bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specific Targeting of Pancreatic Islet Cells In Vivo by Insulin‐Promoter‐Driven Adenoviral Conjugated Reporter Genes
Authors: Wang Xiaoping , Olmsted‐Davis Elizabeth , Davis Alan , Liu Shihe , Li Zhijun , Yang Jie , Brunicardi F. Charles 
Published: July 2006

AbstractBackgroundThe objective of this study was to determine whether rat insulin promoter (RIP) could, in a mouse model, direct expression of an adenovirus‐mediated reporter gene specifically into pancreatic islets via systemic delivery.MethodsFive hundred and eight base pairs of the RIP DNA sequence were constructed into an adenoviral vector containing a lacZ reporter gene (Adeno‐RIP‐lacZ). The cytomegalovirus (CMV) promoter was constructed to drive lacZ reporter‐gene expression (Adeno‐CMV‐lacZ) and used as controls. In vitro transient transfection assays were performed to determine levels of reporter‐gene expression and compared with that of liposome‐mediated plasmid transfection. SCID mice were bred and housed in the barrier BL‐4 animal facility. At 2 months of age, the human pancreatic cancer cell PANC‐1 was intraperitoneally injected into male mice. Two months after the tumor cell inoculation, mice were injected with 107 adenoviral particles via tail veins. After gene delivery, mice were sacrificed at different time points to determine transgene expression levels. Complete necropsies were performed. Morphological alterations were determined using hematoxylin and eosin (H&E) staining, and distribution of the reporter lacZ gene was determined by immunohistochemistry analyses.ResultsAdenoviral‐driven reporter‐gene expression resulted in more than 5 times higher transgene expression compared with conventional plasmid transfections. In Adeno‐RIP‐lacZ‐injected mice, lacZ expression was specifically detected in pancreatic islets. By contrast, in Adeno‐CMV‐lacZ‐injected mice, lacZ gene expression was observed in multiple organs and tissues. Mononuclear cell infiltration and liver cell inflammation were found in Adeno‐CMV‐lacZ‐treated mice. Similar phenomena were observed in islet cells of Adeno‐RIP‐lacZ‐treated mice. A significantly higher level of reporter‐gene expression was also found at the edge of in‐vivo‐inoculated human pancreatic tumors.ConclusionThese results demonstrate that RIP‐directed reporter‐gene expression was found specifically in mouse pancreatic islets and implanted human pancreatic cancer cells. These data thus demonstrate that the combination of an adenoviral vector and a tissue‐specific promoter could lead to an enhanced and more specific transgene expression in vivo.
Leaf Physiognomy and Climate: A Multivariate Analysis
Authors: Davis J. M. , Taylor S. E. 
Published: July 2006

AbstractResearch has demonstrated that leaf physiognomy is representative of the local or microclimate conditions under which plants grow. The physiognomy of leaf samples from Oregon, Michigan, Missouri, Tennessee, and the Panama Canal Zone has been related to the microclimate using Walter diagrams and Thornthwaite water-budget data. A technique to aid paleoclimatologists in identifying the nature of the microclimate from leaf physiognomy utilizes statistical procedures to classify leaf samples into one of six microclimate regimes based on leaf physiognomy information available from fossilized samples.
Magnetostratigraphy and Pliocene-Pleistocene Boundary in Italy
Authors: Arias Claudio , Azzaroli Augusto , Bigazzi Giulio , Bonadonna Francescopaolo 
Published: July 2006

AbstractAnalysis of some sedimentary series near Rome and comparison with other series in northern and southern Italy give evidence that Arctica islandica, considered a marker species for the beginning of the Pleistocene, appears during the Réunion paleomagnetic event (about 2 my ago). A period of erosion, called the Aullan erosional phase, is evident in the lower part of the late Villafranchian (= early Pleistocene, Olivola faunal unit).
Age of Tunica Hills (Louisiana-Mississippi) Quaternary Fossiliferous Creek Deposits; Problems of Radiocarbon Dates and Intermediate Valley Terraces in Coastal Plains
Authors: Otvos Ervin G. 
Published: July 2006

AbstractAmong numerous stream-valley terrace deposits of the Gulf and Atlantic coastal plains that occupy chronologically and spatially intermediate positions between the youngest coastwise (coast-parallel) Pleistocene surface and the present, active floodplain, those of the Tunica Hills seem to provide by far the best opportunity for radiometric dating. Earlier views on the age of the Little Bayou Sara creek alluvium, represented by a single, 8 to 10-m-thick unit, ranged between the last interglaciation and middle Holocene. Reexamination of these deposits in the Little Bayou Sara and adjacent valleys clearly suggests their Late Pleistocene (apparently Farmdalian Interstade) age. The majority of the 14 available dates from the Little Bayou Sara and Tunica Bayou valleys proved to be too young, due to postdepositinal contamination. Dates ranging between 33,720 and 25,965 yr B.P. came from samples thought to be uncontaminated. Plant and faunal elements with boreal affinities in the unique fossil assemblage appear to be relicts of a preceding, full-glacial period, as regarded by Brown (1938). The absence of colder climate taxa from the Wilcox Bluff flora on Bayou Sara is insufficient evidence for a suggested Sangamon Interglacial age of the flora, and the terrace stratigraphy holds no proof for that view either. Only a single, loess-mantled, constructional, Quaternary, valley-terrace surface is present in the area. A narrow, low, actively developing floodplain terrace along Little Bayou Sara, cut into the Pleistocene alluvial unit, is primarily erosional in origin and has no bearing on the age of that unit. The age of the Tunica Hills terrace unit may provide comparison for dating intermediate valley-terrace deposits in favorable coastal settings elsewhere.
Quaternary Vegetation History of the Mississippi Embayment,
Authors: Delcourt Paul A. , Delcourt Hazel R. , Brister Ronald C. , Lackey Laurence E. 
Published: July 2006

AbstractNonconnah Creek, located in the loess-mantled Blufflands along the eastern wall of the Lower Mississippi Alluvial Valley in Tennessee displays a sedimentary sequence representing the Altonian Substage through the Woodfordian Substage of the Wisconsinan Stage. The site has a biostratigraphic record for the Altonian and Farmdalian Substages that documents warm-temperate upland oak-pine forest, prairie, and bottomland forest. At 23,000 yr B.P., white spruce and larch migrated into the Nonconnah Creek watershed and along braided-stream surfaces in the Mississippi Valley as far as southeastern Louisiana. The pollen and plant-macrofossil record from Nonconnah Creek provides the first documentation of a full-glacial locality in eastern North America for beech, yellow poplar, oak, history, black walnut, and other mesic deciduous forest taxa. During the full and late glacial, the Mississippi Valley was a barrier to the migration of pine species, while the adjacent Blufflands provided a refuge for mesic deciduous forest taxa. Regional climatic amelioration, beginning about 16,500 yr B.P., is reflected by increases in pollen percentages of cooltemperate deciduous trees at Nonconnah Creek. The demise of spruce and jack pine occurred 12,500 yr B.P. between 34° and 37° N in eastern North America in response to postglacial warming.
Palynology of the Last Interglacial-Glacial Cycle in Midlatitudes of Southern Chile
Authors: Heusser Calvin J. 
Published: July 2006

AbstractPollen and spores in stratigraphic sections located between 40 and 42°S range in age from the Holocene, through much of the Llanquihue Glaciation, to the last interglaciation. Chronology of the stratigraphy derives from some 35 14C ages and the age relations of Llanquihue Drift and related deposits. Q-Mode, rotated, principal-components analysis of four key pollen records covering the last interglacial-glacial cycle resulted in four leading components: Nothofagus dombeyi type, Gramineae, Weinmannia-Fitzroya type, and Myrtaceae. Analysis emphasizes interaction between the first two components. Loadings of Gramineae during the interglaciation are high, unlike the Holocene; Weinmannia-Fitzroya-type loadings, prominent in the Holocene, are negligible during the interglaciation. N. dombeyi type is the primary component during Llanquihue Glaciation; it becomes modified by increases of Gramineae sometime after 31,000 and before 14,000 yr B.P. and of Myrtaceae later. The Myrtaceae with Weinmannia-Fitzroya type also registers some activity around 42,000 yr B.P. Fluctuations in the belt of westerly winds, reflecting changing meteorological conditions in polar latitudes, are suggested by these data. With the belt located farther south than it is today, interglacial climate was much drier and warmer than during the Holocene; more northerly displacement of the belt obtained when climate was colder during Llanquihue Glaciation. Evidence from comparable latitudes in the Southern Hemisphere points toward a synchrony of major climatic events indicating harmonious fluctuations in the position of the westerlies.
Quantitative Estimates of Temperature Changes Over the Last 2700 Years in Michigan Based on Pollen Data
Authors: Bernabo J. Christopher 
Published: July 2006

AbstractTemperatures for the past 2700 yr are estimated using well-dated pollen data from northwestern lower Michigan. The pollen data were sampled from sediment cores of four lakes along a 75-km transect, with fine-grained morainic soils around the two western lakes and sandy outwash soils around the lakes to the east. Climatic reconstructions based on the pollen data from the sandy sites show less temperature change than the reconstructions from the other sites, because variations in the composition of the vegetation at the sandy sites are edaphically restricted. One of the cores studied was dated by counting visible annual laminations (varves). The cores from the other lakes were dated based on three radiocarbon dates per core as well as the historically determined age of the settlement horizons. All the time scales were cross-checked using pollen-stratigraphic correlation between the four sites. A calibration function was developed using a network of modern pollen and climate data covering all of lower Michigan. Based on this calibration function, the 2700-yr reconstruction for Marion Lake indicates an estimated growing-season temperature range of 1.3°C between extreme 30-yr means. Mild conditions persisted prior to ca. A.D. 400, but a cold interval occurred between ca. A.D. 500 and 800. The well-marked warm period evident from ca. A.D. 1000 to 1200 was the last time when temperatures were about equal to the 1931–1960 mean. A prolonged longed cooling occurred after A.D. 1200 and reached 1°C below the 1931–1960 mean by the 1700s. A warming of 0.5°C is indicated from ca. A.D. 1750 to 1850. The estimated temperatures for the 1830s at Marion Lake agree with the instrumental data for that period and this provides some validation of the calibration-function results.
Ephemeral-Stream Processes: Implications for Studies of Quaternary Valley Fills
Authors: Patton Peter C. , Schumm Stanley A. 
Published: July 2006

AbstractThree unstable ephemeral-stream channels (arroyos), which drain source areas that have high sediment yields ranging from predominantly sand (Arroyo Calabasas) to a mixture of sand, silt, and clay (Sand Creek) to largely silt and clay (Sage Creek), were resurveyed to provide data on the rates and mechanics of erosion and sedimentation processes during periods ranging from 14 to 22 yr. Channel morphology changed significantly. Erosion occurred through nickpoint recession and bank collapse, but erosional reaches are separated by aggrading or stable-channel reaches. In general, sediment that is eroded, as the nickpoint recedes upstream, is trapped in the widened channel downstream. In this manner sediment is transported episodically out of these basins during a series of cut-and-fill cycles. The manner by which the channels aggrade and the morphology of the aggraded stable channels are controlled by the sediment type. The wide and shallow channel of Arroyo Calabasas is filled by vertical accretion of sand-size sediment. The narrow and deep channels of Sage Creek and Sand Creek are created by the lateral accretion of cohesive fine-grained sediment. The channel modification and the cut-and-fill episodes are dependent on high sediment yields, and therefore they are independent of subtle climatic shifts. Cut-and-fill deposits that have been created in this manner should not be equivalent in age from basin to basin, and therefore channel trenching and filling in the semiarid western United States during the Holocene need not be synchronous.
Late Quaternary Glacial History of George VI Sound Area, West Antarctica
Authors: Clapperton Chalmers M. , Sugden David E. 
Published: July 2006

AbstractDuring the last glacial maximum in West Antarctica separate ice caps developed on Alexander Island and on Palmer Land, became confluent in George VI Sound, and discharged northward from latitude 72° S. Radiocarbon (>32,000 yr) and amino acid (approximately 120,000 yr) age determinations on shell fragments (Hiatella solida) found in basal till suggest a Wisconsin age for the glaciation that incorporated them. The pattern of ice flow differed from that deduced for this area in the CLIMAP reconstruction. Following the maximum stage, there was a stadial event when outlet valley glaciers flowed from smaller ice caps into George VI Sound. More widespread recession permitted the George VI ice shelf to deposit Palmer Land erratics on eastern Alexander Island before isostatic recovery raised them to final elevations of about 82 m. The ice shelf may have been absent at about 6500 yr B.P., when large barnacles (Bathylasma corolliforme) were living in the sound. Small glaciers readvanced to form at least two terminal moraines before the ice shelf re-formed and incorporated the barnacle shells into its moraine on Alexander Island. The shells gave a 14C age (corrected for Antarctic conditions) of about 6500 yr B.P. and an amino acid ratio consistent with a Holocene age. Valley glaciers readvanced over the ice-shelf moraine before oscillations of both valley glaciers and the ice shelf led to the formation of the present sequence of contiguous ice-cored moraines, probably during the Little Ice Age. Such oscillations may represent a climatic control not yet observed in the dry valleys of Victoria Land, the only other part of Antarctica studied in detail for glacier fluctuations.
Amino Acid Age Estimates, Quaternary Atlantic Coastal Plain: Comparison with U-series Dates, Biostratigraphy, and Paleomagnetic Control
Authors: Wehmiller J. F. , Belknap D. F. 
Published: July 2006

AbstractAmino acid enantiomeric (D/L) ratios in the mollusk Mercenaria are compared with recently published biostratigraphic and/or U-series solitary coral data from 22 Quaternary localities on the central and southern Atlantic Coastal Plain. In all cases, local relative aminostratigraphic sequences are consistent with relative ages inferred from U-series or biostratigraphic data, although occasionally more depositional events are recognized by aminostratigraphic than biostratigraphic methods. However, if the U-series data are used as age calibrations for the D/L values, latitudinal trends of “isochronous” D/L values are highly variable and conflict with trends expected from the present temperature gradient, which is smooth and nearly linear between 45° and 25° N. Age estimation can be performed independently of the U-series data using a kinetic model that relies on the assumption that Pleistocene temperature gradients have also been smooth functions of latitude, although significantly steeper than the present temperature gradient. Within the uncertainties of this assumption, kinetic model age estimates for localities in the coastal plain fall into the following groups: 70,000–130,000 yr, 200–250,000 yr, 300,000–400,000 yr, 500,000–600,000 yr, 700,000–800,000 yr, and > 1,000,000 yr. Major conflicts between these model age estimates are observed for localities near Charleston, South Carolina and in central Virginia. These conflicts could indicate that the basic temperature assumptions of aminostratigraphy are incorrect, and that apparent local aminostratigraphic sequences (clusters of different D/L values) could be due to factors other than age difference. Alternatively, some of the U-series dates may be only minimum ages for these localities.
Comparison of Amino Acid Racemization Geochronometry with Lithostratigraphy, Biostratigraphy, Uranium-Series Coral Dating, and Magnetostratigraphy in the Atlantic Coastal Plain of the Southeastern United States
Authors: McCartan L. , Owens J. P. , Blackwelder B. W. , Szabo B. J. , Belknap D. F. , Kriausakul N. , Mitterer R. M. , Wehmiller J. F. 
Published: July 2006

AbstractThe results of an integrated study comprising litho- and biostratigraphic investigations, uranium-series coral dating, amino acid racemization in molluscs, and paleomagnetic measurements are compared to ascertain relative and absolute ages of Pleistocene deposits of the Atlantic Coastal Plain in North and South Carolina. Four depositional events are inferred for South Carolina and two for North Carolina by all methods. The data suggest that there are four Pleistocene units containing corals that have been dated at about 100,000 yr, 200,000 yr, 450,000 yr, and over 1,000,000 yr. Some conflicts exist between the different methods regarding the correlation of the younger of these depositional events between Charleston and Myrtle Beach. Lack of good uranium-series dates for the younger material at Myrtle Beach makes the correlation with the deposits at Charleston more difficult.
Late Holocene Lacustrine Chronology and Archaeology of Ancient Lake Cahuilla, California
Authors: Waters Michael R. 
Published: July 2006

AbstractFreshwater lakes existed intermittently in the Salton Trough of southern California during the late Holocene. The lakes formed north of the subaerial Colorado River Delta whenever the Colorado River flowed west into the trough instead of south to the Gulf of California. Water filled the trough to a maximum altitude of 12 m. Stratigraphy, radiocarbon dates, and supplementary evidence document four lacustral intervals of Lake Cahuilla between A.D. 700 and 1580. Archaeological sites are associated with the 12-m shoreline and their occupation correlates with these lacustral intervals.
Late Holocene Vegetational Change in Central Madagascar
Authors: Burney David A. 
Published: July 2006

AbstractA sediment core from Lake Kavitaha, central Madagascar, provides a stratigraphic record of changes in pollen spectra and charcoal influx in the late Holocene. The earliest pollen spectra distantly resemble the modern pollen rain of a vegetational mosaic in northern Madagascar, although results of principal component analysis suggest no close modern analog. At about 1300 yr B.P., a marked rise in charcoal is followed by a decline in pollen of woody taxa, culminating in a change to grass-dominated pollen spectra within about 4 centuries. Pollen of woody taxa decline below 15% of total terrestrial pollen and spores beginning about 600 yr B. P. The influx of charcoal from graminoid sources remains high until recent centuries. The late Holocene changes in vegetation and fire ecology at the site were approximately contemporaneous with the latest 14?C dates for the extinct megafauna and the earliest dates for human occupation.
Pedogenic Gradients for Iron and Aluminum Accumulation and Phosphorus Depletion in Arctic and Alpine Soils as a Function of Time and Climate
Authors: Birkeland Peter W. , Burke Raymond M. , Benedict James B. 
Published: July 2006

AbstractPedogenically significant chemical extracts of iron, aluminum, and phosphorus are related mainly to time in chronosequences from Baffin Island (Canadian Arctic), the alpine Sierra Nevada and Wind River Range (western United States), the alpine Khumbu Glacier area (Himalaya, Nepal), and the alpine Southern Alps (New Zealand). Based on the accumulation index for Fe and Al, and the depletion index for P in each region, the following ranking of chemical pedogenic development is obtained: Southern Alps > Khumbu Glacier area ≅ Wind River Range > Sierra Nevada > coastal Baffin Island > inland Baffin Island. The ranking mainly follows regional climate, with the greatest accumulation and depletion to the warmest and wettest environment, and the least accumulation and depletion in the coldest and driest environment.
Radiocarbon Dating of Pollen by Accelerator Mass Spectrometry
Authors: Brown Thomas A. , Nelson D. Erle , Mathewes Rolf W. , Vogel John S. , Southon John R. 
Published: July 2006

AbstractRadiocarbon dating of bulk sediments has been the standard method for establishing chronologies in the studies of lake sediment cores which have contributed significantly to our knowledge of late Quaternary paleo-environments. These bulk sediment dates are presumed to be direct ageindicators for the speciments (e.g., pollen or macrofossils) which are actually being studied. However, several recent studies have reinforced long-standing apprehensions concerning this presumption. In this study, we demonstrate for the first time the radiocarbon dating of pollen concentrate samples by accelerator mass spectrometry. The dates obtained by this method should provide more reliable radiocarbon chronologies for paleo-environmental studies than have been obtainable by bulk sediment dating.
Chronology of Inland Shell Deposits on the Southern Coast of Sri Lanka
Authors: Katupotha Jinadasa , Wijayananda N.P. 
Published: July 2006

AbstractExtensive patches of fossil shell deposits are found in many places along the rims of emerged coastal embayments and lagoon floors on the southern coast of Sri Lanka. Compositional and depositional sequences of fossil shells (Veneridae, Cerithidae, and Nassaridae) reveal that the bulk of the valves has been accumulated by three processes: (a) the shells have been piled up on the rims of emerged coastal embayments mainly by wave action; (b) following coastal progradation since the late Subboreal the shells possibly gathered on lagoon floors; and (c) the valves on the coastal hilly areas and dune areas were discarded by early human inhabitants in the course of their daily activities. Radiocarbon dates of fossil corals along the southwest and south coasts support this interpretation and indicate that mean sea level was at least 1 m higher than present in the middle Holocene. The fossil species may have lived in an intertidal zone of embayments and lagoons that extended 3 km or more inland form the present shore in the middle Holocene.