654
Ann. Surg. o November 1976
LETTERS TO THE EDITOR
saw "endothelium." We could not judge it to be pseudoendothelium according to our rather stringent criteria. There were, however, cell zones on the graft typical of pseudoendothelium. The case reported in our paper appeared "out of the blue," as it were, and in 1973 we were not in a position to carry out the electron microscopy Dr. Imparato recommends. However, in view of the paucity of reports on cell coverage in human prostheses, we felt this case should be reported. We hope that others will find such cell linings in man and report more fully on their nature. When we have another chance at such a specimen, we will be better prepared for more extensive studies. Lester R. Sauvage, M.D. Knute Berger, M.D. Reconstructive Cardiovascular Research Center Providence Medical Center Seattle, Washington 98122
References 1. Harker, L. A., Slichter, S. J. and Sauvage, L. R.: Platelet Consumption by Arterial Prostheses: Natural History in Relation to Endothelialization and Influence of Pharmacologic Inhibition of Platelet Function in Unhealed Grafts (In prepara-
cessful vein grafts, by J. Hogarth Pringle of Glasgow in 1912.4 A four-inch segment of saphenous vein was inserted following excision of a popliteal artery aneurysm in a man aged 49. When the patient died of a heart attach 3-½2 years later, the patent graft was preserved and is on display in the museum of the Royal College of Surgeons of Edinburgh. These comments are intended to help place in its proper perspective this interesting aspect of recent surgical history. Roger N. Baird, F.R.C.S.Ed. William M. Abbott, M.D. Harvard Medical School Massachusetts General Hospital Department of Surgery Boston, Massachusetts 02114 References 1. Hughes, C. W.: Arterial Repair During the Korean War. Ann.
Surg. 147:555, 1958. 2. dos Santos, R., Lamas, A. C. and Caldas, P. J.: Arteriografia da Aorta e Dos Vasos Abdominais. Med. Contemp., 47:93, 1929. 3. Leriche, R. and Kunlin, J.: Possibilite de Greffe Veineuse de Grande Dimension (15a 47 cm) dans les Thromboses Arterielles Etendues. Lyon Chir., 44:13, 1949. 4. Pringle, J. H.: Two Cases of Vein-grafting for the Maintenance of a Direct Arterial Circulation. Lancet, 1:1795, 1913.
tion). 2. Pugatch, E. M. J.: The Growth of Endothelium and Pseudoendothelium on the Healing Surface of Rabbit Ear Chambers. Proc. R. Soc. Lond., 160:412-422, 1964. 3. Warren, B. A.: Fibrinolytic Activity of Vascular Endothelium. Br. Med. Bull., 20:213-216, 1964. 4. Warren, B. A.: The Electron Microscopic Features and Fibrinolytic Properties of "Neo-intima." Br. J. Exp. Pathol., 45: 612-617, 1964. 5. Yates, S. G., Nakagawa, Y., Berger, K. and Sauvage, L. R.: Surface Thrombogenicity of Arterial Prostheses. Surg. Gynecol. Obstet., 136:12-16, 1973. 6. Yates, S. G.: Unpublished results, 1976.
February 27, 1976 Dear Editor: We were interested to read "Historical Aspects of Venous Autografts" by Lynn H. Harrison, Jr., M.D. The article, however, fails to mention a number of important landmarks, including Leriche and Kunlin's report of the first vein bypass grafts for femoral artery occlusion,3 which is of greater historical interest than the more recent quoted case. Also, it is not clear from the account that the introduction of vein grafting in the primary repair of arterial injuries was in 1952 during the Korean War, and resulted in a reduction in the amputation rate from 50o to 12%.1 Finally, since the author clearly wishes to acknowledge the importance of radiology in the development of vascular surgery, surely the major contribution of Reynaldo dos Santos deserves mention.2 It may be of interest to recall one of the earliest suc-
March 16, 1976 Dear Editor: The letter of Doctors Baird and Abbott emphasizes several noteworthy points. The achievement of Pringle is particularly deserving of mention and should certainly have been included in the article. The bane of the historical survey is that, although its scope is broad, its depth is limited, and important contributions are invariably omitted. I wish to thank Doctors Baird and Abbott for their comments and for underlining the work of these important contributors to the development of the venous
autograft. Lynn H. Harrison, Jr., M.D. Staff Surgeon McCain Hospital McCain, North Carolina 28361
April 14, 1976 Dear Editor: The negative comments by Wise, Vaughan, and Stein (Ann. Surg. 183:259-262, 1976), concerning the conclusions and statistics in our paper in Surgery 75:821, 1974, entitled, "Effect of Small Bowel Bypass on Gastric Secretory Function: Postintestinal Exclusion Hypersecretion, a Phenomenon in Search of a Syndrome,"
Vol. 184 * No. 5
LETTERS TO THE EDITOR
prompt us to reply. In so perpetuating the discussion, our primary aim is to foment intellectual reflection on the problem per se and not to discredit the reasoning of Wise and associates. However, Wise and co-workers are wrong; they misread, misquote, and miscalculate. First of all, they misquote our data when they state that our histalog-stimulated secretion data is expressed in mEq/hr, when it is actually given in mEq/30 min.; however, they have no statistical quarrel with the significant changes which we demonstrated in histalog-stimulated gastric acid output. Their quarrel was based on our conclusion that "Gastric hypersecretion frequently occurs following jejunoileal bypass, with an incidence as high as 43%." We unequivocally defined our criteria for this chemical hypersecretion to be an acid value two S.E.M. above the mean in our gastric analysis laboratory. We clearly state in our effort that, "None of the patients in Groups A, B, and C with hypersecretion preoperatively or postoperatively manifested clinical evidence of acidpeptic disease." We emphasized our doubts of the clinical significance of the secretory findings by including in the title of our paper- a phenomenon in search of a syndrome. We have been able further to substantiate our chemical findings (Arch. Surg., 110:1036, 1975) in a sequential study of 37 patients in whom we found a significant increase in free acid (P < 0.05) in histalogstimulated gastric juice one year after jejuno-ileal bypass. Our continuous interest in this field is demonstrated in our investigation of a possible protective metabolic role of the bypassed bowel on gastrin metabolism (J. Surg. Res., publication scheduled April, 1976). Actually, Wise and co-workers do not question our arbitrary criteria for establishing hypersecretion. Yet, a valid argument can be made here and this was done by Dr. James Thompson following the presentation of this material before the 1974 meeting of the Society of University Surgeons. Possibly, other arbitrary (and they are all arbitrary) criteria of chemical hypersecretion can be applied. Wise and co-workers, unwisely, choose to take issue with our statistical analyses. They state, and state correctly, that it is legitimate to compare statistically two groups of data by evaluation of their means and S.E.M. by an unpaired t-test. They go on to state that "singular data from a group, however, can only be compared to the mean ± S.D." This statement assumes (statistically) that we either: 1) did an unpaired t-test comparing our gastric secretory laboratory's normal population and our test population and of course we did not do that (doing an unpaired t-test reveals no statistically significant difference between those two groups at the P < 0.05 level); or 2) that we calculated 95% confidence limits from our patient's data and thus compared them to themselves
655
again, we did not do this. Statistically, this second approach would indeed have been invalid because, if we assume the Central Limit Theorem applies to our patient population, this would have automatically defined 2.5% of the patients as hyposecretors and 2.5% as hypersecretors. Thus, we are totally innocent of the statistical misdemeanors attributed to us. It becomes obvious that, since there are no universal criteria, one must establish arbitrary criteria by which to define hypersecretion. We did! And we clearly stated that this was done. We invite questioning of our criteria for hypersecretion but we must deny the charge of faulty statistical analysis leveled against us. In conclusion, we stand on our published data and their analyses. We urge students of this problem to focus on the body mechanisms and not the generated polemics. Henry Buchwald, M.D., Ph.D. John J. Coyle, M.D. Richard L. Varco, M.D., Ph.D. University of Minnesota Department of Surgery Medical School Mayo Memorial Building Minneapolis, Minnesota 55455 May 12, 1976 Dear Editor: We certainly share with Drs. Buchwald, Coyle and Varco a common goal to understand and define any alterations of gastric physiology which may follow jejunoileal bypass. Our evaluation of their data, statistical methods and conclusions (Surgery 75:821, 1974), which appeared in our paper, "Studies on the Effect of Small Bowel Bypass for Massive Obesity on Gastric Secretory Function" (Ann. Surg., 183:259, 1976), was intended to clarify and prevent a misunderstanding of the 183:259, 1976), was intended to clarify and prevent a misunderstanding of the incidence of gastric acid hypersecretion following this type of surgical procedure. We agreed that in the 14 patients they studied, there was a significant increase in the histalog-stimulated gastric acid output. Inadvertently, we stated that the increase was from 13.9 + 6.0 mEq/hour to 17.9 + 6.6 mEq/hour, whereas both these values referred to 30 minute periods. We still disagree, however, with Buchwald and his co-workers' statistical approach and their conclusion that they can statistically validly state from their results that the incidence of gastric hypersecretion following jejunoileal bypass is 43%. Since the standard error of the mean (SEM) is a statistic which measures the standard deviation of the mean and is a measure of the variability of the estimated mean, it may be used to
Ann. Surg. o November 1976
LETTERS TO THE EDITOR
saw "endothelium." We could not judge it to be pseudoendothelium according to our rather stringent criteria. There were, however, cell zones on the graft typical of pseudoendothelium. The case reported in our paper appeared "out of the blue," as it were, and in 1973 we were not in a position to carry out the electron microscopy Dr. Imparato recommends. However, in view of the paucity of reports on cell coverage in human prostheses, we felt this case should be reported. We hope that others will find such cell linings in man and report more fully on their nature. When we have another chance at such a specimen, we will be better prepared for more extensive studies. Lester R. Sauvage, M.D. Knute Berger, M.D. Reconstructive Cardiovascular Research Center Providence Medical Center Seattle, Washington 98122
References 1. Harker, L. A., Slichter, S. J. and Sauvage, L. R.: Platelet Consumption by Arterial Prostheses: Natural History in Relation to Endothelialization and Influence of Pharmacologic Inhibition of Platelet Function in Unhealed Grafts (In prepara-
cessful vein grafts, by J. Hogarth Pringle of Glasgow in 1912.4 A four-inch segment of saphenous vein was inserted following excision of a popliteal artery aneurysm in a man aged 49. When the patient died of a heart attach 3-½2 years later, the patent graft was preserved and is on display in the museum of the Royal College of Surgeons of Edinburgh. These comments are intended to help place in its proper perspective this interesting aspect of recent surgical history. Roger N. Baird, F.R.C.S.Ed. William M. Abbott, M.D. Harvard Medical School Massachusetts General Hospital Department of Surgery Boston, Massachusetts 02114 References 1. Hughes, C. W.: Arterial Repair During the Korean War. Ann.
Surg. 147:555, 1958. 2. dos Santos, R., Lamas, A. C. and Caldas, P. J.: Arteriografia da Aorta e Dos Vasos Abdominais. Med. Contemp., 47:93, 1929. 3. Leriche, R. and Kunlin, J.: Possibilite de Greffe Veineuse de Grande Dimension (15a 47 cm) dans les Thromboses Arterielles Etendues. Lyon Chir., 44:13, 1949. 4. Pringle, J. H.: Two Cases of Vein-grafting for the Maintenance of a Direct Arterial Circulation. Lancet, 1:1795, 1913.
tion). 2. Pugatch, E. M. J.: The Growth of Endothelium and Pseudoendothelium on the Healing Surface of Rabbit Ear Chambers. Proc. R. Soc. Lond., 160:412-422, 1964. 3. Warren, B. A.: Fibrinolytic Activity of Vascular Endothelium. Br. Med. Bull., 20:213-216, 1964. 4. Warren, B. A.: The Electron Microscopic Features and Fibrinolytic Properties of "Neo-intima." Br. J. Exp. Pathol., 45: 612-617, 1964. 5. Yates, S. G., Nakagawa, Y., Berger, K. and Sauvage, L. R.: Surface Thrombogenicity of Arterial Prostheses. Surg. Gynecol. Obstet., 136:12-16, 1973. 6. Yates, S. G.: Unpublished results, 1976.
February 27, 1976 Dear Editor: We were interested to read "Historical Aspects of Venous Autografts" by Lynn H. Harrison, Jr., M.D. The article, however, fails to mention a number of important landmarks, including Leriche and Kunlin's report of the first vein bypass grafts for femoral artery occlusion,3 which is of greater historical interest than the more recent quoted case. Also, it is not clear from the account that the introduction of vein grafting in the primary repair of arterial injuries was in 1952 during the Korean War, and resulted in a reduction in the amputation rate from 50o to 12%.1 Finally, since the author clearly wishes to acknowledge the importance of radiology in the development of vascular surgery, surely the major contribution of Reynaldo dos Santos deserves mention.2 It may be of interest to recall one of the earliest suc-
March 16, 1976 Dear Editor: The letter of Doctors Baird and Abbott emphasizes several noteworthy points. The achievement of Pringle is particularly deserving of mention and should certainly have been included in the article. The bane of the historical survey is that, although its scope is broad, its depth is limited, and important contributions are invariably omitted. I wish to thank Doctors Baird and Abbott for their comments and for underlining the work of these important contributors to the development of the venous
autograft. Lynn H. Harrison, Jr., M.D. Staff Surgeon McCain Hospital McCain, North Carolina 28361
April 14, 1976 Dear Editor: The negative comments by Wise, Vaughan, and Stein (Ann. Surg. 183:259-262, 1976), concerning the conclusions and statistics in our paper in Surgery 75:821, 1974, entitled, "Effect of Small Bowel Bypass on Gastric Secretory Function: Postintestinal Exclusion Hypersecretion, a Phenomenon in Search of a Syndrome,"
Vol. 184 * No. 5
LETTERS TO THE EDITOR
prompt us to reply. In so perpetuating the discussion, our primary aim is to foment intellectual reflection on the problem per se and not to discredit the reasoning of Wise and associates. However, Wise and co-workers are wrong; they misread, misquote, and miscalculate. First of all, they misquote our data when they state that our histalog-stimulated secretion data is expressed in mEq/hr, when it is actually given in mEq/30 min.; however, they have no statistical quarrel with the significant changes which we demonstrated in histalog-stimulated gastric acid output. Their quarrel was based on our conclusion that "Gastric hypersecretion frequently occurs following jejunoileal bypass, with an incidence as high as 43%." We unequivocally defined our criteria for this chemical hypersecretion to be an acid value two S.E.M. above the mean in our gastric analysis laboratory. We clearly state in our effort that, "None of the patients in Groups A, B, and C with hypersecretion preoperatively or postoperatively manifested clinical evidence of acidpeptic disease." We emphasized our doubts of the clinical significance of the secretory findings by including in the title of our paper- a phenomenon in search of a syndrome. We have been able further to substantiate our chemical findings (Arch. Surg., 110:1036, 1975) in a sequential study of 37 patients in whom we found a significant increase in free acid (P < 0.05) in histalogstimulated gastric juice one year after jejuno-ileal bypass. Our continuous interest in this field is demonstrated in our investigation of a possible protective metabolic role of the bypassed bowel on gastrin metabolism (J. Surg. Res., publication scheduled April, 1976). Actually, Wise and co-workers do not question our arbitrary criteria for establishing hypersecretion. Yet, a valid argument can be made here and this was done by Dr. James Thompson following the presentation of this material before the 1974 meeting of the Society of University Surgeons. Possibly, other arbitrary (and they are all arbitrary) criteria of chemical hypersecretion can be applied. Wise and co-workers, unwisely, choose to take issue with our statistical analyses. They state, and state correctly, that it is legitimate to compare statistically two groups of data by evaluation of their means and S.E.M. by an unpaired t-test. They go on to state that "singular data from a group, however, can only be compared to the mean ± S.D." This statement assumes (statistically) that we either: 1) did an unpaired t-test comparing our gastric secretory laboratory's normal population and our test population and of course we did not do that (doing an unpaired t-test reveals no statistically significant difference between those two groups at the P < 0.05 level); or 2) that we calculated 95% confidence limits from our patient's data and thus compared them to themselves
655
again, we did not do this. Statistically, this second approach would indeed have been invalid because, if we assume the Central Limit Theorem applies to our patient population, this would have automatically defined 2.5% of the patients as hyposecretors and 2.5% as hypersecretors. Thus, we are totally innocent of the statistical misdemeanors attributed to us. It becomes obvious that, since there are no universal criteria, one must establish arbitrary criteria by which to define hypersecretion. We did! And we clearly stated that this was done. We invite questioning of our criteria for hypersecretion but we must deny the charge of faulty statistical analysis leveled against us. In conclusion, we stand on our published data and their analyses. We urge students of this problem to focus on the body mechanisms and not the generated polemics. Henry Buchwald, M.D., Ph.D. John J. Coyle, M.D. Richard L. Varco, M.D., Ph.D. University of Minnesota Department of Surgery Medical School Mayo Memorial Building Minneapolis, Minnesota 55455 May 12, 1976 Dear Editor: We certainly share with Drs. Buchwald, Coyle and Varco a common goal to understand and define any alterations of gastric physiology which may follow jejunoileal bypass. Our evaluation of their data, statistical methods and conclusions (Surgery 75:821, 1974), which appeared in our paper, "Studies on the Effect of Small Bowel Bypass for Massive Obesity on Gastric Secretory Function" (Ann. Surg., 183:259, 1976), was intended to clarify and prevent a misunderstanding of the 183:259, 1976), was intended to clarify and prevent a misunderstanding of the incidence of gastric acid hypersecretion following this type of surgical procedure. We agreed that in the 14 patients they studied, there was a significant increase in the histalog-stimulated gastric acid output. Inadvertently, we stated that the increase was from 13.9 + 6.0 mEq/hour to 17.9 + 6.6 mEq/hour, whereas both these values referred to 30 minute periods. We still disagree, however, with Buchwald and his co-workers' statistical approach and their conclusion that they can statistically validly state from their results that the incidence of gastric hypersecretion following jejunoileal bypass is 43%. Since the standard error of the mean (SEM) is a statistic which measures the standard deviation of the mean and is a measure of the variability of the estimated mean, it may be used to
