We have examined the lysis of fibrin and plasma clots supplemented with supraphysiological concen... more We have examined the lysis of fibrin and plasma clots supplemented with supraphysiological concentrations of recombinant factor XIII (rFXII1) prior to clotting with thrombin. rFXII1 supplements of up to 200uglmL reduced the lysis rate of fibrin clots by either plasmin or leucocyte elastase in a dose-dependent fashion. Plasma clots supplemented with rFXII1 were larger and more resistant to plasmin lysis relative to controls. These effects were all greater when the clots were incubated for 20h compared to 1 h. To determine whether these in vitro findings might have an in vivo correlate, rFXII1 supplemented and unsupplemented fibrin clots labelled with '251-fibrin were implanted into the peritoneum of mice and lysis followed by the appearance of '*'I in the urine. Supplemented clots released significantly less "'1 over the first 10 days post-surgery. We conclude that supraphysiological concentrations of rFXII1 reduce lysis to both plasmin and leucocyte elastase in vitro and that supplemented clots show a similar resistance in vivo.
Factor XIII is an endogenous clotting factor that retards thrombus degradation by cross-linking f... more Factor XIII is an endogenous clotting factor that retards thrombus degradation by cross-linking fibrin. To determine the efficacy of Factor XIII as a topical clot-stabilizing agent in preventing postoperative hemorrhage associated with coagulopathy, a rat model of experimental craniotomy and standardized bilateral frontal corticectomy was developed. In 25 rats (50 lesions), recombinant human Factor XIII or placebo solution was topically applied to corticectomy cavities after hemostasis was achieved; each animal served as its own control. In 20 rats, heparin sulfate (100 U/kg.h) was initiated intraperitoneally 3 days after surgery and was continually administered by an Alzet pump for 7 days, compared with a control group of 5 rats receiving saline intraperitoneally. The volume of intracranial hemorrhage was quantitatively determined from coronal sections by use of automated image analysis. Large (> 50 mm3) intracerebral hemorrhages were significantly more frequent in placebo (60%)- compared with recombinant Factor XIII (15%)-treated lesions (P < 0.01) in animals receiving heparin. The topical application of clot-stabilizing agents such as Factor XIII may reduce the risk of postoperative intracranial hemorrhage, especially in high-risk patients with coagulopathy.
In this study, we have investigated estrogen's capacity to regulate bone formation and resorption... more In this study, we have investigated estrogen's capacity to regulate bone formation and resorption in the ovariectomized mouse, evaluating the dose and site dependence of estrogen action on bone modeling and remodeling surfaces. To quantitate bone resorption, the skeletons of fifty 8-week-old Swiss-Webster mice were prelabeled with [lH]tetracycline ('H-T) before initiation of treatment protocols. Ovanectomies (OVX) and sham surgeries were performed 3 days after the final lH-T injection, and the animals were assigned to treatment groups and injected once per week for 4 weeks with one of the following doses of 17P-estradiol (Ed: sham/oil vehicle (SV), OVX/oil vehicle, OVX/SO pg E,, OVX/250 pg E,, and OVX/500 pg E,. To assess bone formation, fluorochrome labels were administered 9 and 2 days before sacrifice. At the conclusion of the 4 week protocol, the femora and thoracic vertebrae were removed to quantitate the levels of bone resorption based on the skeletal retention of 'H-T. The tibiae were excised for histomorphometric evaluation of the proximal metaphyses and middiaphyses. Indicative of increased bone resorption, vehicle-treated OVX animals had significantly reduced levels of 'H-T in femora and vertebrae compared to SV mice. This result was consistent with histomorphometric data showing a 49% decrease in cancellous bone area of the proximal tibiae in the OVX/oil-treated group. Treatment of OVX animals with 50 pg E, was sufficient to maintain 3H-T levels in vertebrae at SV values, with higher E, doses leading to a dose-dependent increase in the retention of 'H-T at this site. In contrast, 'H-T levels in the femora of mice treated with 50 and 250 pg E, were intermediate between the SV-and vehicle-treated OVX animals. Only at 500 pg E, per week were lH-T values in femora maintained at SV values compared to OVX mice treated with vehicle. Histology data indicated that treatment of OVX mice with 250 pg E, prevented osteopenia in the proximal metaphyses of the tibiae; the 500 pg dose of E, led to a fivefold increase in cancellous bone volume compared to SV mice. In OVX mice treated with 500 pg E,, cancellous bone formation rates were increased 83% compared to SV animals and 35% compared to the OVX/oil-treated group. These increases were a consequence of increased boneforming surface. E, treatment also stimulated bone formation on the endosteal surface of the diaphysis. In summary, these results indicate that E, inhibits bone resorption in femora and vertebrae of OVX mice in a dose-dependent fashion and has the capacity to stimulate bone formation on both endosteal and cancellous bone surfaces.
We have examined the lysis of fibrin and plasma clots supplemented with supraphysiological concen... more We have examined the lysis of fibrin and plasma clots supplemented with supraphysiological concentrations of recombinant factor XIII (rFXII1) prior to clotting with thrombin. rFXII1 supplements of up to 200uglmL reduced the lysis rate of fibrin clots by either plasmin or leucocyte elastase in a dose-dependent fashion. Plasma clots supplemented with rFXII1 were larger and more resistant to plasmin lysis relative to controls. These effects were all greater when the clots were incubated for 20h compared to 1 h. To determine whether these in vitro findings might have an in vivo correlate, rFXII1 supplemented and unsupplemented fibrin clots labelled with '251-fibrin were implanted into the peritoneum of mice and lysis followed by the appearance of '*'I in the urine. Supplemented clots released significantly less "'1 over the first 10 days post-surgery. We conclude that supraphysiological concentrations of rFXII1 reduce lysis to both plasmin and leucocyte elastase in vitro and that supplemented clots show a similar resistance in vivo.
Factor XIII is an endogenous clotting factor that retards thrombus degradation by cross-linking f... more Factor XIII is an endogenous clotting factor that retards thrombus degradation by cross-linking fibrin. To determine the efficacy of Factor XIII as a topical clot-stabilizing agent in preventing postoperative hemorrhage associated with coagulopathy, a rat model of experimental craniotomy and standardized bilateral frontal corticectomy was developed. In 25 rats (50 lesions), recombinant human Factor XIII or placebo solution was topically applied to corticectomy cavities after hemostasis was achieved; each animal served as its own control. In 20 rats, heparin sulfate (100 U/kg.h) was initiated intraperitoneally 3 days after surgery and was continually administered by an Alzet pump for 7 days, compared with a control group of 5 rats receiving saline intraperitoneally. The volume of intracranial hemorrhage was quantitatively determined from coronal sections by use of automated image analysis. Large (> 50 mm3) intracerebral hemorrhages were significantly more frequent in placebo (60%)- compared with recombinant Factor XIII (15%)-treated lesions (P < 0.01) in animals receiving heparin. The topical application of clot-stabilizing agents such as Factor XIII may reduce the risk of postoperative intracranial hemorrhage, especially in high-risk patients with coagulopathy.
In this study, we have investigated estrogen's capacity to regulate bone formation and resorption... more In this study, we have investigated estrogen's capacity to regulate bone formation and resorption in the ovariectomized mouse, evaluating the dose and site dependence of estrogen action on bone modeling and remodeling surfaces. To quantitate bone resorption, the skeletons of fifty 8-week-old Swiss-Webster mice were prelabeled with [lH]tetracycline ('H-T) before initiation of treatment protocols. Ovanectomies (OVX) and sham surgeries were performed 3 days after the final lH-T injection, and the animals were assigned to treatment groups and injected once per week for 4 weeks with one of the following doses of 17P-estradiol (Ed: sham/oil vehicle (SV), OVX/oil vehicle, OVX/SO pg E,, OVX/250 pg E,, and OVX/500 pg E,. To assess bone formation, fluorochrome labels were administered 9 and 2 days before sacrifice. At the conclusion of the 4 week protocol, the femora and thoracic vertebrae were removed to quantitate the levels of bone resorption based on the skeletal retention of 'H-T. The tibiae were excised for histomorphometric evaluation of the proximal metaphyses and middiaphyses. Indicative of increased bone resorption, vehicle-treated OVX animals had significantly reduced levels of 'H-T in femora and vertebrae compared to SV mice. This result was consistent with histomorphometric data showing a 49% decrease in cancellous bone area of the proximal tibiae in the OVX/oil-treated group. Treatment of OVX animals with 50 pg E, was sufficient to maintain 3H-T levels in vertebrae at SV values, with higher E, doses leading to a dose-dependent increase in the retention of 'H-T at this site. In contrast, 'H-T levels in the femora of mice treated with 50 and 250 pg E, were intermediate between the SV-and vehicle-treated OVX animals. Only at 500 pg E, per week were lH-T values in femora maintained at SV values compared to OVX mice treated with vehicle. Histology data indicated that treatment of OVX mice with 250 pg E, prevented osteopenia in the proximal metaphyses of the tibiae; the 500 pg dose of E, led to a fivefold increase in cancellous bone volume compared to SV mice. In OVX mice treated with 500 pg E,, cancellous bone formation rates were increased 83% compared to SV animals and 35% compared to the OVX/oil-treated group. These increases were a consequence of increased boneforming surface. E, treatment also stimulated bone formation on the endosteal surface of the diaphysis. In summary, these results indicate that E, inhibits bone resorption in femora and vertebrae of OVX mice in a dose-dependent fashion and has the capacity to stimulate bone formation on both endosteal and cancellous bone surfaces.
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Papers by m w edwards