High performance liquid chromatography (HPLC) in the investigation of gout in palaeopathology

Gout is a disease caused by the abnormal accumulation of uric acid in the body, which can result in sodium urate crystals forming tophi at joints, with associated erosion of bone and cartilage. Only two examples of tophi have been reported from archaeological individuals, and the diagnosis of gout based on dry bone manifestations can be difficult. This paper presents preliminary results of a new technique to aid the diagnosis of gout in palaeopathology, namely high performance liquid chromatography (HPLC). Five archaeological skeletons with suspected gout (diagnosed using visual and radiological analysis) and three controls were analysed. Two of the gouty individuals had a white powder in their erosive lesions. HPLC showed the presence of uric acid in bone in four of the five individuals with evidence of gouty arthritis and was negative for uric acid in bone from the three controls. The white powder was also positive for uric acid. With reliance on the presence of articular erosions, cases of gout will be missed in archaeological human bone. HPLC measurement of uric acid could prove useful in the differential diagnosis of erosive arthropathy in archaeology. It may also be useful in identifying individuals with an increased body pool of uric acid, linked to conditions included in the term ‘metabolic syndrome’. As a result, HPLC uric acid measurement also has the potential to provide additional information on health and lifestyle in past communities. Copyright © 2008 John Wiley & Sons, Ltd.     

Rates of retrograde metamorphism and their implications for crustal rheology

The rate of reaction of a natural hornblende garnet granulite with water under a range of mid- to lower crustal conditions has been investigated experimentally. In runs of between 7 and 84 days small but measurable amounts of water were consumed, and sheet silicates (300°C, 300 MPa and 400°C, 400 MPa) and/or secondary actinolite (400°C, 400 MPa and 500°C, 500 MPa) were observed to have grown. When normalized to the surface area of the starting materials, hydration rates were in the range of 2–5 × 10⁻⁸ g m⁻² sec⁻¹. These reaction rates imply that a film of water that infiltrated a planar crack with a half width of 100 μm would be completely consumed within c. 100 years. These results imply that where water infiltrates the crust along faults or underlying shear zones in response to a deformation, it will remain as a free phase for only a finite period of time, which in some cases will be less than the repeat time for major earthquakes in the fault system. Thus, the rheology of fault zones and shear zones is likely to be cyclical, with the zone becoming stronger with time as water is consumed, and then weakened by infiltration of water after each rupture.     

Downward hydrocarbon migration predicted from numerical modeling of fluid overpressure in the Paleozoic Anticosti Basin,eastern Canada

The Anticosti Basin is a large Paleozoic basin in eastern Canada where potential source and reservoir rocks have been identified but no economic hydrocarbon reservoirs have been found. Potential source rocks of the Upper Ordovician Macasty Formation overlie carbonates of the Middle Ordovician Mingan Formation, which are underlain by dolostones of the Lower Ordovician Romaine Formation. These carbonates have been subjected to dissolution and dolomitization and are potential hydrocarbon reservoirs. Numerical simulations of fluid‐overpressure development related to sediment compaction and hydrocarbon generation were carried out to investigate whether hydrocarbons generated in the Macasty Formation could migrate downward into the underlying Mingan and Romaine formations. The modeling results indicate that, in the central part of the basin, maximum fluid overpressures developed above the Macasty Formation due to rapid sedimentation. This overpressured core dissipated gradually with time, but the overpressure pattern (i.e. maximum overpressure above source rock) was maintained during the generation of oil and gas. The downward impelling force associated with fluid‐overpressure gradients in the central part of the basin was stronger than the buoyancy force for oil, whereas the buoyancy force for gas and for oil generated in the later stage of the basin is stronger than the overpressure‐related force. Based on these results, it is proposed that oil generated from the Macasty Formation in the central part of the basin first moved downward into the Mingan and Romaine formations, and then migrated laterally up‐dip toward the basin margin, whereas gas throughout the basin and oil generated in the northern part of the basin generally moved upward. Consequently, gas reservoirs are predicted to occur in the upper part of the basin, whereas oil reservoirs are more likely to be found in the strata below the source rocks. Geofluids (2010) 10 , 334–350     

The evolution of rice: molecular vignettes on its origins and spread

The domesticated species Oryza sativa or Asian rice evolved starting approximately 9,000 years ago and from its centers of origin in China and India has subsequently spread throughout the Old World (and in historical times in the New World as well). This species is one of the key domesticated crop plants in the world and has emerged as a model for studying the origins and spread of domesticated taxa as well as in investigating the genetic basis for plant variation under domestication. Archaeological data has been critical in dissecting the origins and spread of rice throughout Asia, but molecular information has also provided a complementary approach to examining the evolutionary dynamics of this species. The evolutionary history of a species can leave its footprints within its genome. Moreover, genetic studies allow us to study the history of traits that do not leave an archaeological record—for example, grain stickiness or flowering time—which can provide insights into how crop species are adopted by different cultures. In this review, several molecular studies into the origin and spread of Asian rice are discussed and we explore the advances these genetic studies offer in our understanding of the evolution of domesticated species. We also explore how archaeological data can provide critical insights that can help refine genetic models of the origin and spread of domesticated species.     

EFFECTS OF MILLING: A POSSIBLE FACTOR INFLUENCING THE DURABILITY OF HISTORICAL MORTARS

In their literary texts, some classical Roman authors such as Gaius Plinius Secundus and Marcus Vitruvius Pollio stress the importance of milling when preparing mortars. Following these indications, this work describes the effects of milling between lime (calcium hydroxide) and clay brick powder before and after the addition of water. Starting and resulting materials were investigated by XRPD, SEM/EDS, differential scanning calorimetry and thermogravimetry (DSC/TC), colorimetry, densimetry and porosimetry. Prolonged milling changes the mineralogy of the starting materials and increases their reactivity. The final lime pastes, starting from materials milled for varying periods of time, had different mineralogical and physical characteristics. These results may help to clarify the reasons for the marked differences in durability of some historical mortars.