Systematic Regional Variations Research Articles

Regional variation of climatological cloudburst frequency estimated from historical observations of daily precipitation sums

AbstractThis study aims to estimate climatological cloudburst frequencies from daily precipitation sums for a dense network of 161 historical Danish stations covering the period 1914–2010, in order to reveal any systematic regional differences. We define a cloudburst day for a given station as a day when the maximum 1‐h precipitation sum exceeds a predefined threshold; we use the thresholds 15, 20 and 25 mm, corresponding to a cloudburst frequency around 0.42, 0.16 and 0.06 year−1, respectively. Supplementing the historical data, we use hourly data from a modern network and relate the daily probability of cloudburst occurrence to the corresponding daily precipitation using binary regression. This allows an estimation of the cloudburst frequency from a series of daily sums. To validate the methods, we use 33 stations that have been operating for 30 years or longer. For these stations, we demonstrate significant skill by comparing observed and estimated cloudburst frequencies with a jackknife procedure. By applying the model to the 161 historical series, we estimate climatological cloudburst frequencies throughout Denmark. We find large systematic regional variations across Denmark and these variations are much larger, but with a similar regional pattern, than obtained by previous work. We suggest applying the approach to the historical daily precipitation series that exist across the world.

Detection of skin thickness and density in healthy Chinese people by using high-frequency ultrasound.

Due to a recent development of high-frequency ultrasound (HFUS) systems, it is easier to realize high-resolution in vivo imaging of the biological tissues. The object of this study was to map the thickness and echo density of skin layers in healthy Chinese people and assess the influence of gender, age, and region on it. A total of 189 volunteers (85 male, 104 female) with age range of 22-75-year old (mean age of 41.2-year old) were enrolled. The thickness and density of the epidermis and dermis layer were detected by high-frequency (22 or 75MHz) ultrasonography at 13 different anatomical sites, including the forehead, cheeks, flexor and extensor forearms, flexor and extensor upper arms, inner and outer legs, inner and outer thighs, back, and abdomen. The thickness and density of epidermis/dermis between different anatomical sites were statistically significant (p<0.05). The epidermis thickness of the face and trunk were less than that of the limbs, whereas the thicknesses of the dermis were on the contrary. The density of the epidermis/dermis of the face and trunk were less than that of the limbs. The thickness of dermis in most of the sites were higher in male than in female, and the density of epidermis and dermis in most of the sites were less in men than in women. The thicknesses/densities of dermis were lower in older age group in almost all sites, whereas only several sites reached statistical. The difference between the north and south regions showed the environment also influenced the thickness and density of the skin. HFUS provides a simple noninvasive method for evaluating the skin thickness and echo-density, which, reflecting intradermal structure, exhibit systematic regional variation. With the establishment of Chinese phenotypic database of skin thickness and density, it will be helpful for the skin disease assessment, skin surgery, and cosmetology technology.

The geography of innovation and technology news - An empirical study of the German news media

Variations in the frequency and tone of news media are the focus of a growing literature. However, to date, empirical investigations have primarily confirmed the existence of such differences at the country level. This paper extends those insights to the subnational level. We provide theoretical arguments and empirical support for systematic regional variations in the frequency and sentiments of news related to innovation and new technologies. These variations reflect regional socio-economic structures. We find that the average newspaper circulating in urban areas features more news on innovation and new technologies than media in more rural areas. Similar findings hold for locations in East Germany and to a certain degree for regions with low unemployment. The sentiments of innovation and new technology news are negatively associated to the unemployment rate, and they tend to be lower in regional newspapers than in national ones. Overall, our results suggest a strong link between the regional socioeconomic conditions and how newspapers circulating in these places report on innovation and new technologies.

Voice onset time variation in natural southern speech

Sociophonetic research has traditionally emphasized vowels and only recently begun to examine consonants. The emerging literature on consonants has found systematic regional variation in consonant production (Jacewicz et al., 2009; Eddington and Turner, 2017). These studies have focused on present-day speakers producing lab-recorded speech and thus provide little historical or naturalistic insight to consonant variation. One way that the production of stop consonants varies is in voice onset time (VOT). In this study, we utilize the Digital Archive of Southern Speech (DASS) (Kretzschmar et al., 2013), a collection of 64 sociolinguistic interviews recorded between 1968 and 1983, to explore consonant variation in an unscripted historical setting. DASS was force-aligned using the Montreal Forced Aligner (McAuliffe et al., 2017), and the VOT of pre-vocalic, word-initial stop consonants in three-minute audio clips from each speaker was measured using AutoVOT (Keshet et al., 2014). VOT was normalized by dividing duration by speaking rate, and this normalized measurement was included as the dependent variable in a mixed effects model. As expected, stress, voicelessness, and a dorsal place of articulation were significant predictors. Our preliminary analysis reveals significant regional and age differences, adding evidence for speaker-specific variation of VOT as a result of sociophonetic variables.

Aerosol influences on low-level clouds in the West African monsoon

Abstract. Low-level clouds (LLCs) cover a wide area of southern West Africa (SWA) during the summer monsoon months and have an important cooling effect on the regional climate. Previous studies of these clouds have focused on modelling and remote sensing via satellite. We present the first comprehensive set of in situ measurements of cloud microphysics from the region, taken during June–July 2016, as part of the DACCIWA (Dynamics–aerosol–chemistry–cloud interactions in West Africa) campaign. This novel dataset allows us to assess spatial, diurnal, and day-to-day variation in the properties of these clouds over the region. LLCs developed overnight and mean cloud cover peaked a few hundred kilometres inland around 10:00 local solar time (LST), before clouds began to dissipate and convection intensified in the afternoon. Regional variation in LLC cover was largely orographic, and no lasting impacts in cloud cover related to pollution plumes were observed downwind of major population centres. The boundary layer cloud drop number concentration (CDNC) was locally variable inland, ranging from 200 to 840 cm−3 (10th and 90th percentiles at standard temperature and pressure), but showed no systematic regional variations. Enhancements were seen in pollution plumes from the coastal cities but were not statistically significant across the region. A significant fraction of accumulation mode aerosols, and therefore cloud condensation nuclei, were from ubiquitous biomass burning smoke transported from the Southern Hemisphere. To assess the relative importance of local and transported aerosol on the cloud field, we isolated the local contribution to the aerosol population by comparing inland and offshore size and composition measurements. A parcel model sensitivity analysis showed that doubling or halving local emissions only changed the calculated cloud drop number concentration by 13 %–22 %, as the high background meant local emissions were a small fraction of total aerosol. As the population of SWA grows, local emissions are expected to rise. Biomass burning smoke transported from the Southern Hemisphere is likely to dampen any effect of these increased local emissions on cloud–aerosol interactions. An integrative analysis between local pollution and Central African biomass burning emissions must be considered when predicting anthropogenic impacts on the regional cloud field during the West African summer monsoon.

Does IIH Alter Brain Microstructures? - A DTI-Based Approach.

To investigate the correlation of microstructural parameters with CSF pressure and macroscopic changes assessed by diffusion tensor imaging (DTI) in patients with idiopathic intracranial hypertension (IIH). Twenty-three patients with IIH as well as age-, sex-, and body mass index (BMI)-matched controls underwent high resolution MR imaging of the optic nerve sheaths (ONS), pituitary gland, and ventricles. For DTI data a voxelwise permutation analysis was performed for the whole brain and ROI analysis was performed for the optic nerve and optic radiation. DTI measurements were correlated to morphometric measurements, CSF opening pressure, and headache intensity. The reliability of diagnostic performance of DTI parameters was assessed using ROC analysis. Analysis of DTI metrics revealed a significant reduction in the fractional anisotropy (FA) of the optic nerve in patients with IIH. In contrast, systematic regional variations between IIH patients and controls were neither observed in the whole brain analysis nor in the optic radiation. FA values of the optic nerve show significant correlations with the optic nerve sheath diameter (P = .003, r = -.589). The correlation of the alterations of the FA values of the optic radiation and the whole brain do not show a significant association to morphometric alterations in the ONS diameter and hypophysis height as well as to CSF opening pressure and headache intensity. The results indicate that IIH is associated with microstructural changes in the optic nerve. These alterations may be the direct consequence of chronically elevated intracranial pressure.

Multisite multivariate modeling of daily precipitation and temperature in the Canadian Prairie Provinces using generalized linear models

Based on the Generalized Linear Model (GLM) framework, a multisite stochastic modelling approach is developed using daily observations of precipitation and minimum and maximum temperatures from 120 sites located across the Canadian Prairie Provinces: Alberta, Saskatchewan and Manitoba. Temperature is modeled using a two-stage normal-heteroscedastic model by fitting mean and variance components separately. Likewise, precipitation occurrence and conditional precipitation intensity processes are modeled separately. The relationship between precipitation and temperature is accounted for by using transformations of precipitation as covariates to predict temperature fields. Large scale atmospheric covariates from the National Center for Environmental Prediction Reanalysis-I, teleconnection indices, geographical site attributes, and observed precipitation and temperature records are used to calibrate these models for the 1971–2000 period. Validation of the developed models is performed on both pre- and post-calibration period data. Results of the study indicate that the developed models are able to capture spatiotemporal characteristics of observed precipitation and temperature fields, such as inter-site and inter-variable correlation structure, and systematic regional variations present in observed sequences. A number of simulated weather statistics ranging from seasonal means to characteristics of temperature and precipitation extremes and some of the commonly used climate indices are also found to be in close agreement with those derived from observed data. This GLM-based modelling approach will be developed further for multisite statistical downscaling of Global Climate Model outputs to explore climate variability and change in this region of Canada.

An index for measuring overuse of health care resources with Medicare claims.

Overuse can be defined as use of a service when the risk of harm exceeds its likely benefit. Yet, there has been little work with composite measures of overuse. Our goal was to create a composite measure of overuse with claims data. Observational study using 5% of Medicare claims from 2008. All inpatient and outpatient settings of care, excluding nursing homes. Older Americans receiving health care services in hospitals or outpatient settings. We applied algorithms to identify specific cases of overuse across 20 previously identified procedures and used multilevel modeling techniques to examine variation in overuse across all procedures. Included in the model were patient-level factors and both procedure and regional fixed effects for the 306 hospital referral regions (HRR). These estimated regional fixed effects, representing the systematic, region variation in overuse across all measures, was then normalized compared with the overall average to generate a Z score for each HRR. The resulting "Overuse Index" was then compared with total costs, 30-day postdischarge mortality, and total mortality at the HRR level, graphically, and associations were tested using Spearman ρ. The Overuse Index varied markedly across regions, but 23 were higher than the average (P<0.05). The Index was positively associated with total costs (ρ=0.28, P<0.0001). It was positively correlated with 30-day postdischarge mortality (ρ=0.18 P≤0.005), and neither positively or negatively correlated with total mortality. This study confirms previous research hypothesizing that systematic regional variation in overuse exists and is measurable. Addition research is needed to validate index and to test its predictive and concurrent validity in panel data.

Global patterns of lightning properties derived by OTD and LIS

Abstract. The satellite instruments Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) provide unique empirical data about the frequency of lightning flashes around the globe (OTD), and the tropics (LIS), which have been used before to compile a well-received global climatology of flash rate densities. Here we present a statistical analysis of various additional lightning properties derived from OTD / LIS, i.e., the number of so-called "events" and "groups" per flash, as well as the mean flash duration, footprint and radiance. These normalized quantities, which can be associated with the flash "strength", show consistent spatial patterns; most strikingly, oceanic flashes show higher values than continental flashes for all properties. Over land, regions with high (eastern US) and low (India) flash strength can be clearly identified. We discuss possible causes for and implications of the observed regional differences. Although a direct quantitative interpretation of the investigated flash properties is difficult, the observed spatial patterns provide valuable information for the interpretation and application of climatological flash rates. Due to the systematic regional variations of physical flash characteristics, viewing conditions, and/or measurement sensitivities, parametrizations of lightning NOx based on total flash rate densities alone are probably affected by regional biases.

Systematic Regional Variations of GABA, Glutamine, and Glutamate Concentrations Follow Receptor Fingerprints of Human Cingulate Cortex

Magnetic resonance spectroscopy (MRS) of glutamatergic or GABAergic measures in anterior cingulate cortex (ACC) was found altered in psychiatric disorders and predictive of interindividual variations of functional responses in healthy populations. Several ACC subregions have been parcellated into receptor-architectonically different portions with heterogeneous fingerprints for excitatory and inhibitory receptors. Similarly, these subregions overlap with functionally distinct regions showing opposed signal changes toward stimulation or resting conditions. We therefore investigated whether receptor-architectonical and functional segregation of the cingulate cortex in humans was also reflected in its local concentrations of glutamate (Glu), glutamine (Gln), and GABA. To accomplish a multiregion estimation of all three metabolites in one robust and reliable session, we used an optimized 7T-stimulated echo-acquisition mode method with variable-rate selective excitation pulses. Our results demonstrated that, ensuring high data retest reliability, four cingulate subregions discerning e.g., pregenual ACC (pgACC) from anterior mid-cingulate cortex showed different metabolite concentrations and ratios reflective of regionally specific inhibition/excitation balance. These findings could be controlled for potential influences of local gray matter variations or MRS voxel-placement deviations. Pregenual ACC was found to have significantly higher GABA and Glu concentrations than other regions. This pattern was not paralleled by Gln concentrations, which for both absolute and relative values showed a rostrocaudal gradient with highest values in pgACC. Increased excitatory Glu and inhibitory GABA in pgACC were shown to follow a regional segregation agreeing with recently shown receptor-architectonic GABAB receptor distribution in ACC, whereas Gln distribution followed a pattern of AMPA receptors.

Mapping the cytoskeletal prestress

Cell mechanical properties on a whole cell basis have been widely studied, whereas local intracellular variations have been less well characterized and are poorly understood. To fill this gap, here we provide detailed intracellular maps of regional cytoskeleton (CSK) stiffness, loss tangent, and rate of structural rearrangements, as well as their relationships to the underlying regional F-actin density and the local cytoskeletal prestress. In the human airway smooth muscle cell, we used micropatterning to minimize geometric variation. We measured the local cell stiffness and loss tangent with optical magnetic twisting cytometry and the local rate of CSK remodeling with spontaneous displacements of a CSK-bound bead. We also measured traction distributions with traction microscopy and cell geometry with atomic force microscopy. On the basis of these experimental observations, we used finite element methods to map for the first time the regional distribution of intracellular prestress. Compared with the cell center or edges, cell corners were systematically stiffer and more fluidlike and supported higher traction forces, and at the same time had slower remodeling dynamics. Local remodeling dynamics had a close inverse relationship with local cell stiffness. The principal finding, however, is that systematic regional variations of CSK stiffness correlated only poorly with regional F-actin density but strongly and linearly with the regional prestress. Taken together, these findings in the intact cell comprise the most comprehensive characterization to date of regional variations of cytoskeletal mechanical properties and their determinants.

Tracing the origins of Panamanian Congo speech

The Afro-descendents of Panama’s Caribbean coast maintain the tradition of the Negros Congos, a series of folkloric manifestations occurring during Carnival season, and including a special cryptolect based loosely on Spanish. According to oral tradition, Congo speech was devised among captive and maroon Africans in colonial Panama as a means of hiding their speech from their colonial masters. Widely felt — both by Congo participants and by outside observers — to consist only of deliberate deformations of Spanish words and semantic inversions, Congo speech in reality also contains numerous elements traceable to Afro-Hispanic communities in other former Spanish-American colonies. Data drawn from twenty-four Congo communities demonstrate systematic regional variation — phonetic and lexical — that verifies the status of Congo speech as a cryptolect undergoing natural language evolution. These data also contribute to the search for the geographical locus of the original Congo dialect.

Distribution of kimberlite and aillikite in the Diamond Province of southern West Greenland: A regional perspective based on groundmass mineral chemistry and bulk compositions

A regional study of dike and sill occurrences of kimberlitic rocks in terms of xenolith and megacryst assemblages from the diamond province in southern West Greenland demonstrates very systematic variation in the composition of melts across the margin of the Archaean core of the North Atlantic craton. Melt derived from the diamond window in the lithospheric mantle below the Archean core in Greenland is kimberlitic. Toward the Palaeoproterozoic Nagssugtoqidian orogen melts (also derived from the diamond window) gradually change to ultramafic lamprophyre compositions evolving toward an end-member akin to the aillikites of the penecontemporaneous Torngat region in Canada. The identification of the types of melts is based on the groundmass paragenesis including the presence or absence of clinopyroxene and chromite, and the compositions of groundmass ilmenite, spinel, and phlogopite. The systematic regional variation is also shown, although somewhat blurred, by the bulk rock major and trace element compositions. The change in melt composition is not a reflection of change in depth of initial melting, but relates to the composition of the deep SCLM. Kimberlite melts in the Archaean craton are suggested to be reaction products between a carbonate-rich astenospheric melt and an orthopyroxene-bearing and phlogopite-poor depleted SCLM, whereas the aillikite type melts across the craton margin are the products of reaction between a similar carbonate-rich asthenospheric melts and a subducted SCLM that had previously been subjected to metasomatism and veining.

Systematic regional variations in diamond carbon isotopic composition and inclusion chemistry beneath the Orapa kimberlite cluster, in Botswana

The carbon isotopic composition, nitrogen content and aggregation state of 95 inclusion bearing diamonds, collected from the production of Damtshaa kimberlites, were investigated. The Damtshaa kimberlites belong to the group of southern African kimberlites showing 12C enrichment in eclogitic compared to peridotitic diamonds. The results were compared with similar studies of the nearby Orapa and Letlhakane kimberlites, providing the opportunity to examine variations in mantle composition on the kilometer scale. While Orapa, Letlhakane and Damtshaa diamonds may share some overall similarities in their δ 13C distribution, there are significant differences among them. These differences support the concept that diamonds from different kimberlite pipes have distinctive features in their δ 13C distribution and that this is true for kimberlite occurrences which are spatially separated by only a few tens of km. Compared to Orapa, peridotitic garnet inclusions from Damtshaa and Letlhakane are derived, in part, from highly depleted dunitic–harzburgitic reservoirs extending to greater depth. In all three kimberlites diamonds with eclogitic garnet inclusions displaying comparatively low Al 2O 3/Cr 2O 3 ratios, characteristic for mantle compositions, show a wide range in carbon isotopic composition from about − 4 to − 18 ‰ vs. PDB. The observed relationship between δ 13C and Al 2O 3/Cr 2O 3 ratios indicates the presence of 13C depleted mantle sources that cannot be explained by subduction. Estimates of possible pressure/temperature conditions, based on the Fe/Mg distribution coefficients of coexisting eclogitic garnets and clinopyroxenes and the Ca mole fraction in garnets, lead to the conclusion that beneath the Orapa, Letlhakane, and Damtshaa kimberlites there is a mantle zone depleted in 13C, approximately 20–30 km thick and extending over an area of at least 200 km 2.

Climbing fiber coupling between adjacent Purkinje cell dendrites in vivo

Climbing fiber discharges within the rat cerebellar cortex have been shown to display synchrony, especially for climbing fibers terminating in the same parasagittal bands. In addition, Purkinje cells which have the smallest rostrocaudal separation also seem to have the highest degree of synchrony. But this has so far only been investigated for distances down to 250 μm. In the present study, we wanted to investigate whether Purkinje cells that are located immediately next to each other display a particularly pronounced synchrony in their climbing fiber discharges. To this end, we used a previously undescribed type of electrophysiological recording, a single electrode, loose patch, dual dendritic recording, from pairs of adjacent Purkinje cells in the decerebrated, non-anesthetized cat. From each recorded dendrite, this technique provided well isolated, unitary calcium spikes, which we found to have a spontaneous activity that was essentially identical with the pattern of spontaneous climbing fiber discharges. By calculating the coupling in firing between the adjacent dendrites, we found that most climbing fiber responses occurred independently of each other and that the probability of coupled discharges was less than 8%. These values are comparable to those obtained in previous studies for Purkinje cells located within the same parasagittal band and show that climbing fiber coupling within a microzone exists also in non-rodent mammalian species. However, since the degree of synchrony of climbing fiber discharge was not particularly pronounced in adjacent Purkinje cells, it seems unlikely that climbing fiber synchrony has pronounced systematic regional variations within the same microzone.

Optically continuous silcrete quartz cements of the St. Peter Sandstone: High precision oxygen isotope analysis by ion microprobe

A detailed oxygen isotope study of detrital quartz and authigenic quartz overgrowths from shallowly buried (<1 km) quartz arenites of the St. Peter Sandstone (in SW Wisconsin) constrains temperature and fluid sources during diagenesis. Quartz overgrowths are syntaxial (optically continuous) and show complex luminescent zonation by cathodoluminescence. Detrital quartz grains were separated from 53 rocks and analyzed for oxygen isotope ratio by laser fluorination, resulting in an average δ 18O of 10.0 ± 0.2‰ (1SD, n = 109). Twelve thin sections were analyzed by CAMECA-1280 ion microprobe (6–10 μm spot size, analytical precision better than ±0.2‰, 1SD). Detrital quartz grains have an average δ 18O of 10.0 ± 1.4‰ (1SD, n = 91) identical to the data obtained by laser fluorination. The ion microprobe data reveal true variability that is otherwise lost by homogenization of powdered samples necessary for laser fluorination. Laser fluorination uses samples that are one million times larger than the ion microprobe. Whole rock (WR) samples from the 53 rocks were analyzed by laser fluorination, giving δ 18O between 9.8‰ and 16.7‰ ( n = 110). Quartz overgrowths in thin sections from 10 rocks were analyzed by ion microprobe and average δ 18O = 29.3 ± 1.0‰ (1SD, n = 161). Given the similarity, on average, of δ 18O for all detrital quartz grains and for all quartz overgrowths, samples with higher δ 18O(WR) values can be shown to have more cement. The quartz cement in the 53 rocks, calculated by mass balance, varies from <1 to 21 vol.% cement, with one outlier at 33 vol.% cement. Eolian samples have an average of 11% cement compared to marine samples, which average 4% cement. Two models for quartz cementation have been investigated: high temperature (50–110 °C) formation from ore-forming brines related to Mississippi Valley Type (MVT) mineralization and formation as silcretes at low temperature (10–30 °C). The homogeneity of δ 18O for quartz overgrowths determined by ion microprobe rules out a systematic regional variation of temperature as predicted for MVT brines and there are no other known heating events in these sediments that were never buried to depths >1 km. The data in this study suggest that quartz overgrowths formed as silcretes in the St. Peter Sandstone from meteoric water with δ 18O values of −10‰ to −5‰ at 10–30 °C. This interpretation runs counter to conventional wisdom based on fibrous or opaline silica cements suggesting that the formation of syntaxial quartz overgrowths requires higher temperatures. While metastable silica cements commonly form at high degrees of silica oversaturation following rapid break-down reactions of materials such as of feldspars or glass, the weathering of a clean quartz arenite is slower facilitating chemical equilibrium and precipitation of crystallographically oriented overgrowths of α-quartz.

Three-dimensional compartmentalization of myosin heavy chain and myosin light chain isoforms in dog thyroarytenoid muscle

The thyroarytenoid muscle, a vocal fold adductor, has important roles in airway protection (e.g., prevention of aspiration) and phonation. Isoform expression of myosin heavy chain (MHC), a major determinant of muscle-shortening velocity, has been reported to be heterogeneous in this muscle in several mammals, differing markedly between the medial and lateral divisions. The objective was to determine the isoform expression patterns of both MHC and myosin light chain (MLC), with the latter having a modulatory role in determining shortening velocity, to further test whether the expression of both myosin subunits differs in multiple specific sites within the divisions of the dog thyroarytenoid muscle, potentially revealing even greater compartmentalization in this muscle. Our results indicate the existence of large gradients in the relative levels of individual MHC isoforms in the craniocaudal axis along the medial layer (i.e., airflow axis), where levels of MHC-I and MHC-IIA are low at both ends of the axis and high in the middle and MHC-IIB has a reciprocal distribution. The lateral layer is more uniform, with high levels of MHC-IIB throughout. The level of MHC-IID is relatively constant along the axis in both layers. Large differences exist in the distribution of MHC isoforms among single fibers isolated from sites along the craniocaudal axis, especially in the lateral layer. Systematic regional variations are apparent in the MLC isoform composition of single fibers as well, including some MLC isoform combinations that are not observed in dog limb muscles. Variations of MHC and MLC isoform expression in the dog thyroarytenoid muscle are greater than previously recognized and suggest an even broader range of contractile properties within this multifunctional muscle.

Human Placenta Secretes Apolipoprotein B-100-containing Lipoproteins

Supply of lipids from the mother is essential for fetal growth and development. In mice, disruption of yolk sac cell secretion of apolipoprotein (apo) B-containing lipoproteins results in embryonic lethality. In humans, the yolk sac is vestigial. Nutritional functions are instead established very early during pregnancy in the placenta. To examine whether the human placenta produces lipoproteins, we examined apoB and microsomal triglyceride transfer protein (MTP) mRNA expression in placental biopsies. ApoB and MTP are mandatory for assembly and secretion of apoB-containing lipoproteins. Both genes were expressed in placenta and microsomal extracts from human placenta contained triglyceride transfer activity, indicating expression of bioactive MTP. To detect lipoprotein secretion, biopsies from term placentas were placed in medium with [(35)S]methionine and [(35)S]cysteine for 3-24 h. Upon sucrose gradient ultracentrifugation of the labeled medium, fractions were analyzed by apoB-immunoprecipitation. (35)S-labeled apoB-100 was recovered in d approximately 1.02-1.04 g/ml particles (i.e. similar to the density of plasma low density lipoproteins). Electron microscopy of negatively stained lipoproteins secreted from placental tissue showed spherical particles with a diameter of 47 +/- 10 nm. These results demonstrate that human placenta expresses both apoB and MTP and consequently synthesize and secrete apoB-100-containing lipoproteins. Placental lipoprotein formation constitutes a novel pathway of lipid transfer from the mother to the developing fetus.

Spatial heterogeneity of endocardial voltage amplitude in viable, chronically dysfunctional myocardium.

Although electromechanical mapping has been used to assess cardiac physiology, interpretation is dependent upon the spatial variability of endocardial voltage and local shortening in normal and viable dysfunctional myocardium, which is currently unknown. NOGA mapping was performed in 13 pigs with an established model of viable dysfunctional myocardium produced by a chronic LAD stenosis, and five uninstrumented controls. Voltage maps (122 +/- 7 points each) were obtained in the closed-chest anesthetized state, and (18)F-2-deoxyglucose uptake and TTC staining confirmed viability. There were systematic regional variations in voltage amplitude in both chronically-instrumented and control animals. Unipolar voltage was ~15% higher in LAD-supplied versus remote myocardium (10.8 +/- 0.3 vs. 8.9 +/- 0.4 mV, p < 0.001), with a similar relative difference in controls (14.0 +/- 0.5 vs. 12.0 +/- 0.4 mV, p < 0.02). In contrast, bipolar voltage was ~35% lower in the LAD territory of both groups (2.2 +/- 0.2 vs. 3.5 +/- 0.2 mV, p < 0.01 and 3.1 +/- 0.3 vs. 5.1 +/- 0.3 mV in controls, p < 0.01). The relative dispersion (SD/mean) of voltage was large, but significantly lower for unipolar versus bipolar measurements (39 +/- 1% vs. 70 +/- 2%, p < 0.001). Variability between hearts was partially related to end-systolic volume (r = 0.58, p < 0.05). Linear local shortening measurements were insensitive to detect anterior hypokinesis. Our data demonstrates significant regional and spatial heterogeneity of endocardial voltage and NOGA-derived linear shortening in normal and viable dysfunctional myocardium, with large confidence intervals for individual measurements. Even though the absence of necrosis in this model precludes assessment of the sensitivity and specificity of NOGA mapping to identify infarction, our findings highlight important methodological limitations in using electromechanical mapping to determine viability.

I-type plutonism in a continental back-arc setting: Miocene granitoids and monzonites from the central Aegean Sea, Greece

Miocene extension in the Aegean Sea was accompanied by the intrusion of granitoid and monzonitic magmas at upper crustal levels. With increasing distance from the trench, the metaluminous to slightly peraluminous I-type intrusives show a systematic regional variation in their compositions: medium- to high-K granodiorites in the WSW, high-K low-silica granites in the central region and high-K high-silica granites, monzonites, monzogranites and composite lamprophyric-monzonitic dikes in the ENE. The granodioritic and low-silica granitic plutons comprise similar ranges of SiO2 (63.5–71.6 wt%) and initial Nd–Sr and O isotopic values [eNd(I)=–7.0 to –9.8; 87Sr/86Sr(I)=0.7092–0.7115; δ18O=9.7–11.5‰], but display significant differences in their chemical compositions. Compared with the granodiorites, the low-silica granites have higher abundances of large ion lithophile, light rare earth and some high-field strength elements. Initial isotopic signatures of the high-silica granites in the ENE [eNd(I)=–9.0 to –9.6; 87Sr/86Sr(I)=0.7128–0.7144; δ18O=10.8–12.0‰] are slightly more 'crust-like' than those of the low-silica granites. In chemical variation diagrams, samples from the high-silica granites continue the trends defined by those from the low-silica granites. It is suggested that all granitoid magmas originated by dehydration melting of metaluminous older crustal sources, most probably metagreywackes. U–Pb systematics of zircon populations in conjunction with Zr–SiO2 systematics and zircon saturation temperatures suggest a high proportion of restitic or assimilated crustal material in these magmas. Monzonitic to monzogranitic rocks show chemical and isotopic characteristics [eNd(I)=–0.8 to –3.6; 87Sr/86Sr(I)=0.7059–0.7071; δ18O=9.4–10.6‰] that are significantly different from those of the granitoids. A small portion of an older crustal component in these magmas is indicated by U–Pb systematics of zircon populations. Lamprophyric dikes display chemical and isotopic signatures [eNd(I)≈+0.5; 87Sr/86Sr(I)≈0.7044; δ18O≈8.9‰] that are compatible with an origin from either a mantle source previously enriched by slab-derived hydrous fluids/melts as suggested by negative Nb–Ta anomalies or a new K-rich basaltic underplate. Abundant composite dikes indicate the coexistence of and mingling/mixing between lamprophyric melts and monzonitic magmas.