target="_blank" rel="nofollow" href="#ulink_3bc40b15-0a8b-5eb4-9b1f-faa42d17abb6">Fig. 2. The hospital Hasenheide in Berlin, where Zülzer’s laboratory was located (postcard, collection Dr. V. Jörgens).
For 12 years – from 1902 to 1914 – Zülzer conducted research aiming at the production of a pancreatic extract for the treatment of diabetes. In the first years he used the laboratory of the institute of Prof. T.W. Engelmann in Berlin. Eight publications and three patent specifications bear witness to this tireless work. He first injected adrenal extract into rabbits and glucosuria occurred. When he injected his pancreatic extract at the same time, this increase of glucosuria did not occur. He did not describe all the details of the methods he used to produce the extract in these early studies [3]. However, he wrote: “In order to obtain a pancreatic preparation that is not too toxic, all proteins of the pancreas must be removed” [3]. At first, Zülzer tried to obtain pancreata from the slaughterhouse, but this proved to be very difficult. Then he came up with the idea of sacrificing large dogs and using theirs. In the hope that the pancreas would then contain more of the hormone, he fed the animals plenty of carbohydrates beforehand. He stated later in his US patent application: “The pancreas preparation may be made as follows: the pancreas gland of an animal in narcosis is laid bare, the animal being preferably in a state when the process of digestion is at its height, the principle efferent vein is ligatured... In a similar manner the remaining veins of the pancreas are tied and swell greatly after the first ligature. After one or two hours the pancreas is removed for further treatment. This treatment consists in cutting it up into small pieces, leaving the same to self-digestion under weak alkaline reaction for several days, although this self-digestion may be omitted. Then precipitating the albuminous bodies by means of alcohol or by boiling” [4].
Zülzer also tried to treat some patients with his extract (in other hospitals, since at his own he did not find suitable cases of diabetes). He presented the results on June 15, 1908 during a meeting on internal medicine in Berlin. He summarized the results as follows: “Intravenously administered this hormone of the pancreas was able to decrease glycosuria and acetonuria for some time” [5]. He did not supervise the patients correctly since they were in different hospitals and the data were not totally convincing. Nevertheless, the results of his research are already quoted in the first textbook on endocrinology, published in 1910 by the Viennese Prof. Arthur Biedl, one of the founding fathers of endocrinology [6].
In later years, Zülzer modified the production of his preparation without describing it more precisely. In contrast to Banting and Best, Zülzer assumed that the hormone was not a protein; he hoped that a prolonged incubation of the crushed pancreas would lead to a breakdown of proteins and therefore result in a better extract – an error! It is interesting that he sometimes did not practice this incubation. This may explain why only some of his extracts were effective and others not. Like Banting and Best, Zülzer used alcohol for extraction. However, in Toronto the chemist Collip achieved a much better degree of purity than Zülzer by doing the following: “He used acid alcohol as the initial extractive but raised the alcohol concentration to about 80%. By this means certain inert objectionable materials were removed. The inert materials were filtered and the insulin precipitated from the alcohol solution by raising the concentration of alcohol to approximately 92%” [7]. Zülzer certainly produced effective extracts, but also repeatedly ineffective samples. This explains the very different results of the experiments on animals and also on people with diabetes. The funding of the work was also difficult. The Schering Co., which had initially financed the investigations, then revoked this financial support. In 1908, Zülzer tried in vain to obtain a scholarship from the University of Berlin for the Zoological Research Institute in Naples. Many years before, Paul Langerhans had received such a scholarship, but Zülzer did not have a godfather named Rudolf Virchow. Zülzer had applied for the extraction of insulin from the insular organ of fish in Naples. If he had been granted these 500 marks, it may, in all probability, have helped him to develop a very effective insulin preparation.
Oskar Minkowski’s Team Missed the Nobel Prize
Zülzer decided to have his extract examined at the Department of Internal Medicine in Breslau where Oskar Minkowski had just been appointed to the chair of Internal Medicine after leaving Greifswald. Minkowski’s collaborator, Joseph Forschbach was asked to carry out the investigations and he began doing so in December 1909. Minkowski later regretted not having looked more closely at this work. Zülzer’s preparations were sent from Berlin to Breslau. Forschbach injected the extract intravenously in 3 experiments on two pancreatectomized dogs. In all three experiments glucosuria decreased immediately after the injection (from 8.2 to 1.3%, from 7.8 to 2.98%, and from 5.63 to 0.68% glucose in the urine) and increased later on. Blood glucose was never measured. Encouraged by these results, Forschbach also administered the extract to people with diabetes. In the first one, glucosuria remained the same after the injection – but the preparation was already 16 days old. The second patient was a 33-year-old man weighing 58 kg. Glucosuria decreased slightly. However, he observed an increase in body temperature, tachycardia, and nausea [8]. Although the experiments on dogs showed an astonishing effect, Forschbach judged the preparation unsuitable for treatment: “The patients showed an almost frightening prostration, the pulse was hunting, in both cases vomiting occurred” [6]. This devastating judgement of a famous working group was of course a terrible setback for Zülzer. In 1914, Forschbach wrote in his textbook: “The attempts to find an organotherapy by administering pancreatic extracts or stimulating the internal secretion of the gland, according to the assumption of a pancreatogenic nature of diabetes, failed. The practitioner must therefore refrain from using the pancreatic hormone prepared by Zülzer” [9]. This Forschbach study, not carried out carefully and badly summarized, was frequently quoted in later years. MacLeod mentioned Zülzer in his Noble Prize lecture: “In 1907 Zülzer published results which must be considered, in the light of what we now know, as really demonstrating the presence of the antidiabetic hormone in alcoholic extracts of pancreas. But unfortunately, even although several diabetic patients were benefited by administration of the extracts, the investigations were not sufficiently completed to convince others, and, apparently, Zülzer himself was discouraged in continuing them because of toxic reactions in the treated patients.” Banting also mentioned Zülzer in his Nobel Prize lecture: “In 1908, Zülzer tried alcoholic extracts on six cases of diabetes mellitus and obtained favorable results, one case of severe diabetes becoming sugar free. His extracts were then tried by Forschbach in Minkowski’s clinic with less favorable results, and the investigation was abandoned by this group of workers” (www.nobelprize.org/prizes/medicine). In the first publications on insulin, the team in Toronto did not quote Zülzer, only mentioning him after the patent issue.
Roche’s Board Members Missed a Big Deal
In 1910, Zülzer negotiated with the Hoechst Company, but they refused to cooperate. Zülzer had to continue working with his limited private means. In 1911, Hoffmann La Roche became interested in his work. With this support, Zülzer was able to set up a laboratory in the Hasenheide hospital and to collaborate with the chemist Dr. Camille Reuter (1886–1974), an employee of Roche working in the company’s laboratory in Grenzach, and pupil of Prof. Richard Martin Willstädter (who received the Nobel Prize for his work on chlorophyll in 1915 and had to emigrate to Switzerland in 1939). In 1914, Reuter continued to produce extracts in the Roche laboratories in Grenzach in Germany, located near Basel in Switzerland. Camille Reuter even processed over 100 kg of pancreata. In August