Dr. John “Jack” Johnston, an expert in lipid biochemistry, died Jan. 11. He was 90.

Born in North Platte, Nebraska, Dr. Johnston attended Hastings College and graduated in 1949 with a B.A. in chemistry and mathematics. His brother, Bob, once a student in Nobel Laureate Dr. Konrad Bloch’s laboratory, sparked his interest in lipid biochemistry. For his graduate studies, Dr. Johnston attended the University of Colorado and then completed his Ph.D. research in the laboratory of Professor Cosmo G. MacKenzie.

After attending Army Officer Training School at Fort Sam Houston in San Antonio, Dr. Johnston was assigned as a research associate to Walter Reed Army Medical Center where he conducted research on the biochemical response of the brain to trauma.

Upon completion of his military obligation in 1955, Dr. Johnston was recruited to UT Southwestern as an Instructor of Biochemistry and began his research on intestinal absorption of lipids. Utilizing everted intestinal sacs – a system he learned at Walter Reed – he discovered the 2-monoglyceride pathway as an energy-efficient lipid absorption pathway used preferentially by the small intestine.

In 1962, Dr. Johnston was invited by the noted Swedish biochemist Dr. Bengt Borgström to join him in a collaborative project at Lund University in Sweden. Their important work led to groundbreaking discoveries regarding how 2-monoglycerides are taken up by the intestine, packaged into lipid particles, and secreted into the blood for use by various tissues of the body.

Following the birth of the Johnstons’ first grandchild, who was premature and suffered from respiratory distress syndrome, Dr. Johnston began to study the biosynthesis and secretion of lung surfactant, a glycerophospholipid-rich, surface tension-lowering lipoprotein that is critical for breathing. Surfactant deficiency in the lungs of premature infants can lead to respiratory distress syndrome, a major cause of infant death.

In the course of these studies, he made the key discovery that the potent proinflammatory glycerophospholipid, platelet-activating factor (PAF), was produced in increasing amounts by the fetal lung near term and was secreted into amniotic fluid in association with surfactant. He also found that PAF levels were increased in the amniotic fluid of women in labor and that PAF caused uterine contractions when applied to tissue strips in vitro. This was the very first indication that the fetal lung may contribute a signal for the initiation of labor. PAF was known to be produced by immune cells and to contribute to allergic and hypersensitivity reactions, but had not been linked to physiological processes.

In subsequent studies, Dr. Johnston and colleagues discovered that PAF served a role in the pathogenesis of necrotizing enterocolitis (NEC), a devastating inflammatory condition of the intestine that affects premature infants. The incidence of NEC was known to be lower in breastfed newborn infants. His lab made the important discovery that human milk contains the enzyme PAF acetylhydrolase (PAF-AH), which inactivates PAF. Interestingly, cow’s milk and infant formula do not contain this enzyme. Notably, he found that administration of recombinant PAF-AH markedly reduced the incidence of NEC in a rat model of the disease. Dr. Johnston’s research has significantly impacted treatment strategies for this disease, which include feeding with human breast milk.

Dr. Johnston’s career continued to flourish at UT Southwestern with his promotion to Professor in 1966. He was granted a joint faculty appointment as Professor of Obstetrics and Gynecology in 1974 and was appointed as Director of the Division of Lipid Research in the Department of Biochemistry in 1980. In 1981, Dr. Johnston was named The Frank C. Erwin, Jr. Professor in Obstetrical Biochemistry, a position he held until 2001. From 1981 to 1985, he served as Interim Chair of Biochemistry.

During his 50 years at UT Southwestern, Dr. Johnston co-authored more than 200 publications and mentored six Ph.D. students and 39 postdoctoral fellows. He received the Distinguished Alumni Award of Hastings College, the Presidential Award of the American Oil Chemists’ Society, and the Purdue-Frederick Award of the American College of Obstetrics.

In 2006, the UT System Board of Regents named Dr. Johnston an Ashbel Smith Professor – the only Systemwide professorship honor and one that is limited to five per UT institution. This great honor was bestowed in recognition of Dr. Johnston’s role as a dynamic teacher and his exceptional academic contributions and achievements. Upon full retirement, Dr. Johnston was named an Ashbel Smith Professor Emeritus.