Parathyroid hormone (PTH) function as immunologic mediator has become interesting with the recent usage of PTH analogue (teriparatide) in the management of osteoporosis. Since the early 1980s, PTH receptors were found on most immunologic cells (neutrophils, B and T cells).
But, the refrigerator will only keep food safely cold for about four hours if unopened during a power outage, according to the USDA. A full freezer will hold the temperature for about 48 hours if full (24 hours of half full), the USDA says. Generally, if the temperature in the thermometer in the freezer reads 40 degrees Fahrenheit or below, the food is safe and can be refrozen, according to the USDA.
How long leftovers can safely stay in your refrigerator depends on the type of food and whether or not your fridge is truly keeping foods cold. It certainly saves you time and money to use leftover vegetables in a pasta or soup the next day, or leftover steak in a green salad. Err on the side of caution and safety, however, when dealing with leftovers in your fridge.