Stem cells have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.

Harvard Science describes how bone marrow stem cells may help control inflammatory bowel disease in “the first demonstration of their ability to suppress a broad-based autoimmune reaction and protect gastrointestinal tissue.” Science News headlines: Bone Marrow Alternative: Stem Cells From Umbilical Cord May Be Used To Treat Hepatic Diseases, in an article pointing to stories about several other uses for bone marrow stem cells.

The Learn.Genetics project at the University of Utah offers a section on Stem Cell Therapies Today with illustrated explanations and links to related tropics. The National Cancer Institute provides detailed discussions of Bone Marrow Transplantation and Peripheral Blood Stem Cell Transplantation.

adult_stem_cells bone bone_marrow bowel cell cure diseases harvard hepatic immune_system intestines marrow peripheral transplant utah university

Looking at the little tiny world – at things like bilayer formation of cells, veins, and neurons in biological membranes – is becoming more an more sophisticated and productive. The image with this post from page 7of Lecture 6: AFM imaging II: Artifacts and Applications from the MIT lecture notes for a course on Nanomechanics of Materials and Biomaterials. The image originates in the LadyofHats collection of public domain images, which is a source of superb drawings of dinosaurs, biology, and other subjects.

A general article describing micro and nanomechanics is available on the IMES Institute of Mechanical Systems website. This is its introductory overview:

Micro- and nanomechanics are concerned with the modelling, design, fabrication and application of three-dimensional structures and systems with dimensions in the range of micrometers and below. These systems incorporate a number of interesting features: The classical fabrication methods of micromachining are extended by those developed in the semiconductor industry during the passed decades. Different quantities scale differently when moving from large to small structures demanding new models to describe the physical behaviour observed on a small scale.Devices used to perform a certain function and found to be optimal for the macroscopic scale are replaced by others exploiting various physical effects suited to the microscopic world.

Last but not least, the limits of classical continuum mechanics have to be explored and extended. New methods need to be developed in order to quantify bonding properties between different layers, residual stresses which are caused by manufacturing processes as well as the elastic constants itself, just to mention a few examples.

Poliovirus Viron (left image):
30 nM diameter virion contains 60 copies each of four proteins (encoded in the viral RNA) – Viral RNA is a single strand mRNA (+) polarityi, is about 8000 bases long, and encodes 11 proteins – Viron is non-enveloped and contains no enzymes

Poliovirus: Intracellular Replication (right image):
1. Attachment to cell via specific receptor (Vpr) on cell membrane 2. Virus entry (endocytosis); extrusion of RNA into cytoplasm 3-5. Translation of viral RNA; processing of polyprotein; formation of RNA replicase protein 8-10. Replication of viral RNA 11. Continued translation and processing; formation of virion proteins 12. Assembly of (+) RNA and rivon proteins into new virions 13. Virion release into the gut

MORE POLIOVIRUS LEARN NODES:

For more about the ongoing fight against polio, the Stony Brook University School of Medicine published an open access article in Virology Journal: “Epidemics to eradication: the modern history of poliomyelitis.”

For a look at sleuths who are tracking the polio viruses as they invade our cells try this open access article from the Public Library of Science BIOLOGY: “Imaging Poliovirus Entry in Live Cells.”

More learn nodes at: learnodes.com