The Stability of Factor VIII in Heparinized Plasma

We studied the stability for 24 hr of factor VIII: C and factor Vm C:Ag in plasma collected in citrate, EDTA or heparin, and confirmed the previously reported two-phase decay of factor VIII:C in plasma when calcium ions have been chelated. We observed that plasma factor VIII:C is remarkably stable at 22° C (±2°) when normal calcium ion concentrations are maintained. The loss of activity of factor VIII:C between one and 24 hr after blood collection was on average only 0.5% per hr for heparinized plasma. There was also an apparent loss of factor VIII C:Ag in plasma where calcium ions had been removed, compared with factor VIII C:Ag in heparinized plasma. However, a comparison of one-site and two-site assays suggested that calcium chelating agents may lead to factor VIII C:Ag levels being under-estimated when one-site fluid-phase assays are employed.

To confirm the action of calcium ions in maintaining factor VIII:C stability, we carried out a series of experiments where calcium chloride was added four hr after blood collection to plasma anticoagulated by a mixture of citrate plus heparin; we observed total recovery of factor VIII:C activity within four hr.

The stability of factor VIII:C, even at room temperature, in the presence of physiological calcium ion concentrations has implications for manufacturers of factor VIH concentrates and cryo-precipitates.

Standardization of Factor VIII – III. Establishment of a Stable Reference Plasma for Factor VIII-Related Activities

An international collaborative study has been carried out to establish a reference plasma for Factor VIII-related activities. The freeze-dried reference plasma, coded 80/511, was assayed against fresh normal plasma, local standards and another freeze- dried plasma. There was good agreement between laboratories for the comparison of the two freeze-dried plasmas, but wide variation in the comparison of plasma 80/511 with fresh normal plasma and local standards, indicating the differences in Factor VIII content of local pooled plasmas. There were no significant differences between the one-stage and two-stage assays of VIII :C, or between electroimmunoassay (EIA) and immuno- radiometric (IRMA) assays of VIII R:Ag. However, in VIII R: RCoF (ristocetin co-factor) assays, the aggregometry methods gave lower values than the macroscopic and counting methods for the comparison of freeze-dried against fresh normal plasmas. From the combined results of assays against each laboratory’s fresh normal plasma, potencies were assigned to plasma 80/511.

Results from accelerated degradation studies indicated that losses of each VIII-related activity in plasma 80/511, when stored at -20° C, should be less than 0.01% per year, indicating its suitability to serve as a long-term reference preparation. Plasma 80/511 has been established by the WHO Expert Committee on Biological Standardization as the 1st International Reference Preparation for Factor VIII-Related Activities in Plasma.

The Effect of Interleukin-1 on Venous Endothelium – An Ultrastructural Study

The effect of systemic interleukin-1 (IL-1) on venous endothelium in the presence and absence of stasis has been studied by scanning electron microscopy (SEM). Recombinant human IL-1β at a concentration of 1 εg/kg or saline was injected intravenously into rabbits and allowed to circulate for 0.5 or 4.0 h after which complete stasis was induced for 1 h in an isolated segment of each jugular vein. One vein segment was then excised and the contents examined macroscopically for thrombi, while the other segment was fixed for SEM examination. When examined by SEM the endothelium from rabbits injected with IL-1β was perturbed with increased surface microvilli, blebs and gaps at cell junctions when compared with saline controls. Fibrin deposition was also observed after IL-1β, as was the adherence of essentially non-activated platelets to intact endothelium. However, macroscopic thrombi were not formed in isolated vein segments. We conclude that although fibrin strands and platelets were deposited on the endothelium, IL-1 is not a sufficiently powerful procoagulant stimulus to lead to an occlusive thrombus in acute experiments.

Potentiation of the Antithrombotic Action of Dermatan Sulphate by Small Amounts of Heparin

We have examined the effect in impairing thrombus formation of a preparation of dermatan sulphate (DS) alone and DS plus small amounts of unfractionated heparin (UFH). In rabbits given a dose of 150 μg/kg of DS alone, there was minimal reduction in serum-induced stasis thrombosis (Wessler model), with an overall score of 92.5% (100% = no impairment of thrombus formation). When the same dose of DS containing UFH was given (two different subgroups given DS containing 0.25 and 2.5% heparin by dry weight, respectively), the overall thrombus score was reduced to 60% (P <0.003), with no significant difference between the two subgroups. To achieve a comparable result with DS alone, a dose of 1 mg/kg was required. We conclude that very small amounts of UFH significantly enhance the antithrombotic action of DS, by a mechanism that has yet to be determined.

Anticoagulant Activities of Pentosan Polysulphate (Hémoclar) Due to Release of Hepatic Triglyceride Lipase (HTGL)

Subcutaneous injections of 50 mg pentosan poly sulphate (Hemoclar) were given to normal volunteers and the effects on anti-Factor Xa activity, thrombin generation and lipase release measured. Concentrations of pentosan polysulphate were measured by a competitive binding assay and the mean peak level found to be 1.6 μg/ml. Anti-Xa clotting activity rose to 0.034 iu/ml and thrombin generation induced by lipid peroxides was inhibited by approximately 50%. Neither of these effects could be accounted for by the direct action of pentosan polysulphate at the concentrations measured. Pentosan poly sulphate was very effective in releasing lipase, approximately 70-80% of the total enzyme activity being due to hepatic triglyceride lipase (HTGL). In vitro addition of purified HTGL to plasma markedly enhanced anti-Xa clotting activity, and caused a 70% inhibition of lipid peroxide induced thrombin generation. Anti-Xa activity of postinjection plasma was increased rather than neutralised by addition of polybrene, and this effect could be mimicked by addition of polybrene to plasma containing pentosan polysulphate and purified HTGL. It is concluded that, when given in low doses subcutaneously, pentosan polysulphate acts as an indirect anticoagulant, its major effects being due to release of HTGL.

Standardization of Low Molecular Weight Heparins : A Collaborative Study

A collaborative study was carried out, in which eight laboratories each assayed eight low molecular weight (LMW) heparins against the International Standard (IS) for heparin. APTT assays and three types of anti-Xa method were used. The results of this study showed that:

1. LMW heparins cannot be validly assayed against the IS by APTT or anti-Xa methods.

2. Potencies of LMW heparins vs. the IS differed considerably between the four types of assay method used and also between different laboratories using the same type of method.

3. Adoption of a single LMW heparin standard would improve validity, improve inter-laboratory variation, and largely abolish the differences between the three types of anti-Xa method. However, since calibration of a LMW heparin standard against the IS would give potencies that differ widely by the different assay methods, a single assay method such as the anti-Xa amidolytic, plasma, would need to be chosen for this calibration.

A Collaborative Study Designed to Establish the 4th International Standard for Heparin

An international collaborative study, in which 22 laboratories participated, was carried out to establish a replacement for the International Standard for Heparin. A total of 248 assays were analyzed, including APTT, thrombin inhibition and anti-Xa assays, as well as pharmacopoeial assays. Overall, there was less than 5% difference in the mean potency estimates of the candidate preparations, by all assay methods. The freeze-dried preparation 82/502 demonstrated the closest parallelism by bioassay to the existing standard and was established by WHO as the 4th International Standard for Heparin, with an assigned unitage of 1780 i.u. per ampoule.

High and Low Affinity Heparin Compared with Unfractionated Heparin as Antithrombotic Drugs

A preparation of heparin was separated by affinity chromatography into two fractions: one of high (HAH) and the other of low (LAH) affinity to antithrombin III. These two fractions were compared with unfractionated heparin (UFH) by in vitro assay and their ability to impair experimental stasis thrombosis was also examined. Although the in vitro activity of HAH was double that of UFH, HAH was less effective than UFH as an antithrombotic drug; LAH was virtually inactive, both in vitro and in vivo. A mixture of 30 μg/kg of HAH and 50 μg/kg of LAH was as effective in preventing thrombosis as 80 μg/kg of UFH, and was more effective than 40 μg/kg of HAH alone, demonstrating that LAH potentiates the action of HAH in vivo.

A Comparison of Heparin Potency Estimates Obtained by Activated Partial Thromboplastin Time and British Pharmacopoeial Assays

Heparin samples from five manufacturers were assayed by the revised British Pharmacopoeia (BP) heparin assay and the results compared with those obtained using the activated partial thromboplastin time (APTT) assay. The United States Pharmacopeia (USP) reference heparin preparation and the 4th International Standard (IS) for heparin were also assayed by the two methods relative to the 3rd IS. The results obtained by the revised BP assay were in close agreement with those obtained by the APTT assay for all the heparins that were tested. The assays revealed that there is at least a 10% discrepancy between the International Unit for heparin and the USP unit.

Standardization of Factor VIII – IV. Establishment of the 3rd International Standard for Factor VIII: C Concentrate

An international collaborative study was carried out to establish a replacement for the current (2nd) international standard for Factor VIII: C, concentrate. Twenty-six laboratories took part, of which 17 performed one-stage assays, three performed two-stage assays and six used both methods. The proposed new standard, an intermediate purity concentrate, was assayed against the current standard, against a high-purity concentrate and against an International Reference Plasma, coded 80/511, previously calibrated against fresh normal plasma.

Assays of the proposed new standard against the current standard gave a mean potency of 3.89 iu/ampoule, with good agreement between laboratories and between one-stage and two- stage assays. There was also no difference between assay methods in the comparison of high-purity and intermediate purity concentrates. In the comparison of the proposed standard with the plasma reference preparation, the overall mean potency was 4.03 iu/ampoule, but there were substantial differences between laboratories, and the two-stage method gave significantly higher results than the one stage method. Of the technical variables in the one-stage method, only the activation time with one reagent appeared to have any influence on the results of this comparison of concentrate against plasma.

Accelerated degradation studies showed that the proposed standard is very stable. With the agreement of the participants, the material, in ampoules coded 80/556, has been established by the World Health Organization as the 3rd International Standard for Factor VIII :C, Concentrate, with an assigned potency of 3.9 iu/ampoule.

A Comparison of Pentosan Polysulphate and Heparin II: Effects of Subcutaneous Injection

A comparison has been made between the effects of pentosan polysulphate (SP54) and mucosal heparin following subcutaneous injection in man. Unlike heparin, pentosan polysulphate has relatively little effect in vivo as measured by anti-factor Xa clotting assay and none by an anti-Xa amidolytic assay (S-2222). However, pentosan polysulphate is at least as potent as heparin on a weight basis in producing activation of lipoprotein lipase, shortening of the euglobulin clot lysis time and impairing the generation of factor Xa. Our data indicate that pentosan polysulphate has more marked effects in vivo than in vitro, that the action of the drug on clotting is mediated mainly via an At III-independent pathway, and that its effects are not confined to the coagulation system.

Effects of Heparin Oligosaccharides with High Affinity for Antithrombin III in Experimental Venous Thrombosis

The in vitro and in vivo characteristics of two oligosaccharide heparin fragments have been compared to those of unfractionated mucosal heparin. A decasaccharide fragment had essentially no activity by APTT or calcium thrombin time assays in vitro, but possessed very high specific activity by anti-Factor Xa assays. When injected into rabbits at doses of up to 80 ¼g/kg, this fragment was relatively ineffective in impairing stasis thrombosis despite producing high blood levels by anti-Xa assays. A 16-18 monosaccharide fragment had even higher specific activity (almost 2000 iu/mg) by chromogenic substrate anti-Xa assay, with minimal activity by APTT. When injected in vivo, this fragment gave low blood levels by APTT, very high anti-Xa levels, and was more effective in preventing thrombosis than the decasaccharide fragment. However, in comparison with unfractionated heparin, the 16-18 monosaccharide fragment was only partially effective in preventing thrombosis, despite producing much higher blood levels by anti-Xa assays.

It is concluded that the high-affinity binding of a heparin fragment to antithrombin III does not by itself impair venous thrombogenesis, and that the anti-Factor Xa activity of heparin is only a partial expression of its therapeutic potential.

A Comparison of Pentosan Polysulphate (SP54) and Heparin I: Mechanism of Action on Blood Coagulation

The effects of SP54 on inhibition of thrombin, factor Xa and factor IXa, in the presence and absence of antithrombin III (At III), have been examined and compared to those of heparin. SP54 potentiated inhibition of thrombin and Xa by purified At III, but crossed immunoelectrophoresis data indicated that these effects were mediated by binding to the enzyme, rather than to At III. Relatively high concentrations of SP54 were required for inhibition of thrombin and Xa in plasma, but at concentrations less than 2 μg/ml there was a marked suppression of the intrinsic activation of factor X. This effect was shown to be independent of At III, and to be due largely to inhibition of factor IXa. Prothrombin activation by factor Xa and phospholipid was also suppressed by SP54 in the absence of At III, and its effect on the APTT was also shown to be independent of At III. It is concluded that at relatively low concentrations the anticoagulant actions of SP54 are mainly due to these At III-independent pathways.

An International Collaborative Study Establishing a Reference Preparation for Antithrombin III

An international collaborative study involving 12 laboratories in 7 countries was carried out to establish a suitable reference preparation of antithrombin III (At III). The amount of At III present in two purified preparations, a freeze-dried normal plasma and local normal plasma pools was measured by clotting, immunological, and amidolytic assays. 120 assays were submitted of which 105 were accepted as valid for inclusion in subsequent analyses. Less laboratory to laboratory variation was found when At III was assayed in freeze-dried normal plasma, as compared to purified preparations of At III, and there was also less method to method variation when At III was measured in freeze-dried plasma. When measured as heparin co-factor activity, the two purified preparations contained only about half the level of At III found by immunoassay or progressive At III clotting assays. In contrast, the use of freeze-dried plasma provided results which showed excellent agreement between the various laboratories by all assays; accordingly, this material has been established by the World Health Organization as the International Reference Preparation for At III, with an assigned potency of 0.9 i. u. per ml.

Studies in Man and Experimental Animals of a Low Molecular Weight Heparin Fraction

In vitro and in vivo studies were carried out on a commercially prepared low molecular weight heparin fraction. By APTT assay the fraction had a specific activity of half that of unfractionated mucosal heparin, yet retained full potency by anti-Xa assay (both clotting and chromogenic substrate). When administered intravenously to human volunteers, the anti-Xa/APTT ratio remained the same as it was in vitro. However, after subcutaneous injection, the ratio increased and anti-Xa activity could not be fully neutralized ex vivo by PF4. The fraction was as effective as unfractionated heparin in preventing experimental serum-induced thrombosis, suggesting that a heparin fraction with high specific activity by anti-Factor Xa assay compared to APTT activity may be an effective drug for the prophylaxis of venous thrombosis.

Experimental Studies on a Recombinant Hirudin, CGP 39393

The in vitro anticoagulant activities of recombinant desulphatohirudin (r-hirudin) were studied in the activated partial thromboplastin time (APTT) and the thrombin generation test : systems. In the APTT at concentrations below 5 μg/ml, r-hirudin showed a dose-response curye. At concentrations above 5 μg/ml, the plasma became unclottable, but in the thrombin generation test , at least 10 μg/ml of r-hirudin was required for full inhibition of thrombin generation. The antithrombotic effect was assessed using a rabbit venous stasis model; 150 μg/ml r-hirudin completely prevented thrombus formation at 10 and 20 min stasis. At antithrombotic dose, the mean bleeding time ratio measured in a rabbit ear template model, was not prolonged over control values. At higher doses, the bleeding time ratios were higher than those observed for the same dosage of heparin. These data indicate that while r-hirudin is an effective antithrombotic agent, antithrombotic doses have to be carefully titrated to avoid excessive bleeding.

Heparin and Bleeding: An Association with Lipase Release

The effects of four sulphated polysaccharides on bleeding time and lipase release in rabbits have been compared. Unfractionated heparin (UFH) and pentosan polysulphate both gave significant prolongation of bleeding times and high lipase release. Low molecular weight heparin had reduced effects on bleeding time and lipase release, while demialan sulphate had no influence on either parameter. There was a highly significant correlation (r = 0.97) between these two measurements.

These results suggest that the same structural featuresinfluence both the haemorrhagic and lipase-releasing properties of sulphated polysaccharides.

An International Standard for Low Molecular Weight Heparin

An international collaborative study has been carried out with the aim of establishing an international standard for low molecular weight (LMW) heparin. Three preparations of LMW heparin were assayed against the International Standard for unfractionated heparin (UFH) by 25 laboratories in 13 countries, using nine different assay methods. The results confirmed previous findings of non-parallel assays, wide interlaboratory variability and differences between methods when LMW heparins are assayed against a UFH standard. Use of one of the LMW heparins as a standard for the other two gave parallel assays and much closer agreement between laboratories. The preparation in ampoules coded 85/600 was selected as likely to give the best agreement with the largest number of LMW heparins; potencies were assigned by taking the mean of all the anti-Xa assays, and the mean of the thrombin and APTT assays, to represent the two major groups of activities. Preparation 85/600 has been established by WHO as the 1st International Standard for LMW heparin, with potencies of 1,680 iu/ampoule by anti-Xa assays and 665 iu/ampoule by thrombin inhibition and APTT assays.

The Relative Antithrombotic Effectiveness of Heparin, a Low Molecular Weight Heparin, and a Pentasaccharide Fragment in an Animal Model

The antithrombotic efficacy of unfractionated heparin (UFH), a low molecular weight heparin (LMWH) and a synthetic pentasaccharide (PENTA) has been compared in an animal model for stasis thrombosis. We have also compared the relative ability of these three agents to impair thrombin generation in vitro and in vivo, and measured their effects on anti-Xa activity and thrombin clotting times. UFH, LMWH and PENTA all had the capacity to impair thrombogenesis, although there were marked differences in their relative effectiveness. Reduction of thrombin generation to 20% of control values was closely correlated with the prevention of thrombosis after 20 minutes’ stasis, but this was only achieved with UFH. The same dry weight dose of LMWH or PENTA reduced thrombin generation to about half control values, and neither significantly impaired thrombus formation after 20 minutes’ stasis. Impaired thrombin generation correlated better than anti-Xa activity with prevention of stasis thrombosis. In this model, UFH was clearly superior to LMWH and PENTA as an antithrombotic agent.

Experimental Studies on the Relative Efficacy of Dermatan Sulphate and Heparin as Antithrombotic Agents

In this study, the anticoagulant and antithrombotic properties of unfractionated heparin (UFH) and dermatan sulphate (DS) were compared. The ability of UFH and DS to impair thrombin generation in vitro and in ex vivo plasma samples was also studied. DS has minimal anticoagulant activity by conventional assays but impairs thrombin generation both in vitro and in ex vivo plasma samples. However, thrombin generation could not be suppressed below about 35% of control values at all doses of DS studied. While this was sufficient to impair experimental venous thrombosis during 10 minutes’ stasis, DS was ineffective in preventing thrombosis following 20 minutes’ stasis in doses up to 1.25 mg/kg. In contrast, 1 μg/ml of UFH completely suppressed thrombin generation in vitro, and 150 μg/kg prevented throm- bogenesis over a period of 20 minutes’ stasis. Neither drug prolonged the bleeding time (BT) at effective antithrombotic doses, but 2.5 mg/kg UFH significantly increased the BT, whereas DS did not. While DS has antithrombotic activity, it is less effective than UFH in inhibiting thrombin generation, and as an antithrombotic agent.

Effects of pericardiectomy on training- and myocardial infarction-induced left ventricular hypertrophy, chamber dimensions and gene expression

The primary purpose of the study was to evaluate whether a pericardiectomy (PERI) alters training- or myocardial infarction (MI)-induced left ventricular hypertrophy (LVH), chamber geometry, gene expression and/or running performance. Mice were randomized into 6 groups: naïve control (CONT)-sedentary (Sed), CONT-trained (Tr), PERI-Sed, PERI-Tr, MI-Sed and MI-Tr. MI mice also received a pericardiectomy as part of the MI surgical procedure. 10 weeks of treadmill running resulted in enhanced running performance-to-exhaustion in all 3 trained groups (CONT-Tr, PERI-Tr, MI-Tr) compared to sedentary cohorts (P<0.001). Training also resulted in similar increases in normalized LVH (LV/BW) in CONT-Tr and PERI-Tr mice. 2D-echocardiographic evaluation of LV internal chamber dimensions revealed that stroke diameter (SD) was larger in PERI compared to MI (P<0.01) but not CONT mice. Ventricular B-type natriuretic peptide mRNA (BNP) was elevated only in the 2 MI groups. Left ventricle β₁-adrenergic receptor (β₁-AR) and melusin transcripts both demonstrated an overall increase in trained compared to sedentary mice (both P<0.05). Additionally long-term pericardiectomy did not further enhance running performance or increase LV/BW in either sedentary or trained mice.

Clinical experience with a highly purified factor IX concentrate in patients undergoing surgical operations

The haemostatic efficacy of a new highly purified factor IX concentrate, prepared by metal chelate affinity chromatography, was assessed in 13 patients with haemophilia B undergoing a variety of surgical operations. Four of the patients had developed post-operative thromboembolic complications following previous operations, when treated with a prothrombin complex concentrate. None of the patients in the present series developed any evidence of post-operative thrombotic complications. Effective haemostasis was achieved in all patients, with the exception of a surgical bleed in one case, and late post-operative bleeding in a second patient when the factor IX activity fell below 20iu/dl. The product is treated with a solvent-detergent process that destroys lipid-enveloped viruses, while the affinity chromatography process during manufacture removes in excess of 4 log10 of a non-lipid-enveloped virus. In follow-up studies, none of the patients has shown evidence of fresh infection from the concentrate, when assessed by virological markers. It is concluded that this high-purity concentrate (tradenane 'Replenine') is effective for the treatment of patients with haemophilia B who undergo surgical operations.

Inhibition of NADPH oxidase alleviates experimental diabetes-induced myocardial contractile dysfunction

AIM

O(2) (-) production is implicated in cardiac dysfunction for a number of diseases including diabetes. Activation of the O(2) (-)-producing enzyme NADPH oxidase is seen in diabetes, although its role in diabetic cardiomyopathy is unclear. This study was designed to evaluate the effect of NADPH oxidase inhibition on cardiac function in diabetes.

METHODS

Experimental diabetes was induced in adult C57 mice using streptozotocin (STZ, 150 mg/kg, i.p.) prior to the administration of the NADPH oxidase inhibitor apocynin (4 mg/kg/day) for 2 weeks. Left ventricular (LV) and myocyte contractile functions were evaluated using echocardiography and edge-detection, respectively.

RESULTS

STZ elicited hyperglycaemia and reduced body weight gain, which was unaffected by apocynin. STZ significantly reduced fractional shortening, LV wall thickness, peak shortening, maximal velocity and duration of shortening or relengthening, the effects of which - with the exception of wall thickness - were significantly attenuated or ablated by apocynin. Western blot analysis revealed that the effects of comparable Akt phosphorylation, reduced AMPK phosphorylation, downregulation of sarco(endo)plasmic reticulum Ca(2+)-ATPase and lessened phosphorylation of phospholamban in diabetic myocardium were unaffected by apocynin. Both apocynin and the nitric oxide synthase (NOS) inhibitor l-arginine methyl ester (L-NAME) inhibited elevated O(2) (-) production in diabetes without any additive effect between the two, indicating the presence of endothelial nitric oxide synthase (eNOS) uncoupling. However, neither diabetes nor apocynin altered the expression of heat shock protein 90 and eNOS phosphorylation (Ser(1177)). In addition, apocynin mitigated elevated levels of nitrotyrosine and nitric oxide in diabetes.

CONCLUSION

Taken together, these data indicate the beneficial role of NADPH oxidase inhibition in diabetes-induced myocardial contractile dysfunction.

Time course of collagen and decorin changes in rat cardiac and skeletal muscle post-MI

We examined the temporal relationship between messages (type I and type III mRNAs) for the principal fibrillar procollagens and subsequent collagen accretion, cross-linking, and decorin expression in the left ventricle (LV) postmyocardial infarction (post-MI). We sought to determine 1) what role the proteoglycan decorin plays in extracellular matrix (ECM) remodeling known to take place as a consequence of MI and 2) the extent skeletal muscle ECM is altered early post-MI. Therefore, after surgically induced production of small- to moderate-sized infarcts (approximately 20% of LV mass), extent and time course of ECM remodeling was evaluated in remaining viable LV free wall and in slow- [soleus (SOL)] and fast-twitch [gastrocnemius (GAST)] skeletal muscles. Decorin, collagen, and hydroxylysylpyridinium cross-link concentrations and alpha1(I) (type I) and alpha1(III) (type III) procollagen mRNAs were measured in LVs from noninfarcted controls and at 72 h, 1, 2, 5, and 13 wk post-MI. These same data were collected in SOL and GAST muscles at all time points except 13 wk. Type I procollagen mRNA increased at both 72-h and 1-wk time points in LVs. Type III procollagen mRNA was elevated at 1 wk, returning to baseline by 2 wk post-MI. Collagen concentration was significantly increased by 1 wk, more than doubled by 5 wk, and was elevated 129% by 13 wk in the remaining viable LV. LV decorin expression was unaltered at early time points, but increased 38% at 5 wk post-MI and doubled by 13 wk post-MI. In skeletal muscle, procollagen mRNAs were transiently altered in SOL and GAST muscles without any demonstrable effect on the measured ECM parameters. This study reports, for the first time, the upregulation time course of decorin and its relationship to increased HP cross-linking and accumulation of collagen in viable myocardium post-MI.

Exercise training attenuates aging-associated increases in collagen and collagen crosslinking of the left but not the right ventricle in the rat

The purpose of this study was to compare the independent and interactive effects of age and exercise training on selected parameters of the right ventricle (RV), left ventricular septum (LVS) and left ventricular free-wall (LVFW) extracellular matrix. Specifically, we evaluated collagen and collagen crosslinking (hydroxylysylpyridinoline, HP) concentrations in the myocardial extracellular matrix in young adult, Y (5.5 months) and old, O (25.5 months) male Fischer 344 rats. Rats were assigned to either a sedentary control (YC, OC) or an exercise training group (YT, OT). Rats were trained for 45 min/day, 5 days/week, for 10 weeks at approximately equals 70% of maximal oxygen consumption. Following the training regimen, rats were sacrificed and their hearts were dissected into the RV, LVS and LVFW. Training resulted in a significant hypertrophy of the left ventricle (LV) but not RV relative to body weight. In young rats, collagen concentration was significantly higher (P<0.01) in RV compared to LVS, but not LVFW. With aging, collagen concentration increased significantly (P<0.05) in both ventricles, but more so in LV than RV so that differences in percent collagen observed between chambers in both YC and YT rats no longer existed in OC and OT animals. This aging effect was attenuated by training in the LVS but not the LVFW, so that collagen concentration, while higher in this region of the LV in OT compared to YT rats, was also lower than that seen in the LVS of OC rats. HP crosslink concentration in the LVS and LVFW, but not the RV of OC rats was significantly elevated above corresponding values seen in YC rats (P < 0.05 or greater). In YT rats, training had no effect on HP crosslinking concentration in any of the three regions of the heart. However, in OT rats, training completely prevented the age-associated increase in crosslinking seen in both the LVS and LVFW of OC animals. These findings illustrate the different responses of the RV, LVS and LVFW extracellular matrix components, collagen and HP crosslinking, to both aging and training in the rodent.

A 'safe' surgical technique for stabilisation of the sternoclavicular joint: a cadaveric and clinical study

In symptomatic patients with recurrent anterior sternoclavicular dislocation, surgery may be required to stabilise the joint. Posterior sternoclavicular dislocations may also require open reduction and stabilisation due to the complications that may arise. We present a new, 'safe' technique of surgical stabilisation of the sternoclavicular joint that is not technically demanding and does not require exposure of the first rib, as is often the case in other methods described. The repair was tested in cadavers before being employed in three patients and was found to be effective under both static and dynamic loading. The early clinical results prove encouraging.

Collagen gene expression in rat left ventricle: interactive effect of age and exercise training

Whether or not exercise training of sufficient intensity and duration to produce left ventricle (LV) hypertrophy also regulates deposition of interstitial collagen and cross-linking at the pretranslational level is unknown. Therefore, the effects of exercise training on gene expression for the two principal fibrillar collagens in LV, types I and III, were assessed in young adult (5 mo), middle-aged (15 mo), and old (26 mo) rats. We also evaluated the potential interaction of changes in mRNA for these procollagens with alterations in LV extracellular matrix characteristics by simultaneously measuring collagen concentration (hydroxyproline) and extent of mature collagen cross-linking (hydroxylysylpyridinoline, HP). Ten weeks of treadmill running resulted in LV hypertrophy and an increased maximal oxygen uptake in all three age groups of trained rats compared with sedentary controls. Percent collagen in rat LV almost doubled (P < 0.0001) from 5 to 26 mo of age, an increase unaffected by exercise training. With aging, a significant decline in expression of mRNAs for both collagen type I (P < 0.005) and type III (P < 0.001) was observed in LV free wall (LVF) but not septum (LVS). Training prevented this decline in LVF mRNAs for the two principal fibrillar collagens in middle-aged rats whereas it attenuated the decline in senescent animals. HP concentration increased significantly with aging in both LVF (P < 0.005) and LVS (P < 0.01). Training modulated this effect, but again only in LVF, so that HP was significantly lower (P < 0.05) in this region of the LV in old trained rats compared with sedentary counterparts. We conclude that exercise training modulates the effects of aging on collagen gene mRNAs and HP cross-linking regionally within the LV.

Helicopter emergency medical services roles in disaster operations

Rotor-wing aircraft have previously proven utility in disaster operations, but recent expert reviewers have identified areas of potential improvement in integration of helicopter emergency medical services (HEMS) resources into disaster planning and management. This paper discusses salient points regarding helicopter operations in disaster management, using prior reports regarding rotor-wing aircraft utilization as a basis upon which to provide a concise review of HEMS operations in disasters.

Osteitis pubis and instability of the pubic symphysis. When nonoperative measures fail

Seven rugby players with osteitis pubis and vertical instability at the pubic symphysis were treated operatively after nonoperative treatment had failed to improve their symptoms. The vertical instability was diagnosed based on flamingo view radiographs showing greater than 2 mm of vertical displacement. The players had undergone at least 13 months of nonoperative therapy before surgery was considered. Operative treatment consisted of arthrodesis of the pubic symphysis by bone grafting supplemented by a compression plate. At a mean follow-up of 52.4 months, all patients were free of symptoms and flamingo views confirmed successful arthrodesis with no residual instability of the pubic symphysis. Based on our results with this procedure, we believe that arthrodesis of the pubic symphysis has a role in the treatment of osteitis pubis that is recalcitrant to nonoperative treatment. The combination of osteitis pubis and vertical pubis symphyseal instability may be the cause of failure of nonoperative treatment.

Biological standards in haemostasis and thrombosis

International standards are used to assess the potency of a variety of biological drugs employed in the field of haemostasis and thrombosis. These include therapeutic concentrates for the treatment of inherited coagulation defects, such as haemophilia, thrombolytic drugs such as streptokinase for the treatment of heart attacks, and anticoagulant drugs such as heparin. Some of these standards have existed for over 25 years, and they continue to play a vital role in ensuring consistent potency, and hence safety, of manufactured drugs. The growing complexity of new products, particularly in the area of recombinant technology, represents a continuing challenge for the field of biological standardization.

Inhibition of chondrocyte differentiation in vitro by constitutive and inducible overexpression of the c-fos proto-oncogene

We have investigated the role of c-Fos in chondrocyte differentiation in vitro using both constitutive and inducible overexpression approaches in ATDC5 chondrogenic cells, which undergo a well-defined sequence of differentiation from chondroprogenitors to fully differentiated hypertrophic chondrocytes. Initially, we constitutively overexpressed exogenous c-fos in ATDC5 cells. Several stable clones expressing high levels of exogenous c-fos were isolated and those also expressing the cartilage marker type II collagen showed a marked decrease in cartilage nodule formation. To investigate further whether c-Fos directly regulates cartilage differentiation independently of potential clonal variation, we generated additional clones in which exogenous c-fos expression was tightly controlled by a tetracycline-regulatable promoter. Two clones, DT7.1 and DT12.4 were capable of nodule formation in the absence of c-fos. However, upon induction of exogenous c-fos, differentiation was markedly reduced in DT7.1 cells and was virtually abolished in clone DT12.4. Pulse experiments indicated that induction of c-fos only at early stages of proliferation/differentiation inhibited nodule formation, and limiting dilution studies suggested that overexpression of c-fos decreased the frequency of chondroprogenitor cells within the clonal population. Interestingly, rates of proliferation and apoptosis were unaffected by c-fos overexpression under standard conditions, suggesting that these processes do not contribute to the observed inhibition of differentiation. Finally, gene expression analyses demonstrated that the expression of the cartilage markers type II collagen and PTH/PTHrP receptor were down-regulated in the presence of exogenous c-Fos and correlated well with the differentiation status. Moreover, induction of c-fos resulted in the concomitant increase in the expression of fra-1 and c-jun, further highlighting the importance of AP-1 transcription factors in chondrocyte differentiation. These data demonstrate that c-fos overexpression directly inhibits chondrocyte differentiation in vitro, and therefore these cell lines provide very useful tools for identifying novel c-Fos-responsive genes that regulate the differentiation and activity of chondrocytes.

Arteriolar reactivity and capillarization in chronically stimulated rat limb skeletal muscle post-MI

The purpose of this study was to assess whether electrical stimulation-induced increases in muscular activity could improve capillary supply and correct previously documented abnormal vasodilator and vasoconstrictor responses of arterioles in limb skeletal muscle post-myocardial infarction (MI). Extensor digitorum longus (EDL) muscle from rats with surgically induced MI ( approximately 30% of the left ventricle) was chronically stimulated (Stim) 8 h/day for 6 +/- 1 days, at 11 wk post-MI. Third- (3A) and fourth-order (4A) arterioles in EDL from nine MI rats and four MI+Stim rats were compared with those of 11 controls (Con). Compared with Con rats, MI alone caused a reduction in the resting diameter of 3A and 4A arterioles, which was completely reversed by MI+Stim. However, Stim did not correct the attenuated vasodilator response to 10(-4) M adenosine seen in 4A arterioles from MI rats compared with Con. The constrictor response of both 3A and 4A vessels in MI rats to low doses of acetylcholine (10(-9) M, 10(-8) M) and norepinephrine (10(-9) M) was accentuated in MI+Stim. The proportion of oxidative fibers in EDL was unaffected by MI or MI+Stim combination. However, Stim significantly increased (P < 0.05) the capillary-to-fiber ratio in this muscle compared with Con. Thus, although the increase in muscle activity induced by chronic electrical stimulation normalized the reduction in resting vessel diameter seen after MI, it failed to correct the abnormalities in vasoreactivity of these same vessels.

Perthes' disease and the relevance of thrombophilia

Recent work has suggested that thrombophilia may be an aetiological factor in up to 50% of children with Perthes' disease, and that up to 75% may have a coagulopathy. Our aim was to test these findings in the local population of children with Perthes' disease and attempt to correlate them with the severity of the condition. In 64 children there were only eight (12%) with low levels of clotting proteins, as defined by normal paediatric ranges. Of these eight, only five could be said to show any thrombophilic tendency.

Perthes’ disease and the relevance of thrombophilia

Recent work has suggested that thrombophilia may be an aetiological factor in up to 50% of children with Perthes’ disease, and that up to 75% may have a coagulopathy. Our aim was to test these findings in the local population of children with Perthes’ disease and attempt to correlate them with the severity of the condition.

In 64 children there were only eight (12%) with low levels of clotting proteins, as defined by normal paediatric ranges. Of these eight, only five could be said to show any thrombophilic tendency.

Posterior sternoclavicular dislocations--a diagnosis easily missed

Posterior dislocation of the sternoclavicular joint is a relatively rare injury and can be difficult to diagnose acutely. We report 3 cases of posterior dislocation of the sternoclavicular joint who presented to the Accident & Emergency Department within a 3 month period. All 3 patients had sustained a significant injury to the shoulder region and complained of pain around the medial clavicle. Two patients had also complained of dysphagia following the injury. Plain X-rays of the shoulder and chest were reported as normal by junior and senior medical staff. The diagnosis was delayed until CT scans were performed, and once this was established, open reduction and stabilisation was performed.

Effect of exercise training on passive stiffness in locomotor skeletal muscle: role of extracellular matrix

The purpose of this study was to evaluate the effect of endurance exercise training on both locomotor skeletal muscle collagen characteristics and passive stiffness properties in the young adult and old rat. Young (3-mo-old) and senescent (23-mo-old) male Fischer 344 rats were randomly assigned to either a control or exercise training group [young control (YC), old control (OC), young trained (YT), old trained (OT)]. Exercise training consisted of treadmill running at approximately 70% of maximal oxygen consumption (45 min/day, 5 days/wk, for 10 wk). Passive stiffness (stress/strain) of the soleus (Sol) muscle from all four groups was subsequently measured in vitro at 26 degreesC. Stiffness was significantly greater for Sol muscles in OC rats compared with YC rats, but in OT rats exercise training resulted in muscles with stiffness characteristics not different from those in YC rats. Sol muscle collagen concentration and the level of the nonreducible collagen cross-link hydroxylysylpyridinoline (HP) significantly increased from young adulthood to senescence. Although training had no effect on Sol muscle collagen concentration in either age group, it resulted in a significant reduction in the level of Sol muscle HP in OT rats. In contrast, exercise had no effect on HP in the YT animals. These findings indicate that 10 wk of endurance exercise significantly alter the passive viscoelastic properties of Sol muscle in old but not in young adult rats. The coincidental reduction in the principal collagen cross-link HP also observed in response to training in OT muscle highlights the potential role of collagen in influencing passive muscle viscoelastic properties.

Alterations in small arterioles precede changes in limb skeletal muscle after myocardial infarction

We tested the hypothesis that alterations in arterioles in locomotor skeletal muscles in rats with myocardial infarction (MI), but before development of congestive heart failure (CHF), precede structural and functional changes commonly observed in limb muscle in association with CHF. Resting diameters of third- (A3) and fourth-order arterioles (A4) in extensor digitorum longus (EDL) muscle were significantly smaller in rats with nonfailing small and medium-sized MI compared with control animals. Dilation of A4 in response to 10(-4) M adenosine was significantly attenuated in both groups (P < 0.05), whereas dilation of A3 was unaltered. Microvessels from both groups of infarcted rats constricted to all doses of acetylcholine (10(-9), 10(-8), and 10(-7) M) and showed a significantly exaggerated vasoconstrictor response to norepinephrine (10(-9), 10(-8), and 10(-7) M) compared with microvessels in control rats (P < 0.05). Peak isometric tension of combined tibialis anterior and EDL muscles and muscle fatigue (final/peak tension x 100), measured during 5-min isometric supramaximal twitch contractions at 4 Hz, were similar in control and MI rats (218 +/- 7 vs. 213 +/- 15 g/g muscle and 52 +/- 1 vs. 51 +/- 9%, respectively; n = 5 for both). There was also no difference with respect to the proportion of oxidative fibers or capillary-to-fiber ratios. Our results indicate that, in rats with left ventricular dysfunction but without failure, decreased diameter and perturbations in reactivity of small arterioles precede alterations in skeletal muscle performance often seen at a later date in association with CHF. These findings are consistent with the notion of aberrant endothelial and smooth muscle function and may contribute to the maintenance of blood pressure after MI but before CHF.