bluuebunny/crossref_metadata_2025 huggingface dataset:
Holocene development of the lower Mary River plains, Northern Territory, Australia
Authors: Mulrennan M. E. , Woodroffe C. D.
Published: January 2003

Extensive coastal and estuarine plains, associated with several large seasonal rivers, characterize the southern shore of van Diemen Gulf, Northern Territory, Australia. The Mary River is unique among these rivers in that, despite a catchment of 7700 km2, it fails to reach the sea as a discrete channel but breaks up into a series of terminating, multiple channels, leaving much of the freshwater discharge to evaporate from the plains. The extent and morphology of these plains have changed markedly during the Holocene. Drilling, radiocarbon dating and pollen analysis indicate a transgressive phase that began about 7000 years ago as the rising seas flooded the prior valley. This was followed by a big swamp phase as sea level stabilized around 6000 years ago, during which widespread mangrove forest development occurred. Rapid progradation of the coast occurred between 6000 and 4000 years BP. The shoreline has prograded little since that time, but has been modified by episodic chenier ridge deposition and palaeochannel abandonment, infill and reoccupation. The lower Mary River differs from adjacent systems in that several former estuarine channels across the plains appear to have become completely blocked with sediment, leaving low-lying billabongs and palaeochannels which have been preferentially reinvaded by later channels. Several alternative explanations are examined, but it remains unclear what has driven major variations in palaeochannel activity and sedimentation during the mid-Holocene, and why these have decreased so markedly in the last 2000 years.
The dynamics of the formation and development of hollows in raised bogs in Estonia
Authors: Karofeld Edgar
Published: January 2003

Hollow-ridge microrelief is a typical surface pattern of raised bogs in the Boreal zone. It may play an essential role in maintaining the balance between bog ecosystems and changing environmental conditions. The data of the location, depth, approximate age, area and length/width ratio of 225 hollows and reconstructions of the shape dynamics of eight hollows from six bogs in Estonia were used to study the dynamics of the formation and development of hollows. The approximate age of hollows was established according to their depth and peat age isolines calculated by the bulk density method and based on radiocarbon dating. The first period of intensive hollow formation in the bogs studied occurred 3200–2800 years ago. The second, still continuing period of intensive hollow formation started c.1800 years ago. No correlation was detected between the temporal distribution of hollows on different profiles within one bog or in different bogs. Therefore, the formation of the hollows could have been initiated by extra-local random factors supported by the cool wet climate. Almost synchronous widening of the area of hollows in different bogs in Estonia about 1600–1400, 1100–900 and 600–400 years ago is contemporaneous with cool and or wet climatic periods and was probably initiated by climatic changes.
Deglaciation, shore displacement and early-Holocene vegetation history in eastern middle Sweden
Authors: Wastegård S. , Björck J. , Risberg J.
Published: January 2003

The sedimentary record at Lake Vibysjo lake basin is situated close to the Närke Strait where the main water exchange occurred between the Vänern basin and Baltic basin during the middle and late phases of the Yoldia Sea stage of the Baltic Sea (c. 10 000– 9500 14C years BP). The area was deglaciated in a glaciomarine environment, as reflected by the occurrence of benthic calcareous fossils (foraminifera, ostracods and the mollusc Portlandia arctica (Gray)) in the lower-most clay units. The estimated date of deglaciation, 10 440 clay-varve years BP, suggests that a saline bottom-water current entered the Baltic basin shortly after the high areas south of Lake Vibysjön became free of ice. The brackish water fauna occurs during a regional Betula-Empetrum-Hippophaë pollen zone, which in southern Sweden is correlated with the early Preboreal. The isolation of the Lake Vibysjön basin is dated to 8100 14C years BP, and occurred during the last part of the Ancylus Lake stage. Based on investigations of other basins in Närke, it is concluded that the Mastogloia Sea reached c. 62 m a.s.l. and that the Litorina Sea reached at least 60 m a.s.l. in the area studied.
Speleothems and climate: a special issue of The Holocene
Authors: Lauritzen Stein-Erik , Lundberg Joyce
Published: January 2003

Speleothems (cave dripstones) are formed as a part of the meteoric water cycle and therefore vari ations in their growth rate and composition reflect environmental changes on the land surface above the cave. Since they are continental deposits, and possess a remarkably accurate dating potential, using TIMS U-series techniques, speleothems are important palaeoclimatic archives for the terrestrial environment, complementing the marine and ice-core records. The climatic proxies that can be deciphered from speleothems are growth rate, stable isotope composition (d18O, d13C), organic (humic) matter and trace element composition, as well as luminescent laminae, which may display annual rhythms. The nine papers in this special issue of The Holocene present the latest results in palaeoclimatic analysis from speleothems.
Spring-temperature variations in western Himalaya, India, as reconstructed from tree-rings: AD 1390-1987
Authors: Yadav Ram R. , Park Won-Kyu , Bhattacharyya Amalava
Published: January 2003

The Himalayan region plays a very important role in influencing the regional and extra-regional circulation system. Long-term instrumental or proxy climate records for this region are scant, but are essential for a global perspective of climate variability. A 598-year (AD 1390-1987) reconstruction of spring (March-May) temperature has been derived for the first time for the western Himalayan region, India using a well replicated ring-width chronology of Himalayan cedar (Cedrus deodara (D. Don) G. Don). The reconstruction showing annual to multi-year episodes of cool and warm springs is well correlated with the instrumental record of spring temperature for 1876-1987 (r = 0.53, p < 0.001). Prominent large-magnitude century-scale excursions in negative anomalies of spring temperature which might reflect the regional influence of the ‘Little Ice Age’ are not indicated in our data. The seventeenth century experienced monotonically warm springs. Neither recostruction or instrumental data provide evidence of warming during the last few decades of this century which could be attributed to anthropogenic causes. A strong out-of-phase relationship between the instrumental sprin-temperature record over the western Himalayan region and sea-surface temperatures (SSTs) of ensuing months (June-May) over the equatorial Pacific Ocean has been noted. This suggests that temperature responsive tree-ring chronologies from the Himalayan region could also serve as a valuable proxy of the Southern Oscillation.
Salt-marsh aggradation in response to late-Holocene sea-level rise at Amherst Point, Nova Scotia, Canada
Authors: Shaw John , Ceman James
Published: January 2003

A radiocarbon 14C chronology determined for plant macrofossils in exposed salt-marsh sediments at Amherst Point, Nova Scotia, Canada, shows that the edge of the high salt marsh aggraded 7.5 m since 900 BC, equivalent to a mean rate of 25.9 cm 100 yr-1. Four phases of rapid aggradation (900–600 BC, 100 bc– AD 200, AD 700–1100, and AD 1600 to present) were interspersed with three phases of slower aggradation (600– 100 BC, AD 200–700, and (tentatively) AD 1100–1600). The stepped pattern of marsh aggradation probably resulted from eustatic sea-level fluctuations superimposed on background signals of crustal subsidence and tidal-range expansion. Because the rate of high salt-marsh aggradation lagged or exceeded the rate of higher high water (HHW) increase at various times, the high salt-marsh aggradation trend only approximates the trend of HHW increase. The eustatic sea-level fluctuations are estimated to have a range of at least 0.8 m.
‘Persistent’ ENSO sequences: how unusual was the 1990-1995 El Niño?
Authors: Allan Robert J. , D'Arrigo Rosanne D.
Published: January 2003

A pronounced climatic pattern, synonymous with protracted El Niño activity, persisted during much of the first half of the 1990s. The impact of this anomaly was primarily a consequence of its duration, which was much longer than the life cycles that have marked a number of the well-documented major El Niño events over the last 30-odd years. Depending on which oceanic or atmospheric parameters or which regions of the Indo-Pacific basin are examined, this recent pattern has been described as either a 'sequence of El Niño events or a ‘persistent’ El Niño episode. Such an occurrence has been attributed to a variety of causes, ranging from an enhanced greenhouse effect to volcanic dust to a major change in the earth's climate system. Much of the above conjecture has occurred because the recent El Niño sequence/climatic anomaly has been considered with regard to only contemporary data and events. This study first expands this perspective by examining evidence for both protracted El Niñino and La Niñfia phases of the El Niño Southern Oscillation (ENSO) in historical instrumental data. However, since the presence of such signals in records of relatively short length is of limited statistical significance, recourse to reconstructions based on longer proxy records is necessary. A reconstruction of the Southern Oscillation Index (SOI) derived using a multiple regression model incorporates tree-ring records from ENSO-sensitive regions of the Pacific, including the southwestern USA, Mexico and Indonesia. This reconstruction shows a number of ‘persistent’ El Niño and La Niñfha event sequences through time. Due to their generally lower and differing temporal and spatial resolution, the length and amplitude of palaeo-events cannot always be compared directly among different proxies or with events in the various instrumentally based records. Nevertheless, the reconstruction demonstrates that features indicative of ‘persistent’ event sequences have occurred prior to the period of instrumentally based indices. This finding is supported by documentary evidence from other ENSO-sensitive regions across the Indo-Pacific basin.
Electric conductivity and temperature variations within a raised bog in Finland: implications for bog development
Authors: Puranen R. , Mäkilä M. , Säävuori H.
Published: January 2003

The deeper parts of raised bogs in Europe have been long regarded as hydraulically stagnant. However, recent reports describe seasonal water movements and solute transport through the deeper layers of some North American bogs, possibly affecting their carbon budgets. Such water movements were not observed in Haukkasuo, a typical raised bog in southeastern Finland, which was thoroughly mapped with a new electric conductivity and temperature probe during four seasons and two successive years. The measured temperature variations can be explained by thermal conduction without convective heat transfer so that the deeper peat layers (2-3 m) reach their highest temperatures in the winter, which possibly affects the methane production. A minimum conductivity (low solute concentration) in the vertical profiles indicates the transition from minerotrophic to ombrotrophic stage of bog development. The seasonal and annual conductivity variations are insignificant, but the conductivity cross-sections of the bog show systematic patterns suggesting slow but persistent advective transport of solutes. The bog mound seems to drive a flow system, which under the central dome forces dilute surface waters to the basal layers, where they pick up nutrients on their way to the discharge sites near the margins. Such translocation of solutes is expected to excite the peat decay at the margins and slow it down near the bog centre. This promotes further doming of the 10 000-year-old bog, which will keep on sequestering carbon although the methane emissions may increase near its margins.
Spectral analysis of a 1000-year stalagmite lamina-thickness record from Shihua Cavern, Beijing, China, and its climatic significance
Authors: Qin Xiaoguang , Tan Ming , Liu Tungsheng , Wang Xianfeng , Li Tieying , Lu Jinpo
Published: January 2003

Stalagmite laminae provide a high-resolution geological record of climate change. In this paper, moving spectral analysis is used to analyse a stalagmite lamina thickness record to study climatic variability. It was found that the dominant cycles of the lamina thickness sequence are 2, 3.3, 5–6, 10–12, 14–18, 133 and 194 years. Some of the cycles are the same as the cycles of modern climatic indices, such as the QBO (Quasi Biennial Oscillation) of 2 years, the QTO (Quasi Triple-year Oscillation) cycle of about 3.5 years, the QFO (Quasi Five-year Oscillation) cycle of 5–6 years and the QEO (Quasi Eleven-year Oscillation) cycle of 11 years. It was also found that there are different dominant cycles in different time periods. Usually, the dominant cycles are stronger in wet periods when the microlaminae are thicker. In dry periods, the microlaminae are thinner and the power of the dominant cycles is also weaker. Another feature is that the power of the dominant cycles and their long-term periods and frequencies appear to change. These phenomena are important for understanding the climatic changes in Beijing area over the last 1 ka.
Comparison of marine and terrestrial Holocene climatic reconstructions from northeastern North America
Authors: Sawada M. , Gajewski K. , de Vernal Anne , Richard Pierre
Published: January 2003

Quantitative climate reconstructions based on marine dinocysts and terrestrial pollen sequences are consistent through the Holocene in northeastern North America. Principal components analysis (PCA) indicates a large-scale climate signal in the dinocysts and pollen. The combined and separate analyses of marine and nearby terrestrial pollen sequences from Hudson Bay, Labrador and the St Lawrence estuary differentiate tun dra, boreal forest and deciduous forest assemblages in time and space. These analyses indicate that the marine pollen record reflects vegetation changes of the regional terrestrial environment and allows direct correlations between the marine and terrestrial stratigraphies. Sea-surface temperatures estimated from dinocysts and terres trial air temperatures from pollen using the method of modern analogs show that the three regions had differing climate histories associated with their location with respect to deglaciation and air mass boundaries. High frequency climatic changes reconstructed for the St Lawrence estuary and Gulf, and a cooling reconstructed for the period prior to 8000 yr BP, are less reliable due to the larger values of the dissimilarity coefficients. Prior to 6000 yr BP, cool temperatures reconstructed along the Labrador margins, both in the marine and terrestrial environments, are in agreement with climate simulations indicating the persistence of an anticyclone over the Québec-Labrador ice sheet. In both Labrador and northwestern Québec, a late-Holocene cooling affects sites in the forest-tundra, but is not evident in Boreal forest sites, suggesting movements in the mean position of the polar front.
Trace element variations in coeval Holocene speleothems from GB Cave, southwest England
Authors: Roberts Mark S. , Smart Peter L. , Hawkesworth Chris J. , Perkins William T. , Pearce Nicholas J.G.
Published: January 2003

We report trace element (Mg, Sr and Ba) records based on laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) from three coeval Holocene speleothems from Great Chamber in GB Cave, southwest England. The trace element records are placed on a common timescale on the basis of a suite of TIMS 230Th-234U ages. This permits assessment of the reproducibility of the trace element record in coeval speleothems. The trace element records are not coherent, raising dobuts over the reliability of individual trace element records as potential archives of palaeoenvironmental information. Mg/Sr in speleothem calcite has been proposed as a potential palaeothermometer as Mg partitioning into calcite from water is temperaturedependent, while Sr partitioning into calcite is temperature-independent. However, we present the results of calculations which demonstrate that the observed Mg/Sr values in the three stalagmites cannot have been produced by Holocene temperature changes alone and that other processes must play a dominant role. We present a model which suggests that the observed trace element variations in the three speleothems reflect hydrological mixing of waters in the epikarstic zone above the cave which have interacted with two geochemi cally distinct source rocks (calcite and dolomite).
Climatic significance of the marginalization of Scots pine (Pinus sylvestris L.)c. 2500 BC at White Moss, south Cheshire, UK
Authors: Lageard Jonathan G.A. , Chambers Frank M. , Thomas Peter A.
Published: January 2003

Subfossil wood from White Moss, south Cheshire, has become the focus of palaeoenvironmental research employing not only conventional coring, pollen analysis, radiocarbon dating and dendrochronology on pine and oak, but also the exhumation of in situ peat areas and dendroecology of the pine ring-width records. Initial dendrochronological research at the site yielded five pine chronologies dating from 3520 to 2462 cal. bc. These and other data indicate three episodes of pine colonization of the mire in the period between 3643 and 1740 cal. bc. Comparison of the pollen and spore records suggest that pine became marginalized at the site c. 2500 cal. bc after successive episodes of increased wetness, and this may represent a staged response to climatic deterioration. Two oak chronologies were dated by reference to the Belfast and to English oak master chronologies to 3228–2898 bc and 2190–1891 bc, respectively, showing the possible co-existence of pine and oak on the mire for part of the time. Further dendrochronological work on subfossil pine at the site resulted in a chronology (WM4) that was cross-matched with pine from elsewhere in England, and subsequently dated absolutely to 2881–2559 bc. Detailed dendroecological information, such as fire episodes and periods of environmental stress indicated in the tree-ring records, have been assigned, precisely and accurately, to calendar years in prehistory. The detailed data show the potential for both dendroecological and wider palaeocli matic and palaeoenvironmental information that may become available from prehistoric bog-pine chronologies, which might then permit precise correlation and comparisons of proxy-climate data between sites.
Speleothem evidence for Holocene fluctuations of the prairie-forest ecotone, north-central USA
Authors: Denniston Rhawn F. , González Luis A. , Baker Richard G. , Asmerom Yemane , Reagan Mark K. , Edwards R. Lawrence , Alexander E. Calvin
Published: January 2003

Carbon and oxygen isotopic trends from seven Midwestern speleothems record significant offsets in the timing of middle-Holocene vegetation change. Interactions of dry Pacific and moist Gulf of Mexico air masses maintained a sharp moisture gradient across Iowa, Minnesota, and Wisconsin such that the arrival of prairie was offset by 2000 years between caves and pollen sites located only 50 km apart. Oxygen isotopes shift concomitantly with carbon in most cases, although these changes are believed to represent increased evaporative enrichment of 18O prior to infiltration during the prairie period.
The role of fire in the carbon dynamics of a mire, eastern Finland
Authors: Pitkänen Aki , Turunen Jukka , Tolonen Kimmo
Published: January 2003

The fire history and the effect of fires on the long-term (apparent) rate of carbon accumulation (LORCA) in the Patvinsuo mire complex, eastern Finland, were determined through stratigraphic and pollen analyses of 98 peat cores. The peat cores were characterized by a large number of charcoal layers and the age of the basal peat varied between 57 and 10 500 years. Mire fires slowed down the progress of vertical peat accumulation and resulted in great carbon losses. The average LORCA in the Patvinsuo cores was clearly lower, 9.2 ± 1.0 (SE) g m-2 yr-1, compared to the average value for all mire sites in the southern half of Finland, 17.7 ± 0.6 (SE) g m-2 yr-1. The average rate of carbon loss in Patvinsuo mire complex was 9.5 ± 1.0 (SE) g m-2 yr-1 and the mean carbon loss in an individual fire was estimated to be 2.5 kg m-2.
Variations in stalagmite luminescence laminae structure at Poole's Cavern, England, AD 1910±1996: calibration of a palaeoprecipitation proxy
Authors: Baker Andy , Proctor Christopher J. , Barnes William L.
Published: January 2003

Duplicate records of variations in the structure of stalagmite annual luminescence laminae are investi gated for the period ad 1910 to 1996 for Poole's Cavern, Buxton, central England. For the two stalagmites, 88% of the years have luminescence laminae that exhibit a near sinusoidal shape with no structural variations. However 10 laminae (12% of total) exhibit a double band structure; these are demonstrated to occur in years with high monthly or daily mean precipitation. It is suggested that high intensity (.60 mm d-1) and high quantity (.250 mm per month) of precipitation may flush luminescent organic material onto the stalagmites from either the soil or groundwater zones and generate a double lamina. However, not all precipitation events generated double laminae. High-intensity events in summer were ineffective due to a soil moisture deficit and/or interception by the woodland canopy. High-rainfall months (.250 mm) failed to generate double laminae when preceded by two or more months of greater than 150 mm, suggesting exhaustion of the organic acid supply can occur. When compared to monthly precipitation data for Buxton, laminae shape and the percentage of double laminae of the Poole's Cavern stalagmites are best explained by a centre-weighted running mean of the preceding six to seven months' precipitation. The palaeoclimate potential of structural variations in stalagmite luminescence laminae is discussed.
Historical evidences of streamflow fluctuations in the Mendoza River, Argentina, and their relationship with ENSO
Authors: del R. Prieto María , Herrera R. , Dussel P.
Published: January 2003

Documentary sources are used to construct records of high and low flows of the Mendoza River and to relate these to ENSO over the historical period. The historical data are calibrated against measured discharge (ad 1909–1940) and validated by precipitation discharge-series reconstructed from tree-rings (ad 1600–1960). An increase in the number of high-streamflow events since the mid-seventeenth century is accompanied by several intervals with an above-average number of high-streamflow events; some of these intervals are also characterized by an above-average number of low-streamflow events. A considerable number of high-streamflow events do not coincide with ENSO events, which are regarded as a necessary but not sufficient cause of the extreme streamflow variations.
The toxicity of exposure to the organochlorine, dieldrin, at a sympathetic junction and on the skin of the frog,Caudiverbera caudiverbera
Authors: Suwalsky M , Norris B , Benites M
Published: January 2003

The effects of the organochlorine, dieldrin, were tested on a noradrenergic synapse of the frog, Caudiverbera caudiverbera. Nerve stimulation induced a transient increase in short circuit current (SCC) and in the potential difference (PD), which consisted of a rapid and then a slow component. Dieldrin in the concentration range 0.01–1.0 mM caused a concentration-dependent block of both components to 32% of their control values, which was partially reversed by washout. In some experiments, this blocking effect was preceded by an initial increase in the magnitude of the electrical parameters of the nonstimulated skin and also in the synaptic response to stimulation when the lowest dieldrin concentration (0.01 mM) was applied; higher concentrations (0.1–1.0 mM) led to progressive reduction of the responses. Results are interpreted as a perturbation of the lipid bilayer structure, which affects the functionality of lipid–protein complexes, leading, on one hand, to glandular Cl¡ channel inactivation and epithelial Na + channel blockade and, on the other hand, to transient glandular Cl¡ activation, opening of a putative Na+channel, and subsequent blockade.
Modification of doxorubicin-induced cardiotoxicity: manipulation of the dosage schedule
Authors: Yeung T K , Chakrabarti K , Wilding D , Hopewell J W
Published: January 2003

Modification of the dosing schedule for doxorubicin (DOX) administration represents a possible method of reducing cardiotoxicity from this potent anti-cancer drug, while at the same time maintaining its cytotoxic action. The quantitative effects of modified dosage scheduling have been investigated in a clinically relevant rat model. Cardiotoxicity to DOX was assessed by the degree of reduction in cardiac output at 4–24 weeks after the intravenous administration of DOX. The effects of dose schedules involving three or six small dose administrations, over one and two weeks, were compared with that produced by large single doses of DOX. The total drug dose administered for each schedule was varied in order to establish dose–effect relationships. After a total dose of 3 mg/kg DOX, given as three or six equal small doses, there was a gradual decline in cardiac output in the first 12 weeks after drug administration. Between 12 and 24 weeks, the reduction in cardiac function was relatively stable at between 65% and 85% of that of age-matched controls for three and six equal small doses, respectively. Dose–effect curves for animals showing a ¶30% reduction in cardiac function after 12 weeks indicated the degree of reduction in cardiac function produced by the modified dose scheduling. Compared with a large single dose, larger total doses were required to produce the same severity of damage. Thus, schedules based on three and six equal small doses resulted in dose modification factor of 1.5 ‘0.23 and 2.1’ 0.28, respectively, when compared with the same effect produced by a large single dose. This appeared to be independent of the severity of cardiac damage, suggesting a simple mathematical relationship between the total acceptable dose of DOX and the dose administered at each intravenous injection. These modifications in the cardiotoxicity of DOX produced by the administration of multiple small doses were of the same order of magnitude as that produced by other methods introduced to reduce anthracycline cardiotoxicity.
The role of matrix metalloproteinases in vascular disease
Authors: Loftus IM , Thompson MM
Published: January 2003

There is growing interest in the role of matrix metalloproteinasesin vascular diseases. These conditions are often characterized by excessive tissue remodelling, and increased matrix metalloproteinase activity has been demonstrated in aneurysms, intimal hyperplasia and atherosclerotic plaque disruption. These enzymes represent a potential target for therapeutic intervention to modify vascular pathology.

The core of this review is derived from a MEDLINE database literature search. The review found that there is convincing evidence of increased matrix metalloproteinase activity in a spectrum of vascular disease. Evidence for an imbalance promoting increased matrix degradation is less well documented. However, studies of matrix metalloproteinase inhibition in vascular disease models suggest potential therapeutic benefit.

In conclusion, in vivo studies of matrix metalloproteinase inhibition are required to further study the potential for reversal or deceleration of the excessive tissue remodelling that accompanies vascular disorders.
Alterations in endothelial cell proliferation and apoptosis contribute to vascular remodeling following hind-limb ischemia in rabbits
Authors: Dai Qunsheng , Thompson Michael A , Pippen Anne M , Cherwek Hunter , Taylor Doris A , Annex Brian H
Published: January 2003

Hind-limb ischemia is a potent stimulus for angiogenesis. However, capillary density does not change in tibialis anterior muscle (TA) following hind-limb ischemia, despite increases in angiogenic growth factors. The objective of this study was to determine whether changes in proliferation and apoptosis occurred in the same muscle.

In total, 19 New Zealand white rabbits underwent femoral artery ligation and excision and the ischemic and contra-lateral (control) TA muscles were harvested after 1 (n = 7), 5 (n = 7) and 21 (n = 5). Terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) was used to detect apoptosis and double staining was used to identify the apoptotic cell types. Proliferation was assessed by immunohistochemistry for proliferating cell nuclear antigen (PCNA) and [3H]thymidine incorporation, in vitro.

TUNEL positive nuclei were greater in ischemic than control muscle at 1 day (1.83 0.70% vs 1.03 0.20%), 5 days (2.13 0.50% vs 1.21 0.42%) and at 21 days the difference was statistically significant (3.42 0.80% vs 0.96 0.40%, p 0.01). The majority of TUNEL positive nuclei were endothelial (Tie2 positive) cells. The number of PCNA positive cells in ischemic versus control muscle was similar at 1 day (0.71 0.20% vs 0.53 0.20%) and 5 days (1.28 0.30% vs 0.77 0.30%), but was significantly (p 0.05) reduced in ischemic muscle at 21 days (0.18 0.20% vs 1.35 0.30%) with no difference in [3H]thymidine incorporation.

Directionally opposite changes in endothelial cell proliferation and apoptosis occur in TA muscle following hind-limb ischemia. Modulating apoptosis in ischemic skeletal muscle may present a novel therapeutic target in peripheral arterial disease.
Vascular viewpoint
Authors: Anand Sonia S
Published: January 2003

Question: Among high-risk patients with vascular disease treated with aspirin, is incomplete suppression of thromboxane generation associated with an increased risk of recurrent cardiovascular events?

Population: Men and women 55 years of age who had a history of coronary artery disease, stroke, peripheral vascular disease, or diabetes plus at least one other CV risk factor who participated in the HOPE trial which was a 2 2 factorial randomized controlled trial of ramipril and vitamin E.1

Design and methods: Nested case-control study of the 5529 patients from the HOPE trial participants from Canada in whom a urine sample was collected at baseline. All samples were sent to a central laboratory and stored at -80°C. Only those patients who were taking aspirin were included. Cases were defined as individuals who had a confirmed MI, stroke, or CV death after randomization. Control subjects were randomly selected from aspirin-treated patients who provided adequate urine samples but did not suffer MI, stroke or CV death after randomization. Cases and controls were matched according to sex and age (5 years) in a ratio of 1:1. Urine was thawed and assayed for 11-dehydro thromboxane B2 levels using the Caymann Chemical immunoassay.

Results: Among 488 cases and 488 matched controls, the odds of an MI, stroke or CV death increased with each increasing quartile of 11-dehydro thromboxane B2, with patients in the upper quartile having a 1.8 times higher risk than those in the lower quartile (OR = 1.8; 95% CI: 1.2-2.7, p = 0.009).

Conclusion: Among aspirin-treated patents who have established vascular disease, urinary 11- dehydro thromboxane B2 predicts the future risk of MI and CV death, and may reflect ‘aspirin resistance’.
Teaching vocabulary in two Chinese classrooms: schoolchildren’s exposure to English words in Hong Kong and Guangzhou
Authors: Tang Eunice , Nesi Hilary
Published: January 2003

In this paper the lexical environment of secondary school English language classrooms in Hong Kong and Guangzhou are compared. Teacher output for one week of first-form lessons was recorded in two representative schools. Lexical richness in terms of type-token ratio and word-type frequency was measured, the words that were explicitly taught were identified and categorized according to whether the teaching was planned or unplanned, and the teaching treatments accorded to these words were examined. The lexical richness of teacher output was found to be greater in the Hong Kong classroom than in the Guangzhou classroom. In the Guangzhou classroom more words were explicitly taught, but learners were exposed to far fewer word types for incidental acquisition. In both classrooms, more unplanned than planned words were explicitly taught. Teachers tended to teach planned words through multiple treatments, with various kinds of input, both modified and unmodified, in different stages of the lesson. They provided almost no opportunities, however, for modified (negotiated) output on the part of the learners, despite the fact that the syllabuses in both Hong Kong and Guangzhou are described as ‘communicative’.
Sameness and difference in classroom learning cultures: interpretations of communicative pedagogy in the UK and Korea
Authors: Mitchell Rosamond , Lee Jenny Hye-Won
Published: January 2003

This paper is a contribution to the growing sociolinguistic literature on classroom foreign/second language learning and teaching (Duff 1995; Willett, 1995; Bailey and Nunan, 1996; Bremer et al., 1996; Coleman, 1996; Toohey, 1998; Heller, 1999; Rampton, 1999). We report two case studies of mainstream beginner-level FL instruction, using observational and interview data gathered in schools in Seoul, Korea, and in Southern England. In both cases, the public rationales offered for foreign language learning include a mix of ‘internationalist’ and ‘instrumental’ values (MoE, 1995; DES, 1991; DfEE/QCA, 1999). The dominant language-teaching ideologies to which the teachers in the different locations declare allegiance are also similar, involving commitment to various principles of the ‘communicative approach’ to language teaching. (In both settings, for example, the speaking skill is given priority, there is use of group work, etc.) Through analysis of selected lesson excerpts we identify similarities and differences in the classroom interpretations of communicative methodology, and in particular the opportunities available for individual students to engage in L2 interaction. We examine how the identity of the ‘good language learner’ is constructed in the different settings, for example, through differing teacher emphases on individual vs. collective responsibility for learning. Differences between the two classrooms are linked to broader features of the educational setting, but we show that these differences do not reflect common stereotypes about Anglo and Asian teaching styles in any simple way.
Human skin sandwich for assessing shunt route penetration during passive and iontophoretic drug and liposome delivery
Authors: Essa Ebtessam A , Bonner Michael C , Barry Brian W
Published: January 2003

This work explored the role of skin appendages (shunt route) in passive and iontophoretic drug and liposome penetration. The technique used an epidermis and stratum corneum sandwich from the same skin donor with the additional stratum corneum forming the top layer of the sandwich. Penetration was monitored during occluded passive and iontophoretic (0.5 mA cm−2) delivery of mannitol and estradiol solutions, and ultradeformable liposomes containing estradiol. The shunt route had a significant role during passive penetration of mannitol (hydrophilic compound), but was negligible during penetration of estradiol (lipophilic drug) and liposomes. In iontophoresis, the shunt route significantly contributed to the overall flux of all preparations, being highest for mannitol. However, shunts were not the only pathway for iontophoretic drug delivery and evidence was observed for the creation of new aqueous pathways via disorganization of the intercellular lipid domain of stratum corneum. The skin sandwich technique should prove valuable for general studies on routes of skin penetration.
Participation of various kinases in staurosporine-induced apoptosis of RAW 264.7 cells
Authors: Yamaki Kouya , Hong JangJa , Hiraizumi Kenji , Ahn Jong Woon , Zee OkPyo , Ohuchi Kazuo
Published: January 2003

Staurosporine induced apoptosis of RAW 264.7 cells, a mouse macrophage-like cell line, as determined by DNA fragmentation, the increase of annexin V-stained cells, and the cleavage of poly(ADP- ribose)polymerase (PARP), a substrate of caspase. Analysis of the increase in the percentage of sub-G1 cells revealed that the DNA fragmentation occurred in a time- and concentration-dependent manner at 0.021–2.1 μm of staurosporine. Staurosporine induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) but suppressed spontaneous phosphorylation of p44/42 MAPK. The p38 MAPK inhibitor SB203580, the MAPK/extracellular signal-regulated kinase kinase inhibitor PD98059 and the phosphatidylinositol 3-kinase (P13K) inhibitor LY294002 potentiated the staurosporine-induced PARP cleavage and DNA fragmentation. The protein kinase A (PKA) inhibitor H-89 potentiated the staurosporine-induced DNA fragmentation without potentiating the PARP cleavage. In contrast, the protein kinase C (PKC) inhibitor Ro-31–8425 suppressed the PARP cleavage and DNA fragmentation. These findings suggested that staurosporine induces apoptosis via the caspase cascade in RAW 264.7 cells. The staurosporine-induced apoptosis is positively regulated by PKC, negatively regulated by p38 MAPK, p44/42 MAPK and P13K via the caspase cascade, and negatively regulated by PKA without regulation of caspase activation.
Diazepam does not reduce infarct size in rats subjected to transient occlusion of the middle cerebral artery when normothermia is maintained
Authors: Kuhmonen Johanna , Lukkarinen Jouko , Gröhn Olli , Jolkkonen Jukka , Sivenius Juhani
Published: January 2003

Activation of the γ-amino butyric acid (GABA)-ergic system might protect against the damage that occurs after cerebral ischaemia. We examined this hypothesis by administering diazepam to rats subjected to transient middle cerebral artery occlusion (MCAO) using the intraluminal thread method. Diffusion MRI (DWI) and perfusion imaging (PI) were acquired during MCAO to assess brain tissue status and haemodynamics, respectively. Rats were intraperitoneally injected with either 10 mg kg−1 diazepam (n = 5) or vehicle (n = 5) both 30 min and 90 min after the onset of MCAO. To exclude the possibility that neuroprotection was due to the hypothermic action of the drug, body temperature was maintained at 37–38°C for up to 7 h postischaemia with a feed-back controlled thermoregulatory unit. Infarct volumes quantified 2 days after MCAO from T2-weighted images were similar in ischaemic control rats and in ischaemic rats treated with diazepam. We conclude that diazepam-induced enhancement of GABAA activity does not effectively protect against neuronal damage that occurs after transient MCAO in normothermic rats.
Covalent coupling of concanavalin A to a Carbopol 934P and 941P carrier in glucose-sensitive gels for delivery of insulin
Authors: Tanna S , Sahota T , Clark J , Taylor M J
Published: January 2003

A novel glucose-sensitive gel formulation, containing concanavalin A and specific polysaccharides, was stabilised via covalent coupling to two structurally different carbomers. The bonding was done to minimise leaching of gel components thereby preventing toxicity and preserving the working mechanism of the gel. Increased gel stability was introduced by covalently bonding amine groups present on the lysine residues of concanavalin A to carboxylic moieties on Carbopol 934P NF and 941P NF using carbodiimide chemistry. The introduction of dextran then produced a glucose-sensitive formulation that transformed from gel to sol in the presence of free glucose. Rheological examination of glucose-sensitive gels stabilised in this way and containing varying concentrations of glucose was conducted with a cone and plate viscometer used in continual rotation mode. A decrease in viscosity over the chosen glucose concentration range was exhibited by both carbomer-stabilised formulations. The subsequent testing of such formulations in in-vitro diffusion experiments revealed that the leaching of concanavalin A from the covalently coupled gels is restricted significantly with respect to non-coupled formulations. In addition, insulin delivery in response to glucose in the physiologically relevant glucose concentration range has been demonstrated using the carbomer-stabilised gels at 37°C. The performance of this self-regulating drug delivery system has been improved in terms of increased gel stability with reduced component leaching.
Hypometabolism, antioxidant defenses and free radical metabolism in the pulmonate land snailHelix aspersa
Authors: Ramos-Vasconcelos Gabriella R. , Hermes-Lima Marcelo
Published: January 2003

The aim of this work was to evaluate the effect of a cycle of estivation and awakening on free radical metabolism in selected organs of the land snail Helix aspersa. Estivation for 20 days induced a 4.9- and 1.8-fold increase in selenium-dependent glutathione peroxidase activity (Se-GPX) and in total glutathione levels (GSH-eq), respectively, in hepatopancreas when compared to activity in active animals 24 h after awakening. Foot muscle Se-GPX activity was also increased 3.9-fold during estivation, whereas GSH-eq did not vary. The activities of other antioxidant enzymes (catalase,superoxide dismutase, glutathione reductase and glutathione S-transferase) and glucose 6-phosphate dehydrogenase were unchanged in both organs. After 15 min of awakening, the glutathione disulphide (GSSG)/GSH-eq ratio increased significantly by 55% in hepatopancreas, slowly returning to the levels observed during estivation. The higher GSSG/GSH-eq ratio may be caused by increased formation of reactive oxygen species (ROS) during awakening. The levels of thiobarbituric acid reactive substances (TBARS) decreased from 49 to 30.7 nmol g-1 wet mass in hepatopancreas after 5 min arousal and,after 30 min, TBARS rose significantly to 39.6 nmol g-1 wet mass,gradually declining thereafter. The levels of lipid hydroperoxides in hepatopancreas and of carbonyl protein in foot muscle both decreased during awakening. The higher levels of products of free radical damage during estivation may have resulted from low levels of ROS formation associated with decreased rates of lipid hydroperoxide detoxification and oxidized protein turnover caused by metabolic depression. The regulation of the antioxidant system during hypometabolism may constitute a mechanism to minimize oxidative stress during cycles of estivation and awakening.
Hydrodynamic stability of swimming in ostraciid fishes: role of the carapace in the smooth trunkfishLactophrys triqueter(Teleostei:Ostraciidae)
Authors: Bartol Ian K. , Gharib Morteza , Weihs Daniel , Webb Paul W. , Hove Jay R. , Gordon Malcolm S.
Published: January 2003

The hydrodynamic bases for the stability of locomotory motions in fishes are poorly understood, even for those fishes, such as the rigid-bodied smooth trunkfish Lactophrys triqueter, that exhibit unusually small amplitude recoil movements during rectilinear swimming. We have studied the role played by the bony carapace of the smooth trunkfish in generating trimming forces that self-correct for instabilities. The flow patterns, forces and moments on and around anatomically exact, smooth trunkfish models positioned at both pitching and yawing angles of attack were investigated using three methods: digital particle image velocimetry (DPIV), pressure distribution measurements, and force balance measurements. Models positioned at various pitching angles of attack within a flow tunnel produced well-developed counter-rotating vortices along the ventro-lateral keels. The vortices developed first at the anterior edges of the ventro-lateral keels,grew posteriorly along the carapace, and reached maximum circulation at the posterior edge of the carapace. The vortical flow increased in strength as pitching angles of attack deviated from 0°, and was located above the keels at positive angles of attack and below them at negative angles of attack. Variation of yawing angles of attack resulted in prominent dorsal and ventral vortices developing at far-field locations of the carapace; far-field vortices intensified posteriorly and as angles of attack deviated from 0°. Pressure distribution results were consistent with the DPIV findings, with areas of low pressure correlating well with regions of attached, concentrated vorticity. Lift coefficients of boxfish models were similar to lift coefficients of delta wings, devices that also generate lift through vortex generation. Furthermore, nose-down and nose-up pitching moments about the center of mass were detected at positive and negative pitching angles of attack, respectively. The three complementary experimental approaches all indicate that the carapace of the smooth trunkfish effectively generates self-correcting forces for pitching and yawing motions — a characteristic that is advantageous for the highly variable velocity fields experienced by trunkfish in their complex aquatic environment. All important morphological features of the carapace contribute to producing the hydrodynamic stability of swimming trajectories in this species.
Characterisation of intestinal peptide transporter of the Antarctic haemoglobinless teleostChionodraco hamatus
Authors: Maffia M. , Rizzello A. , Acierno R. , Verri T. , Rollo M. , Danieli A. , Döring F. , Daniel H. , Storelli C.
Published: January 2003

H+/peptide cotransport was studied in brush-border membrane vesicles (BBMV) from the intestine of the haemoglobinless Antarctic teleost Chionodraco hamatus by monitoring peptide-dependent intravesicular acidification with the pH-sensitive dye Acridine Orange. Diethylpyrocarbonate-inhibited intravesicular acidification was specifically achieved in the presence of extravesicular glycyl-L-proline (Gly-L-Pro) as well as of glycyl-L-alanine (Gly-L-Ala) and D-phenylalanyl-L-alanine(D-Phe-L-Ala). H+/Gly-L-Pro cotransport displayed saturable kinetics, involving a single carrier system with an apparent substrate affinity (Km,app) of 0.806±0.161 mmol l-1. Using degenerated primers from eel and human (PepT1)transporter sequence, a reverse transcription-polymerase chain reaction(RT-PCR) signal was detected in C. hamatus intestine. RT-PCR paralleled kinetic analysis, confirming the hypothesis of the existence of a PepT1-type transport system in the brush-border membranes of icefish intestine.

Functional expression of H+/peptide cotransport was successfully performed in Xenopus laevis oocytes after injection of poly(A)+ RNA (mRNA) isolated from icefish intestinal mucosa. Injection of mRNA stimulated D-Phe-L-Ala uptake in a dose-dependent manner and an excess of glycyl-L-glutamine inhibited this transport. H+/peptide cotransport in the Antarctic teleost BBMV exhibited a marked difference in temperature optimum with respect to the temperate teleost Anguilla anguilla, the maximal activity rate occurring at approximately 0°C for the former and 25°C for the latter. Temperature dependence of icefish and eel intestinal mRNA-stimulated uptake in the heterologous system (oocytes) was comparable.