Limpet Shells from the Aterian Level 8 of El Harhoura 2 Cave (Témara, Morocco): Preservation State of Crossed-Foliated Layers

International audienceThe exploitation of mollusks by the first anatomically modern humans is a central question for archaeologists. This paper focuses on level 8 (dated around * 100 ka BP) of El Har-houra 2 Cave, located along the coastline in the Rabat-Témara region (Morocco). The large quantity of Patella sp. shells found in this level highlights questions regarding their origin and preservation. This study presents an estimation of the preservation status of these shells. We focus here on the diagenetic evolution of both the microstructural patterns and organic components of crossed-foliated shell layers, in order to assess the viability of further investigations based on shell layer minor elements, isotopic or biochemical compositions. The results show that the shells seem to be well conserved, with microstructural patterns preserved down to sub-micrometric scales, and that some organic components are still present in situ. But faint taphonomic degradations affecting both mineral and organic components are nonetheless evidenced, such as the disappearance of organic envelopes surrounding crossed-foliated lamellae, combined with a partial recrystallization of the lamellae. Our results provide a solid case-study of the early stages of the diagenetic evolution of crossed-foliated shell layers. Moreover, they highlight the fact that extreme caution must be taken before using fossil shells for palaeoenvironmental or geochronological reconstructions. Without thorough investigation, the alteration patterns illustrated here would easily have gone unnoticed. However, these degradations are liable to bias any proxy based on the elemental, isotopic or biochemical composition of the shells. This study also provides significant data concerning human subsistence behavior: the presence of notches and the good preservation state of limpet shells (no dissolution/recrystallization, no bioerosion and no abrasion/fragmentation aspects) would attest that limpets were gathered alive with tools by Middle Palaeolithic (Aterian) populations in North Africa for consumption

Analysis of the Learning Curve Effect on the Quality of the Surgical Procedure in 300 Laparoscopic Colorectal Surgeries

Introduction: We compared the quality of the surgical procedure during our training in laparoscopic coloproctology. Materials and Methods: The study included 300 laparoscopic colorectal surgeries due to colorectal cancer in the period March 1, 2009 - May 31, 2013. They were performed at UMHAT - Evrohospital, Plovdiv. The patients were divided into three groups according to the number of interventions performed. The first group was 1-20 surgeries, the second one 20-40 and the third one - more than 40 procedures. Results: We observed a significant reduction in the operating time in laparoscopic right hemicolectomy (185 min. vs 100 min.). Anterior resection operating time for upper rectal cancer was reduced to 120 min, rather than 210 min. We did not find a significant reduction in the duration of surgery for distal rectal surgeries. Patients with convertion decreased from 11% in the first group to 4% in the third, as these were mostly patients with distal rectal cancer. The frequency of insufficiency was 6% in the first group, with no significant difference in perspective.Conclusion: With the ascent of the training curve the operating time was reduced as well as the percentage of convertion rate. The nature of the complications changed. The major surgical complications did not change with training. There is probably an extension of the indications for laparoscopic surgery with the accumulation of relevant experience

Two-stage hepatectomy for colorectal liver metastases in elderly adults

Two-stage hepatectomy is a surgical strategy developed for cases of bilobar multinodular liver metastases. It is performed when all lesions cannot be removed in a single procedure due to a too small remnant liver volume. The main principle in this approach is a consecutive resection in two stages. It relies on the liver regeneration between the two interventions, allowing the second hepatectomy to be performed with a lower risk of complications. Subjects are patients with colorectal cancer liver metastases who undergo surgery at the surgical departments of Military Medical Academy of Plovdiv and Eurohospital of Plovdiv. For the period 2009-2013, 96 radical resections (58 metachronous and 38 synchronous). Of them, 58 are patients over 65 years of age. We performed 7 two-stage hepatectomies, 4 of these patients are aged over 65 years. Blood loss and blood transfusion were without significant differences between these two age groups. Complications rate in the postoperative period and the length of hospital stay were comparable, despite the higher level of comorbidity in the group aged over 65 years. Two-stage liver resections are a good opportunity for a small group of patients with bilobar metastases. The indications for this procedure can be successfully applied for elderly patients with appropriate perioperative management concerning the high co-morbidity in this group