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Mortimer Mendelsohn

 Nearly 50 years ago, Lawrence Livermore National Laboratory hired an eminent cancer researcher from the University of Pennsylvania to renovate and expand the Laboratory’s small biomedical research program.

The scientist, Mortimer Mendelsohn, arrived in 1972, accompanied by several university colleagues.  In the years that followed, he assembled a team that helped spur a revolution in understanding how and why human cells mutate and sometimes become cancerous.

Mendelsohn died early last year, honored by former scientific colleagues from around the country and abroad. 

More recently, the scientific journal Cytometry recognized his career with a series of memorial essays writteen by colleagues, including several from LLNL whose careers were influenced by Mendelsohn’s leadership.

Born in New York City, Mendelsohn earned an MD at Harvard Medical School in 1948 before specializing in oncology, practicing medicine and carrying out research at Walter Reed Medical Center. 

After getting a PhD at Cambridge University in the UK, he had a distinguished career at the University of Pennsylvania, helping to set up a cancer center there before moving to Livermore. 

He joined the national laboratory at a time when biology was undergoing a transition from the painstaking examination of microscope slides to the development of instruments that measure features of thousands of cells per second.

Much of the development of these high speed systems took place at LLNL in the 1970s under Mendelsohn’s leadership.  Colleagues credited the capabilities of the systems, and Mendelsohn’s personal eloquence, with persuading the U.S. government that scientists could and should map the human genome — the complete set of genetic instructions in human cells.

By the late 1980s, LLNL and its fellow national laboratories at Los Alamos and Oak Ridge were creating the world’s most precise maps of the gene-carrying concentrations of genetic material called chromosomes, according to Tom Slezak, a computer scientist who worked with Mendelsohn for many years.

‘Like all great scientists…’

In its tribute to Mendelsohn, the journal Cytometry wrote, “Like all great scientists, Mort was driven by curiosity and the refusal to accept the status quo.”

His approach to science emphasized the demand for quantitative information, “applying the tools of statistics and mathematical modeling to data extracted from individual cells.” 

Former colleagues remembered him as a demanding but always constructive leader.

Bart Gledhill recalled Mendelsohn’s rare ability to probe someone’s argument — to “dig until he could see the logic” — without causing offense.

Gledhill was part of the original group from the University of Pennsylvania, a research veterinarian.  At LLNL, he became a senior manager in Mendelsohn’s program.

Another member of the Penn group, Dan Moore, a statistician, remembers that Mendelsohn “made everyone feel important,” fostering an atmosphere of cooperation and support rather than competition.  

A third member of the Penn group who moved to LLNL, Brian Mayall, recalled both the “congenial” atmosphere of Mendelsohn’s research program and its wide range of scientific disciplines.

“People visiting from abroad were really delighted and at the same time puzzled at how well we had been able to create that environment and collegial atmosphere, which was very different from the usual academic environment,” he said. 

Mayall was an LLNL group leader under Mendelsohn, a physician who later transferred to the University of California, San Francisco as a professor. He was founding editor of Cytometry and organized the journal’s recent tribute.

In addition to medicine, mathematics and veterinary science, the group incorporated expertise in physics, engineering, computer science, marine biology, environmental science and more.

‘Wonderful mentor’

Joe Gray, a physicist, regarded Mendelsohn as a “wonderful mentor.” After nearly 20 years at LLNL, Gray has had a distinguished career in biomedical research at UC-San Francisco, Lawrence Berkeley National Laboratory, and now the Oregon Health Sciences University in Portland.

Mendelsohn “created a multidisciplinary environment where people from a variety of walks of life could work together in a supportive way to tackle problems too big for one person to go after,” Gray said.

“He brought all these people together in a very rich milieu that allowed progress to be made on important problems of the time.

“He was tough in the sense of demanding scientific rigor, but he was incredibly supportive as a mentor and uncharacteristically generous. He stayed out of the way when it came time for assigning credit … he wanted his people to get credit, wasn’t interested in the limelight himself. That’s pretty rare.”

To still another of his colleagues with a distinguished career, Elbert Branscomb, Mendelsohn had a “sense of sacredness” in undertaking biomedical research. 

He meant by this that Mendelsohn was very conscious of spending public money and felt he had to produce genuine value for it. “He (carried out research programs) carefully and respectfully, not just putting up numbers.”

Branscomb later became an associate director at LLNL and head of the U.S. Department of Energy’s Joint Genome Institute. 

The move to Livermore gave the Pennsylvania team, and the colleagues they attracted to their programs, resources not readily available in a university setting.

‘Incredible panorama’

Gledhill, the research veterinarian, said working at a big national laboratory “meant opening an incredible panorama of researchers and research tools and skills that were not available anywhere else.”

Gray commented, “People (at LLNL) with measurement technologies could work with people interested in biological problems, could work with people who were math oriented, could work with people who had a chemistry background.”   

Because of his renown in cell science, Mendelsohn was chosen as vice chair of the joint U.S.-Japanese Radiation Effects Research Foundation, which studied survivors of the Hiroshima and Nagasaki atomic bombings for health effects.

He moved to Japan for several years as part of this responsibility. The Japanese government recognized his contributions by awarding him the Third Order of the Sacred Treasure, one of that country’s highest civilian awards.

Friends and neighbors remembered Mendelsohn as an excellent tennis player.  He was musical as well. He played the flute, and a daughter recalls live chamber groups performing in the house while she was growing up in Pennsylvania.

A Livermore resident, he served on the board of Del Valle Fine Arts and the founding board of Livermore Valley Performing Arts Center.