Free Protein S Deficiency in Patients with Chronic Inflammatory Bowel Disease E. AADLAND, 0. R. BDEGAARD, A. R0SETH & K. TRY Medical and Clinical Chemical Dept., Aker Hospital, Oslo, Norway
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
Aadland E, 0degaard OR, Rsseth A, Try K . Free protein S deficiency in patients with chronic inflammatory bowel disease. Scand J Gastroenterol 1992;27:957-960. Free protein S, protein C, and C4b-binding protein (C4b-BP) were measured in randomly selected outpatients: 22 with Crohn’s disease (CD) and 16 with ulcerative colitis (UC). Active disease was recorded in 10 patients with CD and 4 with UC. Fourteen patients (63.6%) with CD and 4 (25%) with UC had free protein S values below the normal range, with mean values of 62% and 78% of that found in healthy control subjects ( p < 0.01). The C4b-BP level was 127% in patients with C D as compared with 89% in both healthy subjects and UC patients ( p < 0.01). The protein C levels were similar in the three groups. The present results add to the factors already known favouring thromboembolic complications in inflammatory bowel disease and which might play a major role both for the pathogenesis and for the increased tendency to venous thromboembolism in these diseases.
Key words: Free protein S; inflammatory bowel disease; thromboembolism
E. Aadland, M . D . , Dept. of Medicine, A k e r Hospital, N-0514 Oslo, Norway
Evidence has recently been found indicating that multifocal gastrointestinal infarctions might be an important pathogenetic mechanism in Crohn’s disease (CD) (1). Free protein S is an anticoagulant exerting its effect in small vessels in close cooperation with protein C and thrombomodulin (2). It is a vitamin K-dependent glycoprotein, acting as a cofactor for the inhibitory effect of activated protein C on factors Va and VIIIa. About 60% of protein S is under normal conditions bound to C4b-binding protein (C4b-BP) (3). Only free protein S participates in the regulation of coagulation. Deficiency of free protein S and protein C predisposes for thrombosis (4,5). C4b-BP is an acute-phase reactant and increases during inflammation (3). Conditions with acute-phase response may thus reduce the free protein S concentration and increase the tendency to thrombosis. The purpose of the present investigation was to study free protein s, C4b-BP, and protein C in patients with inflammatory bowel disease (1BD)-that is, CD and ulcerative colitis (UC). MATERIALS AND METHODS In the present study 25 outpatients with CD and 25 with UC were randomly selected and invited to participate. Twentytwo patients with CD and 16 with UC accepted and were included in the study. The diagnosis of IBD had previously been ascertained by radiology and colonoscopy with histology in all patients. Some relevant clinical data of the patients are shown in Table I. The patients were examined in the outpatient clinic by one of us (A. Roseth). Disease activity was clinically assessed
by the simple index for CD (6) and an activity index for UC (7). Active disease was defined as simple index >5 or activity index >3. Blood samples were drawn for analysis of haematologic variables, liver function tests, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), serum albumin, serum iron, and orosomucoid. Of the 11 medically treated patients with CD, 5 used oral prednisone; 3, azathioprine; 5, sulphasalazine; and 3 used 5-acetylsalicylic acid (5-ASA) preparations. Of the 16 patients with UC, 10 used oral sulphasalazine, 4 used 5-ASA preparations, and 2 patients had no medication. One patient used oral prednisone and one prednisone enema. The control group consisted of 30 healthy subjects, 16 women and 14 men, with a mean age of 39 years (range, 26-66 years). For analysis of protein S, protein C, and C4b-BP, citrated blood (1/10 vol, 0.13 M sodium citrate) was centrifuged at 2000g for 20 min at 4°C. Plasma was pipetted off and kept at -70°C until analysed. Free protein S was measured with an electroimmunoassay (EIA kits, Diagnostica Stago, Paris)
Table I. Clinical data on patients with Crohn’s disease (CD) and ulcerative colitis (UC)
No. of patients Female to male ratio Age (years) Duration of disease (years) Previous intestinal surgery Totallleft-sided colitis (UC) Ileocolitis (CD) Ileitis (CD) Colitis (CD)
CD
UC
22 1517 41 13 12 0 16 4 2
16 6/10 38 9 0 15/1 0 0 0
958
E. Aadland et al.
Table 11. Parameters of inflammation in patients with Crohn’s disease (CD) ( n = 22) and ulcerative colitis (UC) ( n = 16) (mean values and ranges)
uc
CD
20 (7-48) 9 (0-71) 1.0 (0.41.8) 10 (2-19) 41 (32-46) 5.7 (1-11)
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
Erythrocyte sedimentation rate (rnm) C-reactive protein (mg/l) Orosomucoid (g/l) Serum iron (pmol/l) Serum albumin (g/l) Simple index (CD) Activity index (UC)
after precipitation with polyethylene glycol 8000 at a final concentration of 5%. C4b-BP was measured with EIA kits from the same manufacturer. Protein C was measured with a chromogenic method (8). The values of free protein S, protein C , and C4b-BP are given in percentage of pooled reference plasma from healthy controls ( n = 30). For statistical analysis Mann-Whitney and t tests were used. RESULTS The indicators of disease activity in the I B D patients are shown in Table 11. The patients with C D had a mean simple index of 5.7 (range, 1-11). Ten patients had active disease with a simple index > 5 . The patients with U C had a mean activity index of 1.6 (range, &7), and four patients had active disease with an index > 3. All patients had normal liver function tests. Both in patients with C D and in those with U C the plasma concentrations of free protein S were significantly lower than in the control group ( p < 0.01) (Table 111). The patients with C D had significantly lower concentrations than the U C patients ( p < 0.05). The individual values for free protein S are shown in Fig. 1. Fourteen of the 22 patients with C D had free protein S values below the normal range, as compared with 8 of 10 patients with active disease (NS). Five of 16 UC patients had low free protein S, and this was found in 2 of 4 patients with active disease. C4b-BP concentrations did not differ significantly between healthy subjects and U C patients. In patients with C D significantly higher concentrations were found ( p < 0.01) (Table 111). The individual values of C4b-BP are shown in
7 (2-20) 1 (C8) 0.8 (0.5-1.2) 14 (5-33) 43 (40-46) 1.6 ( C 7 )
Fig. 2. Ten of the 22 patients with CD had C4b-BP values above the upper normal range. The mean C4b-BP concentration measured in each of the healthy subjects was somewhat lower than the value of the pooled reference plasma, which was defined as 100%. This may indicate a greater variation of the C4b-BP levels than those of free protein S and protein C in the normal population. No significant differences were found in the values of protein C in the three groups studied. Mean values for healthy subjects, C D , and U C were 101.7% (range, 57135%), 95.8% (range, 43-112%), and 88.4% (range, 57122%), respectively.
200
175
150
tB
.v1 .-80 C
e a
!i
loo
8 88 8
75
em
em 50
Table 111. Mean percentage concentrations of frcc protein S and C4b-binding protein (C4b-BP) in healthy subjects ( n = 30) and patients with ulcerative colitis (UC) ( n = 16) and Crohn’s disease (CD) ( n = 22) Free pr0t.S Healthy 5ubjeCt5
C4-BP 89
HC
UC CD
* p < 0.05; * * p < 0.01
25
127
CD
UC
Fig. 1. Free protein S levels (%) in healthy controls (HC) and patients with Crohn’s disease (CD) and ulcerative colitis (UC). Mean and individual values.
Free Protein S Deficiency in IBD
.
200
175
0.
.e 150
88
.*
Fp 125 E
0.
B
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
i2 100
.w c .a 9
75
U 50
.. . .*
.
.*** 8 *.
0.
0.
11111
80
*.
25
HC
CD
uc
Fig. 2. C4b-binding protein (%) in healthy controls (HC) and patients with Crohn’s disease (CD) and ulcerative colitis (UC). Mean and individual values.
The number of patients with active disease was small, and no correlation between free protein S and any of the selected indicators of disease activity was found. C4b-BP correlated significantly with ESR ( r = 0.59, p < 0.01), CRP ( r = 0.58, p < 0.01), and orosomucoid ( r = 0 . 5 2 , < ~ 0.05) but not with the simple index, albumin, or serum iron. A weak but significant positive correlation was also found between free protein S and C4b-BP (r = 0.45, p < 0.05).
959
In patients with UC free protein S was significantly reduced as compared with healthy subjects but less than in the patients with CD. In UC the level of C4b-BP was similar to that of healthy subjects, but only 4 of the 16 patients had active disease at the time of investigation. None of the patients with C D or UC had evidence of liver disease or diseases known to influence the concentration of free protein S. It may thus be assumed that the reduction of free protein S found in these patients may be due to specific processes taking place in the two diseases. The levels of protein C were similar in the three groups studied. The present results fit well with the hypothesis of Wakefield et al. (1) that the development of endothelial damage and microthrombi may play an important role in the pathogenesis of IBD. Accordingly, the thrombomodulin/protein S/protein C system will be impaired and favour coagulation especially in small vessels. It remains to be established whether steroids or sulphasalazine influences the thrombomodulin/protein S/protein C system. In this respect it should be pointed out that many of the patients studied were receiving medical therapy at the time of investigation. However, the mean free protein S value in the 11 medically treated CD patients was not significantly different from that of the 11 patients who received no such treatment at the time of investigation. The thromboembolic complications occurring in IBD patients have been attributed to hypercoagulation, as manifested by elevation of fibrinogen, factors V and VIII, thrombocytosis, and depression of antithrombin 111 (9-13). The impairment of the thrombomodulin/protein S/protein C system adds to the factors already known and may play a major role both in the pathogenesis and in the increased tendency to venous thromboembolism in IBD. The present results may have implications for the choice of treatment of venous thrombosis and pulmonary embolism in IBD patients. Vitamin K antagonists will further reduce the free protein S/protein C levels in these patients, leading to recurrent thrombosis during such treatment (14, 15). Prolonged heparin treatment might therefore be preferable in these conditions.
DISCUSSION In the present study significantly decreased levels of free protein S were found in patients with CD as compared with healthy subjects. The low levels of free protein S were not correlated with any of the disease activity variables recorded. C4b-BP correlated with some of the variables of disease activity in patients with CD and may thus be used as an indicator of activity in these patients. When C4b-BP is increased, more protein S is bound, reducing the concentration of free protein S in plasma. However, the lacking correlation between free protein S and disease activity and a weak positive correlation between free protein S and C4bBP suggest that the low values of free protein S found in CD may be due to factors not related to C4b-BP.
REFERENCES 1. Wakefield AJ, Dhillon AP, Rowles PM, et al. Pathogenesis of Crohn’s disease: multi-focal gastrointestinal infarction. Lancet 1989;2: 1057-62. 2. Comp PC, Esmon CT. Recurrent thromboembolism in patients with a partial deficiency of protein S . N Engl J Med 1984; 311:1525-8. 3. Dahlback B. Protein S and C4b-binding protein: components involved in the regulation of the protein C anticoagulant system. Thromb Haemostas 1991;66:49-61. 4. Bertina RM. Hereditary protein S deficiency. Haemostasis 1985;15:241-6. 5. Griffin JH, Evatt B, Zimmermann TS, Kleiss AJ, Wideman C. Deficiency of protein C in congenital thrombotic disease. J Clin Invest 1981;68:1370. 6. Harvey RF, Bradshaw JM. A simple index of Crohn’s-disease activity. Lancet 1980;1:514.
960
E. Aadland et a1
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
7. Rachmilewitz D. Coated mesalazine (5-aminosalisylic acid) versus sulphasalazine in the treatment of active ulcerative colitis: a randomised trial. Br Med J 1989;298:82-6. 8. Bdegaard OR, Try K, Anderson TR. Protein C : an automated activity assay. Haemostasis 1987;17:109-13. 9. Lam A, Borda IT, Inwood MJ, Thomson S. Coagulation studies in ulcerative colitis and Crohn’s disease. Gastroenterology 1975;681245-5 1. 10. Talstad I, Rootwelt K, Gjone E. Thrombocytosis in ulcerative colitis and Crohn’s disease. Scand J Gastroenterol 1973;8:1358. 11. Lee JCL, Spitell JA, Sauer WG, Owen CA, Thompson JH. Hypercoagulability associated with chronic ulcerative colitis: changes in blood coagulation factors. Gastroenterology 1968; 54176-85. 12. Lake AM, Stauffer JQ, Stuart MJ. Hemostatic alterations in Received 24 March 1992 Accepted 2 June 1992
inflammatory bowel disease. Response to therapy. Dig Dis 1978;23:897-902. 13. Ghosh S, Mackie MJ, McVerry BA, Galloway M, Ellis A, McKay J. Chronic inflammatory bowel disease, deep-venous thrombosis and antithrombin activity. Acta Haematoi (Basel) 1983;70:5O-3. 14. 0degaard OR, Lindahl AK, Try K , Kvalheim G. Recurrent venous thrombosis during warfarin treatment related to acquired protein S deficiency. In: Nagy I, Losonczy H, Vinazzer H, editors. Thrombosis and haemorrhagic disorders. Proceedings of the 7th international meeting of the Danubian League against thrombosis and haemorrhagic disorders, Pecs, Hungary 1990: 152-7. 15. Wyshock E, Caldwell M, Crowley JP. Deep venous thrombosis, inflammatory bowel disease, and protein S deficiency. Am J Clin Pathol 1988;90:633-5.
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
Aadland E, 0degaard OR, Rsseth A, Try K . Free protein S deficiency in patients with chronic inflammatory bowel disease. Scand J Gastroenterol 1992;27:957-960. Free protein S, protein C, and C4b-binding protein (C4b-BP) were measured in randomly selected outpatients: 22 with Crohn’s disease (CD) and 16 with ulcerative colitis (UC). Active disease was recorded in 10 patients with CD and 4 with UC. Fourteen patients (63.6%) with CD and 4 (25%) with UC had free protein S values below the normal range, with mean values of 62% and 78% of that found in healthy control subjects ( p < 0.01). The C4b-BP level was 127% in patients with C D as compared with 89% in both healthy subjects and UC patients ( p < 0.01). The protein C levels were similar in the three groups. The present results add to the factors already known favouring thromboembolic complications in inflammatory bowel disease and which might play a major role both for the pathogenesis and for the increased tendency to venous thromboembolism in these diseases.
Key words: Free protein S; inflammatory bowel disease; thromboembolism
E. Aadland, M . D . , Dept. of Medicine, A k e r Hospital, N-0514 Oslo, Norway
Evidence has recently been found indicating that multifocal gastrointestinal infarctions might be an important pathogenetic mechanism in Crohn’s disease (CD) (1). Free protein S is an anticoagulant exerting its effect in small vessels in close cooperation with protein C and thrombomodulin (2). It is a vitamin K-dependent glycoprotein, acting as a cofactor for the inhibitory effect of activated protein C on factors Va and VIIIa. About 60% of protein S is under normal conditions bound to C4b-binding protein (C4b-BP) (3). Only free protein S participates in the regulation of coagulation. Deficiency of free protein S and protein C predisposes for thrombosis (4,5). C4b-BP is an acute-phase reactant and increases during inflammation (3). Conditions with acute-phase response may thus reduce the free protein S concentration and increase the tendency to thrombosis. The purpose of the present investigation was to study free protein s, C4b-BP, and protein C in patients with inflammatory bowel disease (1BD)-that is, CD and ulcerative colitis (UC). MATERIALS AND METHODS In the present study 25 outpatients with CD and 25 with UC were randomly selected and invited to participate. Twentytwo patients with CD and 16 with UC accepted and were included in the study. The diagnosis of IBD had previously been ascertained by radiology and colonoscopy with histology in all patients. Some relevant clinical data of the patients are shown in Table I. The patients were examined in the outpatient clinic by one of us (A. Roseth). Disease activity was clinically assessed
by the simple index for CD (6) and an activity index for UC (7). Active disease was defined as simple index >5 or activity index >3. Blood samples were drawn for analysis of haematologic variables, liver function tests, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), serum albumin, serum iron, and orosomucoid. Of the 11 medically treated patients with CD, 5 used oral prednisone; 3, azathioprine; 5, sulphasalazine; and 3 used 5-acetylsalicylic acid (5-ASA) preparations. Of the 16 patients with UC, 10 used oral sulphasalazine, 4 used 5-ASA preparations, and 2 patients had no medication. One patient used oral prednisone and one prednisone enema. The control group consisted of 30 healthy subjects, 16 women and 14 men, with a mean age of 39 years (range, 26-66 years). For analysis of protein S, protein C, and C4b-BP, citrated blood (1/10 vol, 0.13 M sodium citrate) was centrifuged at 2000g for 20 min at 4°C. Plasma was pipetted off and kept at -70°C until analysed. Free protein S was measured with an electroimmunoassay (EIA kits, Diagnostica Stago, Paris)
Table I. Clinical data on patients with Crohn’s disease (CD) and ulcerative colitis (UC)
No. of patients Female to male ratio Age (years) Duration of disease (years) Previous intestinal surgery Totallleft-sided colitis (UC) Ileocolitis (CD) Ileitis (CD) Colitis (CD)
CD
UC
22 1517 41 13 12 0 16 4 2
16 6/10 38 9 0 15/1 0 0 0
958
E. Aadland et al.
Table 11. Parameters of inflammation in patients with Crohn’s disease (CD) ( n = 22) and ulcerative colitis (UC) ( n = 16) (mean values and ranges)
uc
CD
20 (7-48) 9 (0-71) 1.0 (0.41.8) 10 (2-19) 41 (32-46) 5.7 (1-11)
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
Erythrocyte sedimentation rate (rnm) C-reactive protein (mg/l) Orosomucoid (g/l) Serum iron (pmol/l) Serum albumin (g/l) Simple index (CD) Activity index (UC)
after precipitation with polyethylene glycol 8000 at a final concentration of 5%. C4b-BP was measured with EIA kits from the same manufacturer. Protein C was measured with a chromogenic method (8). The values of free protein S, protein C , and C4b-BP are given in percentage of pooled reference plasma from healthy controls ( n = 30). For statistical analysis Mann-Whitney and t tests were used. RESULTS The indicators of disease activity in the I B D patients are shown in Table 11. The patients with C D had a mean simple index of 5.7 (range, 1-11). Ten patients had active disease with a simple index > 5 . The patients with U C had a mean activity index of 1.6 (range, &7), and four patients had active disease with an index > 3. All patients had normal liver function tests. Both in patients with C D and in those with U C the plasma concentrations of free protein S were significantly lower than in the control group ( p < 0.01) (Table 111). The patients with C D had significantly lower concentrations than the U C patients ( p < 0.05). The individual values for free protein S are shown in Fig. 1. Fourteen of the 22 patients with C D had free protein S values below the normal range, as compared with 8 of 10 patients with active disease (NS). Five of 16 UC patients had low free protein S, and this was found in 2 of 4 patients with active disease. C4b-BP concentrations did not differ significantly between healthy subjects and U C patients. In patients with C D significantly higher concentrations were found ( p < 0.01) (Table 111). The individual values of C4b-BP are shown in
7 (2-20) 1 (C8) 0.8 (0.5-1.2) 14 (5-33) 43 (40-46) 1.6 ( C 7 )
Fig. 2. Ten of the 22 patients with CD had C4b-BP values above the upper normal range. The mean C4b-BP concentration measured in each of the healthy subjects was somewhat lower than the value of the pooled reference plasma, which was defined as 100%. This may indicate a greater variation of the C4b-BP levels than those of free protein S and protein C in the normal population. No significant differences were found in the values of protein C in the three groups studied. Mean values for healthy subjects, C D , and U C were 101.7% (range, 57135%), 95.8% (range, 43-112%), and 88.4% (range, 57122%), respectively.
200
175
150
tB
.v1 .-80 C
e a
!i
loo
8 88 8
75
em
em 50
Table 111. Mean percentage concentrations of frcc protein S and C4b-binding protein (C4b-BP) in healthy subjects ( n = 30) and patients with ulcerative colitis (UC) ( n = 16) and Crohn’s disease (CD) ( n = 22) Free pr0t.S Healthy 5ubjeCt5
C4-BP 89
HC
UC CD
* p < 0.05; * * p < 0.01
25
127
CD
UC
Fig. 1. Free protein S levels (%) in healthy controls (HC) and patients with Crohn’s disease (CD) and ulcerative colitis (UC). Mean and individual values.
Free Protein S Deficiency in IBD
.
200
175
0.
.e 150
88
.*
Fp 125 E
0.
B
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
i2 100
.w c .a 9
75
U 50
.. . .*
.
.*** 8 *.
0.
0.
11111
80
*.
25
HC
CD
uc
Fig. 2. C4b-binding protein (%) in healthy controls (HC) and patients with Crohn’s disease (CD) and ulcerative colitis (UC). Mean and individual values.
The number of patients with active disease was small, and no correlation between free protein S and any of the selected indicators of disease activity was found. C4b-BP correlated significantly with ESR ( r = 0.59, p < 0.01), CRP ( r = 0.58, p < 0.01), and orosomucoid ( r = 0 . 5 2 , < ~ 0.05) but not with the simple index, albumin, or serum iron. A weak but significant positive correlation was also found between free protein S and C4b-BP (r = 0.45, p < 0.05).
959
In patients with UC free protein S was significantly reduced as compared with healthy subjects but less than in the patients with CD. In UC the level of C4b-BP was similar to that of healthy subjects, but only 4 of the 16 patients had active disease at the time of investigation. None of the patients with C D or UC had evidence of liver disease or diseases known to influence the concentration of free protein S. It may thus be assumed that the reduction of free protein S found in these patients may be due to specific processes taking place in the two diseases. The levels of protein C were similar in the three groups studied. The present results fit well with the hypothesis of Wakefield et al. (1) that the development of endothelial damage and microthrombi may play an important role in the pathogenesis of IBD. Accordingly, the thrombomodulin/protein S/protein C system will be impaired and favour coagulation especially in small vessels. It remains to be established whether steroids or sulphasalazine influences the thrombomodulin/protein S/protein C system. In this respect it should be pointed out that many of the patients studied were receiving medical therapy at the time of investigation. However, the mean free protein S value in the 11 medically treated CD patients was not significantly different from that of the 11 patients who received no such treatment at the time of investigation. The thromboembolic complications occurring in IBD patients have been attributed to hypercoagulation, as manifested by elevation of fibrinogen, factors V and VIII, thrombocytosis, and depression of antithrombin 111 (9-13). The impairment of the thrombomodulin/protein S/protein C system adds to the factors already known and may play a major role both in the pathogenesis and in the increased tendency to venous thromboembolism in IBD. The present results may have implications for the choice of treatment of venous thrombosis and pulmonary embolism in IBD patients. Vitamin K antagonists will further reduce the free protein S/protein C levels in these patients, leading to recurrent thrombosis during such treatment (14, 15). Prolonged heparin treatment might therefore be preferable in these conditions.
DISCUSSION In the present study significantly decreased levels of free protein S were found in patients with CD as compared with healthy subjects. The low levels of free protein S were not correlated with any of the disease activity variables recorded. C4b-BP correlated with some of the variables of disease activity in patients with CD and may thus be used as an indicator of activity in these patients. When C4b-BP is increased, more protein S is bound, reducing the concentration of free protein S in plasma. However, the lacking correlation between free protein S and disease activity and a weak positive correlation between free protein S and C4bBP suggest that the low values of free protein S found in CD may be due to factors not related to C4b-BP.
REFERENCES 1. Wakefield AJ, Dhillon AP, Rowles PM, et al. Pathogenesis of Crohn’s disease: multi-focal gastrointestinal infarction. Lancet 1989;2: 1057-62. 2. Comp PC, Esmon CT. Recurrent thromboembolism in patients with a partial deficiency of protein S . N Engl J Med 1984; 311:1525-8. 3. Dahlback B. Protein S and C4b-binding protein: components involved in the regulation of the protein C anticoagulant system. Thromb Haemostas 1991;66:49-61. 4. Bertina RM. Hereditary protein S deficiency. Haemostasis 1985;15:241-6. 5. Griffin JH, Evatt B, Zimmermann TS, Kleiss AJ, Wideman C. Deficiency of protein C in congenital thrombotic disease. J Clin Invest 1981;68:1370. 6. Harvey RF, Bradshaw JM. A simple index of Crohn’s-disease activity. Lancet 1980;1:514.
960
E. Aadland et a1
Scand J Gastroenterol Downloaded from informahealthcare.com by RMIT University on 08/18/15 For personal use only.
7. Rachmilewitz D. Coated mesalazine (5-aminosalisylic acid) versus sulphasalazine in the treatment of active ulcerative colitis: a randomised trial. Br Med J 1989;298:82-6. 8. Bdegaard OR, Try K, Anderson TR. Protein C : an automated activity assay. Haemostasis 1987;17:109-13. 9. Lam A, Borda IT, Inwood MJ, Thomson S. Coagulation studies in ulcerative colitis and Crohn’s disease. Gastroenterology 1975;681245-5 1. 10. Talstad I, Rootwelt K, Gjone E. Thrombocytosis in ulcerative colitis and Crohn’s disease. Scand J Gastroenterol 1973;8:1358. 11. Lee JCL, Spitell JA, Sauer WG, Owen CA, Thompson JH. Hypercoagulability associated with chronic ulcerative colitis: changes in blood coagulation factors. Gastroenterology 1968; 54176-85. 12. Lake AM, Stauffer JQ, Stuart MJ. Hemostatic alterations in Received 24 March 1992 Accepted 2 June 1992
inflammatory bowel disease. Response to therapy. Dig Dis 1978;23:897-902. 13. Ghosh S, Mackie MJ, McVerry BA, Galloway M, Ellis A, McKay J. Chronic inflammatory bowel disease, deep-venous thrombosis and antithrombin activity. Acta Haematoi (Basel) 1983;70:5O-3. 14. 0degaard OR, Lindahl AK, Try K , Kvalheim G. Recurrent venous thrombosis during warfarin treatment related to acquired protein S deficiency. In: Nagy I, Losonczy H, Vinazzer H, editors. Thrombosis and haemorrhagic disorders. Proceedings of the 7th international meeting of the Danubian League against thrombosis and haemorrhagic disorders, Pecs, Hungary 1990: 152-7. 15. Wyshock E, Caldwell M, Crowley JP. Deep venous thrombosis, inflammatory bowel disease, and protein S deficiency. Am J Clin Pathol 1988;90:633-5.
