Aharon Lubetsky

Recombinant activated factor VII for adjunctive hemorrhage control in trauma.

BACKGROUND Recombinant activated factor VII (rFVIIa) was approved for treatment of hemorrhages in patients with hemophilia who develop inhibitors to factors VIII or IX. Conditions with increased thromboembolic risk, including trauma with or without disseminated intravascular coagulation, were considered a contraindication for the drug. The mechanism of action of rFVIIa suggests enhancement of hemostasis limited to the site of injury without systemic activation of the coagulation cascade. Therefore, use of the drug in trauma patients suffering uncontrolled hemorrhage appears to be rational. METHODS Seven massively bleeding, multitransfused (median, 40 units [range, 25-49 units] of packed cells), coagulopathic trauma patients were treated with rFVIIa (median, 120 microg/kg [range, 120-212 microg/kg]) after failure of conventional measures to achieve hemostasis. RESULTS Administration of rFVIIa resulted in cessation of the diffuse bleed, with significant decrease of blood requirements to 2 units (range, 1-2 units) of packed cells (p < 0.05); shortening of prothrombin time and activated partial thromboplastin time from 24 seconds (range, 20-31.8 seconds) to 10.1 seconds (range, 8-12 seconds) (p < 0.005) and 79 seconds (range, 46-110 seconds) to 41 seconds (range, 28-46 seconds) (p < 0.05), respectively; and an increase of FVII level from 0.7 IU/mL (range, 0.7-0.92 IU/mL) to 23.7 IU/mL (range, 18-44 IU/mL) (p < 0.05). Three of the seven patients died of reasons other than bleeding or thromboembolism. CONCLUSION The results of this report suggest that in trauma patients rFVIIa may play a role as an adjunctive hemostatic measure, in addition to surgical hemostatic techniques, and provides the motivation for controlled animal and clinical trials.

Interindividual variability in sensitivity to warfarin‐Nature or nurture?

Interindividual variability in responses to warfarin is attributed to dietary vitamin K, drug interactions, age, or genetic polymorphism in the cytochrome P4502C9 enzyme (CYP2C9) (allelic variants 2C9*2 and 2C9*3) linked with impaired metabolism of the potent enantiomere S ‐warfarin.

Single and Combined Prothrombotic Factors in Patients With Idiopathic Venous Thromboembolism: Prevalence and Risk Assessment

The inherited thrombophilias--deficiencies of protein C, protein S, and antithrombin III--and the prothrombotic polymorphisms factor V G1691A and factor II G20210A predispose patients toward venous thromboembolism (VTE). The aim of this study was to determine the prevalence of single and combined prothrombotic factors in patients with idiopathic VTE and to estimate the associated risks. The study group consisted of 162 patients referred for work-up of thrombophilia after documented VTE. The controls were 336 consecutively admitted patients. In all subjects factor V G1691A, factor II G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T were analyzed by specific polymerase chain reactions and restriction enzymes. Activities of antithrombin III and protein C, free protein S antigen, and lupus anticoagulant were determined in a subset of 109 patients who were not receiving oral anticoagulants. The prevalences of heterozygotes and homozygotes for factor V G1691A and factor II G20210A among patients and controls were 40.1% versus 3.9% and 18.5% versus 5.4%, respectively (P=0.0001). The prevalence of homozygotes for MTHFR C677T in patients was 22.8% and in controls, 14.3% (P=0.025). Heterozygous and homozygous factor V G1691A, factor II G20210A, and homozygous MTHFR C677T were found to be independent risk factors for VTE, with odds ratios of 16.3, 3.6, and 2.1, respectively. Two or more polymorphisms were detected in 27 of 162 patients (16.7%) and in 3 of 336 controls (0.9%). Logistic regression analysis disclosed odds ratios of 58.6 (confidence interval [CI], 22.1 to 155.2) for joint occurrence of factor V and factor II polymorphisms, of 35.0 (CI, 14.5 to 84.7) for factor V and MTHFR polymorphisms, and of 7.7 (CI, 3.0 to 19.6) for factor II and MTHFR polymorphisms. Among 109 patients in whom a complete thrombophilic work-up was performed, 74% had at least 1 underlying defect. These data indicate that in most patients referred for evaluation of thrombophilia due to idiopathic VTE, 1 or more underlying genetic predispositions were discernible. The presence of >1 of the prothrombotic polymorphisms was associated with a substantial risk of VTE.

Impaired wound healing in factor XIII deficient mice

Factor XIII that stabilizes fibrin clots in the final stages of blood coagulation also participates in wound healing, as can be inferred from a delay in wound repair in some patients with inherited FXIII deficiency. In this study we evaluated the effect of FXIII on wound healing in FXIII-deficient mice. Three groups of mice (n = 10) were employed: control group, FXIII-deficient group and FXIII-deficient group treated with FXIII concentrate. Excisional wounds were left unsutured and undressed, and mice were followed for eleven days. FXIII-deficient mice exhibited impaired wound healing as has been demonstrated by 15%, 27% and 27% decrease in percentage of wound closure on day 4, 8 and 11, respectively. On day 11 complete healing was observed in control (100% closure), 73.23% in FXIII-deficient and 90.06% in FXIII deficient/FXIII-treated groups (p = 0.007 by ANOVA and p = 0.001 by t-test between control and FXIII-deficient groups). Scoring system representing maturation rate of the wounds showed that the scores for the control, FXIII-deficient and FXIII deficient/FXIII treated groups were 94.9 +/- 4.7, 61.5 +/- 14.5 and 94.5 +/- 6.4, respectively (p < 0.001 by ANOVA). Histological analysis of the lesions performed at day 11 disclosed delayed reepithelization and necrotized fissure in FXIII-deficient mice and normal healing in FXIII-deficient/FXIII-treated mice. The findings of this study confirm that in FXIII-deficient mice wound healing is delayed and the cellular and tissue defects can be corrected by treatment with FXIII, providing evidence for the essential role of FXIII in wound repair and remodeling.

Urinary loss of thiamine is increased by low doses of furosemide in healthy volunteers

Prolonged furosemide treatment is associated with urinary loss of thiamine and thiamine deficiency in some patients with congestive heart failure and low dietary thiamine intake. In the rat, diuretic-induced thiamine urinary loss is solely dependent on increased diuresis and is unrelated to the type of diuretic used. We studied the effects of single intravenous doses of furosemide (1, 3, and 10 mg) and of normal saline infusion (750 mL) on urinary thiamine excretion in 6 volunteers. Over a 6-hour period, furosemide induced dose-dependent increases in urine flow and sodium excretion rates (mean +/- SD), from 51 +/- 17 mL/h at baseline to 89 +/- 29 mL/h, 110 +/- 38 mL/h, and 183 +/- 58 mL/h (F = 10.4, P < .002) and from 5.1 +/- 2.3 mmol/h to 9.4 +/- 6.8 mmol/h, 12.1 +/- 2.6 mmol/h, and 20.9 +/- 10.6 mmol/h (F = 6.3, P < .005) for the three doses, respectively (104 +/- 35 mL/h and 13.0 +/- 6.2 mmol/h for the saline infusion). During this period the thiamine excretion rate doubled from baseline levels (mean of four 24-hour periods before the diuretic interventions) of 6.4 +/- 5.1 nmol/h to 11.6 +/- 8.2 nmol/h (F = 5.03, P < .01, for all four interventions, no difference being found between them), then returning over the following 18 hours to 6.1 +/- 3.9 nmol/h. The thiamine excretion rate was correlated with the urine flow rate (r = 0.54, P < .001), with no further effect of the type of intervention or sodium excretion rate. These findings complement our previous results in animals and indicate that sustained diuresis of >100 mL/h induces a nonspecific but significant increase in urinary loss of thiamine in human subjects. Thiamine supplements should be considered in patients undergoing sustained diuresis, when dietary deficiency may be present.

Thyrotropin Suppression by Thyroid Hormone Replacement is Correlated with Thyroxine Level Normalization in Central Hypothyroidism

We have retrospectively studied 41 patients with hypothalamic-pituitary disease and central hypothyroidism associated with hypopituitarism. Sixteen patients had nonsecreting pituitary macroadenoma, whereas different sellar and suprasellar pathologies affected all other patients. Pretreatment thyrotropin (TSH) level (mean +/- standard error of the mean [SEM]) was 2.04 +/- 0.25 mU/L (normal, 0.4-4), and gradually decreased to 0.51 +/- 0.19 mU/L (range, 0.009-3.38) by treatment with levothyroxine in a mean dose of 86 +/- 6 microg/d. TSH was suppressed by thyroid replacement to less than 0.5 mU/L in 80% of patients. Mean baseline free thyroxine (FT4) was 7.55 +/- 0.51 pmol/L (normal, 11.8-24.6) and gradually increased with thyroid hormone to 15.19 +/- 1.0 pmol/L, whereas total thyroxine (TT4) increased from 57.4 +/- 2.6 to 104.4 +/- 5.0 nmol/L (normal, 77-154). Mean pretreatment total triiodothyronine (TT3) was 1.44 +/- 0.09 nmol/L (normal, 1.1-2.7), and was not altered by treatment. Thyrotropin-releasing hormone (TRH) test was performed in 20 patients before thyroid replacement, and mean baseline and peak TSH levels were 1.33 +/- 0.3 and 7.14 +/- 1.62 mU/L, respectively. In 5 subjects TSH was stimulated to 6 mU/L or more, whereas in 5 others TSH was not affected. Based on linear regression of logarithm (Ln) TSH against FT4, a leftward shift of the TSH/FT4 ratio was demonstrated in patients with central hypothyroidism compared to 17 patients with primary hypothyroidism. Plotting measurements of TSH against FT4 for 6 individuals with central hypothyroidism showed different regression slope for each patient. Suppression of TSH by thyroid replacement to levels below 0.1 mU/L predicted euthyroidism in 92% of cases, compared to 34% when TSH was above 1 mU/L (p < 0.0001). In conclusion, in central hypothyroidism baseline TSH is usually within normal values, and is further suppressed by exogenous thyroid hormone as in primary hypothyroidism, but to lower levels. Thus, insufficient replacement may be reflected by inappropriately elevated TSH levels, and may lead to dosage increment.

Urinary thiamine excretion in the rat: effects of furosemide, other diuretics, and volume load.

Long-term furosemide therapy is associated with increased urinary loss of thiamine. To examine the mechanism of furosemide-induced urinary thiamine loss, we measured urinary excretion of thiamine in rats in response to increasing doses of furosemide, acetazolamide, chlorothiazide, amiloride, mannitol, and extracellular fluid (ECF) volume loading by saline infusion. All animals were in normal thiamine balance as reflected by a thiamine pyrophosphate effect (TPPE) of 2.25% +/- 0.60% (mean +/- SEM), and all had normal renal function. Urinary flow increased in response to diuretic administration in a dose-dependent manner, reaching (mean) peak urinary flow rates of 283 to 402 microL/min. Fractional excretion of sodium (FE(Na)) exhibited the same pattern, reaching peak values of 12.3% to 23.2%. Urinary thiamine excretion increased in proportion to the incremental doses of diuretic agents, reaching (mean) maximal values of 7.44 to 9.34 pmol/min, with no significant difference (P = .11) between the various diuretics tested nor in response to saline loading. None of the diuretics tested differed in the effect on thiamine excretion, which was clearly flow dependent and only partially related to fractional sodium excretion. Urinary flow rate, being the single significant predictor, explained 78% (R2 = 0.78) of the variability in thiamine excretion rates. These findings indicate that urinary thiamine loss is caused by a nonspecific, flow-dependent mechanism common to all of the diuretics tested.

Non-invasive biomarkers of liver fibrosis in haemophilia patients with hepatitis C: can you avoid liver biopsy?

Summary.  Introduction:  Liver biopsy remains the gold standard for the evaluation of fibrosis despite its risks and limitations, especially in haemophilia patients. Recently, non‐invasive biomarkers have been used to assess histological features. The most thoroughly evaluated biomarker is the FibroTest (FT) (AUROC 0.80 for fibrosis stages F2F3F4 vs. F0F1).

Platelet Function of Newborns as Tested by Cone and Plate(let) Analyzer Correlates with Gestational Age

The issue of platelet function in infants and neonates is of interest, and current data are debatable. A new method for assessing platelet function involves using the cone and plate(let) analyzer (CPA), applicable for small (0.2 ml) whole blood volumes. We used polystyrene surface-coated plates to evaluate cord blood neonatal platelet function under flow. One hundred and sixty full-term and 29 preterm infants born at the Sheba Medical Center between March 2003 and January 2004 were evaluated for platelet adhesion measured as surface coverage (SC; the percentage of total area covered by platelets) and platelet aggregation, defined as the average size (AS) of the aggregates. Platelets from preterm infants displayed less platelet adhesion than did those from full-term infants. Platelet SC correlated with gestational age in all infants (p < 0.05), and both groups exhibited similar aggregation (AS). AS values, however, were significantly lower than the normal adult range in our laboratory. Infants born to mothers with pregnancy-induced hypertension displayed significantly lower SC. No association was found between CPA and postnatal complications. Conclusion: CPA provides a rapid, feasible option for testing platelet function in neonates. Its potential predictive value deserves further attention, and more extensive studies are warranted.

Multivitamin supplements may affect warfarin anticoagulation in susceptible patients.

OBJECTIVE: To report an interaction of a multivitamin preparation containing small amounts of vitamin K1 (25 μg) with warfarin in a case series and to assess the prevalence of vitamin K1 deficiency in ambulatory anticoagulated patients. CASE SUMMARIES: We describe 3 patients whose anticoagulation was stabilized with warfarin in whom initiation or cessation of a self-prescribed multivitamin supplement delivering 25 μg of vitamin K1 daily was associated with an otherwise unexplained significant fall or rise in international normalized ratio (INR), respectively, with major thrombosis or hemorrhage in 2. This interaction was rated probable on the Naranjo probability scale. Suspecting vitamin K1 deficiency as an explanation for this oversensitivity, we assessed the prevalence of vitamin K1 deficiency in our clinic by determining plasma vitamin K1 levels in 179 stable consecutive patients, finding very low levels (<0.1 ng/mL) in 22 of 179 (12%). DISCUSSION: Vitamin K1 supplements of 25 μg daily are far below the dose thought to affect anticoagulant control. We hypothesize that, in our patients, unsuspected vitamin K1 deficiency caused an oversensitivity to small vitamin K1 supplements. In patients with low vitamin K1 status, even such low doses represent a significant increment in daily intake, thus lowering the sensitivity to warfarin. Our analysis suggests that low vitamin K1 status exists in a small, but important, minority of ambulatory patients undergoing anticoagulation. CONCLUSIONS: Clinicians should instruct anticoagulated patients to report the use of multivitamin supplements and inquire about it in cases of unexplained INR changes.