vitro
Authors: Bermejo-Álvarez P. , Rizos D. , Rath D. , Lonergan P. , Gutierrez-Adan A.
Published: November 2007

Epigenetic differences between male and female bovine blastocysts provide a plausible link between physiological and gene transcription differences observed between male and female embryos. The aim of this study was to examine sex-related epigenetic differences in bovine blastocysts produced in vitro. Oocytes were matured in vitro and inseminated with frozen-thawed sex-sorted (X or Y) and unsorted (control) bull sperm. Zygotes were cultured to blastocyst stage and were analyzed for embryo sexing, mtDNA content, telomere lengths, methylation analysis, and quantification of mRNA transcripts of DNA methyltransferases (Dnmt1, Dnmt3a, Dnmt3b) HMT1 hnRNP methyltransferase-like 2 (Hmt1), and interleukin enhancer binding factor 3 (Ilf3). There was a difference ( P < 0.05) in the mean mtDNA copy number between male (410,000 ± 23,000) and female (360,000 ± 21,000) blastocysts. Telomere length was shorter in male blastocysts ( P < 0.01). The level of methylation in a sequence near a variable number of tandem repeats minisatellite region [variable number of tandem repeats (VNTR)] in males (39.8% ± 4.8) was higher than in females (23.7% ± 3.1) ( P < 0.05); however, no differences were found in other regions analyzed. Moreover, transcription differences between sexes were observed for Dnmt3a, Dnmt3b, Hmt1, and Ilf3. These results provide evidence of epigenetic differences between male and female bovine in vitro produced embryos and suggest that before initiation of gonadal differentiation, epigenetic events may modulate the difference between speed of development, metabolism, and transcription observed during preimplantation development between male and female embryos.
Vancomycin Disposition and Penetration into Ventricular Fluid of the Central Nervous System following Intravenous Therapy in Patients with Cerebrospinal Devices
Authors: Jorgenson Laney , Reiter Pamela D. , Freeman Jane E. , Winston Ken R. , Fish Douglas , McBride Lori A. , Handler Michael H.
Published: November 2007

Objective/Aims: To determine the cerebrospinal fluid concentrations and percent CNS penetration of intravenous vancomycin in patients with cerebrospinal devices at a pediatric institution. Methods: We performed a prospective evaluation of intravenous (IV) vancomycin in patients who received a single prophylactic dose of vancomycin (15–20 mg/, maximum dose 1 g) prior to insertion of a CNS shunt (group I) or a therapeutic regimen (a dose of 10–20 mg/kg every 6–12 h) for a documented/suspected shunt infection (group II). Ventricular cerebrospinal fluid (VCSF) samples were taken during the procedure in group I and multiple serum and VCSF samples were collected in group II. Pharmacokinetic parameters were calculated using a one-compartment model, and percent CNS penetration was estimated using area-under-the-curve methodology. Results: Group I: 21 VCSF samples were analyzed from 19 patients (mean age 7.2 ± 6.4 years). Over 40% of samples failed to have detectable vancomycin concentrations (range 0–2 µg/ml). Group II: 6 patients (mean age 11 ± 8.7 years) had VCSF concentrations ranging from nondetectable to 6.59 µg/ml (mean 2.48 ± 0.52 µg/ml). Percent penetration ranged from 0.77 to 18%. Conclusions: Single-dose, pre-operative vancomycin results in low VCSF vancomycin concentrations and repeated dosing in patients with documented/presumed device infections yields variable CNS penetration.
Proton Magnetic Resonance Spectroscopy of Hydrocephalic Infants
Authors: McNatt Sean A. , McComb J. Gordon , Nelson Marvin D. , Bluml Stefan
Published: November 2007

Objective: The authors present the first report evaluating neonates with chronic hydrocephalus using proton magnetic resonance spectroscopy (1H MRS). The goals of the study were (1) to determine absolute brain metabolite concentrations in premature infants and neonates with hydrocephalus and age-matched controls, (2) conduct an initial survey of potential biochemical abnormalities of the newborn hydrocephalic brain, and (3) determine whether 1H MRS can be used for outcome prediction in this population. Methods: Thirteen infants with chronic hydrocephalus were imaged with magnetic resonance imaging (MRI) and 1H MRS during an 18-month interval. Absolute metabolite concentrations were tabulated and compared with those of 26 age-matched controls. Metabolite abnormalities were evaluated for correlation with clinical outcome at last follow-up. Results: Mean lactate (Lac), glutamine (Gln) and alanine (Ala) concentrations in hydrocephalic patients were significantly elevated. These metabolite elevations did not correlate significantly with outcome. There was no evidence of altered neuronal maturation in patients with congenital hydrocephalus. Two patients with dramatically reduced N-acetyl-aspartate and elevated Lac had poor neurologic outcome and were found to have neurologic disease that had not been identified with prior diagnostic tests. Conclusions: Premature infants and neonates with hydrocephalus have elevated Lac, Gln and Ala compared with age-matched controls. Further investigation and follow-up is required to assess the significance of these findings. In general, 1H MRS is of limited value in predicting outcome in infants with hydrocephalus. However, 1H MRS may be useful in identifying subsets of hydrocephalic neonates that, in fact, have severe neurologic disease and poor prognosis.
Jefferson Fracture in a Child – Illustrative Case Report
Authors: Korinth Marcus C. , Kapser Alexandra , Weinzierl Martin R.
Published: November 2007

In adults, atlas burst fractures (Jefferson fractures) are not uncommon. In the pediatric population, they are extremely rare, and only few cases have been reported so far. They all showed a highly consistent clinical presentation with rare neurological deficits as well as recovery with full function without any surgical intervention. We describe a case of a Jefferson fracture in a 7.5-year-old-boy after falling onto the top of his head, presenting solely with slight neck pain. The initial radiological characteristics are presented on magnetic resonance imaging (MRI) and computer tomography (CT); the bony bridging and fusion of the fracture sites are demonstrated on CT during the course of the healing. The patient was placed in a rigid cervical collar, and his physical examination results remained normal according to age. Complete fusion of both fracture sites was seen on the third follow-up 6.5 months after presentation. In this rare case of a Jefferson fracture in a child monitored by radiological imaging techniques, important aspects of conservatively treated atlas burst fractures are illustrated. It underlines their benign character and favorable outcome with full functional recovery without any surgical intervention.
The Italian Register of Cardiovascular Diseases: Attack Rates and Case Fatality for Cerebrovascular Events
Authors: Palmieri L. , Barchielli A. , Cesana G. , de Campora E. , Goldoni C.A. , Spolaore P. , Uguccioni M. , Vancheri F. , Vanuzzo D. , Ciccarelli P. , Giampaoli S.
Published: October 2007

Background: The Italian register of cardiovascular diseases is a surveillance system of fatal and nonfatal cardiovascular events in the general population aged 35–74 years. It was launched in Italy at the end of the 1990s with the aim of estimating periodically the occurrence and case fatality rate of coronary and cerebrovascular events in the different geographical areas of the country. This paper presents data for cerebrovascular events. Methods: Currentevents were assessed through record linkage between two sources of information: death certificates and hospital discharge diagnosis records. Events were identified through the ICD codes and duration. To calculate the number of estimated events, current events were multiplied by the positive predictive value of each specific mortality or discharge code derived from the validation of a sample of suspected events. Attack rates were calculated by dividing estimatedevents by resident population, and case fatality rate at 28 days was determined from the ratio of estimated fatal to total events. Results: Attack rates were found to be higher in men than in women: mean age-standardized attack rate was 21.9/10,000 in men and 12.5/10,000 in women; age-standardized 28-day case fatality rate was higher in women (17.1%) than in men (14.5%). Significant geographical differences were found in attack rates of both men and women. Case fatality was significantly heterogeneous in both men and women. Conclusions: Differences still exist in the geographical distribution of attack and case fatality rates of cerebrovascular events, regardless of the north-south gradient. These data show the feasibility of implementing a population-based register using a validated routine database, necessary for monitoring cardiovascular diseases.
Asymptomatic Pericardial Effusion in Patients with Rheumatoid Arthritis
Authors: Sugiura Tetsuro , Kumon Yoshitaka , Kataoka Hiromi , Matsumura Yoshihisa , Takeuchi Hiroaki , Doi Yoshinori
Published: October 2007

Objectives: The aim of this study was to determine the frequency and clinical correlates of asymptomatic pericardial effusion (PE) detected by echocardiography in patients with rheumatoid arthritis (RA). Methods: Echocardiography and electrocardiography were performed in 87 consecutive patients with RA. Asymptomatic PE was correlated with electrocardiographic changes and laboratory findings. Results: Among 87 patients with RA, 20 patients (23%) had PE and 28 patients (32%) had hypoalbuminemia. The patients with PE had significantly lower serum albumin level (p < 0.001), higher rheumatoid factor (RF)titer (p = 0.002) and higher incidence of impaired left ventricular relaxation (55 vs. 28%, p = 0.028) and tended to have a higher incidence of PR-segment depression than those without PE (p = 0.085). When five variables (PR-segment depression, C-reactive protein, serum albumin, RF and impaired left ventricular relaxation) were used in the multivariate analysis, serum albumin (p = 0.003, Odds ratio = 0.131) and RF (p = 0.020, Odds ratio = 3.775) emerged as significant variables related to the presence of asymptomatic PE. Conclusions: In addition to pericardial inflammation due to more severe RA, hypoalbuminemia was an important factor associated with the presence of asymptomatic PE.
Proinsulin Is an Independent Predictor of the Angiographical Characteristics of Coronary Atherosclerosis
Authors: Jia En-Zhi , Yang Zhi-Jian , Zhu Tie-Bing , Wang Lian-Sheng , Chen Bo , Cao Ke-Jiang , Huang Jun , Ma Wen-Zhu
Published: October 2007

Objective: The objective of this survey was to study the association between circulating proinsulin level and the severity of coronary atherosclerosis. Methods: The study population consisted of 1,039 consecutive patients (775 males and 264 females) who underwent coronary angiography for suspected or known coronary atherosclerosis. The patients’ anthropometric and plasma measurements including body mass index, blood pressure, blood lipid, blood glucose, and proinsulin level were performed. The severity of coronary atherosclerosis was defined by the Gensini’s score system. Results: When proinsulin level was examined as a categorical variable classified by quartile values, subjects with a high proinsulin level had significantly higher values of Gensini’s score than those with a low proinsulin level (p = 0.000). The Spearman correlation analysis suggests that the Gensini’s score was significantly correlated with proinsulin level (r = –0.177, p = 0.000). Multiple stepwise linear regression analysis demonstrated that glucose (β= 0.136, p = 0.000), age (β= 0.189, p = 0.000), proinsulin (β= 0.135, p=0.000), SBP (mm Hg) (β= –0.061, p = 0.043), fasting low-density lipoprotein cholesterol (mmol/l) (β= 0.141, p = 0.003), and total cholesterol (β= –0.105, p = 0.029) are significantly independently associated with the Gensini’s score. Conclusions: Proinsulin is a strong and statistically highly significant pre- dictor of coronary atherosclerosis independent of the other major risk factors including age, body mass index, blood pressure, fasting blood glucose, and blood lipid. The exact mechanisms need further study.
Clinical Heterogeneity in Sodium Channelopathies
Authors: Oliva Antonio , Bjerregaard Preben , Hong Kui , Evans Steven , Vernooy Kevin , McCormack Jorge , Brugada Josep , Brugada Pedro , Pascali Vincenzo L. , Brugada Ramon
Published: October 2007

Background: Mutations in the SCN5A gene have been linked to a variety of diseases causing sudden cardiac death, with important variability in expressivity and phenotypic overlap. With the availability of genetic testing family members may now be diagnosed as carriers based solely on the presence of the genetic defect. Clinical decision making in this situation is complex and generates important ethical and medicolegal issues.Methods:Wedescribe two families, 24-328 and 24-588, originally diagnosed with Brugada syndrome after the probands experienced cardiac arrest and we performed clinical and genetic analysis in their members. Results: Both families had members with various electrocardiographic abnormalities including some with Brugada syndrome, long QT syndrome and conduction system disease. Both families had an important family history of sudden cardiac death. Direct sequencing of exons and exon-intron boundaries of the sodium channel gene SCN5A identified mutations in both families. Conclusions: These two families illustrate an increasingly common scenario when encountering families with ion channelopathies. Because a defibrillator is the only available therapeutic option at present in Brugada syndrome, physicians will be faced with extremely difficult therapeutic decisions that also have important legal, social and ethical implications, especially in children. These data indicate the need to develop guidelines on how to approach the results of genetic testing, especially in asymptomatic individuals.
Myocardial Stress in Patients with Acute Cerebrovascular Events
Authors: Jespersen Christian M. , Fischer Hansen Jørgen
Published: October 2007

Signs of myocardial involvement are common in patients with acute cerebrovascular events. ST segment deviations, abnormal left ventricular function, increased N-terminal pro-brain natriuretic peptide (NT-proBNP), prolonged QT interval, and/or raised troponins are observed in up to one third of the patients. The huge majority of these findings are fully reversible. The changes may mimic myocardial infarction, but are not necessarily identical to coronary thrombosis. Based on the literature these signs may represent an acute catecholamine release provoked by the cerebrovascular catastrophe itself and not coronary thrombosis. However, all patients with signs of cardiac involvement during acute cerebrovascular events should receive a cardiological follow-up in order to exclude concomitant ischemic heart disease.
Morphology and Evolutionary Biology of the Dolphin (Delphinus sp.) Brain – MR Imaging and Conventional Histology
Authors: Oelschläger H.H.A. , Haas-Rioth M. , Fung C. , Ridgway S.H. , Knauth M.
Published: October 2007

Whole brains of the common dolphin (Delphinus delphis) were studied using magnetic resonance imaging (MRI) in parallel with conventional histology. One formalin-fixed brain was documented with a Siemens Trio Magnetic Resonance scanner and compared to three other brains which were embedded in celloidin, sectioned in the three main planes and stained for cells and fibers. The brain of the common dolphin is large, with the telencephalic hemispheres dominating the brain stem. The neocortex is voluminous and the cortical grey matter thin but extremely extended and densely convoluted. There is no olfactory ventricular recess due to the lack of an anterior olfactory system (olfactory bulb and peduncle). No occipital lobe of the telencephalic hemisphere and no posterior horn of the lateral ventricle are present. A pineal organ could not be detected. The brain stem is thick and underlies a very large cerebellum. The hippocampus and mammillary body are small and the fornix is thin; in contrast, the amygdaloid complex is large and the cortex of the limbic lobe is extended. The visual system is well developed but exceeded by the robust auditory system; for example, the inferior colliculus is several times larger than the superior colliculus. Other impressive structures in the brainstem are the peculiar elliptic nucleus, inferior olive, and in the cerebellum the huge paraflocculus and the very large posterior interpositus nucleus. There is good correspondence between MR scans and histological sections. Most of the brain characteristics can be interpreted as morphological correlates to the successful expansion of this species in the marine environment, which was characterized by the development of a powerful sonar system for localization, communication, and acousticomotor navigation.