Five months ago, a smiling Dr. Gerald Schatten appeared before reporters alongside South Korean stem cell researcher Dr. Hwang Woo-suk to present a scientific feat — the first cloned dog. It seemed a proud moment for the 56-year-old University of Pittsburgh scientist who had long studied embryonic stem cells and tirelessly promoted their possible use in fighting disease.Three months later, however, Schatten abruptly ended his 20-month partnership with Hwang, accusing the renowned researcher of unethical practices for a 2004 report that claimed Hwang had created the world’s first stem cells from cloned human embryos. Investigators later said much of Hwang’s work was faked. The uproar has prompted a University of Pittsburgh investigation and driven Schatten from public view amid questions about his dealings with Hwang.In interviews with The Associated Press over the past week, former colleagues called Schatten a man of high standards with an irrepressible enthusiasm for science, although one former collaborator questioned whether his drive for recognition may have hurt him."From my perspective, he’s a completely honest and ethical person, and I think that if he were directly involved in some of this misconduct that went on, that’s completely out of character,” said Duane Compton, a Dartmouth College biochemistry professor who collaborated with Schatten over a period of about 10 years.Schatten has said that he was not directly involved in Hwang’s laboratory research, and thus could not vouch for it, although he was listed as senior author or co-author on some of the South Korean’s papers. Those papers include a May 2005 article claiming that Hwang had derived patient-specific stem cell lines from cloned human embryos.In South Korea, prosecutors have found no evidence to substantiate Hwang’s claims of creating cloned stem cells. The scientist has accused colleagues of deceiving him and alleged that some of the cloned embryonic stem cells had been switched without his knowledge.Schatten did not respond to interview requests by phone and e-mail. A university spokeswoman did not return calls seeking comment on the investigation. The university is expected to release a statement on its findings by early February.Possible consequences of the investigation remain unclear.Dr. Arthur Levine, dean of the university’s medical school and Schatten’s boss, has said only that he will consider appropriate disciplinary action when the probe is complete.Compton said the possible demise of Schatten as a vocal supporter of stem cell research — a contentious field because of its use of human embryos — is “one of the saddest parts of this whole thing.” Schatten has helped educate members of Congress and other laymen about the potential therapeutic benefits of stem cells."He’s always been really good at that and he’s always been very balanced about the potential gains as well as the potential problems that exist,” Compton said. “He’s never painted some pie-in-the-sky picture."Joan Hunt, a professor at the University of Kansas Medical Center, who worked with Schatten at the Woods Hole Oceanographic Institution in Massachusetts, complimented his skill as a researcher but said his public support of stem cell research “is his tendency and maybe his weakness.""I think that Jerry, more often than not, if asked to be senior author, would say yes if he thought it was a good publication,” she said. However, “he has hundreds of publications, so it’s not as if he needs another paper."Schatten was already a prominent reproductive biologist specializing in monkeys by the time he arrived at the University of Pittsburgh in 2001.He is credited with having created the first monkey to contain DNA from another animal — in this case a jellyfish. He was reportedly interested in adapting Hwang’s techniques for use in the primates.Robert Lanza, a cloning expert at the Worcester, Mass.-based biotechnology company Advanced Cell Technology Inc., said he has a high regard for Schatten’s work. “It’s just a real shame that this has happened to him,” he said.