Modeling and measuring the elastic properties of an archaeal surface, the sheath of Methanospirillum hungatei, and the implication of methane production.

We describe a technique for probing the elastic properties of biological membranes by using an atomic force microscope (AFM) tip to press the biological material into a groove in a solid surface. A simple model is developed to relate the applied force and observed depression distance to the elastic modulus of the material. A measurement on the proteinaceous sheath of the archaebacterium Methanospirillum hungatei GP1 gave a Young's modulus of 2 x 10(10) to 4 x 10(10) N/m2.

Transmission electron microscopy, scanning tunneling microscopy, and atomic force microscopy of the cell envelope layers of the archaeobacterium Methanospirillum hungatei GP1.

Methanospirillum hungatei GP1 possesses paracrystalline cell envelope components including end plugs and a sheath formed from stacked hoops. Both negative-stain transmission electron microscopy (TEM) and scanning tunneling microscopy (STM) distinguished the 2.8-nm repeat on the outer surface of the sheath, while negative-stain TEM alone demonstrated this repeat around the outer circumference of individual hoops.

Technical difficulties with the Brooker-Wills nail in acute fractures of the femur.

In this series of 41 cases of acute fractures of the femur treated with the Brooker-Wills nail, 20 technical problems with insertion or removal of the nail occurred in 19 of the total. Final outcomes were determined in 33 cases followed for 1 year or more. Technical difficulties had a deleterious effect on the outcome in three of these 33 cases.