Post-ischaemic silencing of p66Shc reduces ischaemia/reperfusion brain injury and its expression correlates to clinical outcome in stroke.

AIM: Constitutive genetic deletion of the adaptor protein p66(Shc) was shown to protect from ischaemia/reperfusion injury. Here, we aimed at understanding the molecular mechanisms underlying this effect in stroke and studied p66(Shc) gene regulation in human ischaemic stroke. METHODS AND RESULTS: Ischaemia/reperfusion brain injury was induced by performing a transient middle cerebral artery occlusion surgery on wild-type mice. After the ischaemic episode and upon reperfusion, small interfering RNA targeting p66(Shc) was injected intravenously. We observed that post-ischaemic p66(Shc) knockdown preserved blood-brain barrier integrity that resulted in improved stroke outcome, as identified by smaller lesion volumes, decreased neurological deficits, and increased survival. Experiments on primary human brain microvascular endothelial cells demonstrated that silencing of the adaptor protein p66(Shc) preserves claudin-5 protein levels during hypoxia/reoxygenation by reducing nicotinamide adenine dinucleotide phosphate oxidase activity and reactive oxygen species production. Further, we found that in peripheral blood monocytes of acute ischaemic stroke patients p66(Shc) gene expression is transiently increased and that this increase correlates with short-term neurological outcome. CONCLUSION: Post-ischaemic silencing of p66(Shc) upon reperfusion improves stroke outcome in mice while the expression of p66(Shc) gene correlates with short-term outcome in patients with ischaemic stroke.

An intensive 5-year-long influenza vaccination campaign is effective among doctors but not nurses.

OBJECTIVE: To double the vaccination rates of hospital employees from 20 to 40% by specific interventions over a 5-year period (2003-2007). The secondary endpoint was to compare the effects of the avian influenza in 2005 (intervention period) and the H1N1 influenza pandemic in 2009 (follow-up period, 2008-2009) on vaccination rates. DESIGN, SETTING, AND PARTICIPANTS: Free vaccination and its intensive propagation from 2003-2007 in a 400-bed teaching hospital with 1,687 hospital employees. Annual vaccination rates were obtained from 2003 through 2009. MAIN OUTCOME MEASUREMENTS: Yearly vaccination rates for the intervention period from 2003-2007 and the observational follow-up period of 2008-2009. RESULTS: The overall rate for seasonal influenza vaccination changed non-significantly during the intervention period from 20% in 2003 to 27% in 2007. At the end of the follow-up period in 2009, the vaccination rate was 26%, which was not significantly higher compared with that in 2003. Physicians interestingly increased from 34% in 2003 to 62% in 2007 and to 66% in 2009 (p < 0.001), while nurses dropped non-significantly from an already low proportion of 18% in 2003 to 15% in 2007 and to 16% in 2009 for seasonal influenza vaccination. The difference between nurses and doctors in 2007 is highly significant (p < 0.001). In the year of the avian influenza threat (2005), a significant increase was observed (30 vs. 20%, p < 0.001). This observation was seen again in 2009 (influenza A/H1N1v pandemic), during which the H1N1 vaccine uptake was 33% (p < 0.001, compared to seasonal flu vaccine in 2003). CONCLUSIONS: Overall, the vaccination rates did not increase over the 7-year study period. Interventions were successful for physicians but not for nurses. The vaccine uptake was significantly higher during the threat of avian influenza and the influenza A/H1N1v pandemic.

In vitro fertilization exacerbates stroke size and neurological disability in wildtype mice.

BACKGROUND AND PURPOSE: Assisted reproductive technologies (ART) induce premature vascular aging in human offspring. The related alterations are well-established risk factors for stroke and predictors of adverse stroke outcome. However, given the young age of the human ART population there is no information on the incidence and outcome of cerebrovascular complications in humans. In mice, ART alters the cardiovascular phenotype similarly to humans, thereby offering the possibility to study this problem. METHODS: We investigated the morphological and clinical outcome after ischemia/reperfusion brain injury induced by transient (45 min) middle cerebral artery occlusion in ART and control mice. RESULTS: We found that stroke volumes were almost 3-fold larger in ART than in control mice (P < 0.001). In line with these morphological differences, neurological performance assessed by the Bederson and RotaRod tests 24 and 48 h after artery occlusion was significantly worse in ART compared with control mice. Plasma levels of TNF-alpha, were also significantly increased in ART vs. control mice after stroke (P < 0.05). As potential underlying mechanisms, we identified increased blood-brain barrier permeability evidenced by increased IgG extravasation associated with decreased tight junctional protein claudin-5 and occludin expression, increased oxidative stress and decreased NO-bioactivity in ART compared with control mice. CONCLUSIONS: In wildtype mice, ART predisposes to significantly worse morphological and functional stroke outcomes, related at least in part to altered blood-brain barrier permeability. These findings demonstrate that ART, by inducing premature vascular aging, not only is a likely risk factor for stroke-occurrence, but also a mediator of adverse stroke-outcome. TRANSLATIONAL PERSPECTIVE: This study highlights that ART not only is a likely risk factor for stroke-occurrence, but also a mediator of adverse stroke-outcome. The findings should raise awareness in the ever-growing human ART population in whom these techniques cause similar alterations of the cardiovascular phenotype and encourage early preventive and diagnostic efforts.

Tumour Necrosis Factor-α Inhibition Improves Stroke Outcome in a Mouse Model of Rheumatoid Arthritis.

Rheumatoid Arthritis (RA) is a chronic inflammatory disorder where incidence and severity of myocardial infarction are increased. Data on the incidence and outcome of stroke are conflicting. Thus, we investigated outcome after Ischemia/Reperfusion (I/R) brain injury in a mouse model of RA and assessed for the role of the tumour necrosis factor-α (TNF-α) inhibitor Infliximab herein. We used a TNF-α reliant mouse model of RA. RA and wildtype (WT) animals were treated with vehicle (RA/WT) or Infliximab (RA Infliximab) for 4 weeks, before undergoing I/R brain injury. RA-animals displayed larger strokes and poorer neurological performance. Immunohistochemistry on brain sections revealed increased numbers of resident and peripheral innate immune cells (microglia and macrophages); increased Blood-Brain-Barrier (BBB)-disruption; decreased levels of the tight junction proteins (TJPs) claudin-5 and occludin; increased expression of matrix-metalloproteinases (MMP)-3 and -9 and enhanced lipid peroxidation. Treatment with Infliximab corrected these alterations. We show that RA associates to worse stroke-outcome via exacerbated BBB degradation by decrease of the TJPs claudin-5 and occludin. We identified MMPs-3 and -9 and increased oxidative stress as potential mediators thereof. Increased numbers of resident and peripheral innate immune cells (microglia and macrophages) may in turn contribute to all these effects. Infliximab-treatment restored the phenotype of RA-mice to baseline. Our data provide evidence clearly linking RA to adverse stroke-outcome in mice and indicate an approved TNF-α inhibitor as a potential strategy to reduce stroke-burden in this setting.

A cost analysis of the first year after stroke - early triage and inpatient rehabilitation may reduce long term costs.

AIM OF THE STUDY: To analyse the costs of stroke in the first year covered by insurance companies and to correlate them with the clinical outcome data. METHODS: We contacted the insurance companies of 172 consecutive stroke patients of a single institution cohort for a detailed report of the stroke costs. A complete data set over one year was obtained from 131 patients (76%). RESULTS: Severity of stroke was significantly associated with increasing total costs (p = 0.0002). The rehabilitation clinic made up 37% of the total costs followed by nursing home with 21% and acute hospital with 21%. Mean cost of stroke per patient was 31,115 CHF in the first year. Costs per patient for inpatient rehabilitation were similar to those for the nursing home after one year; however, the Barthel-index of patients with inpatient rehabilitation increased by 42 +/- 29 points as compared to patients without inpatient rehabilitation by 23 +/- 26 points (p <0.05), and 86% resp. 81% of patients with inpatient stroke rehabilitation lived independently after 6 and 12 months respectively. CONCLUSIONS: The high level of independence after inpatient stroke rehabilitation underlines the importance of patient selection and/or rehabilitation. Therefore, long-term stroke costs may be significantly reduced by an early and careful triage in the case management after stroke and a case-dependent investment in initial costly appearing inpatient rehabilitation.

Thromboerythrocytes. In vitro studies of a potential autologous, semi-artificial alternative to platelet transfusions.

In an attempt to overcome the limitations and drawbacks of using fresh platelets for transfusion therapy of thrombocytopenic patients, we have performed in vitro experiments on an autologous, semi-artificial alternative to platelet transfusions. Based on our previous studies of the interactions of unactivated and activated platelets with beads coated with peptides of various lengths, all of which contained the arginine-glycine-aspartic acid (RGD) cell recognition sequence, the peptide Ac-CGGRGDF-NH2 was chosen for covalent coupling to erythrocytes. A heterobifunctional crosslinking reagent (N-maleimido-6-aminocaproyl ester of 1-hydroxy-2-nitrobenzene-4-sulfonic acid) was used to crosslink via the peptide's free sulfhydryl group and the erythrocyte's surface amino groups. Approximately 0.5-1.5 x 10(6) peptide molecules bound per erythrocyte after 2 h of incubation, and most of the peptides appeared to crosslink to glycophorin A. The resulting cells, termed thromboerythrocytes, interacted selectively with activated platelets to form mixed aggregates. Studies with fluid phase RGD peptides and monoclonal antibodies indicated that the RGD peptides on the thromboerythrocytes interacted with the GPIIb/IIIa receptors on activated platelets. Thromboerythrocytes could also bind to platelets adherent to collagen. There was minimal erythrocyte hemolysis during the formation of thromboerythrocytes and studies of thromboerythrocyte osmotic fragility and cellular deformability showed no significant changes from control erythrocytes. Whereas there is a 20:1 ratio of erythrocytes to platelets in the circulation of normal individuals, the erythrocytes from as little as 50 ml of blood could be transformed into the equivalent of 2 U of platelets by numbers (equivalent to 18 U of platelets by mass), and reinfused into the same individual within several hours. These data encourage us to proceed to in vivo studies to assess the hemostatic efficacy of thromboerythrocytes in thrombocytopenic animals.

Omega-3 fatty acids predict recurrent venous thromboembolism or total mortality in elderly patients with acute venous thromboembolism.

Essentials The role of omega-3 fatty acids (n-3 FAs) in recurrent venous thromboembolism (VTE) is unknown. Association of n-3 FAs with recurrent VTE or total mortality was investigated in 826 patients. Whole blood n-3 FAs were inversely correlated with recurrent VTE or total mortality. Major and non-major bleeding was not increased in patients with higher levels of n-3 FAs. SUMMARY: Background The role of omega-3 fatty acids (n-3 FAs) in recurrent venous thromboembolism (VTE) remains unknown. Objectives To investigate the association of n-3 FAs with recurrent VTE or total mortality at 6 months and 3 years. Methods N-3 FAs were assessed in 826 patients aged ≥ 65 years, categorized into low, medium and high based on the 25th and 75th percentile. Mean follow-up was 29 months. Results At 6 months, subjects with medium (adjusted hazard ratio [HR], 0.37; 95% confidence interval [CI], 0.22-0.62) and high n-3 FA levels (adjusted HR, 0.36; 95% CI, 0.20-0.67) were less likely to develop recurrent VTE or total mortality, compared with those with low n-3 FAs. At 3 years, medium levels (adjusted HR, 0.67; 95% CI, 0.47-0.96) were associated with lower risk of recurrent VTE or total mortality. As compared with low n-3 FAs, the adjusted sub-hazard ratio [SHR] of recurrent VTE was 0.39 (95% CI, 0.15-0.99) in patients with medium and 0.17 (95% CI, 0.03-0.82) in patients with high n-3 FAs. The cumulative incidence of recurrent VTE was lower in the medium and high n-3 FA groups as compared with the low n-3 FA groups, but seems to have worn off after 3 years. The incidence of major and non-major bleeding was not greater in the high n-3 FA group. Conclusion Higher levels of n-3 FAs were associated with a lower risk of recurrent VTE or total mortality in elderly patients with VTE, but not with greater bleeding risk.

Frequency of use and acceptability of clinical prediction rules for pulmonary embolism among Swiss general internal medicine residents.

INTRODUCTION: Whether clinical prediction rules for pulmonary embolism are accepted and used among general internal medicine residents remains uncertain. We therefore evaluated the frequency of use and acceptability of the Revised Geneva Score (RGS) and the Pulmonary Embolism Severity Index (PESI), and explored which factors were associated with rule use. MATERIALS/METHODS: In an online survey among general internal medicine residents from 10 Swiss hospitals, we assessed rule acceptability using the Ottawa Acceptability of Decision Rules Instrument (OADRI) and explored the association between physician and training-related factors and rule use using mixed logistic regression models. RESULTS: The response rate was 50.4% (433/859). Overall, 61% and 36% of the residents reported that they always or regularly use the RGS and the PESI, respectively. The mean overall OADRI score was 4.3 (scale 0-6) for the RGS and 4.1 for the PESI, indicating a good acceptability. Rule acceptability (odds ratio [OR] 6.19 per point, 95% confidence interval [CI] 3.64-10.51), prior training in emergency medicine (OR 5.14, CI 2.20-12.01), and availability of internal guidelines recommending RGS use (OR 4.25, CI 2.15-8.43) were associated with RGS use. Rule acceptability (OR 6.43 per point, CI 4.17-9.92) and rule taught at medical school (OR 2.06, CI 1.24-3.43) were associated with PESI use. CONCLUSIONS: The RGS was more frequently used than the PESI. Both rules were considered acceptable. Rule acceptability, prior training in emergency medicine, availability of internal guidelines, and rule taught at medical school were associated with rule use and represent potential targets for quality improvement interventions.

Long-term outcomes of elderly patients with CYP2C9 and VKORC1 variants treated with vitamin K antagonists.

Essentials The long-term effects of VKORC1 and CYP2C9 variants on clinical outcomes remains unclear. We followed 774 patients ≥65 years with venous thromboembolism for a median duration of 30 months. Patients with CYP2C9 variants are at increased risk of death and non-major bleeding. Patients with genetic variants have a slightly lower anticoagulation quality only. SUMMARY: Background The long-term effect of polymorphisms of the vitamin K-epoxide reductase (VKORC1) and the cytochrome P450 enzyme gene (CYP2C9) on clinical outcomes remains unclear. Objectives We examined the association between CYP2C9/VKORC1 variants and long-term clinical outcomes in a prospective cohort study of elderly patients treated with vitamin K antagonists for venous thromboembolism (VTE). Methods We followed 774 consecutive patients aged ≥ 65 years with acute VTE from nine Swiss hospitals for a median duration of 30 months. The median duration of initial anticoagulant treatment was 9.4 months. The primary outcome was the time to any clinical event (i.e. the composite endpoint of overall mortality, major and non-major bleeding, and recurrent VTE. Results Overall, 604 (78%) patients had a CYP2C9 or VKORC1 variant. Three hundred and thirty-four patients (43.2%) had any clinical event, 119 (15.4%) died, 100 (12.9%) had major and 167 (21.6%) non-major bleeding, and 100 had (12.9%) recurrent VTE. After adjustment, CYP2C9 (but not VKORC1) variants were associated with any clinical event (hazard ratio [HR], 1.34; 95% confidence interval [CI], 1.08-1.66), death (HR, 1.74; 95% CI, 1.19-2.52) and clinically relevant non-major bleeding (sub-hazard ratio [SHR], 1.39; 95% CI, 1.02-1.89), but not with major bleeding (SHR, 1.03; 95% CI, 0.69-1.55) or recurrent VTE (SHR, 0.95; 95% CI, 0.62-1.44). Patients with genetic variants had a slightly lower anticoagulation quality. Conclusions CYP2C9 was associated with long-term overall mortality and non-major bleeding. Although genetic variants were associated with a slightly lower anticoagulation quality, there was no relationship between genetic variants and major bleeding or VTE recurrence.

Shorter PFA-100-closure times in laparoscopic versus conventional hysterectomy are not caused by increased vasopressin levels.

BACKGROUND/OBJECTIVES: Bleeding problems during laparoscopic surgery are infrequent. We hypothesised that increased abdominal pressure during the application of the pneumoperitoneum would lead to an increased release of endogenous vasopressin which could then contribute to the hemostasis by increasing platelet reactivity, FVIII and von Willebrand-factor. PATIENTS AND METHODS: We compared the vasopressin levels, the platelet function as measured by the PFA-100-test, aPTT and FVIII in 39 consecutive patients who underwent elective hysterectomy (20 with the laparoscopic and 19 with the conventional, "open" method). Blood was sampled the day before surgery and 2, 4 and 72 h after the induction of anaesthesia. RESULTS: After two hours, the PFA-100 closure times with collagen/ADP decreased to lower levels in the laparoscopic group (from 93 +/- 22 to 82 +/- 20, mean +/- SD) and even further down to 65 +/- 13 s (compared to 82 +/- 20 s) (p = 0.024)) four hours after the beginning of surgery. Vasopressin levels and F VIII increased in both groups but there was no significant difference between the groups (21 vs. 17.8 pmol/l for vasopressin, differences of the mean). Bleeding was minimal, with a trend to lower Hb-levels in the laparotomy group. CONCLUSIONS: The procedural difference of laparoscopic vs. open hysterectomy appears to enhance platelet reactivity by other mechanisms than increased vasopressin levels and may contribute to an enhanced hemostatic competence in laparoscopic surgery.

Association between thyroid dysfunction and venous thromboembolism in the elderly: a prospective cohort study.

BACKGROUND: Venous thromboembolism (VTE) and subclinical thyroid dysfunction (SCTD) are both common in elderly patients. SCTD has been related to a hypercoagulable state and an increased thromboembolic risk. However, prospective data on the relationship between SCTD and VTE are lacking. OBJECTIVES: To investigate the relationship between SCTD and recurrent VTE (rVTE), all-cause mortality, and thrombophilic biomarkers. Patients Elderly patients with VTE were studied. METHODS: In a prospective multicenter cohort, thyroid hormones and thrombophilic biomarkers were measured 1 year after acute VTE, as both may be influenced by acute thrombosis. We defined subclinical hypothyroidism (SHypo) as elevated thyroid-stimulating hormone (TSH) levels (4.50-19.99 mIU L(-1) ), and subclinical hyperthyroidism (SHyper) as TSH levels of < 0.45 mIU L(-1) , both with normal free thyroxine levels. Outcomes were incidence of rVTE and overall mortality during follow-up starting after the 1-year blood sampling. RESULTS: Of 561 participants (58% with anticoagulation), 6% had SHypo and 5% had SHyper. After 20.8 months of mean follow-up, 9% developed rVTE and 10% died. The rVTE incidence rate was 7.2 (95% confidence interval [CI] 2.7-19.2) per 100 patient-years in SHypo participants, 0.0 (95% CI 0.0-7.6) in SHyper participants, and 5.9 (95% CI 4.4-7.8) in euthyroid participants. In multivariate analyses, the sub-hazard ratio for rVTE was 0.00 (95% CI 0.00-0.58) in SHyper participants and 1.50 (95% CI 0.52-4.34) in SHypo participants as compared with euthyroid participants, without increased levels of thrombophilic biomarkers. SHyper (hazard ratio [HR] 0.80, 95% CI 0.23-2.81) and SHypo (HR 0.99, 95% CI 0.30-3.29) were not associated with mortality. CONCLUSION: In elderly patients, SHyper may be associated with lower rVTE risks. SHypo showed a non-statistically significant pattern of an association with rVTE, without increased mortality or differences in thrombophilic biomarkers.

Severe episode of high fever with rash, lymphadenopathy, neutropenia, and eosinophilia after minocycline therapy for acne.

Minocycline is a tetracycline agent frequently used for acne therapy. It has a few rare but severe side effects that are not widely known but should be recognized early as drug related. These include acute hepatitis and liver failure; a Löffler-like syndrome with pulmonary infiltrates, wheezing, fever, and eosinophilia; skin eruptions, eosinophilic cellulitis, and pustular folliculitis with eosinophilia; and a lupuslike syndrome. Side effects that are better known and recognized include photosensitization, skin exanthema with pruritus, and pseudotumor cerebri.

Evaluation of back pain secondary to spinal epidural hematoma associated with aspirin intake and a partial platelet glycoprotein Ia/IIa deficiency.

We report a case of spontaneous spinal epidural hemorrhage with three unusual features: (1) the hemorrhage was associated with aspirin ingestion and a reduced level of platelet glycoprotein Ia/IIa; (2) the patient presented with typical severe back pain but without neurologic dysfunction; and (3) the patient initially recovered without surgical decompression but suffered from recurrent epidural hematoma.

[Alpine cheese--healthy for your heart or just a lifestyle product?]. / Alpkäse--herzhaft gesund oder ein Lifestyle- Produkt?

Until the 19th and the early 20th century, milk and milk products, particularly of alpine origins, seemed of special nutritional and health value and were highly recommended for the therapy resp. the therapeutic adjunct of various diseases, particularly for pulmonary tuberculosis. More recently, the association of saturated fat intake and arteriosclerosis led to the reduced use of milk and cheese resp. to the introduction of low-fat milk products. Again, alpine milk and cheese seem to differ somewhat from the others, since they appear to contain 4 times more alpha linolenic acid, three times more conjugated linoleic acid, a lower n-6:n-3 ratio, more total n-3 fatty acids and less palmitic acid as a measure of total saturated fat compared to cheese produced with silage feed in the lowlands (e.g. english cheddar). Even cheese from cows fed with linseed supplementations did not reach the n-3 concentrations of the alpine probes. Thus, alpine milk products from cows kept traditionally, and fed predominantly with alpine grass seem to have an interesting cardiovascular and possibly an economically favourable potential.

Preparation and characterization of 'heparinocytes': erythrocytes with covalently bound low molecular weight heparin.

In an attempt to create the possibility of stable, long acting, intravascular anticoagulation, low molecular weight heparin was modified by introducing a sulfhydryl group into the molecule (LMWH-SH). Human erythrocytes were covalently grafted with LMWH-SH by the use of a heterobifunctional coupling reagent which reacts with the SH group of LMWH-SH and surface exposed amino groups of erythrocytes now called 'heparinocytes' (HC). HC were morphologically indistinguishable from untreated erythrocytes and displayed identical osmotic resistance. The functionality of HC was analyzed by classical coagulation tests in which they dose dependently inhibited clot formation. HC were also functional in recalcified whole blood inhibiting thrombin formation as assessed by the cleavage of the chromogenic substrate S-2238. The system appears applicable as a potential autologous, long-term anticoagulant treatment or prophylaxis.

Defective interaction between von Willebrand factor and platelet glycoprotein Ib--a familial study of peripheral arterial occlusive disease.

Hemostatic variables and platelet function were assessed as a part of a genetic study in 15 patients with symptomatic peripheral arterial occlusive disease (PAOD) and 15 healthy siblings from ten families. D-dimer, a degradation product of cross-linked fibrin, was increased in the PAOD group (mean +/- SD) (448 +/- 177 vs. 333 +/- 121 ng/ml, p < 0.05). Ristocetin-induced maximal platelet aggregation (RIPA) was reduced in the PAOD group in response to both a higher (0.75 mg/ml) (67 +/- 28 vs. 87 +/- 14%, p = 0.02) and a lower (0.55 or 0.60 mg/ml) (33 +/- 21 vs. 59 +/- 32%, p = 0.02) concentration of ristocetin. Accordingly, the rate of primary aggregation was smaller, and a larger threshold concentration of ristocetin was needed to cause aggregation. However, ristocetin cofactor activity, von Willebrand factor (vWF) antigen and its multimer distribution, plasma glycocalicin, platelet glycoprotein Ib content and the binding of vWF to frozen and thawed washed platelets were equal in both groups. Thus, the observed reduced RIPA in patients with PAOD is less likely to reflect a down-regulation or blunted binding affinity in the platelet surface glycoprotein Ib.

Coagulation markers predict survival in cancer patients.

In order to prospectively evaluate the predictive value of coagulation markers such as the fibrin Ddimer for survival of cancer patients, we analyzed their role in a prospective study at a University Hospital Institute of Medical Oncology. 268 consecutive outpatients with cancer were included, 72 in remission and 196 with active disease. All cause mortality in relation to the marker levels was measured. 99/268 patients died during the observation period of 4,484 patient months (mean: 17 months). Patients with active disease had a significant, 1.5-5-fold increased marker concentration compared to patients in remission. When analyzed in quartiles, the data showed a lower than predicted death rate in the first quartile and a significantly elevated mortality in the fourth marker quartile. The odds ratio for death predicted by the fibrin monomer (FM) in the fourth vs. the first quartile was 4.1 (95% C.I.: 1.7-9.7) and p = 0.005 for the multivariate analysis of the markers. We conclude that a single determination of coagulation markers, particularly of TAT, FM, and Ddimer is sufficient to strongly predict survival in cancer patients over the following 1-3 years.

Quantitative and qualitative analysis of platelet GPIb and von Willebrand factor in liver cirrhosis.

Numerous abnormalities of plasmatic coagulation and platelet function may contribute to the bleeding in liver cirrhosis with a defective platelet-von Willebrand factor interaction being a potential mechanism. To analyze GPIb and von Willebrand factor in cirrhosis, we quantified the number of GPIb molecules on the platelet surface by flow cytometry, assessed the total (and indirectly the internal) pool of GPIb by ELISA and measured the circulating amount of glycocalicin in plasma as a measure of proteolytic activity and platelet turnover. Von Willebrand factor was characterized by ELISA, by its ristocetin-cofactor activity and by multimer analysis. Botrocetin-induced agglutination was used for functional analysis. The data from 8 well-characterized cirrhosis patients indicate that total GPIb is insignificantly increased to 46,000 +/- 5,000 molecules/P (normal: 39,500 +/- 2,000 [SEM]), surface-GPIb is normal with some variability and that the glycocalicin levels are 2-3 times higher than would be expected from the platelet count (= 100 +/- 5 x 10(9)/l). Von Willebrand factor antigen levels and activity were 400-500% of normal with a 22% reduction of the high molecular weight multimers. A significant hyperagglutination response to botrocetin was observed with platelets from both patients and controls using patient plasma as a source of von Willebrand factor. In conclusion, a hyperresponsiveness rather than a defective platelet-von Willebrand factor interaction can be observed in cirrhosis which may compensate for other hemostatic problems and appears to be mediated primarily by increased levels of von Willebrand factor.

Whole blood clot lysis: enhanced by exposure to autologous but not to homologous plasma.

A new phenomenon is described: Whole blood clots lyse faster in the plasma of the same donor than in another donor's plasma. We have confirmed this finding in 68 healthy volunteers by a standardized, pair-wise analysis and have found a mean difference in clot weights of 8.8 +/- 0.99% (SEM, p < 0.0001) after 6 h of urokinase-induced (200 U/ml) clot lysis. No difference was found in a group of 7 pairs of identical twins. Further analysis revealed that increasing concentrations of platelets in the plasma reduced the difference significantly but did not abolish it. A 1:1 mixture of autologous with homologous plasma reduced the autologous advantage by almost 50%, thus making an inhibitor unlikely. The absence of cellular components in clots of platelet-poor plasma resulted in the loss of the advantage after 2 h of lysis, but not in the early phase. We conclude that there is a clear advantage of autologous over homologous clot lysis. Potential mechanisms are discussed and include an increased affinity of enzymes for their substrates in a given individual.