Alleged differences of two commercial collagen preparations to aggregate platelets

Alleged differences of two commercial collagen preparations to aggregate platelets

THROXBOSIS Printed RESEARCH in Great 1-01. Britain LETTER TO THE 11, pp. Pergamon 91j-917, Press, 197; Ltd. EDITORS-IN-CHIEF ALLEGED DIFFERE...

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THROXBOSIS Printed

RESEARCH in Great

1-01. Britain

LETTER

TO

THE

11, pp. Pergamon

91j-917, Press,

197; Ltd.

EDITORS-IN-CHIEF

ALLEGED DIFFERENCES OF TWO COMMERCIAL COLLAGEN PREPARATIONS TO AGGREGATE PLATELETS Fritz Schulte Hormon-Chemie Mtinchen GmbH, P. 0. Box 101 D-8000 Mtinchen 45, F. R. G.

(Received

22.7.1977; Accepted

in by

revised 'form A.L. Copley)

18.10.1977.

Recently I have read with interest the communication of Dag Nyman (1) about platelet aggregation induced by two commercial collagen preparations. The following comments seem necessary: 1) For turbidimetrical testing of PRP the addition of the aggregating agent at a volume of 0.1 ml (e.g. collagen suspension) to 0.4 ml of PRP is unfavourable for easily noticeable reasons. Using Collagenreagent “Harm” (CRH) this ratio (1:4) is detrimental, completely unnecessary and contradictory to the directions for use. 2) The results of Table I in Nyman’ s work were obtained by using 20 )a” of CRH per 1 ml of PRP. This dosage is much too high and is also in contradiction to the directions (3-4 &ml). If collagen is overdosed weak disturbances of the platelet aggregability cannot be traced clearly. 3) The data of strewing from Nyman’s Table II are recalculated as percentage and summarized in Table I. The lower percentage of s in Collagen “Harm” points to the fact that relatively higher doses of Collagen ”Horm” than of Collagen ”Stage” have been used. The remark by Nyman “the lag phase is consistently longer with Collagen “Stage’! supports this suggestion. 4) In the investigations of Nyman’s Table II low doses under 2.5 w/ml are lacking. In the directions for the use of CRH it is mentioned “According to existing data maximum aggregation of fully functioning of thrombocytes is in general already obtained with doses of 3 Collagenreagent “Harm” per 1 ml PRP or titrated blood. If Yarger dosles 915

916

COLLXGEBS

dc PLATELET

AGGREGATIOTi

Vol.ll,No.6

TABLE I Recalculated Percentage of Strewing from Nyman’s Table II Lag Phase s (%) ST+

Ho+

31.3 38.2

Ho

3.7

23

8. 9

65.7

15.4

136.8

26.4

12.1 16

ST: Collagen “Stage”;

ST 12.7

9.3 7. 7

Max. Vel. s (%)

9.4

37.9

Ho: Collagen “Harm”

than 4 s of CRH per 1 ml PRP or titrated blood are required for obtaining maximum aggretation, the aggregability of these platelets may be disturbed, for example, by the ingestion of drugs containing Aspirin”. 5) If platelets of normal controls are aggregated with 5 and 1Oclg of Collagen “Harm” no significant differences between these doses can be noted because 5 p already aggregate the platelets maximally. 6) The equieffective doses of Collagen “Stage”, and Collagen “Harm” have been chosen arbitrarily. For this purpose the author in an unintelligible way uses only the Vmax of 20~ Collagen “Stage” and 10 F Collagen ”Harm”. Jf all results summarized in Nyman’s Table II are taken into consideration one easily realizes that the best comparative results are the results of 10 w Collagen ” Stage” and 2.5 N Collagen “Harm”, of 20 pg Collagen “Stage” and 5 w Collagen “Harm” and finally of 40 w Collagen “Stage” and 10 w Collagen ”Horm”. 7) The dose-response curves as listed by Nyman are incorrect and misleading as they are not based on the real equieffective doses (s.para 6). 8) The author asserts ”Collagen “H orm” thus has the ability to induce platelet release inspite of ASA in a concentration which almost completely blocks the effect of Collagen ”Stage” . This is incorrect. It should read: “Overdoses of Collagen “Harm” thus II. have the ability . . . . . . . . ...*... 9) The nice discussion of the commented paper is limited by the fact that it is based on results which do not correspond to the sophisticated hypotheses made in the discussion.

COLLAGE%

I: PLATELET

AGGRECXTIOS

FtEFERJZNCE 1. NYMAN, D. Collagen-induced platelet aggregation: Evidence of several mechanisms for the induction of platelet release by collagen. Thrombosis Research, 10,743,1977.