bluuebunny/crossref_metadata_2025 huggingface dataset:
Climatic Interpretation of Alpine Snowline Variations on Millennial Time Scales
Authors: Seltzer Geoffrey O.
Published: October 2002

The depression of snowlines, or equilibrium-line altitudes, of alpine glaciers is often used by glacial geologists to infer variations in mass balance. The climatic interpretation of snowline depression, however, is complicated by the number of factors that control glacier mass balance. The simple lapse-rate method of temperature interpretation ignores the effects of changes in radiation and snow accumulation. The statistical approach to temperature interpretation, which regresses precipitation and temperature against snowline altitude, neglects the effect of radiation. The most comprehensive approach for the climatic interpretation of snowline depression couples the heat and mass balances of a glacier surface. A sensitivity analysis that utilizes the coupled heat- and mass-balance approach indicates that the ∼1000-m variation in snowline of alpine glaciers on glacial-to-interglacial time scales could be a result of significant changes in temperature, and to a lesser extent changes in insolation. Snowline variations are sensitive only to relatively large changes in annual accumulation, which should also be evident in other proxy records of moisture change. The approaches outlined here provide glacial geologists with a summary of how various climatic forcings associated with glaciation may be quantified from snowline data.
Evidence for a Large Earthquake and Tsunami 100-400 Years Ago on Western Vancouver Island, British Columbia
Authors: Clague John J. , Bobrowsky Peter T.
Published: October 2002

A peaty marsh soil is sharply overlain by a sand sheet and intertidal mud at tidal marshes near Tofino and Ucluelet, Vancouver Island, British Columbia. Foraminifera and vascular plant fossils show that the buried soil was submerged suddenly and was covered quickly by sand. Radiocarbon ages place this event between 100 and 400 yr ago. The coastal subsidence suggested by the submergence occurred in an area of net late Holocene emergence, perhaps during the most recent great earthquake on the northern part of the Cascadia subduction zone. The sand sheet overlying the peaty soil records the tsunami triggered by this earthquake. Similar stratigraphic sequences of about the same age have been reported from estuaries along the outer coasts of Washington and northern Oregon, suggesting that hundreds of kilometers of the Cascadia subduction zone may have ruptured during one, or a series of plate-boundary earthquakes less than 400 yr ago.
Glacier Modeling and the Climate of Patagonia during the Last Glacial Maximum
Authors: Hulton Nick , Sugden David , Payne Antony , Clapperton Chalmers
Published: October 2002

Ice cap modeling constrained by empirical studies provides an effective way of reconstructing past climates. The former Patagonian ice sheet is in a climatically significant location since it lies athwart the Southern Hemisphere westerlies and responds to the latitudinal migration of climatic belts during glacial cycles. A numerical model of the Patagonian ice cap for the last glacial maximum (LGM) is developed, which is time-dependent and driven by changing the mass balance/altitude relationship. It relies on a vertically integrated continuity model of ice mass solved over a finite difference grid. The model is relatively insensitive to ice flow parameters but highly sensitive to mass balance. The climatic input is adjusted to produce the best fit with the known limits of the ice cap at the LGM. The ice cap extends 1800 km along the Andes and has a volume of 440,000 km3. During the LGM the equilibrium line altitude (ELA) was lower than at present by at least 560 m near latitude 40°S, 160 m near latitude 50°S, and 360 m near latitude 56°S. The latitudinal variation in ELA depression can be explained by an overall fall in temperature of about 3.0°C and the northward migration of precipitation belts by about 5° latitude. Annual precipitation totals may have decreased by about 0.7 m at latitude 50°S and increased by about 0.7 m at latitude 40°S. The ELA rises steeply by up to 4 m per kilometer from west to east as the westerlies cross the Andes and this prevents ice growth to the east. The limited decrease in temperature during the LGM could be related to the modest migration of the Antarctic convergence between South America and the Antarctic Peninsula.
Continuous Holocene Record of Diatom Stratigraphy, Paleohydrology, and Anthropogenic Activity in a Spring-Mound in Southwestern United States
Authors: Blinn Dean W. , Hevly Richard H. , Davis Owen K.
Published: October 2002

This study presents the first continuous record of fossil diatoms taken from an open spring-mound in southwestern United States. Diatoms were analyzed from a radiocarbon-dated core taken from Montezuma Well, a near thermally constant spring in northcentral Arizona. Fluctuations in total diatom density, oscillations in the relative abundance of Anomoeoneis sphaerophora, and intermittent deposition of calcite suggest that water levels in Montezuma Well underwent dramatic fluctuations to the degree of being intermittently dry, or at least very shallow, during the middle Holocene (∼8000-5000 yr B.P.). The fluctuations in water level probably correspond to oscillations in regional temperature and precipitation, which regulate hydrologic input and evaporation rates. The dramatic fluctuations in water level during the middle Holocene suggest that the endemic biota of Montezuma Well underwent relatively rapid speciation within the past ∼5000 yr. The appearance of endemic species (Gomphonema montezumense and Cyclotella pseudostelligera f. parva ) at ∼5000-3000 yr B.P. supports this hypothesis. Diatom indicators for organic enrichment (Aulacoseira granulata and A. islandica) closely coincide with the prehistoric native occupation of Montezuma Well.
A Multiproxy Investigation of Late-Glacial Climate and Vegetation Change at Pine Ridge Pond, Southwest New Brunswick, Canada
Authors: Levesque André J. , Cwynar Les C. , Walker Ian R.
Published: October 2002

Pollen, plant macrofossil, chironomid, and lithological analyses of late-glacial sediment from Pine Ridge Pond all indicate that the warming following deglaciation was punctuated on two separate occasions by a return to colder climes; initially by a brief and moderate cold episode (the Killarney Oscillation), followed shortly by the Younger Dryas. The Killarney Oscillation, AMS 14C dated at between 11,290 and 10,960 yr B.P., is characterized by abrupt and simultaneous increases in Betula (birch) pollen and Betula glandulosa (dwarf birch) macrofossils and a decline in tree pollen. The Younger Dryas is distinguished by the reversion of a short-lived closed Picea (spruce) forest to a prolonged forest-tundra stage (ca. 10, 820 to 9500(?) yr B.P.), during which macrofossils of arctic/alpine plants such as Salix herbaces, Cassiope hypnoides, Armeria maritima, and Thalictrum alpinum make their sole late-glacial appearance. Chironomid-inferred summer surface-water temperatures indicate a cooling of approximately 8 and 12°C during the Killarney Oscillation and Younger Dryas, respectively, and coarse-sand analysis indicates increased erosion on the landscape during these same intervals.
Particle-Size Evidence for Source Areas of Charcoal Accumulation in Late Holocene Sediments of Eastern North American Lakes
Authors: Clark James S. , Royall P.Dan
Published: October 2002

Two methods of analyzing charcoal in sediment reveal changes in charcoal accumulation across temperate eastern North America during the last several hundred years. In one method the analyst counts mostly small particles that reflect regional emissions; in the other, the analyst counts only larger particles derived mostly from such local sources as catchment fires. We used these methods to compare charcoal accumulation at 14 lakes from the prairie/forest border in Minnesota to eastern Maine. The two methods gave concordant accumulation rates for sediments of pre-1850 age at each of 4 lakes analyzed by both methods. This concordance is consistent with the interpretation that pre-1850 emissions were controlled by broad-scale factors, such as climatically controlled regional differences in fuels and moisture. Since 1900 large particles decreased greatly, and small particles decreased slightly, in Minnesota and Wisconsin. By contrast in the Northeast the large particle accumulation has remained at the low values measured in pre-1900 sediments at most sites, while small particles increased everywhere east of central New York and Pennsylvania. The observed patterns suggest that (1) large particles primarily reflect local fires that were common in the Midwest before fire suppression became effective, (2) large particles were rare in the Northeast, especially before extensive land clearance, (3) small particles reflect regional combustion that increased in the Northeast after extensive use of fire for land clearance and wood burning for industrial purposes of the 19th century, and (4) small particles remain abundant in the Midwest long after effective fire suppression, probably because these well-dispersed small particles have a large source area that extends beyond the local wildfires that account for large particles before European settlement.
Sedimentary and Paleoclimatic Controls on Caddisfly (Insecta: Trichoptera) Assemblages during the Last Interglacial-to-Glacial Transition in Southern Ontario
Authors: Williams Nancy E. , Eyles Nicholas
Published: October 2002

Southern Ontario, Canada, has late Pleistocene deposits that contain evidence for climatic cooling during the last interglacial/glacial transition and much of the succeeding Wisconsin glaciation. Fossils of lacustrine and riverine caddisflies (Insecta: Trichoptera) are abundant and well-preserved in these deposits. We examined 26 samples from the interglacial section exposed in the Don Valley Brickyard and compared their caddisfly assemblages with those recovered from the overlying early Wisconsin Scarborough Formation deposits at nearby Scarborough Bluffs. Fifty-one caddisfly taxa in 16 families were recovered from the Don Valley site. Fossil abundance and species richness appear related to the storm or fair-weather conditions inferred from the sedimentary facies. Caddisfly fossils were most abundant and species richness highest in fair-weather, peaty, rippled sands. Highest proportions of river species as opposed to lake species were recovered from sands (storm and fair-weather). Assemblages from both sites indicate the presence of a large and productive river flowing into ancestral Lake Ontario. However, the river assemblage appeared to be far more sensitive to environmental change than the relatively stable assemblage representing the thermally buffered lake. Warm temperate river species such asHydropsyche bidens, Hydropsyche mississippiensis, Macrostemum carolina, and Potamyia flavaare present in the lower Don samples but absent from the Scarborough Bluffs deposits, while indicators of cooler than present climatic conditions such asArctopsyche IndogensisandHagenella canadensisare present in the Scarborough Bluffs sediments but absent from the lower Don samples. For the interval from about 80,000 to 55,000 yr B.P., we infer a climatic cooling from temperature about 2°C warmer than present to about 3°C cooler than present.
Buried Soils in a Perched Dunefield as Indicators of Late Holocene Lake-Level Change in the Lake Superior Basin
Authors: Anderton John B. , Loope Walter L.
Published: October 2002

A stratigraphic analysis of buried soils within the Grand Sable Dunes, a dune field perched 90 m above the southern shore of Lake Superior, reveals a history of eolian activity apparently linked with lake-level fluctuations over the last 5500 yr. A relative rise in the water plane of the Nipissing Great Lakes initially destabilized the lakeward bluff face of the Grand Sable plateau between 5400 and 4600 14C yr B.P. This led to the burial of the Sable Creek soil by eolian sediments derived from the bluff face. Subsequent episodes of eolian activity appear to be tied to similar destabilizing events; high lake levels may have initiated at least four and perhaps eleven episodes of dune building as expressed by soil burials within the dunes. Intervening low lake levels probably correlate with soil profile development, which varies from the well-developed Sable Creek Spodosol catena to thin organic layers containing in-place stumps and tree trunks. Paleoecological reconstructions available for the area do not imply enough climatic change to account for the episodic dune activity. Burial of soils by fine-fraction sediments links dune-building episodes with destabilization of the lower lake-facing bluff, which is rich in fines.
Mid-Holocene Hemlock Decline in Eastern North America Linked with Phytophagous Insect Activity
Authors: Bhiry Najat , Filion Louise
Published: October 2002

Macrofossil evidence indicates that the mid-Holocene hemlock [Tsuga canadensis L. (Carr.)] decline that occurred over a wide area in eastern North America was associated with phytophagous insect activity. In situ hemlock macrofossils and insect remains found in a paludified dunefield at the northern limit of hemlock testify that two defoliation events occurred at 4910 ± 90 and 4200 ± 100 yr B.P., respectively. The sharp coincidence of remains from hemlock needles with chewing damage typical of hemlock looper feeding, head capsules from the hemlock looper (Lambdina fiscellaria) and the spruce budworm (Choristoneura fumiferana), absence of hemlock fruiting remains, and tree-ring anomalies in fossil hemlocks that died prematurely (<165 yr) suggest that defoliation affected hemlock reproductive capacity and pollen productivity, or more likely caused mass mortality. Our findings indicate that defoliation can affect ecosystems for centuries, especially when long-lived tree species are involved.
Palaeoecology and Archaeology of the Kärlich–Seeufer Open-Air Site (Middle Pleistocene) in the Central Rhineland, Germany
Authors: Gaudzinski Sabine , Bittmann Felix , Boenigk Wolfgang , Frechen Manfred , Kolfschoten Thijs Van
Published: October 2002

The Kärlich–Seeufer archaeological site in Germany's central Rhineland was excavated between 1980 and 1992. The site provides evidence for hominid activity during a Middle Pleistocene interglaciation known up to now only from the Kärlich clay pit and therefore defined as the Kärlich Interglaciation, which is considered to be post-Cromer IV and pre-Holstein (sensu stricto) in age. The site is characterized by Acheulean artifacts, a fauna dominated by Elephas (Palaeoloxodon) antiquus, and a unique and outstanding preservation of wooden and other palaeobotanical remains. Assuming all finds are associated, the site previously was interpreted as an elephant hunting camp with a wooden structure, together with wood and bone implements preserved in situ. Recent analysis of the same features has shown that the site can also be interpreted as a reworked archaeological sample. Hominid occupation occurred in the vicinity of a small lake with prevailing meso-oligotrophic conditions. Expanding boreal forests and fen vegetation characterized the landscape.
Astronomical Forcing of Contrasting Rainfall Changes in Tropical South America between 12,400 and 8800 cal yr B.P.
Authors: Martin Louis , Bertaux Jacques , Corrège Thierry , Ledru Marie-Pierre , Mourguiart Philippe , Sifeddine Abdelfettah , Soubiès François , Wirrmann Denis , Suguio Kenitiro , Turcq Bruno
Published: October 2002

Today, precipitation over tropical South America is largely controlled by the seasonal movements of the Inter-Tropical Convergence Zone (ITCZ). During the summer, the ITCZ is shifted southward due to the warming of the continent. Paleoclimate data from southeastern Amazonia and the central Andes indicate that these two areas evolved similarly during the last 30,000 yr. However, between 12,400 and 8800 cal yr B.P., eastern Amazonia received substantial moisture whereas the Bolivian Altiplano was arid. This suggests that the ITCZ during summer was then farther north than it is today.
Late Quaternary Paleoclimate in the Eastern Mediterranean Region from Stable Isotope Analysis of Speleothems at Soreq Cave, Israel
Authors: Bar-Matthews Miryam , Ayalon Avner , Kaufman Aaron
Published: October 2002

The eastern Mediterranean continental paleoclimate during the past 25,000 years was determined by a high-resolution petrographic, stable isotopic, and age study of speleothems from Soreq Cave, Israel. δ18O–δ13C trends indicate that all speleothems older than 7000 yr formed under conditions that differ from those of today. The period from 25,000 to 17,000 yr B.P. was characterized by the highest δ18O and δ13C values, which indicate deposition at temperatures of 12°–16°C, annual rainfall of 300–450 mm, and vegetation typical of a mixed C3–C4type. From 17,000 to 10,000 yr B.P. (deglaciation in northern Europe) δ18O values dropped progressively, correlative with warming (2°–3°C) and a gradual increase in precipitation. A simultaneous decrease in δ13C gives a range expected for C3-type vegetation. This period also shows significant δ18O and δ13C “spikes” which are correlatable with global events (e.g., Heinrich events and the Younger Dryas Stade). The speleothems that grew between 10,000 and 7000 yr B.P. have a unique petrography showing irregular thin laminae of various colors and much detritus. They have the lowest δ18O (corresponding to ∼1000 mm rain) coupled with the highest δ13C (caused by flooding events which stripped the soil cover). From 7000 to 1000 yr B.P. conditions became closer to those of today. This study demonstrates that global events which were recognized in Northern Europe and North Africa are also evident in the eastern Mediterranean and are reflected principally by large changes in the rainfall rate.
Paleobiological Implications of the Isotopic Signatures (13C,15N) of Fossil Mammal Collagen in Scladina Cave (Sclayn, Belgium)
Authors: Bocherens Hervé , Billiou Daniel , Patou-Mathis Marylène , Bonjean Dominique , Otte Marcel , Mariotti André
Published: October 2002

An isotopic investigation of upper Pleistocene mammal bones and teeth from Scladina cave (Sclayn, Belgium) demonstrated the very good quality of collagen preservation. A preliminary screening of the samples used the amount of nitrogen in whole bone and dentine in order to estimate the preserved amount of collagen before starting the extraction process. The isotopic abundances of fossil specimens from still-extant species are consistent with their trophic position. Moreover, the15N isotopic abundance is higher in dentine than in bone in bears and hyenas, a phenomenon already observed in modern specimens. These results demonstrate that the isotopic compositions of samples from Scladina cave can be interpreted in ecological terms. Mammoths exhibit a high15N isotopic abundance relative to other herbivores, as was the case in Siberian and Alaskan samples. These results suggest distinctive dietary adaptations in herbivores living in the mammoth steppe. Cave bears are clearly isotopically different from coeval brown bears, suggesting an ecological separation between species, with a pure vegetarian diet for cave bear and an omnivorous diet for brown bear.
Late-Glacial Vegetation and Climate Change in Western Oregon
Authors: Grigg Laurie D. , Whitlock Cathy
Published: October 2002

Pollen records from two sites in western Oregon provide information on late-glacial variations in vegetation and climate and on the extent and character of Younger Dryas cooling in the Pacific Northwest. A subalpine forest was present at Little Lake, central Coast Range, between 15,700 and 14,850 cal yr B.P. A warm period between 14,850 and 14,500 cal yr B.P. is suggested by an increase in Pseudotsuga pollen and charcoal. The recurrence of subalpine forest at 14,500 cal yr B.P. implies a return to cool conditions. Another warming trend is evidenced by the reestablishment of Pseudotsuga forest at 14,250 cal yr B.P. Increased haploxylon Pinus pollen between 12,400 and 11,000 cal yr B.P. indicates cooler winters than before. After 11,000 cal yr B.P. warm dry conditions are implied by the expansion of Pseudotsuga. A subalpine parkland occupied Gordon Lake, western Cascade Range, until 14,500 cal yr B.P., when it was replaced during a warming trend by a montane forest. A rise in Pinuspollen from 12,800 to 11,000 cal yr B.P. suggests increased summer aridity. Pseudotsuga dominated the vegetation after 11,000 cal yr B.P. Other records from the Pacific Northwest show an expansion of Pinus from ca. 13,000 to 11,000 cal yr B.P. This expansion may be a response either to submillennial climate changes of Younger Dryas age or to millennial-scale climatic variations.
Mean July Temperatures during the Younger Dryas in Northwestern and Central Europe as Inferred from Climate Indicator Plant Species
Authors: Isarin René F.B. , Bohncke Sjoerd J.P.
Published: October 2002

We estimated minimum mean July temperatures in northwestern and central Europe during the Younger Dryas (10,950–10,15014C yr B.P.) from distributions of climate indicator plant species, which were reconstructed from 140 pollen and plant macrofossil diagrams. Paleobotanical records, mainly from the central and eastern part of the study area, show that the coldest conditions occurred early in the Younger Dryas (before ∼10,55014C yr B.P.). For this phase, mean July temperatures at sea level of around 10°C are suggested for the northern part of the British Isles and for ice-free Scandinavia. We estimated a mean July temperature of 12°C for central England, The Netherlands, and northern Germany. The 13°C mean July isotherm—largely based on the modern distribution ofTypha latifolia—was most probably located in southern England, Belgium, central Germany, and Poland. The reappearance of thermophilous elements in the records after ∼10,55014C yr B.P. suggests a summer warming, at least temporarily, of 1° to 2°C in the study area. The reconstructed temperatures are comparable with temperature estimates based on beetle data. However, they appear rather high when compared with estimates based on glaciological evidence.
Physiological Significance of Low Atmospheric CO2 for Plant–Climate Interactions
Authors: Cowling Sharon A. , Sykes Martin T.
Published: October 2002

Methods of palaeoclimate reconstruction from pollen are built upon the assumption that plant–climate interactions remain the same through time or that these interactions are independent of changes in atmospheric CO2. The latter may be problematic because air trapped in polar ice caps indicates that atmospheric CO2 has fluctuated significantly over at least the past 400,000 yr, and likely the last 1.6 million yr. Three other points indicate potential biases for vegetation-based climate proxies. First, C3-plant physiological research shows that the processes that determine growth optima in plants (photosynthesis, mitochondrial respiration, photorespiration) are all highly CO2-dependent, and thus were likely affected by the lower CO2 levels of the last glacial maximum. Second, the ratio of carbon assimilation per unit transpiration (called water-use efficiency) is sensitive to changes in atmospheric CO2 through effects on stomatal conductance and may have altered C3-plant responses to drought. Third, leaf gas-exchange experiments indicate that the response of plants to carbon-depleting environmental stresses are strengthened under low CO2 relative to today. This paper reviews the scope of research addressing the consequences of low atmospheric CO2 for plant and ecosystem processes and highlights why consideration of the physiological effects of low atmospheric CO2 on plant function is recommended for any future refinements to pollen-based palaeoclimatic reconstructions.
Middle and Late Holocene Sea-Level Changes in Eastern Maine Reconstructed from Foraminiferal Saltmarsh Stratigraphy and AMS 14C Dates on Basal Peat
Authors: Gehrels W.Roland
Published: October 2002

A relative sea-level history is reconstructed for Machiasport, Maine, spanning the past 6000 calendar year and combining two different methods. The first method establishes the long-term (103 yr) trend of sea-level rise by dating the base of the Holocene saltmarsh peat overlying a Pleistocene substrate. The second method uses detailed analyses of the foraminiferal stratigraphy of two saltmarsh peat cores to quantify fluctuations superimposed on the long-term trend. The indicative meaning of the peat (the height at which the peat was deposited relative to mean tide level) is calculated by a transfer function based on vertical distributions of modern foraminiferal assemblages. The chronology is determined from AMS 14C dates on saltmarsh plant fragments embedded in the peat. The combination of the two different approaches produces a high-resolution, replicable sea-level record, which takes into account the autocompaction of the peat sequence. Long-term mean rates of sea-level rise, corrected for changes in tidal range, are 0.75 mm/yr between 6000 and 1500 cal yr B.P. and 0.43 mm/yr during the past 1500 year. The foraminiferal stratigraphy reveals several low-amplitude fluctuations during a relatively stable period between 1100 and 400 cal yr B.P., and a sea-level rise of 0.5 m during the past 300 year.
The Toba Volcanic Event and Interstadial/Stadial Climates at the Marine Isotopic Stage 5 to 4 Transition in the Northern Indian Ocean
Authors: Schulz Hartmut , Emeis Kay-Christian , Erlenkeuser Helmut , von Rad Ulrich , Rolf Christian
Published: October 2002

The Toba volcanic event, one of the largest eruptions during the Quaternary, is documented in marine sediment cores from the northeastern Arabian Sea. On the crest of the Murray Ridge and along the western Indian continental margin, we detected distinct concentration spikes and ash layers of rhyolithic volcanic shards near the marine isotope stage 5–4 boundary with the chemical composition of the “Youngest Toba Tuff.” Time series of the Uk′37-alkenone index, planktic foraminiferal species, magnetic susceptibility, and sediment accumulation rates from this interval show that the Toba event occurred between two warm periods lasting a few millennia. Using Toba as an instantaneous stratigraphic marker for correlation between the marine- and ice-core chronostratigraphies, these two Arabian Sea climatic events correspond to Greenland interstadials 20 and 19, respectively. Our data sets thus depict substantial interstadial/stadial fluctuations in sea-surface temperature and surface-water productivity. We show that variable terrigenous (eolian) sediment supply played a crucial role in transferring and preserving the productivity signal in the sediment record. Within the provided stratigraphic resolution of several decades to centennials, none of these proxies shows a particular impact of the Toba eruption. However, our results are additional support that Toba, despite its exceptional magnitude, had only a minor impact on the evolution of low-latitude monsoonal climate on centennial to millennial time scales.
Automatic Verification of a Behavioural Subset of UML Statechart Diagrams Using the SPIN Model-checker
Authors: Latella Diego , Majzik Istvan , Massink Mieke
Published: October 2002

Statechart Diagrams provide a graphical notation for describing dynamic aspects of system behaviour within the Unified Modelling Language (UML). In this paper we present a translation from a subset of UML Statechart Diagrams - covering essential aspects of both concurrent behaviour, like sequentialisation, parallelism, non-determinism and priority, and state refinement - into PROMELA, the specification language of the SPIN model checker. SPIN is one of the most advanced analysis and verification tools available nowadays. Our translation allows for the automatic verification of UML Statechart Diagrams. The translation is simple, proven correct, and promising in terms of state space representation efficiency.
Early prediction of acute pancreatitis: Prospective study comparing computed tomography scans, ranson, glasgow, acute physiology and chronic health evaluation II scores, and various serum markers
Authors: Robert John H. , Frossard Jean Louis , Mermillod Bernadette , Soravia Claudio , Mensi Nouri , Roth Marc , Rohner Adrien , Hadengue Antoine , Morel Philippe
Published: October 2002

The aim of this study was to assess the predictability of the outcome of acute pancreatitis using the Ranson, Glasgow, and Acute Physiology and Chronic Health Evaluation (APACHE) II scores, the computed tomography (CT) scan, and several serum markers. Altogether, 137 consecutive patients with acute pancreatitis confirmed by CT scan were prospectively included. Blood samples were obtained daily for 6 days. The predictive value of each parameter was studied by univariate and multivariate analyses comparing mild and severe pancreatitis. A total of 111 attacks were graded as mild (81%) and 26 as severe (19%). Ranson (p=0.3) and APACHE II (p=0.049) scores appeared insufficiently predictive in the univariate analysis. Pancreatic imaging by CT scan was insufficiently predictive (p>0.05), whereas the presence of extrapancreatic fluid collections was more indicative of outcome (p<0.05). With the univariate analysis, the four most reliable serum markers were pancreatic amylase (p<0.001), neutrophil elastase (p<0.05), albumin (p<0.002), and C‐reactive protein (p<0.001). Results became homogeneous when the CT results were added; serum albumin plus extrapancreatic fluid collections (negative predictive value 92%–96% and positive predictive value 67%–100%) comprised the best indicator of severity. None of the parameters tested achieved sufficient predictability when used alone. Serum albumin plus extrapancreatic fluid collections comprise the best indicator of severity at the time of admission.
Enhancing Foot Skin Blood Flux in Peripheral Vascular Disease Using Intermittent Pneumatic Compression: Controlled Study on Claudicants and Grafted Arteriopaths
Authors: Delis Konstantinos T. , Husmann Mark J.W. , Nicolaides Andrew N. , Wolfe John H. , Cheshire Nick J.
Published: October 2002

Intermittent pneumatic leg compression
(IPC) increases arterial calf inflow and foot skin blood flux in normal subjects and claudicants. Our hypothesis was that IPC could enhance foot skin blood flux after infrainguinal grafting and thus promote distal perfusion in limbs with tissue loss. The aim of this study was to compare the effects of three IPC modes [applied to the foot
(IPCfoot), the calf (IPCcalf), or both
(IPCfoot+calf)] on foot skin perfusion in healthy individuals, claudicants, and patients after infrainguinal arterial revascularization performed for critical or subcritical limb ischemia.
Altogether, 20 healthy limbs, 22 claudicating limbs, and 36 limbs of arteriopaths with prior successful autologous femoropopliteal and femorodistal (18 each) grafts were examined. Five‐minute laser Doppler recordings were obtained from the pulp of the big toe in the sitting position, at rest, and during random applications of IPCfoot, IPCcalf, and IPCfoot+calf delivered at 120 mmHg for 4 seconds three times per minute. Foot skin blood flux increased using all IPC modes (p <0.001),
with IPCfoot and IPCfoot+calf generating higher flux levels than IPCcalf (p <0.01) in all groups. Intergroup differences of flux with each of the three IPC modes were not significant. IPCfoot and IPCfoot+calf similarly (p > 0.14)
produced a higher percentage flux increase than IPCcalf in all groups (p <0.004). Controls had a higher percentage flux increase with both IPCcalf and IPCfoot than did claudicants (p ≤ 0.016).
No differences were documented between normal and grafted limbs
(p > 0.05). The percentage flux increase with IPCfoot+calf and IPCcalf was significantly higher in femorodistal grafts than in femoropopliteal ones
(p ≤ 0.026). IPC enhances skin blood flux in limbs with infrainguinal bypass, claudication, and normal arteries, with IPCfoot and IPCfoot+calf being more effective than IPCcalf. Our findings suggest that IPC may be beneficial in limbs with impaired distal perfusion and thus may have clinical implications in the treatment of leg ulcers either prior to or after revascularization.
Pain management of patients with unresectable peripancreatic carcinoma
Authors: van Geenen Rutger C. I. , Keyzer‐Dekker Claudia M. G. , van Tienhoven Geertjan , Obertop Huug , Gouma Dirk J.
Published: October 2002

In patients with unresectable peripancreatic carcinoma, pain is generally treated with pain medication or with a celiac plexus blockade. Radiotherapy has also been reported to reduce pain. The efficacy of these treatment modalities is still under discussion. The aim of this study was to analyze the effects of the various types of pain management on patients who underwent palliative bypass surgery for unresectable peripancreatic carcinoma. During the period January 1995 to December 1998 a series of 98 patients underwent palliative bypass surgery, mostly for unresectable disease found during exploration. Patients were divided into three groups: palliative bypass surgery (BP), palliative bypass surgery with an intraoperative celiac plexus blockade (CPB), and palliative bypass surgery with or without celiac plexus blockade followed by high‐dose conformal radiotherapy (RT). Radiotherapy was performed only in selected patients with locally advanced disease and without metastases, implying a better prognosis of the last group. The pain medication consumption, pain medication‐free survival, hospital‐free survival, and overall survival were analyzed. The preoperative consumption of pain medication was significantly higher in the CPB group than in the BP or RT group. The postoperative consumption of pain medication in the CPB, BP, and RT groups increased during follow‐up from 15%, 17%, and 13% before surgery to 52%, 57%, and 46%, respectively, at three‐fourths of the survival time (NS). This increase in consumption of pain medication was not different in the three groups. In the RT group the median pain medication‐free survival was significantly longer than in the BP or CPB group (9.3 vs. 3.1 and 3.3 months; p=0.02). The median hospital‐free survival and median overall survival were significantly longer in the RT group than in the CPB group (10.3 vs. 6.8 months, p=0.01; and 7.1 vs. 10.8 months, p=0.01). Celiac plexus blockade as pain management did not result in an increase of the pain medication‐free survival or overall survival. Therefore a positive effect of a celiac plexus blockade on pain could not be confirmed in the present study. Radiotherapy resulted in increased pain‐medication survival, hospital‐free survival, and overall survival compared to celiac plexus blockade. These effects are probably partly related to patient selection.
Induction of Drug Resistance in Human Rhabdomyosarcoma Cell Lines is Associated with Increased Maturation: Possible Explanation for Differentiation in Recurrences?
Authors: Leuschner Ivo , Heuer Thomas , Harms Dieter
Published: October 2002

In rhabdomyosarcoma (RMS) of childhood and adolescence very little is known about interactions of cytotoxic drugs and tumor cells. In recurrent RMS the tumor cells are often more mature than in the primary tumor. The biological properties of these cells are still a subject of controversy. We investigated two human (RD2 and TE 671) cell lines by cultivating them with doxorubicin, cisplatinum, and etoposide. Degree of differentiation and proliferation rate were estimated morphologically and by means of immunohistochemistry and a mono-layer proliferation assay. Both morphological and immunohistochemical maturation was measurable in most resistant cell lines. An increase in myosin expression was most marked in the etoposide- and doxorubicin-resistant RD cell lines. The proliferation rate was decreased in almost all resistant cell lines. Nevertheless, the resistant cell lines tolerated high-dose levels of cytotoxic drugs at a higher proliferation rate than parental cell lines cultivated under similar conditions. The maturation seen in some recurrent tumors of RMS can be simulated in vitro by cultivating cell lines with cytotoxic drugs at sublethal doses. Interestingly, the resistance-associated induced maturation was not accompanied by p170 expression. After comparing these in vitro results with the maturation seen in RMS specimens after chemotherapy, we conclude that chemotherapy-induced differentiation in vivo might be a morphological sign of chemoresistance.
Functional and Gene Expression Analysis of the p53 Signaling Pathway in Clear Cell Sarcoma of the Kidney and Congenital Mesoblastic Nephroma
Authors: Brownlee Noel A. , Hazen-Martin Debra J. , Garvin A. Julian , Re Gian G.
Published: October 2002

Mutation of p53 has been implicated in progression of classical Wilms tumor (WT) into the anaplastic variant (AWT), drug resistance, and poor prognosis. Because of prognostic similarities, clear cell sarcoma of the kidney (CCSK) has been classified with AWT and other aggressive pediatric renal tumors, apart from congenital mesoblastic nephroma (CMN), which is instead a relatively benign tumor of neonates. Initially, CCSK and CMN were assumed to be ontologically related, but the role of p53 in the pathogenesis of either disease has not been sufficiently evaluated as in AWT. We examined the status of p53 in CMN and CCSK in comparison to AWT by immunohistochemistry and mRNA analysis of p53, the downstream effector p21 WAF-1/CIP-1 ( p21), the multidrug resistance gene MDR-1, a putative target of p53, and the p53-antagonist Mdm-2. Surprisingly, strong p53 nuclear immunoreactivity was found in cultures from two CMN specimens, but not in frozen or fixed tumor tissue from five other CMN specimens, nor in cell lines or tumor tissue from CCSK. Sequence analysis excluded p53 mutations. The size of the p53 mRNA in CMN and CCSK primary tumors excluded gross deletions or rearrangements. Low levels of Mdm-2 mRNA in CCSK and CMN primary tumors and cultures did not support a role for Mdm-2. Absence of MDR-1 mRNA excluded MDR-1 in the drug-resistant phenotype of CCSK. Cisplatin-induced p21 transactivation assays and G1 cell cycle arrest analyses showed that p21 transactivation and G1 arrest occurred in both CCSK and CMN cultures, demonstrating integrity of the p53 signal transduction pathway. Absence of p53 functional abnormalities excluded relationships between CCSK and CMN as in AWT, supporting the association of cellular CMN with congenital fibrosarcomas as more recently proposed.
Crashing memories and reality monitoring: distinguishing between perceptions, imaginations and ‘false memories’
Authors: Ost James , Vrij Aldert , Costall Alan , Bull Ray
Published: October 2002

Research has shown that the memory characteristics questionnaire (MCQ) can be used to discriminate between ‘memories’ of perceived events and ‘memories’ of imagined events. The present study extended this research by examining the utility of the MCQ in distinguishing impossible memories (i.e., reports of an event a person could not have witnessed). Congruent with previous research, a considerable number of participants in both the pilot study (45%) and the main study (44%) were willing to report that they had seen a non‐existent film of the car crash in which Diana, Princess of Wales was killed. The MCQ ratings of three groups of participants were therefore compared: (1) those who indicated that they had seen the non‐existent film, (2) those who were asked to imagine having seen the film, and (3) a control group who were asked to rate their memory of when they first heard the news of the crash. The MCQ did not serve to distinguish impossible memories, but there were reliable differences on one of the MCQ subscales between those who imagined the film and controls. Furthermore, participants who reported that they had seen the film gave higher scores on the Self Monitoring scale. Implications are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Experimental evaluation of combined model reference adaptive controller in a pH regulation process
Authors: Duarte‐Mermoud Manuel A. , Rojo Franklin A. , Pérez Ricardo
Published: October 2002

An experimental evaluation of the combined model reference adaptive control (CMRAC) is presented in this paper. This adaptive control scheme was used to control a relatively complex process like the pH of a solution in a tank reactor at laboratory level. For comparison purposes, some very well‐known control strategies were also implemented, which include PID control and standard model reference adaptive control (MRAC). Tracking and regulation capabilities of the control strategies studied were analysed and compared. Experimental results indicate that CMRAC behaves as well as the standard MRAC and a very well‐tuned PID for a specific and known operating point. Advantages of the adaptive controllers are shown when the operating point changes. Copyright © 2002 John Wiley & Sons, Ltd.
Autoimmune hemolytic anemia in patients infected with human immunodeficiency virus‐1
Authors: Koduri Prasad Rao , Singa Prema , Nikolinakos Petros
Published: October 2002

Four men were diagnosed with advanced human immunodeficiency virus infection (AIDS) and autoimmune hemolytic anemia (HIV‐AIHA) during the years 1997–2000 at Cook County Hospital, Chicago. All patients presented with the acute onset of severe hemolytic anemia, fever, and splenomegaly. The direct and indirect antiglobulin tests were positive in all, and three patients had mixed warm and cold autoantibody hemolytic anemia. Shortly after admission, two patients died of severe anemia. Two patients responded to prednisone therapy and remain in remission from AIHA for 15 and 30 months, respectively. Am. J. Hematol. 70:174–176, 2002.© 2002 Wiley‐Liss, Inc.
Increased circulating activated endothelial cells, vascular endothelial growth factor, and tumor necrosis factor in thalassemia
Authors: Butthep Punnee , Rummavas Saknarong , Wisedpanichkij Raewadee , Jindadamrongwech Sumalee , Fucharoen Suthat , Bunyaratvej Ahnond
Published: October 2002

An increased number of circulating endothelial cells (CECs) was demonstrated in α‐ and β‐thalassemic patients, β‐thalassemia/hemoglobin E (BE), both splenectomized (BE[S]) and non‐splenectomized (BE[NS]), had higher numbers of CECs than α‐thalassemia, both HbH (α‐thal l/α‐thal 2; H) and HbH with hemoglobin Constant Spring (α‐thal 1/CS; H/CS). CECs were also increased in heterozygous HbE (EA) and homozygous HbE (EE). The highest level of tumor necrosis factor‐α (TNF‐α) was found in HbH/CS patients, whereas the highest levels of vascular endothelial growth factor (VEGF) was observed in BE[S] patients. Significant decreases, in protein C and protein S levels were found in both α‐ and β‐thalassemia compared with normal. Good correlations between the numbers of CEC and TNF‐α, VEGF, protein C, and protein S levels were demonstrated in this study. In addition, markers for endothelial cell activation and injury (intercellular adhesion molecule‐1, ICAM‐1/CD54; vascular cell adhesion molecule‐1, VCAM‐1/CD106; and E‐selectin, ELAM‐1/CD62E) were detected on the surface of isolated CECs using immunofluorescence technique. Appearance of CECs with markers for endothelial cell activation, together with increased levels of TNF‐α and VEGF and decreased levels of protein C and protein S in the circulation, may account for the propensity of vascular perturbation in thalassemic subjects. Am. J. Hematol. 70:100–106, 2002. © 2002 Wiley‐Liss, Inc.
Lipoprotein lipase and APOE/APOC‐I/APOC‐II gene cluster diversity in native Brazilian populations
Authors: De Andrade Fabiana Michelsen , Ewald Gisele Menezes , Salzano Francisco Mauro , Hutz Mara Helena
Published: October 2002

Allele and haplotype frequencies for the T‐93G, Hind III, and Pvu II variants of the lipoprotein lipase gene (LPL), and Hpa I and Ava II restriction site polymorphisms (RSP) of the APOE/C‐I/C‐II gene cluster were determined in 143 individuals from five Brazilian Indian tribes. These results were integrated with those previously reported for APOE. Marked interethnic variability occurs in these sites. A strong linkage disequilibrium was observed between the APOE and APOC‐I loci (D′ = 0.81; P < 0.00001). Linkage disequilibrium between the Hind III and Pvu II RSPs of the LPL gene was also observed (D′ = 1; P < 0.001), but none of these RSPs were in linkage disequilibrium with the T‐93G mutation. Considering both loci, heterozygosity was estimated as 0.45, but it was lower in the Xavante and Surui populations, in accordance with the historical and biodemographical data of these Amerindians. The results reported here may have implications for understanding interpopulation differences in lipid levels and coronary heart disease prevalences. Am. J. Hum. Biol. 14:511–518, 2002.© 2002 Wiley‐Liss, Inc.
Does indirect speech promote nondirective genetic counseling? Results of a sociolinguistic investigation
Authors: Benkendorf Judith L. , Prince Michele B. , Rose Mary A. , De Fina Anna , Hamilton Heidi E.
Published: October 2002

To date, research examining adherence to genetic counseling principles has focused on specific counseling activities such as the giving or withholding of information and responding to client requests for advice. We audiotaped 43 prenatal genetic counseling sessions and used data‐driven, qualitative, sociolinguistic methodologies to investigate how language choices facilitate or hinder the counseling process. Transcripts of each session were prepared for sociolinguistic analysis of the emergent discourse that included studying conversational style, speaker–listener symmetry, directness, and other interactional patterns. Analysis of our data demonstrates that: 1) indirect speech, marked by the use of hints, hedges, and other politeness strategies, facilitates rapport and mitigates the tension between a client‐centered relationship and a counselor‐driven agenda; 2) direct speech, or speaking literally, is an effective strategy for providing information and education; and 3) confusion exists between the use of indirect speech and the intent to provide nondirective counseling, especially when facilitating client decision‐making. Indirect responses to client questions, such as those that include the phrases “some people” or “most people,” helped to maintain counselor neutrality; however, this well‐intended indirectness, used to preserve client autonomy, may have obstructed direct explorations of client needs. We argue that the genetic counseling process requires increased flexibility in the use of direct and indirect speech and provide new insights into how “talk” affects the work of genetic counselors. © 2001 Wiley‐Liss, Inc.
Novel mutation in the Δ‐sterol reductase gene in three Lebanese sibs with Smith‐Lemli‐Opitz (RSH) syndrome
Authors: Nezarati Marjan M. , Loeffler Judith , Yoon Grace , MacLaren Linda , Fung Ernest , Snyder Floyd , Utermann Gerd , Graham Gail E.
Published: October 2002

The Smith‐Lemli‐Opitz syndrome (SLOS), or RSH syndrome, is a well‐characterized multiple congenital anomalies/mental retardation syndrome. The phenotype has been redefined to include mildly affected individuals with minor anomalies and developmental delay, and severe malformations with pre‐ and perinatal mortality. The condition is due to the deficient activity of the enzyme 7‐dehydrocholesterol (7‐DHC) reductase [Shefer et al., 1995: J Clin Invest 96:1779–1785], and the gene has been mapped to chromosome 11q13 [Moebius et al., 1998: Proc Natl Acad Sci USA 95:1899–1902]. We describe here a consanguineous family of Syrian‐Lebanese ancestry with three sibs affected with SLOS: two with a mild variant, while the other had severe disease and died in the first year of life. Mutation analysis demonstrated a novel mutation in the DHCR7 gene, present in homozygous form in the two affected individuals available for testing, and heterozygous in the parents. The wide intrafamilial variation of clinical severity in these three sibs is an important finding in SLOS. © 2002 Wiley‐Liss, Inc.