the operation of the present invention is seen more fully by the example given below . leukocyte suspensions were obtained using a modification of the method of henson , j . immun . 107 : 1535 ( 1971 ). seven domestic short hair adult cats ( 4 - 5 kg ) were anesthesized with sodium thiamyl ( 25 mg / kg i . v .) ( parke - davis , morris plains , nj ), and 30 ml of blood was drawn by heart puncture into 1 / 7 volume of acid citrate dextrose ( acd ). the blood was centrifuged at 150g ( 850 rpm ) for 10 minutes at room temperature using a beckman tj - 6 refrigerated centrifuge . the supernatant , which was platelet - rich plasma ( prp ), and the buffy coat were removed using a polyethylene pasteur pipette ( centaur chemical co ., stamford , cn ). ( this supernatant was centrifuged for 10 minutes at 1800g at 4 ° c . to remove all suspended particles , and the plasma was saved in a refrigerator ). the red blood cells and leukocytes were suspended in pyrogen free saline containing 2 . 5 % gelatin ( difco laboratories , detroit , mi ). the solution was mixed by inversion , and the erythrocytes were allowed to sediment at 1g for 30 minutes at 37 ° c . a white cell button was obtained by centrifuging the supernatant at 400g ( 1400 rpm ) for 10 minutes at room temperature . the leukocyte button was resuspended in 0 . 87 % ammonium chloride in water ( ph 7 . 2 ) to cause lysis of the remaining red cells . after 5 minutes the cells were centrifuged at 200g ( 1000 rpm ) for 10 minutes at 4 ° c . the supernatant was removed , and the cells were washed with albumin tyrode &# 39 ; s solution ( 2 . 5 %). the cells were centrifuged down as before and resuspended in albumin tyrode &# 39 ; s solution ( 2 . 5 %). in order to maintain cell viability , the leukocytes were kept on ice until used . before being radioactively labeled the cells were counted and tested for viability to insure that viable cells had been isolated . white cell counts were made using a neubauer hemocytometer ( american optical , buffalo , ny ). viability was tested by trypan blue exclusion . acid citrate dextrose was prepared with 80 mg of citric acid , 224 mg of anhydrous sodium citrate , and 120 mg of anhydrous dextrose per 10 ml of solution . the saline used ( isotonic buffered saline , american scientific products , mcgraw park , il ) contained , per liter : 180 meq na , 5 . 1 meq k , 153 meq cl , 1 . 0 mmol edta , and trace amounts of 2 - phenoxyethanol . tyrode &# 39 ; s solution was made by adding , per liter : 200 mgcacl 2 , 100 mg mgcl 2 ( 6h 2 o ), 200 mg kcl , 8000 mg nacl , 50 mg nah 2 po 4 ( h 2 o ), 100 mg glucose , and 1000 mg nhco 3 . ( the nhco 3 was added last until a ph of 7 . 35 to 7 . 40 was achieved ). bovine albumin powder ( armour pharmaceutical co ., kankakee , il ) was added 2 . 5 % by weight . all solutions were sterilized in 115 nalgene sterilization filter units ( nalge co ., rochester , ny ) with 0 . 20 micron pores . indium - 111 was purchased as the hydrochloride from new england nuclear corporation and converted to the membrane soluble oxine using a modification of the method of thakur ( 1977 ). approximately 150 microcuries in indium - 111 oxine ( 2 . 0 mci / 300 μl ) were added to leukocytes suspended in 2 to 4 ml of albumin tyrode &# 39 ; s solution ( 2 . 5 %) and allowed to incubate 20 minutes . the solution was centrifuged at 850g ( 2000 rpm ) for 5 minutes at 4 ° c . the button was resuspended in albumin tyrode &# 39 ; s solution ( 2 . 5 %) and centrifuged as above . after a final washing in chilled plasma the cells were suspended in 2 . 000 or 4 . 000 ml of plasma , depending on the quantity of cells isolated . the leukocyte suspensions of four cats were treated with nordihydroguaiaretic acid ( ndga ; 4 , 4 &# 39 ;-( 2 , 3 - dimethyl tetramethylene ) dipyrocatechol , 100 μg / ml ). this compound is a potent inhibitor of the lipoxygenase enzyme ( bokoch , 1981 ). white cell count and viability were again tested and recorded at this point . also , a measured volume of the suspension was placed in a 12 by 75 mm test tube to serve as a standard . each cat was anesthesized intravenously with nembutal ( 500 mg pentobarbital sodium / ml ) ( abbott laboratories , north chicago , il ) and tied in the dorsal recumbant position . the ventral side of the neck was sheared with clippers and then shaved with a razor blade . the area was sterilized using betadine soap and betadine with 10 % iodine . after scrubbing and donning sterile gloves , the surgical area was carefully covered with sterile towels and a drape . a 6 to 8 cm longitudinal incision was made medial to each external jugular vein . connective tissue , fat , and adventitia were restricted away so as to expose the jugular veins . care was taken in ligating and detaching all side branches from a 3 to 4 cm section of the vessel ( 4 - 0 silk , american cyanamide co ., pearl river , ny ). a 5 / 8 inch 26 gauge needle with a bent tip was inserted into the cranial end of the isolated section of the vessel , and suture ( 4 - 0 silk ) was used to hold the needle in position . the vessel was flushed with sterile saline and tied off proximal to the heart . all fluid was extracted from the vessel and approximately 0 . 2 ml of the labeled leukocyte solution was injected . upon removal of the needle , the cranial end was tied off , and the distended vessel was allowed to sit for one hour . at the end of one hour the vessel was removed and placed in tyrode &# 39 ; s solution . the wound was closed using a continuous lock stitch ( 2 - 0 or 3 - 0 dexon , absorbable , davis and geck , inc ., manati , pr ). suture and excess tissue were removed from the jugular vein . half of the vessel was weighed , and radioactivity of the specimen was counted in a packard gamma scintillation spectrometer . for each vessel the following computations were made : total counts per minute ( cpm ), cpm / gm of tissue , total number of white cells adhered , and number of white cells adhered / gm of tissue . the other half of the vessel was opened with a longitudinal cut and mounted luminal side up on a cork board to be prepared for scanning electron microscopy . one - half of each jugular vein was prepared for scanning electron microscopy ( sem ) whenever sufficient tissue was available for both counting and microscopy . sections of jugular vein were tied onto glass microscope slides using 4 - 0 dexon and immersed in 2 . 5 % glutaraldehyde in tyrode &# 39 ; s solution . samples were rinsed 3 times in tyrode &# 39 ; s solution and post - fixed overnight in 1 % osmium tetroxide . after rinsing 3 times with distilled water , tissues were dehydrated in absolute ethanol 2 times for one hour each and once overnight . ethanol was substituted by amyl acetate , and the samples were permitted to air dry . the veins were mounted on stubs ( ted pella , inc ., tustin , ca ), gold coated on a denton dv - 502 vacuum evaporator , and examined on a cambridge stereoscan 150 scanning electron microscope for deposition of leukocytes on the luminal surface . two leukocyte suspensions were fixed for transmission electron microscopy ( tem ) to verify the purity and types of leukocytes found in the isolated material . briefly , 1 ml of suspension was diluted with 10 ml of 1 % glutaraldehyde in tyrode &# 39 ; s buffer and allowed to fix for 1 hour . the cells were washed 2 times in tyrode &# 39 ; s buffer and post - fixed in 1 % osmium tetroxide for 15 minutes . the suspensions were washed in tyrode &# 39 ; s solution , dehydrated in absolute ethanol , substituted with propylene oxide , and infiltrated with medcast / araldite ( ted pella , inc ., tustin , ca ). tissues were sectioned with a diamond knife ( dupont instruments , bear , de ) on a porter / blum mt2 - b ultra - microtome . all sections were stained with uranyl acetate and lead citrate and examined on a phillips 301 transmission electron microscope . table 1 shows the number of leukocytes deposited per gram of tissue for each jugular vein . values for both the treated and untreated groups appear relatively consistent with the exception of those for cat 466 , both of which are significantly higher than the corresponding values for other treated vessels . in general deposition is shown to occur in the untreated group , but this can best be verified by sem analysis . vessels prepared for sem were each graded for four conditions : ( 1 ) white cell adhesion , ( 2 ) white cell invasion , ( 3 ) endothelial damage , and ( 4 ) fibrin deposition , as explained in table 2 . the results are summarized in tables 3 and 4 . excellent correlations can be seen between the calculated ( table 1 ) and observed results ( tables 3 and 4 ). upon sem analysis untreated vessels showed greater amounts of leukocyte adhesion , leukocyte invasion , endothelial damage , and fibrin deposition compared to treated vessels . untreated vessels typically exhibited extensive white cell adhesion and invasion resulting in total destruction of the luminal surface and exposure of the subendothelium . in areas of greatest disruption fibrin deposits were frequently present in varying amounts . under high magnification ( 2000x ) white cells could be clearly identified and it was evident that their normally smooth surfaces had become ruffled and distorted , a sign of activation . in some areas fibrin deposits were so extensive that leukocytes were literally buried in fibrin , and abnormally high magnification ( 2000x ) was required to differentiate between normal endothelium and regions of thick fibrin deposits . in most of the treated vessels normal and intact endothelium comprised the major portion of the lumen . at high enough magnification ( 1000x ) raised nuclei and intracellular junctions were readily visible . some samples exhibited mild distortion of the endothelium including splitting , craters , and dissociation of nuclei from their cells ; however , this seemed to occur in the absence of leukocyte deposition . occasionally , a treated vessel whose surface was grossly intact and free of leukocytes would display extensive leukocyte deposition in selective areas such as regions adjacent to valve pockets , side branches , and luminal ridges . the opportunity for blood stasis is greater in these areas , and thus the chance of leukocyte deposition in response to leukotactic gradients is higher . several of the treated vessels did exhibit extensive regions of leukocyte adhesion , leukocyte invasion , endothelial damage , and fibrin deposition . the extent to which each of these occurred in treated vessels varied so greatly that it is possible to deduce the probable sequence in which these events normally occur . some areas clearly showed extensive adhesion and invasion rendering the surface extremely lumpy and uneven as emigrating leukocytes forced up the endothelium . however , the endothelium in these regions was grossly intact , although somewhat distorted , and no fibrin deposits were evident . in other regions the endothelium was severely damaged , although no fibrin deposition had occurred . large portions of intact endothelium remained through which leukocytes apparently had yet to emigrate . finally , there were regions in which the endothelium had been either removed or entirely damaged by the action of emigrating leukocytes . often basement membrane was visible , as were fibrin deposits . nine adult domestic short hair cats weighing 4 . 5 - 5 kg were anesthetized with sodium pentabarbital ( 25 - 30 mg / kg i . v .). the neck area was prepared for a sterile cut down procedure and the jugular veins were exposed . after exposure of the veins each animal was injected with epsilon amino caproic acid ( eaca ) to inhibit plasminogen activation ( 2 . 5 grams i . v . in tyrode &# 39 ; s solution ). this was done to reduce the normally high active feline fibrinolytic mechanism and thus reduce lysis of fibrin thrombi which might form in the vessel . six of the cats were also treated with 2 , 3 - diethyl - 4 - methoxy - 1 - naphthalenol , acetate . three of the cats were given 1 mg / kg i . v . and 3 of the cats were treated with 5 mg / kg i . v . prior to venous occlusion . the jugular veins were carefully dissected free of surrounding connective tissue and the vein was ligated at the thoracic inlet with 3 - 0 dexon . the skin incision was closed and the animals were maintained in surgical anesthesia for two hours . at the end of the 2 hour waiting period , the jugular veins were exposed again . a 25 gauge butterfly needle was positioned into the lumen and blood was flushed out of the vein with heparinized tyrode &# 39 ; s solution ( 1u heparin / ml ). the veins were tied off and removed under physiologic pressure . the vessels were immediately immersed in a 2 . 5 % glutaraldehyde solution prepared in tyrode &# 39 ; s solution for fixation . the veins were fixed overnight at 5 ° c ., postfixed in 1 % osmium tetroxide overnight , dehydrated in ethanol and substituted by amyl acetate . all veins were critical point dried from carbon dioxide using a denton dcp - 1 critical point drying apparatus . the veins were mounted on stubs , gold coated on a denton dv - 502 modified vacuum evaporator and examined on a cambridge stereoscan 150 scanning electron microscope . two hours of jugular vein stasis following the trauma of dissection caused massive white cell adhesion to and migration under the venous endothelium of non - treated cats and produced sloughing of the endothelium and exposure of the basement membrane . this damage was sufficient to initiate thrombosis . many of the exposed areas of basement membrane had adherent platelets . the platelets were adherent as monolayers or as aggregates . in some areas fibrin was found deposited on the endothelium or exposed basement membrane . leukocytes were occasionally associated with the fibrin . 2 , 3 - diethyl - 4 - methoxy - 1 - naphthalenol , acetate had a dose dependent effect on the vascular changes described above . the 1 mg / kg dose did not reduce leukocyte adhesion or migration . most of the surface of all the veins examined in this group had multiple aggregates of leukocytes visible under the intact endothelium . although leukocyte migration was not inhibited , leukocyte release of hydrolytic enzymes and production of superoxide &# 39 ; s was apparent inhibited . few areas with detached endothelial cells or exposed basement membrane were found in this group . the 5 mg / kg dose had an even greater inhibitory effect on leukocyte mediated damage . in this group only patchy areas of adherent leukocytes were observed . in most of these areas leukocytes were also found under the endothelium . it was only in these areas , however , that endothelial cell loss and platelet deposition were observed . the numbers of adhering and migrating leukocytes found in this group appeared to be less than in either the control or 1 mg / kg treated group . with the exception of one vein , approximately half or more of the vascular surface had an intact endothelial cell cover with few adherent leukocytes . only occasional small areas of fibrin deposition were found in this group . table 1______________________________________ number of cellscat # vessel per gram of tissue * ______________________________________ ( untreated ) 334 left 41 . 4 right 18 . 6332 left 14 . 8 right 17 . 9325 left 64 . 3 right 22 . 0 mean = 29 . 8 s . e . = 7 . 91 ( treated ) 398 left 3 . 07 right 4 . 99228 left 7 . 39466 left 17 . 3 right 56 . 1457 left 7 . 73 right 6 . 04 mean = 14 . 7 s . e . = 7 . 12 p . = 0 . 0321 ** excluding 466 : mean = 5 . 84 s . e . = 0 . 85 p . = 0 . 0062 ** ______________________________________ * values expressed in millions . ** wilcoxon &# 39 ; s ranksum test for pairwise comparisons table 1 . leukocyte deposition on jugular veins of untreated and ndgatreated cats : the cats in both groups were held under anesthesia for approximately the same length of time , and the veins were exposed , perfused , and processed by the same methods . the only variable was the presence of ndga in the leukocyte suspensions used for the treated group . table 2______________________________________description ratings______________________________________1 . extent none rare sparse moderate heavy2 . arrangement patchy uniform3 . amount of luminal estimated % surface involved______________________________________ table 2 . description of luminal surface of jugular veins as seen under sem : all ratings were made as relative estimates by the same individual t insure greatest possible accuracy . table 3______________________________________cat white cell white cell endothelial fibrin # vessel adhesion invasion damage deposition______________________________________325 left heavy heavy heavy moderate uniform uniform uniform patchy 90 % 90 % 90 % 15 % 334 right sparse sparse moderate sparse patchy patchy patchy patchy 25 % 25 % 25 % 5 % 334 left moderate moderate moderate sparse patchy patchy patchy patchy 50 % 50 % 50 % 10 % 332 right moderate moderate heavy sparse uniform uniform uniform patchy 80 % 80 % 80 % 10 % ______________________________________ table 3 . sem analysis of untreated jugular veins : for any given animal th descriptions for white cell adhesion , white cell invasion , and endothelia damage are comparable , indicating a close relationship between these characteristics . fibrin deposition , although minimal in some cases , was a least exhibited by all the vessels . table 4______________________________________cat white cell white cell endothelial fibrin # vessel adhesion invasion damage deposition______________________________________398 left sparse sparse rare rare uniform patchy patchy patchy 90 % 20 % & lt ; 1 % 1 % 398 right sparse sparse rare rare patchy patchy patchy patchy 20 % 20 % & lt ; 1 % & lt ; 1 % 457 right rare none none none patchy -- -- -- & lt ; 1 % -- -- -- 228 left sparse none none none patchy -- -- -- 10 % -- -- -- 466 left heavy heavy moderate none uniform uniform uniform -- 90 % 90 % 90 % -- 466 right heavy heavy heavy moderate uniform uniform uniform uniform 90 % 90 % 90 % 15 % ______________________________________ table 4 . sem analysis of ndgatreated jugular veins : the results appear fa less consistent for this group than for the untreated group . values of 1 % or less are common throughout the table , especially in the areas of endothelial damage and fibrin deposition , two important precursors to thrombus formation .
the present invention provides a novel methoda for preventing deep vein thrombosis comprising the administration of lipoxygenase inhibitors of formula i ## str1 ##