Symposium Pays 'Glowing' Tribute to Inventor Robert Bowman
By Deborah Noble
Two and a half years after his death, Dr. Robert L. Bowman, former chief of the NHLBI Laboratory of Technical Development, is being honored for his most influential invention, the Aminco-Bowman spectrophotofluoro-meter (SPF), which popularized UV-visible fluorometry. A permanent exhibit in the Clinical Center opened recently with a day-long symposium on the instrument's modern research legacy.
Dr. Robert Bowman
Bowman's widow, Alice, and family members attended the symposium, part of NHLBI's yearlong 50th anniversary celebration.
Two of the symposium's organizers, Drs. Robert Berger and Jay Knutson, worked closely with Bowman on research instrumentation design in NHLBI intramural laboratories. The third, NIH historian Dr. Victoria Harden, interviewed Bowman before his death and conducted the historical research for the exhibit. Harden is also director of the DeWitt Stetten, Jr., Museum of Medical Research, which cosponsored the exhibit and symposium with NHLBI.
The story of the SPF reveals the serendipitous path of medical research," said Harden. The spectrophoto-fluorometer was originally designed to quantitate antimalarial drugs, but its commercialization in the 1950's has led to innumerable contributions in protein and DNA research. Harden added that one of her most important resources for the historical exhibit was Bowman's early notes on instrument design. "Hold onto your laboratory notebooks," she cautioned symposium attendees.
In his keynote address, Dr. Robert Berliner, former NIH deputy director for science, explained how Bowman came to invent the SPF. Although Bowman had served in the medical corps during World War II, he was more interested in designing and building instruments to solve research problems. He kept a full-scale machine shop in his basement at home and had a great appreciation for the hidden potential of spare parts. In later years, his love of salvaged equipment led to the acquisition of a Norton bomb sight and the inclusion of periscope prisms recovered from army tanks in some of his spectroscopic inventions.
Just after the war, Bowman joined Dr. James Shannon's research team, which included Berliner, at Goldwater Memorial Hospital in New York. The SPF grew out of the laboratory's wartime research on antimalarial drugs. One colleague, Dr. Bernard B. "Steve" Brodie, was using the Coleman filter fluorometer to measure quinine concentrations in plasma, but many candidate drugs were undetectable in the visible region. A few had been reported to fluoresce in the ultraviolet, but at the time, commercial UV fluorometers were nonexistent, and even quartz optics were scarce. Bowman, Brodie, and Sidney Udenfriend decided to build a practical fluorometer that would span the UV and visible regions. When Shannon moved to NIH, they followed, and in the early 1950's, Bowman designed the prototype.
The standard visible-range fluorometer demanded a separate filter for each wavelength of interest. Such a design would be prohibitively expensive for UV work, because no one knew which wavelengths were critical. UV grating monochromators had just come on the market, but they cost $5,000 apiece -- about $100,000 in today's money. Shannon originally denied the purchase, but later relented and allowed Bowman to buy just one of the two he needed. Undaunted, Bowman contacted sources in his network of instrument manufacturers and junk shop scavengers back in New York. They sent him a Steinheil quartz prism spectrograph that had been "liberated" from Germany during the war, and he used parts of it to build the second monochromator at considerably lower cost than the grating.
Clipping of Bowman from a June 1956 publication
Other wartime instruments also found their way into the SPF. Bowman chose a xenon arc lamp from a German searchlight as the source because it provided a nearly continuous spectrum far into the UV region. Photomultiplier tubes, modified during the war as high-noise generators to jam enemy radar, had originally been designed for high-sensitivity, low-noise light amplification. When substituted for the more common vacuum tubes, they greatly enhanced UV fluorescence detection.
The optics were stuck to a benchtop with wax and used successfully for in-house experiments. Soon the SPF attracted the attention of the American Instrument Co. (Aminco), which cooperated with NIH to bring it into commercial production and marketed it successfully to laboratories nationwide.
Since then, new optical configurations and fluorescent dyes, coupled with advances in computing, have spawned an incredible variety of UV-visible fluorescence techniques. Symposium speakers presented recent work, including time-resolved spectrofluorometry, which permits observation of molecular flexibility and interactions between proteins, membranes and DNA molecules; and two-photon fluorescence microscopy, which provides sharp confocal images and allows 3-D optical reconstruction of cell contents. One of the more eye-popping new developments is the use of green fluorescent protein (GFP) gene expression in transgenic animal models as an internal fluorescent "tag" for a protein of interest. Production and migration of the GFP-coupled protein can be monitored in tissues and cells, and as an added benefit, GFP gene splicing makes it easy to tell transgenic and control mice apart -- the transgenic mice turn bright green under a UV lamp.
Perhaps what survives most in the memories of Bowman's successors and former students is his cheerful hands-on approach to analytical problems. Knutson remembers a typical incident. "I was hired by Dr. Bowman and Ray Chen as a staff fellow in 1984. A few weeks after I arrived, Dr. Bowman appeared in my lab with an imposing piece of optical equipment mounted in a large aluminum box. It was secured by dozens of screws, all covered with a label that said "DO NOT OPEN! NO USER SERVICEABLE PARTS INSIDE." He asked me what that meant. I paused a moment, then declared "We open it!" He straightened up with a big smile and proclaimed, "You pass the test! We'll get along just fine."
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