Postcranial evidence of late Miocene hominin bipedalism in Chad.

Bipedal locomotion is one of the key adaptations that define the hominin clade. Evidence of bipedalism is known from postcranial remains of late Miocene hominins as early as 6 million years ago (Ma) in eastern Africa1-4. Bipedality of Sahelanthropus tchadensis was hitherto inferred about 7 Ma in central Africa (Chad) based on cranial evidence5-7. Here we present postcranial evidence of the locomotor behaviour of S. tchadensis, with new insights into bipedalism at the early stage of hominin evolutionary history. The original material was discovered at locality TM 266 of the Toros-Ménalla fossiliferous area and consists of one left femur and two, right and left, ulnae. The morphology of the femur is most parsimonious with habitual bipedality, and the ulnae preserve evidence of substantial arboreal behaviour. Taken together, these findings suggest that hominins were already bipeds at around 7 Ma but also suggest that arboreal clambering was probably a significant part of their locomotor repertoire.

Biomechanical demands of percussive techniques in the context of early stone toolmaking.

Recent discoveries in archaeology and palaeoanthropology highlight that stone tool knapping could have emerged first within the genera Australopithecus or Kenyanthropus rather than Homo. To explore the implications of this hypothesis determining the physical demands and motor control needed for performing the percussive movements during the oldest stone toolmaking technology (i.e. Lomekwian) would help. We analysed the joint angle patterns and muscle activity of a knapping expert using three stone tool replication techniques: unipolar flaking on the passive hammer (PH), bipolar (BP) flaking on the anvil, and multidirectional and multifacial flaking with free hand (FH). PH presents high levels of activity for Biceps brachii and wrist extensors and flexors. By contrast, BP and FH are characterized by high solicitation of forearm pronation. The synergy analyses depict a high muscular and kinematic coordination. Whereas the muscle pattern is very close between the techniques, the kinematic pattern is more variable, especially for PH. FH displays better muscle coordination and conversely lesser joint angle coordination. These observations suggest that the transition from anvil and hammer to freehand knapping techniques in early hominins would have been made possible by the acquisition of a behavioural repertoire producing an evolutionary advantage that gradually would have been beneficial for stone tool production.

Bifid liver in a patient with diaphragmatic hernia.

Liver malformations including lobe and segmental abnormalities are rare. We report a 65-year-old lady with complaints of breathlessness and fullness after meals for two months. Investigations revealed a diaphragmatic hernia on the right side with a bifid liver; the right lobe of the liver was among the hernia contents. The lady is asymptomatic after surgical repair.

Surgical site infection in clean and clean-contaminated cases.

The rate of surgical site infections and the frequency of various pathogens causing surgical site infection with their antibiotic resistance pattern in general surgery units were studied. In the period from May 2001 to July 2002, 190 patients admitted for surgery (clean and clean-contaminated elective cases) were assessed preoperatively, intraoperatively and postoperatively. Normal microbial flora was studied within 24 to 48 hours of admission and patients were followed up to 30 days postoperatively. Infected wounds were studied bacteriologically and clinically. The overall infection rate was 8.95%. Surgical site infection rate was 3.03% in clean surgeries and 22.41% in clean-contaminated surgeries. Significant increase was seen in surgical site infection rate with an increase in preoperative stay. The increase in duration of surgery was associated with a significant rise in the rate of surgical site infection. Surgical site infection rate was much higher (22.41%) in cases where a drain was used than in non-drained wounds (3.03%). The most common isolate was Staphylococcus aureus followed by Pseudomonas aeruginosa.