John Calam combined the intellect of a first-rate clinical scientist with an inclusive humanity and humour that ensured him a wide range of friends. His father was a microbiological chemist, his mother a teacher. He was educated at the King's School in Macclesfield, and trained at Liverpool University, where he graduated MB BCh in 1972, with an intercalated BSc in biochemistry.
His undergraduate career was dotted with multiple distinctions, prizes, scholarships and medals. One of his lifelong friends from those days summarized features of John's time there: an intensively gifted and interested student, whose enthusiasm drew others along in his slipstream; president of the medical students society by a landslide; an unmistakable physical presence - an elongated frame and large head; an amazing grin always lurking near the surface.
John hated pomposity, and despite the distinction of his subsequent career, there was always the hint of an element of subversion about him. Whilst an undergraduate he came under the influence of R A Gregory [Munk's Roll, Vol.IX, p.211], professor of physiology, who kindled John's interest in the problem that dominated his research career, the control of gastric secretion in man.
After his initial clinical training, with house officer posts in Liverpool, SHO posts in Liverpool and Worcester, and registrar posts at Broadgreen Hospital and Walton Hospital, Liverpool, John returned to the department of physiology at Liverpool as an MRC clinical fellow to study the hormonal control of gastro-intestinal secretion, with Graham Dockray. He gained his MD for studies on the effects of gastrin and cholecystokinin, investigating the effect of different molecular forms of these hormones, and their perturbed physiology in malabsorption.
He moved to St Mary's in London as a lecturer in 1980 and was subsequently appointed senior lecturer at Hammersmith in 1983.
Shortly afterwards, an observation that overturned 100 years of interpretation of the relationship between gastric acidity and gastro-duodenal was made by Barry Marshall in Australia, with the recognition of the relevance of gastric infection with Helicobacter pylori. It was subsequently apparent from clinical observations that treatment regimes which cleared the infection gave sustained remission of duodenal ulcers, whilst simple acid reduction without Helicobacter eradication merely healed ulcers transiently. However the mechanism of the link between the infection and ulcers remained obscure. John Calam's training as a physiologist who understood the interplay of influences that affect normal and abnormal function, combined with his skills and immediate practice as a clinical gastroenterologist, allowed him to provide a rational explanation for the relationship between Helicobacter infection of the stomach and acid-related duodenal ulceration. He surmised that this infection made the stomach respond as if it had just been fed, and inappropriately turn on the secretion of the gastric hormone gastrin that lead to acid secretion. This hypothesis, subsequently amply supported by evidence, has entered the textbooks as 'the gastrin link.' He demonstrated that successful eradication of H. pylori reversed this hypergastrinaemia. The mechanisms underlying the link proved complex, and John's laboratory contributed to unravelling these, in particular elucidating a second link in the chain, the modulation of gastrin-producing cells by somatostatin-producing cells, and the effect of inflammatory mediators for leukocytes in initiating this pathway.
He forged a productive collaboration with Walsh in Los Angeles, with whom he spent a three-month sabbatical in 1992, and with Yamada in Ann Arbor. His long-standing interest in cholecystokinin led him into the investigation of the effects of dietary lectins on gastrointestinal hormone release, and potential carcinogenic mechanisms. In addition to his laboratory research, he produced a widely acclaimed monograph on H.pylori aimed at clinicians rather than researchers (Clinician's guide to Helicobacter pylori, London, Chapman & Hall Medical, 1996).
He published widely and contributed to numerous editorial boards, gastroenterological societies and grant committees. He chaired the basic science group of the British Society of Gastroenterology, and the Hammersmith Hospital's ethics committee. He raised the funds to build a modern gastrointestinal cell biology laboratory at Hammersmith. He maintained this substantial academic and administrative load whilst remaining an active clinician with a warm rapport with his patients, ever popular with his colleagues. His lanky figure, his ever-changing expression, from deep concentration as he sorted out a complex intellectual problem, to infectious laughter, were for seventeen years a central part of the gastroenterology unit at the Hammersmith. During that time he trained a series of clinicians and PhD students, and had the satisfaction of seeing one of his first clinical fellows returning to the unit with a personal chair.
In his last year he had begun to feel that he could make a more effective contribution by moving his career into a different field, and had first spent a sabbatical and then been recruited to a major post in an international pharmaceutical concern to provide clinical direction for their research efforts. Tragically, he developed a glioma, and bore six months of deteriorating health with immense dignity. Irrepressively, during that illness, he asked a friend,"Do you think I might have overheated my brain to cause this tumour?"
He met his wife Joyce, subsequently a teacher of design technology, in their first term at Liverpool. They had three children and a wide circle of friends. Joyce looked after John selflessly during his last illness, almost entirely out of hospital. He had the satisfaction of seeing their three children well established in or on the way to their careers.
Humphrey Hodgson
[British Society of Gastroenterology News, Vol.9, No.3, Autumn 2001]