The origins and development of Zuwīla, Libyan Sahara: an archaeological and historical overview of an ancient oasis town and caravan centre

Zuwīla in southwestern Libya (Fazzān) was one of the most important early Islamic centres in the Central Sahara, but the archaeological correlates of the written sources for it have been little explored. This paper brings together for the first time a detailed consideration of the relevant historical and archaeological data, together with new AMS radiocarbon dates from several key monuments. The origins of the settlement at Zuwīla were pre-Islamic, but the town gained greater prominence in the early centuries of Arab rule of the Maghrib, culminating with the establishment of an Ibāḍī state ruled by the dynasty of the Banū Khaṭṭāb, with Zuwīla its capital. The historical sources and the accounts of early European travellers are discussed and archaeological work at Zuwīla is described (including the new radiocarbon dates). A short gazetteer of archaeological monuments is provided as an appendix. Comparisons and contrasts are also drawn between Zuwīla and other oases of the ash-Sharqiyāt region of Fazzān. The final section of the paper presents a series of models based on the available evidence, tracing the evolution and decline of this remarkable site

PDGF-induced signaling in proliferating and differentiated vascular smooth muscle: effects of altered intracellular Ca2+ regulation

Objective: Platelet-derived growth factor-BB (PDGF)-induced intracellular signaling is involved in phenotypic modulation of vascular smooth muscle (VSM). This study has examined the PDGF-induced Ca2+ increase and the resultant effect on signaling pathways in proliferative compared with fully differentiated VSM. Methods: PDGF-induced changes in Ca2+ were measured in portal vein (PV) myocytes from 2–4-day-old (proliferating), compared to 6-week-old (differentiated), Sprague Dawley rats. Phospholipase C (PLC)g expression and activation of extracellular signal-regulated kinase (ERK) 1/2 was determined by immunoblotting or confocal immunolabelling. Activation of the Ca2+-dependent transcription factor, nuclear factor of activated T-cells (NFATc), was assessed by electromobility shift assay. Results: PDGF increased the intracellular Ca2+ concentration in differentiated, but not in proliferating, PV myocytes. This is probably due to very low expression of PLCg in proliferating PV. In 6-week-old PV, PDGF stimulation induced nuclear translocation and activation of NFATc. PDGF did not induce NFATc activation in neonatal PV. PDGF-induced ERK1/2 activation was observed in both 2–4-day-old and 6-week-old PV. In 6-week-old PV, ERK1/2 activation was Ca2+-dependent and protein kinase C-dependent. However in 2–4-day-old PV, PDGF-induced ERK1/2 activation was via a Ca2+-independent, atypical protein kinase C. PLCg expression was also decreased in the neointima, compared to media, of balloon-injured rabbit subclavian arteries. Conclusions: The regulation of PDGF-induced Ca2+ increases by PLCg expression in VSM may provide a mechanism for coordinating different signaling pathways leading to activation of specific transcription factors. This may play an important role in the phenotypic modulation of VSM

Why U.S. health care expenditure and ranking on health care indicators are so different from Canada’s

Health care expenditure, United States, Canada, I10, I12,