内容摘要：of a heart from a genetically altered pig into another dying man. David Bennett survived two months before that heart failed, for reasons that aren’t completely clear although

of a heart from a genetically altered pig into another dying man. David Bennett survived two months before that heart failed, for reasons that aren’t completely clear although

Twice a week, slaughterhouses ship Revivicor hundreds of eggs retrieved from sow ovaries. Working in the dark with the light-sensitive eggs, scientists peer through a microscope while suctioning out the maternal DNA. Then they slip in the genetic modifications.A worker at United Therapeutics’ designated pathogen-free facility in Christiansburg, Va., on May 29, 2024 retrives a UV sterilized item from behind a protected barrier within the facility. (AP Photo/Shelby Lum)

A worker at United Therapeutics’ designated pathogen-free facility in Christiansburg, Va., on May 29, 2024 retrives a UV sterilized item from behind a protected barrier within the facility. (AP Photo/Shelby Lum)“Tuck it in nice and smooth,” murmurs senior researcher Lori Sorrells, pushing to just the right spot without rupturing the egg. Mild electric shocks fuse in the new DNA and activate embryo growth.Ayares, a molecular geneticist who heads Revivicor and helped create the world’s first cloned pigs in 2000, says the technique is “like playing two video games at the same time,” holding the egg in place with one hand and manipulating it with the other. The company’s first modified pig, the

single gene knockout, now is bred instead of cloned. If xenotransplantation eventually works, other pigs with the desired gene combinations would be, too.Hours later, embryos are carried to the research farm in a handheld incubator and implanted into waiting sows.

United Therapeutics’ designated pathogen-free facility in Christiansburg, Va., on May 29, 2024. (AP Photo/Shelby Lum)

United Therapeutics’ designated pathogen-free facility in Christiansburg, Va., on May 29, 2024. (AP Photo/Shelby Lum)Responding to Sen. Chris Murphy, a Democrat of Connecticut, Kennedy refused to recommend that parents follow the nation’s childhood vaccination schedule, which includes shots for measles, polio and whooping cough. He, instead, wrongly claimed that the vaccines have not been safety tested against a placebo.

Sen. Bill Cassidy, a Republican of Louisiana and chairman of the health committee, had extracted a number of guarantees from Kennedy that he would not alter existing vaccine guidance and work at the nation’s health department. Cassidy, correcting Kennedy, pointed out that rotavirus, measles and HPV vaccines recommended for children have all been tested in a placebo study.As health secretary, Kennedy has called the measles, mumps and rubella vaccine — a shot given to children to provide immunity from all three diseases — “leaky,” although

from the measles for most people. He’s also said, although none has been documented among healthy people.