- Email: [email protected]
GASTROINTESTINAL CANCER
849
potent monoamine-oxidase inhibitor
to
19
patients with
chronic schizophrenia to increase urinary excretion of amines: they could find no evidence of D.M.P.E. or of the related compound p-methoxyphenylethylamine in the urine of these patients. It now seems open to question, therefore, whether D.M.P.E. has any significant association with schizophrenia. Indeed, D.M.P.E. may have more significance in Parkinson’s disease, for Barbeau et al.10 reported large quantities of the amine in the urine of these patients; and the finding 11 that D.M.P.E. will produce akinesia in animals strengthens the view that it may play some part The illusive spot, found by some in parkinsonism. an not but by increasing number of others, may turn out to be due to medication, diet, gut bacteria, or other factors which are a consequence rather than a cause of
schizophrenia.
GASTROINTESTINAL CANCER
AT the 3rd World Congress of Gastroenterology, held in Tokyo on Sept. 18-24, much time was devoted to gastric carcinoma (the incidence of this disease in Japan is one of the highest in the world) and to the epidemiology of gastrointestinal cancer in general. The mortality-rates for gastric cancer (which are almost equivalent to incidence estimates) vary greatly between different countries: rates are high in Japan and Finland but low in the U.S.A.probably a reflection of environmental influences. Among Japanese migrants who had moved to California and Hawaii the incidence of gastric cancer fell sharply within a few years; but the frequency of cancer of the colon rose towards the higher United States rate. Something in the diet seems the most likely cause of these differences; but surveys of food intake in patients with cancer and in controls have proved of little value, for accurate retrospective information on diet has been hard to obtain. Comparisons of diets in countries with high and low cancer incidence have also been unhelpful, probably because of the many simultaneous and irrelevant variations. In any case the nutritional characteristics concerned are probably sophisticated and not to be found by simple comparisons of protein and carbohydrate intake or analyses of constituents, such as smoked or salted foods. These problems were emphasised by one study of diets in patients with gastric and colonic cancer and in controls. There is a strong suggestion that the factors which predispose to gastric and colonic cancer are diametrically opposed, for countries with a high incidence of one have a low frequency of the other and, as in the U.S.A., a falling incidence of gastric cancer seems to be balanced by a rise in the frequency of colonic cancer. No differences could be found, however, between the diets of the patients with gastric and colonic cancer. Similar difficulties seemed to be hindering work in other areas, and one speaker at Tokyo (referring to the treatment of peptic ulcer) concluded sadly that at each of these meetings the same points were discussed. Although it may be unreasonable to expect a much faster rate of progress, a more hopeful report may be possible after the next meeting in four years’ time. 9. Perry, T.
L., Hansen, S., MacDougall, L., Schwarz, C. J. ibid. 1966,
212, 146. 10. Barbeau, A.,
de Groot, J., Joly, J., Raymond-Tremblay, D., Donaldson, J. Rev. canad. Biol. 1963, 22, 469. 11. Barbeau, A., Tetreault, L., Oliva, L., Morazain, L., Cardin, L. Nature, Lond. 1966, 209, 719.
PELAGIAN MAN
THOUGH they go off in opposite directions, astronauts and divers have much in common: both explore an unknown milieu; both have physiological handicaps to contend with; both carry their atmosphere with them; and neither can return to the earth’s surface directly. When aviation began, diving physiology was already an established (if not very advanced) science, with obvious lessons for the new medium. The first high-altitude suits looked very like diving-gear: but since those early days, the air has taken most of the physiological and technological research effort, and, until recently, diving physiology had evolved little beyond the point at which Haldane left it. The invention of the aqualung, which gives the diver greater freedom of movement and makes diving much more comfortable and enjoyable so that it is now a sport practised by thousands instead of the arduous occupation of a few hardy professionals, has led to a new phase of exploitation of the oceans. The descent in water is something of a trial for ears and sinuses. So great is the rate of pressure change that a diver must constantly try to equate internal with external pressure. If his efforts fail, severe pain obliges him to ascend, and he may be unable to dive again for weeks, until the barotrauma has resolved. But the main barrier to the depths has always been the difficulty of getting back to the surface. Even a brief dive to no very great depth means a long and tedious ascent by stages to prevent nitrogen, kept in solution under the great pressure below the surface of the water, from forming bubbles as the diver rises towards normal pressure. Every 30 ft. of vertical movement in water represents -a pressure change of about an atmosphere. The greater the depth of the dive, the longer the time needed for decompression: so that single dives of any consequence are hopelessly uneconomic in time and effort. The French and the Americans have overcome this handicap by the new technique of " saturation " diving: once a diver has spent a short time at a depth, his tissues may be regarded as saturated with nitrogen; and however long he stays there, the decompression procedure does not substantially change. The work of the French and American under-sea research groups is, therefore, directed towards keeping a diver below the water at constant pressure for weeks instead of hours, in order to obtain a fair return for the boredom (and dangers) of the eventual decompression. If he is given warm, dry, comfortable living-quarters at the pressure to which his body has become accustomed, he can explore, experiment, and work at great depths; and he can achieve in a week what formerly might have taken months of short dives, long decompressions, and constant struggles with adverse weather at the surface. Even so, the diver must exert great care, when working, to maintain his depth: if he rises the equivalent of an atmosphere-about 30 ft.-he may expose himself to unintentional decompression. The treatment of decompression sickness is difficult enough at sea-level: 400 ft. down on the continental shelf, it is not impossible, but the problems are enormous. Decompression is by no means the only complication of deep dives. Simple compressed air for breathing is of limited use: the partial pressure of the oxygen increases to toxic levels at moderate depths, so that’the content in the breathing-mixture must be reduced pro rata with the ambient pressure: nitrogen, which under pressure produces narcosis (Cousteau’s l’ivresse des grandes profondøurs),
potent monoamine-oxidase inhibitor
to
19
patients with
chronic schizophrenia to increase urinary excretion of amines: they could find no evidence of D.M.P.E. or of the related compound p-methoxyphenylethylamine in the urine of these patients. It now seems open to question, therefore, whether D.M.P.E. has any significant association with schizophrenia. Indeed, D.M.P.E. may have more significance in Parkinson’s disease, for Barbeau et al.10 reported large quantities of the amine in the urine of these patients; and the finding 11 that D.M.P.E. will produce akinesia in animals strengthens the view that it may play some part The illusive spot, found by some in parkinsonism. an not but by increasing number of others, may turn out to be due to medication, diet, gut bacteria, or other factors which are a consequence rather than a cause of
schizophrenia.
GASTROINTESTINAL CANCER
AT the 3rd World Congress of Gastroenterology, held in Tokyo on Sept. 18-24, much time was devoted to gastric carcinoma (the incidence of this disease in Japan is one of the highest in the world) and to the epidemiology of gastrointestinal cancer in general. The mortality-rates for gastric cancer (which are almost equivalent to incidence estimates) vary greatly between different countries: rates are high in Japan and Finland but low in the U.S.A.probably a reflection of environmental influences. Among Japanese migrants who had moved to California and Hawaii the incidence of gastric cancer fell sharply within a few years; but the frequency of cancer of the colon rose towards the higher United States rate. Something in the diet seems the most likely cause of these differences; but surveys of food intake in patients with cancer and in controls have proved of little value, for accurate retrospective information on diet has been hard to obtain. Comparisons of diets in countries with high and low cancer incidence have also been unhelpful, probably because of the many simultaneous and irrelevant variations. In any case the nutritional characteristics concerned are probably sophisticated and not to be found by simple comparisons of protein and carbohydrate intake or analyses of constituents, such as smoked or salted foods. These problems were emphasised by one study of diets in patients with gastric and colonic cancer and in controls. There is a strong suggestion that the factors which predispose to gastric and colonic cancer are diametrically opposed, for countries with a high incidence of one have a low frequency of the other and, as in the U.S.A., a falling incidence of gastric cancer seems to be balanced by a rise in the frequency of colonic cancer. No differences could be found, however, between the diets of the patients with gastric and colonic cancer. Similar difficulties seemed to be hindering work in other areas, and one speaker at Tokyo (referring to the treatment of peptic ulcer) concluded sadly that at each of these meetings the same points were discussed. Although it may be unreasonable to expect a much faster rate of progress, a more hopeful report may be possible after the next meeting in four years’ time. 9. Perry, T.
L., Hansen, S., MacDougall, L., Schwarz, C. J. ibid. 1966,
212, 146. 10. Barbeau, A.,
de Groot, J., Joly, J., Raymond-Tremblay, D., Donaldson, J. Rev. canad. Biol. 1963, 22, 469. 11. Barbeau, A., Tetreault, L., Oliva, L., Morazain, L., Cardin, L. Nature, Lond. 1966, 209, 719.
PELAGIAN MAN
THOUGH they go off in opposite directions, astronauts and divers have much in common: both explore an unknown milieu; both have physiological handicaps to contend with; both carry their atmosphere with them; and neither can return to the earth’s surface directly. When aviation began, diving physiology was already an established (if not very advanced) science, with obvious lessons for the new medium. The first high-altitude suits looked very like diving-gear: but since those early days, the air has taken most of the physiological and technological research effort, and, until recently, diving physiology had evolved little beyond the point at which Haldane left it. The invention of the aqualung, which gives the diver greater freedom of movement and makes diving much more comfortable and enjoyable so that it is now a sport practised by thousands instead of the arduous occupation of a few hardy professionals, has led to a new phase of exploitation of the oceans. The descent in water is something of a trial for ears and sinuses. So great is the rate of pressure change that a diver must constantly try to equate internal with external pressure. If his efforts fail, severe pain obliges him to ascend, and he may be unable to dive again for weeks, until the barotrauma has resolved. But the main barrier to the depths has always been the difficulty of getting back to the surface. Even a brief dive to no very great depth means a long and tedious ascent by stages to prevent nitrogen, kept in solution under the great pressure below the surface of the water, from forming bubbles as the diver rises towards normal pressure. Every 30 ft. of vertical movement in water represents -a pressure change of about an atmosphere. The greater the depth of the dive, the longer the time needed for decompression: so that single dives of any consequence are hopelessly uneconomic in time and effort. The French and the Americans have overcome this handicap by the new technique of " saturation " diving: once a diver has spent a short time at a depth, his tissues may be regarded as saturated with nitrogen; and however long he stays there, the decompression procedure does not substantially change. The work of the French and American under-sea research groups is, therefore, directed towards keeping a diver below the water at constant pressure for weeks instead of hours, in order to obtain a fair return for the boredom (and dangers) of the eventual decompression. If he is given warm, dry, comfortable living-quarters at the pressure to which his body has become accustomed, he can explore, experiment, and work at great depths; and he can achieve in a week what formerly might have taken months of short dives, long decompressions, and constant struggles with adverse weather at the surface. Even so, the diver must exert great care, when working, to maintain his depth: if he rises the equivalent of an atmosphere-about 30 ft.-he may expose himself to unintentional decompression. The treatment of decompression sickness is difficult enough at sea-level: 400 ft. down on the continental shelf, it is not impossible, but the problems are enormous. Decompression is by no means the only complication of deep dives. Simple compressed air for breathing is of limited use: the partial pressure of the oxygen increases to toxic levels at moderate depths, so that’the content in the breathing-mixture must be reduced pro rata with the ambient pressure: nitrogen, which under pressure produces narcosis (Cousteau’s l’ivresse des grandes profondøurs),