442 LETTERS TO THE EDITOR 2. Lipinski B, Fedennan SM, Krolewski AS. Macromolecular protein complex of human plasma: interaction with fibrin and fibrinolysis. Thromb Res 1995;78:461-5. 3. Lipinski B, Federman SM, Krolewski AS. Comments on plasma fibrinogen levels measured by functional methods. Thromb Haemost 1994;72:985-9. Reply to 8 Lipinski Institute for Thrombosis Research South Jutland University Centre Esbjerg, Denmark Moniek PM de Maat J¢rgen Jespersen Tine Tholstrup Peter Marckmann Dear Sir: In our recent article we state that neither a diet high in myristic acid nor a diet high in palmitic acid changes lhe functional plasma fibrinogen concentrations, measured with a modification of the Clauss assay (1). Lipinski questions whether the fibrinogen concentrations may in fact be changed, but that it just cannot be proved by the Clauss assay. He suggests that if the fibrinogen concentrations were determined by a method that measures the amount of clottable protein, it may in fact have been changed by the diet because of changes in the amount of macromolecular protein complex (MPC). We believe that if this clottable protein method gives spuri- ously high concentrations, it would not be due to a changed amount of fibrinogen but to increased concentrations of MPC, which would then be incorporated in the clot and incorrectly be measured as fibrinogen. Because this protein will not affect the Clauss assay, it may be concluded that when changes in MPC are expected, one should not use clottable protein-based assays (2). There are no indications that the amount of MPC in the plasma would be changed after the two diets, because the only identified state that increases MPC thus far is insulin-depen- dent diabetes mellitus (IDDM). Lipinski further states that high MPC concentrations give a higher resistance to fibrinolysis of the fibrin (+ MPC) clot. The evidence given to support this is his finding that washed fibrin clots prepared from IDDM patients could only be lysed by urokinase, streptokinase, or tissue-plasminogen activator (t- PA) when plasminogen was added to the incubation mixture (3). Patients with IDDM are known to have normal or de- creased concentrations of plasminogen activator inhibitor-l (PAl-I) and t-PA in contrast with patients with non-insulin- dependent diabetes mellitus (4, 5). Therefore, disturbed fibrin- olysis cannot explain the resistance to lysis of the fibrin clots. Nonetheless, we feel that these experiments are not fully con- vincing because the appropriate control experiments have not been performed. It may for example be that there is no fibrin- olysis because the washing of the fibrin clots removed all the plasminogen. An experiment with normal plasma and plasma supplemented with MPC may give more convincing evidence. If increased MPC does give resistance to lysis, it might be of interest to measure MPC concentrations, possibly by compar- ing fibrinogen concentrations measured by both the Clauss method and by a c1ottable-protein method. However, even if MPC concentrations are changed by diets high in palmitic or myristic acid, the actual plasma fibrinogen concentration will not be changed when more MPC is present, and therefore we believe that we can maintain our conclusion that fibrinogen concentrations are not changed by these fatty acids. Research Department of Human Nutrition Department of Dairy and Food Science The Royal Veterinary and Agricultural University Copenhagen, Denmark REFERENCES 1. Tholstrup T, Marckmann P, Jespersen J, Vessby B, Jart A, Sandstrom B. Effect on blood lipids, coagulation, and fibriuolysis of a fat high in myristic acid and a fat high in palmitic acid. Am J Clin Nutr 1994; 60:919-25. 2. de Maat MPM, Haverkate F. Critical evaluation of fibrinogen assays. In: Samama M, Seghatchian J, eds. Hypercoagulable state: Biological aspects and clinical management. Boca Raton, FL: CRC Press (in press). 3. Lipinski B, Federman SM, Krolewski AS. Plasma macromolecular protein complex: interaction with fibrin and fibrinolysis. Thromb Res (in press). 4. Mahmoud R, Raccah D, Alessi MC, Aillaud MF, Juhan-Vague I, Vague P. Fibrinolysis in insulin dependent diabetic patieuts with or without nephropathy. Fibrinolysis 1992;6:105-9. 5. Myrup B, Rossing P, Jensen T, Gram J, Kluft C, Jespersen J. The effect of the relationship between tissue.type plasminogen activator and plasminogen activator inhibitor type 1 on tissue-type plasminogen activator activity in insulin-dependent diabetes mellitus. Fibrinolysis 1994;8(suppl 2):22-4. Hypothalamic control of gastric motility Dear Sir: We read with interest the recent paper by Bursztein-De Myttenaere et al (1) in your journal, which correctly addresses the issue of changes in gastric motility during parenteral nu- trition as they relate to the anorectic effects of total parenteral nutrition (TPN). In their study, the authors propose that the reduction of food intake during TPN is mediated by the inhi- bition of gastric emptying and that brain serotonin plays a significant role in this me"hanism. We agree with Bursztein-De Myttenaere et al that gastric motility is involved in the devel- opment of reduced food intake during TPN. However, we believe that additional factors other than brain serotonin are involved in this process. Using the rat TPN model, we showed that the determinants of food intake, meal size, and meal number are independently but reciprocally regulated in the hypothalamus (MM Meguid, Z-J Yang, JR Gleason, et ai, unpublished observations, 1995). Meal size is controlled by dopamine concentrations in the lateral hypothalamic area (LHA) (2). LHA is functionally re- Downloaded from https://academic.oup.com/ajcn/article/62/2/442/4651309 by guest on 14 March 2023