Sunday, May 29, 2005

Common chemical may cause defects in baby boys - Yahoo! News

Common chemical may cause defects in baby boys - Yahoo! News: "Common chemical may cause defects in baby boys By Elizabeth Weise, USA TODAY
Fri May 27, 9:22 AM ET

For the first time, scientists have shown that pregnant mothers exposed to high but common levels of a widely used ingredient in cosmetics, fragrances, plastics and paints can have baby boys with smaller genitals and incomplete testicular descent.

The paper, published Friday in the journal Environmental Health Perspectives, found that the more a mother was exposed to the chemicals, called phthalates (THAL-ates), the greater the chance her boy's reproductive development would be harmed. Similar changes have led to decreased semen quality and fertility in rodents.

"We'll follow our children to see what the consequences are," says lead researcher Shanna Swan, a professor of epidemiology at the University of Rochester (N.Y.) School of Medicine.


Sunday, May 22, 2005

Ion Channels and the Electrical Properties of Membranes

WOW, looks like I found my test case... MS often starts with kids 8-13 years old... Emily and Chris started at about this age... PERFECT!!! lol... wow, so cool, thanks Jared!!

Ion Channels and the Electrical Properties of Membranes: "Myelination Increases the Speed and Efficiency of Action Potential Propagation in Nerve Cells

The axons of many vertebrate neurons are insulated by a myelin sheath, which greatly increases the rate at which an axon can conduct an action potential. The importance of myelination is dramatically demonstrated by the demyelinating disease multiple sclerosis, in which myelin sheaths in some regions of the central nervous system are destroyed; where this happens, the propagation of nerve impulses is greatly slowed, often with devastating neurological consequences.

Myelin is formed by specialized supporting cells called glial cells. Schwann cells myelinate axons in peripheral nerves and oligodendrocytes do so in the central nervous system. These glial cells wrap layer upon layer of their own plasma membrane in a tight spiral around the axon (Figure 11-30), thereby insulating the axonal membrane so that little current can leak across it. The myelin sheath is interrupted at regularly spaced nodes of Ranvier, where almost all the Na+ channels in the axon are concentrated. Because the ensheathed portions of the axonal membrane have excellent cable properties (in other words, they behave electrically much like well-designed underwater telegraph cables), a depolarization of the membrane at one node almost immediately spreads passively to the next node. Thus, an action potential propagates along a myelinated axon by jumping from node to node, a process called saltatory conduction. This type of conduction has two main advantages: action potentials travel faster, and metabolic energy is conserved because the active excitation is confined to the small regio"