An Interview with Manuel F. Varela and Ann F. Varela—Mildred Cohn and Isotopes. 

Jun 10, 2021 by

Mildred Cohn

In 1958, using nuclear magnetic resonance, I saw the first three peaks of ATP. That was exciting.”  

—Mildred Cohn 

Michael Shaughnessy 

1) Mildred Cohn was a biochemist, mother, researcher, and scientist—not to mention a woman. Where and when was Cohn born, and what do we know about her family? 

Dr. Mildred Cohn is best noted for her scientific contributions to biophysics and biochemistry. She made significant discoveries about enzyme catalysis and the generation of energy in the living cell. Cohn was born in New York on July 12, 1913, and died on October 12, 2009, in Philadelphia, Pennsylvania. Her parents were Jewish-Russian immigrants.

Cohn was a talented, intelligent student and graduated from high school at the age of fourteen. In 1931, Cohn earned her bachelor’s degree in chemistry from Hunter College. In 1932, at age 18, Cohn had earned a master’s degree with cum laude honors in chemistry from Columbia University. She later earned her Ph.D. in physical chemistry in 1938 at Columbia University after working a temporary job for two years to earn money to fund her college tuition. At one point in her career, Cohn was the only female scientist amongst 70 male scientists. Fortunately, Cohn secured employment at NACA (National Advisory Committee for Aeronautics), a predecessor of NASA (National Aeronautics & Space Administration), where they apparently recognized and appreciated her abilities. This research position was quite a feat because, in those times, it was common practice for white male Christians to have preference over Jewish females when it came to filling job vacancies. 

Cohn married Henry Primakoff, a theoretical physicist, in 1938. She once said, “He was an excellent scientist, and he treated me as an intellectual equal.” The happy couple had two daughters, and a son, all of whom earned a college degree. Throughout her lifetime, she persevered in welcoming exciting challenges such as going hang-gliding for her 90th birthday. 

2) In Cohn’s time, there was anti-Semitism and a disregard for women in science. Finally, she got into Columbia University—what happened to her then?  

The road to Columbia for Cohn was fraught with barriers. When she graduated from public high school at the age of 15, she had enrolled in Hunter College, an institution for women-only. She had attributed her interest in the sciences to an inspirational high school teacher. Before taking her undergraduate B.A. degree in chemistry with a physics minor in 1931, however, Cohn encountered several adversities, which affected her attempts to enter graduate school. Nevertheless, she overcame each of these impediments on her path to graduate school. 

The first impediment was at Hunter College, where Cohn considered education in the sciences inferior in quality. Further, for one of her favorite topics, physics, no such major was offered at Hunter. The chemistry department chair at Hunter College had even discouraged an interest in chemistry and physics, as these disciplines were considered “unladylike” unless the women students were to become teachers of science rather than principal independent investigators. Thus, the educational climate for Cohn in her time was less than conducive. Cohn overcame this obstacle by a sheer determination to stay fascinated in the topics, remarking once that her scientific interests in chemistry and physics were “sufficiently strong to withstand the erosion of an inferior education.”  

Secondly, the Great Depression was in full swing while she was in college. Because her father’s family business failed, no funds were available for graduate tuition or living expenses. This particular barrier was more challenging to overcome. Her applications for graduate scholarships and other forms of financial assistance, more than 20 of them, were rejected. In addition, graduate teaching assistantships, which might have readily solved Cohn’s economic problems, were not made available to women—the assistantships were given only to men. Thus, the financial climate in Cohn’s time was another barrier to Columbia. To pay the necessary $300 for graduate school, Cohn lived with her parents, took a job babysitting, and used all her paltry savings. These efforts helped pay for the first year of graduate school.  

Unfortunately, when funds for graduate school ran out, Cohn was forced to leave Columbia, completing only one year of study, which was insufficient for the Ph.D. However, enough course work had been done for the masters, and Cohn earned the M.S. degree from Columbia in 1932. Cohn’s endeavor to garner a Ph.D., however, had to be put on hold. To acquire additional funds for the Ph.D., Cohn went to work at a government-run aeronautical institution in Langley, Virginia. She worked two years researching the factors affecting the function of a fuel injector system to obtain maximum combustion efficiency. At Langley, Cohn published her first two papers.

The first article, published in 1934, reported on these factors, such as the injector angle, the sparking location, fuel composition, and temperature and their effects on combustion in an airplane engine, called at the time a “combustion apparatus.” In Cohn’s second publication, she was the first author, and it reported on a similar sort of combustion process but this time in a bomb. In the new work, they built the “apparatus,” i.e., a spherical-shaped bomb, and measured the explosion reaction times, the pressures released, and the heat generated as a function of various mixtures of air-to-fuel ratios. This new work was published in 1936.  

Cohn’s supervisor at Langley was reported to have been supportive of her work. After two years, however, Cohn was told that there would be no further opportunities for advancement at the Langley Memorial Aeronautical Laboratory in Virginia. To complicate matters for Cohn, successfully garnering another job in the industry would prove impossible. Industry recruiters at the time, in the 1930s and well beyond, had no apparent shame or uneasiness whatsoever in publicly posting job ads for strictly “Male, Christian” applicants as essential qualifications for available jobs. Cohn’s scarcity of these sought-after attributes for a job would reemerge even later when seeking a postdoctoral position.  

Attempting to return to Columbia University for the Ph.D., Cohn was duly informed by the chemical engineering department chair that no women had ever been accepted into their program. No women were allowed in the chemical engineering program, period, and Cohn was further told that this policy would not change anytime soon and in the foreseeable future. Therefore, she turned to physical chemist Harold Urey, a freshly minted 1934 Nobel Laureate. He quickly informed Cohn that she likely wouldn’t want to be his graduate student because he routinely ignored graduate students. Urey’s thinking was that a female student would need constant supervision. Reluctantly, however, Urey accepted Cohn into his laboratory, where she studied the so-called stable isotopes and eventually took her Ph.D. degree in 1938 from Columbia University. It had been an unduly prolonged and arduous journey to the doctorate for Cohn. Undeniably, the Ph.D. journey had been made challengingprecisely because Cohn was a woman. 

3) Mentors for women—let us review her work with Harold Urey—what was he researching, and how did Mildred Cohn fit into this picture? 

Cohn had taken her Ph.D. at Columbia under her graduate advisor Harold Urey, whose Nobel Prize had been awarded for his discovery of deuterium, a heavy isotope of the hydrogen atom. The Nobel accolade had been announced only a few months after Cohn had entered Urey’s laboratory. At first, Cohn had begun a dissertation project devoted to separating carbon isotopes into pure forms. Isotopes are known as atoms with identical proton numbers (i.e., atomic number) in the nucleus but differing in the number of neutrons. However, the laboratory instrument used for this purpose, called a mass spectrometer, did not cooperate, and the project ultimately failed. Nevertheless, Cohn used the time spent during that period to finish her Ph.D. level coursework in 1934, making her an official doctoral candidate, a universal milestone in graduate studies.  

While still at Columbia, Cohn moved to another dissertation project involving isotopes of oxygen atoms. In particular, Cohn focused on a heavy oxygen atom denoted as oxygen-18 (18O). This atomic isotope has eight protons but ten neutrons, in contrast to a regular non-radioactive oxygen atom (8O) with an atomic number of eight protons and eight neutrons. The inner orbital shell has two electrons, and the second has six electrons. See Figure 1. The 18O atom is a naturally occurring and stable isotope. The radiative energy of the 18O element, like many isotopes, meant that they could be readily detected, separated, and tracked as they exchanged their atoms between various molecules. Cohn would be able to take advantage of these isotopic properties to study the exchange reactions of the 18O oxygen atom in heavy radioactive water (H218O) and various organic molecules. These studies would form the basis of Cohn’s new Ph.D. dissertation project at Columbia.  

File:Electron shell 008 Oxygen.svg

Figure 1. Electron shell diagram for oxygen, the eighth element in the periodic table of elements.  

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As a preliminary experiment, Cohn standardized the 18O detection method by measuring the rates of atomic exchange between 16O in carbon dioxide (CO2) and 18O in water (H2O). Cohn found that it took only three hours of vigorously shaking a mixture of the CO2 containing a 16O label and H2O harboring an 18O tag. The radioactive CO2 + H2O mixtures had to be physically shaken to switch these atoms (i.e., 16O and 18O) to form CO2 containing 18O and H2O having 16O instead. Cohn then used these radioactive atom exchange rates as a standard for measuring oxygen-18 transfer between water and a group of organic molecules. Just getting to this preliminary stage was an arduous, labor-intensive process. Cohn had to make sure that the equipment worked well—she fully remembered the problem with the mass spectrometer—and she had to calibrate the machines and “bake out” the equipment after each use to reduce unwanted contamination. The CO2 had to be distilled before its use in the exchange reactions. For Cohn to use the heavy water, it had first to be “electrolyzed” to reduce contaminating radioactive hydrogen atoms and to ensure that only oxygen of the heavy H2O molecule was labeled. The amounts of 18O in her heavy water had to be independently confirmed using two different methods. One is called the Gilfillan pressure float technique, and the other uses the finicky mass spectrometer. These preliminary laboratory processes were time-consuming, exhausting work, but in the end, Cohn had been successful in knowing precisely how much 18O was present in her heavy radioactive water.  

Once Cohn’s methods of atomic exchange analysis were established, she then conducted a series of exploratory experiments to determine the most suitable organic chemicals to exchange with the oxygen in her newly made isotopic water with known amounts of 18O atoms in it. She chose about a dozen organic molecules based on their oxygen-containing properties and measured their abilities to exchange oxygen atoms with her newly calibrated heavy water.  

Cohn made mixtures of her radioactive water (containing known amounts of 18O isotopes) with each of the organics. She vigorously shook each of the various combinations. She varied the temperatures between room- and boiling temperatures for each water-organic mixture. Cohn also adjusted the lengths of the mixture times for the varieties that were processed, ranging between six hours and two weeks. Then Cohn recovered the heavy water from each mixture type by refluxing once and then distilling each sample several times. Likewise, she recovered each of the organics, all 12 of them. Each organic chemical was unique and required a separate process for their recovery from their various mixtures with heavy water. Somewhat disappointingly, only two mixture types ultimately exchanged the heavy oxygen atoms from the water isotope. The organic molecules were trichloroacetic acid and acetaldehyde.  Likewise, only two mixtures showed a partial atomic isotope exchange with heavy water: monochloroacetic acid and acetone.

Her preliminary experiments complete, Cohn went to work measuring atomic exchange rates between heavy water oxygen and the good organics. These organics included trichloroacetic acid, acetaldehyde, monochloroacetic acid, and acetone. As before, she had to prepare the mixtures in buffers, recover the end products by refluxing, distilling, etc., and then plot the kinetics. For Cohn’s kinetics work, she determined the amount of atomic exchanging as a function of time (the oxygen exchange rates). She also had to discern how much the kinetics were affected by each type of buffer used in the water-organic acid combinations. The kinetics data that Cohn had amassed was extensive, not to say also complicated in its design—she had to keep track of each mixture-type, buffer-type, the temperature used, mixing times, and amounts of heavy oxygen in the starting reactions and the products made.  

From the massive data she collected at Columbia, Cohn then astutely determined the mechanism of the oxygen exchange reactions. She elucidated each of the steps that occurred during the atomic exchange between water and the organic molecules. Cohn had discovered that in the mechanism, hydrogen ions played a role in enhancing the oxygen exchanges. In 1937, Cohn completed her Ph.D. dissertation project and successfully defended it in 1938. Dr. Mildred Cohn graduated from Columbia University with her doctorate and published the work in March of 1938 in the Journal of the American Chemical Society.  

The body of work completed by Cohn during graduate school at Columbia constituted a significant discovery in the chemical catalysis of atomic exchanges in water and essential organic molecules. The successful completion of the massive project had also been a testament to overcoming bias, sexism, and anti-Semitism in Cohn’s pursuit to acquire the coveted Ph.D. degree. These were unprecedented and astonishing achievements in Cohn’s day. 

It might have seemed that Dr. Cohn had finally triumphed over adversity for good. She did not. After graduating, she found it almost impossible to acquire an academic position as a professor! Even after making such a remarkable discovery in isotope chemistry, no one in academia would hire Dr. Cohn, a Jewish woman who had studied under a Nobel Laureate. Urey had offered her a postdoctoral position, which would have provided Dr. Cohn the chance to pursue her interest in isotope chemistry. Still, she was fortunate enough to be offered another postdoctoral position at George Washington University by Vincent du Vigneaud, a prominent biochemist.  

5) Her contributions were to enzymology and oxygen-18—what did Cohn discover, and how did she use oxygen-18? 

Dr. Cohn was once asked what her most exciting scientific moments had been, looking back on a prestigious career. Two of these exciting moments had to do with enzymology and oxygen-18. To an inquiring reporter, Cohn had replied that her discovery in the early 1960s of the various phosphorylated forms of ATP using nuclear magnetic resonance (enzymology) was particularly exciting. Another exciting discovery for Cohn (and her readers) was the 1953 breakthrough that oxygen in inorganic phosphate switched with water through oxidative phosphorylation (oxygen-18). In 2004, both of these discoveries were featured in a Classic Papers series published in the prestigious Journal of Biological Chemistry (JBC). 

The first featured classic JBC article concerned Cohn’s oxygen-18 studies. The authoritative work was published in April of 1953 with Cohn as the sole author. She had conducted the work partly as a research associate at Washington University and later at Harvard Medical School. Using her radiolabeled oxygen-18 attached to phosphate, Cohn made a definitive connection between the electron transport chain, known as the respiratory chain, and the phosphorylating system; see Figure 2. These two mechanisms were known to work together to provide energy for the living cell. Cohn had been curious whether biochemical intermediates that lost phosphate molecules could take oxygen-18 atoms with them or if the oxygen-18 was lost from an inorganic phosphate molecule.  

P

File:Chemiosmotic coupling mitochondrion.gif

Figure 2. Chemiosmotic coupling in the mitochondrion.  

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To distinguish between these two hypotheses, Cohn prepared phosphate molecules that were labeled with oxygen-18 and measured the oxygen consumption and phosphorylation activities in mitochondria that had been isolated from rat liver. These methods permitted Cohn to track the oxygen-18 atoms lost from inorganic phosphate while oxidative phosphorylation proceeds in the mitochondria. Cohn found that the oxygen-18 atom was lost from inorganic phosphate and coupled to the oxidation of α-ketoglutarate and β-hydroxybutyrate. In contrast, the oxidation of succinate was independent of the oxygen loss by the inorganic phosphate. Cohn thus discovered that oxidation of specific metabolic intermediates entailed replacing oxygen atoms in inorganic phosphate. These oxygen exchanges paralleled the phosphorylating action on ATP that occurred during oxidation. It was a significant scientific discovery that would propel Cohn into the spotlight and establish her as a world-renowned biochemist.  

The second classic JBC paper (about enzymology) dealt with Cohn’s discovery, in 1962, of the interaction of metal ions with various phosphorylated forms of ATP. She had previously established in 1960 that the three phosphates of the ATP structure, as seen in Figure 3, could be seen as individual peaks in the magnetic resonance spectrum when studied with nuclear magnetic resonance imaging. Cohn could see each spectral peak denoting the three phosphates, labeled as alpha (α), beta (β), and gamma (γ), on the ATP molecule. The α-phosphate of ATP is closest to the ribose sugar. Likewise, the γ-phosphate is farthest from the ribose, and the β-phosphate is in the middle of the three phosphates. In the classic 1962 work, Cohn discovered that so-called divalent cations played a role in the enzymatic reactions that formed ADP and ATP by interacting with the various phosphates, forming specific complexes. For example, Cohn demonstrated that magnesium ion (Mg2+), calcium ion (Ca2+), and zinc ion (Zn2+) bound to both β- and γ-phosphates of ATP.  

Furthermore, Cohn showed that these divalent cations formed complexes with the α- and β-phosphates on the ADP molecule. These findings by Cohn were important for shedding light on the influence that metals have on the nature of the ATP and ADP structures. What’s more, Cohn had discovered that these divalent metal ions played integral roles in the enzymatic steps that formed the ATP and ADP structures, as certain enzymes were needed for these energetic molecules to be created. Later, Cohn conducted several groundbreaking studies of ATP metabolism using oxygen isotopes. In one study reported in the early 1960s, she found that oxygen-18 in arsenate ended up in the oxygen atoms of the phosphates for ADP and ATP.  

File:230 Structure of Adenosine Triphosphate (ATP)-01.jpg

Figure 3. Structure of ATP. 

https://commons.wikimedia.org/wiki/File:230_Structure_of_Adenosine_Triphosphate_(ATP)-01.jpg

6) The “utilization of isotopes”—how did Cohn contribute here? 

Cohn would become one of the world’s leading investigators on isotopes for scientific studies in biochemistry and biophysics. She began the road to isotope research in graduate school. She acquired expertise using the oxygen isotope 18O to measure its ability to switch its location to those on different molecules, thereby exchanging atoms in a detectable way. Cohn’s graduate work with oxygen isotopes is described above.  

Shortly after graduation from Columbia, where Cohn had obtained her doctorate, she began work in du Vigneaud’s laboratory at Cornell. She employed an isotope of hydrogen, called hydrogen-3 (3H), deuterium, and sometimes tritium. Cohn had used the isotope to trace the movement of deuterium-labeled methyl groups (CH3—) during rat amino acid metabolism. Cohn and du Vigneaud had hypothesized that methyl groups from the amino acid methionine were used to make choline and creatine, both of which are critical biochemical molecules in the body. To test their hypothesis, they prepared 3H-methionine and 3H-choline, fed these isotope-labeled molecules to rats, and isolated the resulting metabolic products. To retrieve these products like creatine, choline, and creatinine from the radioactive laboratory rats, Cohn, du Vigneaud, and colleagues Joseph Chandler, Jay Schenck, and Sofia Simmonds had to collect the rat urine and extract their tissues. In one rather gruesome experiment, they isolated the resulting choline. They emptied the gut contents of the radioactive rats, then froze the intact bodies of the rats into solid masses using carbon dioxide ice and ground the entire frozen bodies in a fine meat chopper. From the ground-up rats, the choline could be prepared and measured.  

Their results had definitively demonstrated for the first time that the amino acid methionine was indeed the source of the choline, which was then used to make creatine and creatinine in the liver. Choline is known to be necessary for making cell membrane lipids. Creatine plays a critical role in the energetics of muscle contraction and is broken down to creatinine, which is a marker for renal disease. These studies by Cohn are to this day still covered in biochemistry textbooks that deal with amino acid catabolism.  

7) Muscle disease was one of Cohn’s areas—how did she employ science to study muscle disease? 

According to the scientific literature, Cohn began studies on the action of muscle in 1948. This early work was focused on the primary mechanism of regular enzyme-substrate interactions. While she was conducting research in the laboratory of Nobel Laureate Gerty T. Cori at the Washington University in St. Louis, MO, Cohn examined the so-called muscle phosphorylase, which cleaves units of glucose-1-phosphates off larger glycogen molecules. While Cohn and Cori reported no exchanges between inorganic phosphate and glucose-1-phosphate, the finding was nevertheless notable enough to be published in the Journal of Biological Chemistry in 1948. Cohn also studied the enzyme adenylate kinase in pig muscle and discovered a region on the enzyme that is the active biochemical site, publishing this work in the same journal in 1975.  

By taking advantage of her expertise in NMR spectroscopy, as seen in Figure 4, Cohn studied the relationship between muscle enzyme function and phosphorus molecules, using the phosphorous-31 isotope for tracing its ATP production during exercise. Cohn’s work in this area, performed in the 1990s at the University of Pennsylvania, would become important because it measured the extent to which muscle disease progressed, as indicated by the variations in ATP concentrations. Cohn’s phosphorous-31 work in cardiac and skeletal muscles had significant implications for several pathological conditions, such as dialysis patients with muscle fatigue or weakness, canine muscular dystrophy, and cardiac muscle or brain tissue with ischemia.  

Figure 4. Nuclear Magnetic Resonance (NMR) Machine. Courtesy of Andrea Starr | Pacific Northwest National Laboratory. 

8) Now, magnesium concentrations in the brain. I personally take a magnesium capsule every morning—but what is it doing in and to my brain? 

Dr. Mildred Cohn conducted a tremendous amount of research on magnesium. One of Cohn’s interests with magnesium was its relationship to the ATP hydrolyzing enzymes. Cohn was widely credited for having started the research field leading to determining the physiological concentration of magnesium in the brain. Cohn, a prominent member of the National Academy of Sciences, had communicated the 1991 publication in the Academy’s Proceedings

Magnesium plays many influential roles in the lives of all organisms on Earth. The metal ion is a so-called inorganic ion, or divalent cation, which means that magnesium carries an ionic charge of +2, and it is frequently denoted as Mg++ or Mg2+. One significant role of magnesium is its catalytic function as a co-factor in various critical enzymes of the living cell, including those of glycolysis. Often magnesium binds to the active sites of enzymes and their substrates and facilitates their biochemical function. Interestingly, mercury, Hg2+, is known to be toxic because it can, in some cases, interrupt the healthy functioning of minerals like copper and magnesium. Hence, magnesium is considered an essential mineral ion, and it is needed for life.  

As we discussed above, Cohn’s early inspiring study in 1962 dealing with magnesium was featured in the Classic JBC Papers series in 2004. In Cohn’s influential study, she had distinguished the three phosphates of ATP by forming detectable complexes with metals such as magnesium and the like. These metal-phosphate complexes had specific chemical shifts in their resonance spectra. The precise resonance shifts resulting from magnesium bound to the β-phosphate of ATP now permitted the group in the PNAS paper that Cohn had sponsored to leap to the notion that phosphorous-31 could be exploited to determine magnesium concentration in the human brain. According to the 1991 study inspired by Cohn, in normal human subjects, the concentration of magnesium in the brain was about 0.30 millimolar (mM).  

Magnesium has many important physiological roles in the brain. The magnesium metal ion (Mg2+) binds to ATP and regulates protein kinases, essential for neurotransmission in the brain. Secondly, a dedicated Mg2+-ATPase transporter protein in the membrane carries Mg2+ across the membrane of neurons in the brain and spinal cord.  

A third essential role for Mg2+ in the brain relates to its function as an inhibitor of the famous neurotransmitter receptor called the NMDA receptor, Figure 5. The acronym NMDA stands for N-methyl-D-aspartate. In general, the NMDA receptors are a family of voltage- and ligand-gated ion channels that function in the brain during human development, learning, memory, and in some instances of nerve damage during brain injuries.  

One of the most fundamental substrates of the NMDA receptor is the neurotransmitter called glutamate. Outside of the brain, glutamate is incorporated into proteins for various cell functions, but this amino acid can serve an excitatory neurotransmitter role for neurons in the brain.  

Figure 5. NMDA receptor in the nervous system. In the diagram, (1) is the cell membrane. The channel that Mg2+ blocks is shown in (2). The Mg2+ blocking site to which the metal binds is in (3). The site where hallucinogenic compounds bind is in (4). The (5) Zn2+ ion binding site is shown in (5). The number (6) shows the binding site for agonists like glutamate (GLU) and antagonist ligands like arginine vasopressin (APV). The number (7) indicates the glycosylation sites where sugars are attached.  The proton binding site is shown in (8), whereas (9) is the glycine neurotransmitter binding site. The number (10) is a polyamine binding site. Lastly, (11) indicates the extracellular space, and (12) shows the intracellular space or cytoplasm.  

File:NMDA receptor.jpg

https://commons.wikimedia.org/wiki/File:NMDA_receptor.jpg

Glutamate opens the gate of the NMDA receptor channel in a depolarized nerve cell membrane. The Mg2+ ions are associated with this function by blocking the channel entryway of NMDA receptors at standard resting potentials. At the resting potential of the nerve membrane, the NMDA receptor is blocked by Mg2+ at its blocking site. Figure 5, number three, represents the Mg2+ blocking site. The NMDA receptor is voltage-dependent. Thus, it can respond to a so-called depolarization of the postsynaptic membrane to permit the entry of Ca2+ ions. Therefore, when the neuron is depolarized, the NMDA receptor overcomes the Mg2+ block and allows Ca2+ access into the presynaptic membrane of the nerve cell. Once the Ca2+ accumulates to sufficient quantities in the cell, it can regulate enzymes called phosphatases and protein kinases. When the Ca2+ concentration inside the neuron is high, it activates a kinase enzyme that phosphorylates a protein. The phosphorylation induces long-term potentiation (LTP), a memory-forming system in the brain. A long-lasting increase in synaptic strength characterizes the LTP. In contrast, when the internal Ca2+ concentration reaches an intermediate level, it activates a phosphatase enzyme, which causes a process called long-term depression (LTD), which is a form of a long-lasting decrease in synaptic strength. Changes in synaptic strength represent a complicated neurophysiological process that deals with the storage of memory.  

9) Cohn saw herself as a scientist first and a woman second—your thoughts? 

Through much of Cohn’s early career, people focused on her gender instead of her accomplishments in chemistry. Cohn was accused of being a “bad mother” because she had a job outside the home. Dr. Cohn was denied a teaching position due to her gender. Male scientists expected her to tidy their labs and clean their lab equipment. Cohn spent twenty-one years conducting scientific research before she obtained a professorship. Perhaps by focusing on being a scientist first, she felt she could discover and contribute some critical findings to the field of biochemistry that would be accepted, based on their merit, instead of whose discovery it was. Cohn adopted Albert Einstein’s philosophy on this topic: “They should be scientists first if that’s what they are interested in, and a woman scientist second.” 

10) What kinds of awards did she garner? 

Cohn was on the editorial board of the Journal of Biological Chemistry as its first women editor. Cohn served on that board for ten years. In 1963, she was awarded the American Chemical Society’s Garvan-Olin Medal. Five years later, she was elected a Fellow of the American Academy of Arts and Sciences. Cohn received the Franklin Institute’s Elliott Cresson Medal in 1975 and the International Organization of Women Biochemists Award in 1979. In 1983, Cohn was the first woman to receive the National Medal of Science. Three years later, she received the Chandler Medal from Columbia University. Cohn has also been inducted into New York’s National Women’s Hall of Fame. 

It is important to note that Cohn is celebrated for her pioneering accomplishments each year with the bestowment of the so-called Mildred Cohn Award in Biological Chemistry. Mildred Cohn attended the Chemical Heritage Foundation Brown Bag Lecture series in 2005. See Figure 6. 

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Figure 6. Mildred Cohn in 2005. 

https://commons.wikimedia.org/wiki/File:Mildred_Cohn_Brown_Bag_Lecture_2005_10_19.JPG

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