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Mylodontidae bones from La Gruta 3 rockshelter, which date to 11,077–10,571 cal BP (9560 ± 30–9470 ± 30 14 C BP) and 9539–9466 cal BP (8540 ± 30 14 C BP), indicate that the extinct giant ground sloth was in the area after it was first occupied by humans during the late Pleistocene at 12,799–12,049 cal BP (10,845 ± 61–10,477 ± 56 14 C BP). Sediment characteristics at La Gruta 1 and 3 rockshelters (LG1 and LG3) suggest that conditions were wetter during major periods of human occupation and this is supported by pollen data. Lacustrine silts and clays in La Barda, and La Gruta Lagoons 1 and 3, provide evidence of an arid interval prior to about 6500 cal BP (5690 ± 35 14 C BP) followed by wetter conditions. This may explain why there is no evidence of humans between ca. 7760 and 5583 cal BP (7500 ± 250 and 4770 ± 25 14 C BP) either at La Gruta or at La Martita and Viuda Quenzana, which are ca. 25 km away. There is considerable evidence for occupation at Viuda Quenzana after 5581 cal BP and scanty evidence for occupation at La Gruta around 3800 cal BP with more abundant evidence after 1880 cal BP. In the last 1500 years, six radiocarbon ages show that humans occupied LG1 and LG3 before (1372–1271 cal BP) and after (539–156 cal BP), but not during, the Medieval Climate Anomaly, which may have been a time of increased aridity in the area. The findings at La Gruta show that Mylodontidae was probably present in the southern Deseado Massif after the first humans arrived but data from southern Patagonia show that it became extinct soon afterwards. [ABSTRACT FROM AUTHOR]

Abstract: A 0.6-m-long horizontal core from a stalagmite in the entrance area of Wonderwerk Cave in South Africa, a National Heritage Site, has provided a 35ka record of environmental change. A pollen sequence from the stalagmite, and two animal dung deposits, is longer and more detailed for the end of the Pleistocene than previous palynological reports from the southern Kalahari region. This pollen record closely matches information from spring peats at Wonderkrater in Northern Province indicating that speleothem pollen can provide reliable paleovegetation data. The δ18O and δ13C records resemble those from Cold Air Cave in Northern Province and parallel variations in Greenland Ice Sheet GISP2 paleotemperature. This indicates that past climate changes in southern Africa were linked to changes in global atmospheric and oceanic circulation patterns possibly triggered by conditions in the North Atlantic region. The Wonderwerk data suggest wetter conditions at ca. 33ka, from 23 to 17ka, and from 4ka to present. Conditions were drier 17–13ka, when microstromatolitic carbonate was deposited on the flank of the stalagmite, and possibly also during depositional hiatuses from 33 to 23ka and 13 to 4ka. [Copyright &y& Elsevier]

Two stalagmites from Anjohibe Cave have annual layers made up of inclusion-rich calcite over inclusion-free calcite or of darker aragonite over clear aragonite. Geochemical evidence indicates that the basal units are deposited slowly in the wet season and the upper units more rapidly in the dry season. For the period with rainfall and temperature data (ad 1951–1992), layer thickness correlates well with the Southern Oscillation Index (SOI), as well as rainfall, water surplus, and actual evapotranspiration (AET) at nearby Majunga. Comparison of the layer record for one stalagmite with 1866–1994 SOI data indicates that layer thickness correlates best with the frequency and intensity of warm, low-phase SO (El Niño) events, not with average SOI conditions. In addition, the 415-year layer thickness time-series from that speleothem agrees remarkably well with historical records of El Niño frequency, with Galápagos (Ecuador) coral records of sea-surface temperature in the eastern Pacific, and with accumulation rates on the Quelccaya Ice Cap of Peru, which are lower at times of high El Niño frequency. [ABSTRACT FROM AUTHOR]

Abstract: In order to define criteria for long-term climate change models in Southern Africa, an overview of the available pollen data during the Late Quaternary is needed. Here we reassess the paleo-climatic conditions in southern Africa by synthesising available fossil pollen data that can provide new insights in environmental change processes. The data considered here include the latest as well as previously published information that has been difficult to assess. Available calibrated pollen sequences spanning the Late Pleistocene and Holocene were subjected to Principal Components Analysis (PCA) to monitor taxa sensitive to moisture and temperature fluctuations. The PCA values are presented graphically as indicators of climate variability for the region. The results cover different biomes that include the summer-rain region in the north and east, the winter-rain area in the south and the dry zone in the west. The PCA plots directly reflect major changes of terrestrial environments due to variations in temperature and moisture. Mostly sub-humid but fluctuating conditions are indicated during the cold Marine Isotope Stage (MIS) 2, which were followed by a dry phase soon after the beginning of the Holocene but before the middle Holocene in the northern, central and eastern parts of the sub-continent. Marked but non-parallel moisture changes occurred in different subregions during the Holocene suggesting that climatic forcing was not uniform over the entire region. Some events seemed to have had a more uniform effect over the sub-continent, e.g., a relatively dry summer rain event at c. two thousand years ago, which can possibly be related to the ENSO phenomenon. The role of anthropogenic activities in some of the most recent vegetation shifts is likely. [Copyright &y& Elsevier]

Abstract: Assessment of the therapeutic potential of interventions to bridge-repair peripheral nerve defects heavily relies on the demonstration of improved functional outcome. In the present study we used CatWalk gait analysis (locomotor-test) and Static Sciatic Index (SSI) (static-toe-spread-test) to assess the behavioural benefits of autologous nerve transplantation (ANT) repair of 2-cm rat sciatic nerve defects (neurotmesis-lesion). A reproducible and standardised rat sciatic nerve crush lesion model (axonotmesis-lesion) was used to assess the extent of recovery supported by maximal axon regeneration (measured by SSI and CatWalk). Animals were behaviourally followed for a period of 10 weeks. SSI analysis showed that ANT induced a significant improvement in motor deficit from about −95 to −65, however, CatWalk analysis did not show any major indication of locomotor recovery. This discrepancy might suggest that improvements in static motor functions (such as toe spreading) could reflect an early indicator for the recovery of function. We also noted differences in axon regeneration including increased axon density, smaller axon diameters and thinner myelin sheaths in the distal region of the ANT in comparison to the equivalent region of crushed and normal nerves. This difference in axon regeneration may be related to the clearly improved toe spreading function. We conclude that SSI and CatWalk present different advantages and disadvantages for the assessment of motor recovery after bridge-repair of peripheral nerve defects. [Copyright &y& Elsevier]

An increasing number of biomaterial nerve guides has been developed that await direct comparative testing with the ‘gold-standard’ autologous nerve graft in functional repair of peripheral nerve defects. In the present study, 20 mm rat sciatic nerve defects were bridged with either a collagen-based micro-structured nerve guide (Perimaix) or an autologous nerve graft. Axons regenerated well into the Perimaix scaffold and, the majority of these axons grew across the 20 mm defect into the distal nerve segment. In fact, both the total axon number and the number of retrogradely traced somatosensory and motor neurons extending their axons across the implant was similar between Perimaix and autologous nerve graft groups. Implantation of Schwann cell-seeded Perimaix scaffolds provided only a beneficial effect on myelination within the scaffold. Functional recovery supported by the implanted, non-seeded Perimaix scaffold was as good as that observed after the autologous nerve graft, despite the presence of thinner myelin sheaths in the Perimaix implanted nerves. These findings support the potential of the Perimaix collagen scaffold as a future off-the-shelf device for clinical applications in selected cases of traumatic peripheral nerve injury. [ABSTRACT FROM AUTHOR]

Abstract: Olfactory ensheathing cells (OEC) are a promising graftable cell population for improving functional outcomes after experimental spinal cord injury. However only few studies have focused on experimental models with large cavitations, which require bridging substrates to transfer and maintain the donor cells within the lesion site. Here, a state-of-the-art collagen-based multi-channeled three dimensional scaffold was used to deliver olfactory ensheathing cells to 2mm long unilateral low-thoracic hemisection cavities. For a period of 10 weeks, allodynia of the hindpaws was monitored using the von Frey hair filament test, while an extensive analysis of motor ability was performed with use of the CatWalk gait analysis system and the BBB locomotor scale. No substantial improvement or deterioration of motor functions was induced and there was no effect on lesion-induced allodynia. On the basis of these data, we conclude that relatively large spinal cord lesions with cavitation may present additional hurdles to the therapeutic effect of OEC. Future studies are needed to address the nature that such lesion cavities place on cell grafts. [Copyright &y& Elsevier]

Abstract: Following peripheral nerve injury repair, improved behavioural outcome may be the most important evidence of functionality of axon regeneration after any repair strategy. A range of behavioural testing paradigms have been developed for peripheral nerve injury research. Complete injury of the adult rat sciatic nerve is frequently used in combination with walking track analysis. Despite its wide-spread use, these walking track analyses are unsuitable for the simultaneous assessment of both dynamic and static gait parameters. Conversely, a novel automated gait analysis system, i.e. CatWalk can simultaneously measure dynamic as well as static gait parameters and, importantly, it''s easy to control for the speed of locomotion which can strongly affect gait parameters. In a previous study, CatWalk was already successfully used to examine deficits in both dynamic and static gait parameters using the sciatic nerve lesion model with a 1cm gap characterized by absence of recovery [Deumens R, Jaken RJ, Marcus MA, Joosten EA. The CatWalk gait analysis in assessment of both dynamic and static gait changes after adult rat sciatic nerve resection. J Neurosci Methods 2007;164:120–30]. Using the sciatic nerve crush injury model (validated with the static sciatic index) and a follow-up period of 12 weeks, we now show that CatWalk can also measure behavioural recovery. In particular dynamic gait parameters, coordination measures, and the intensity of paw prints are of interest in detecting recovery as far as these parameters completely return to pre-operative values after crush injury. We conclude that CatWalk can be used as a complementary approach to other behavioural testing paradigms to assess clinically relevant behavioural benefits, with a main advantage that CatWalk demonstrates both static and dynamic gait parameters at the same time. [Copyright &y& Elsevier]