From Wikipedia on the Yew tree toxicity:
The major toxin is the alkaloid taxane. The foliage remains toxic even when wilted or dried. Horses have the lowest tolerance, with a lethal dose of 200–400 mg/kg body weight, but cattle, pigs, and other livestock are only slightly less vulnerable. Symptoms include staggering gait, muscle tremors, convulsions, collapse, difficulty breathing, and eventually heart failure. However, death occurs so rapidly that many times the symptoms are missed.
Jonathon Hamilton a talented design engineer who had recently lost majority control of his an implant business he'd founded when he was forced to sell stock to cover his debts. His company "Smart Implant" has a proprietary design where the filler of an implant is composed of hundreds of solid silicone beads instead of a viscous silicone gel.
Having never seen one of these implants in person, I'm not sure there's much to this departure from conventional design that is much of an advantage but it's an interesting idea. These type of implants are not available in the United States and I'm not aware that they've even applied to the FDA to conduct clinical trials here.