Temperature-dependent dynamic structure factors for liquid water inferred from inelastic neutron scattering measurements.

Temperature-dependent dynamic structure factors S(Q, ω) for liquid water have been calculated using a composite model, which is based on the decoupling approximation of the mean square displacement of the water molecules into diffusion and solid-like vibrational parts. The solid-like vibrational part Svib(Q, ω) is calculated with the phonon expansion method established in the framework of the incoherent Gaussian approximation. The diffusion part Sdiff(Q, ω) relies on the Egelstaff-Schofield translational diffusion model corrected for jump diffusions and rotational diffusions with the Singwi-Sjölander random model and Sears expansion, respectively. Systematics of the model parameters as a function of temperature were deduced from quasi-elastic neutron scattering data analysis reported in the literature and from molecular dynamics (MD) simulations relying on the TIP4P/2005f model. The resulting S(Q, ω) values are confronted by means of Monte Carlo simulations to inelastic neutron scattering data measured with IN4, IN5, and IN6 time-of-flight spectrometers of the Institut Laue-Langevin (ILL) (Grenoble, France). A modest range of temperatures (283-494 K) has been investigated with neutron wavelengths corresponding to incident neutron energies ranging from 0.57 to 67.6 meV. The neutron-weighted multiphonon spectra deduced from the ILL data indicate a slight overestimation by the MD simulations of the frequency shift and broadening of the librational band. The descriptive power of the composite model was suited for improving the comparison to experiments via Bayesian updating of prior model parameters inferred from MD simulations. The reported posterior temperature-dependent densities of state of hydrogen in H2O would represent valuable insights for studying the collective coupling interactions in the water molecule between the inter- and intramolecular degrees of freedom.

Dipolar Spin Ice States with a Fast Monopole Hopping Rate in CdEr_{2}X_{4} (X=Se, S).

Excitations in a spin ice behave as magnetic monopoles, and their population and mobility control the dynamics of a spin ice at low temperature. CdEr_{2}Se_{4} is reported to have the Pauling entropy characteristic of a spin ice, but its dynamics are three orders of magnitude faster than the canonical spin ice Dy_{2}Ti_{2}O_{7}. In this Letter we use diffuse neutron scattering to show that both CdEr_{2}Se_{4} and CdEr_{2}S_{4} support a dipolar spin ice state-the host phase for a Coulomb gas of emergent magnetic monopoles. These Coulomb gases have similar parameters to those in Dy_{2}Ti_{2}O_{7}, i.e., dilute and uncorrelated, and so cannot provide three orders faster dynamics through a larger monopole population alone. We investigate the monopole dynamics using ac susceptometry and neutron spin echo spectroscopy, and verify the crystal electric field Hamiltonian of the Er^{3+} ions using inelastic neutron scattering. A quantitative calculation of the monopole hopping rate using our Coulomb gas and crystal electric field parameters shows that the fast dynamics in CdEr_{2}X_{4} (X=Se, S) are primarily due to much faster monopole hopping. Our work suggests that CdEr_{2}X_{4} offer the possibility to study alternative spin ice ground states and dynamics, with equilibration possible at much lower temperatures than the rare earth pyrochlore examples.

Changes in dynamics of α-chymotrypsin due to covalent inhibitors investigated by elastic incoherent neutron scattering.

An essential role of enzymes is to catalyze various chemical reactions in the human body and inhibition of the enzymatic activity by small molecules is the mechanism of action of many drugs or tool compounds used to study biological processes. Here, we investigate the effect on the dynamics of the serine protease α-chymotrypsin when in complex with two different covalently bound inhibitors using elastic incoherent neutron scattering. The results show that the inhibited enzyme displays enhanced dynamics compared to the free form. The difference was prominent at higher temperatures (240-310 K) and the type of motions that differ include both small amplitude motions, such as hydrogen atom rotations around a methyl group, and large amplitude motions, such as amino acid side chain movements. The measurements were analyzed with multivariate methods in addition to the standard univariate methods, allowing for a more in-depth analysis of the types of motions that differ between the two forms. The binding strength of an inhibitor is linked to the changes in dynamics occurring during the inhibitor-enzyme binding event and thus these results may aid in the deconvolution of this fundamental event and in the design of new inhibitors.

From crystal to glass-like thermal conductivity in crystalline minerals.

The ability of some materials with a perfectly ordered crystal structure to mimic the heat conduction of amorphous solids is a remarkable physical property that finds applications in numerous areas of materials science, for example, in the search for more efficient thermoelectric materials that enable to directly convert heat into electricity. Here, we unveil the mechanism in which glass-like thermal conductivity emerges in tetrahedrites, a family of natural minerals extensively studied in geology and, more recently, in thermoelectricity. By investigating the lattice dynamics of two tetrahedrites of very close compositions (Cu12Sb2Te2S13 and Cu10Te4S13) but with opposite glasslike and crystal thermal transport by means of powder and single-crystal inelastic neutron scattering, we demonstrate that the former originates from the peculiar chemical environment of the copper atoms giving rise to a strongly anharmonic excess of vibrational states.

Liquid 1-propanol studied by neutron scattering, near-infrared, and dielectric spectroscopy.

Liquid monohydroxy alcohols exhibit unusual dynamics related to their hydrogen bonding induced structures. The connection between structure and dynamics is studied for liquid 1-propanol using quasi-elastic neutron scattering, combining time-of-flight and neutron spin-echo techniques, with a focus on the dynamics at length scales corresponding to the main peak and the pre-peak of the structure factor. At the main peak, the structural relaxation times are probed. These correspond well to mechanical relaxation times calculated from literature data. At the pre-peak, corresponding to length scales related to H-bonded structures, the relaxation times are almost an order of magnitude longer. According to previous work [C. Gainaru, R. Meier, S. Schildmann, C. Lederle, W. Hiller, E. Rössler, and R. Böhmer, Phys. Rev. Lett. 105, 258303 (2010)] this time scale difference is connected to the average size of H-bonded clusters. The relation between the relaxation times from neutron scattering and those determined from dielectric spectroscopy is discussed on the basis of broad-band permittivity data of 1-propanol. Moreover, in 1-propanol the dielectric relaxation strength as well as the near-infrared absorbance reveal anomalous behavior below ambient temperature. A corresponding feature could not be found in the polyalcohols propylene glycol and glycerol.

Translational and rotational diffusion in water in the Gigapascal range.

First measurements of the self-dynamics of liquid water in the GPa range are reported. The GPa range has here become accessible through a new setup for the Paris-Edinburgh press specially conceived for quasielastic neutron scattering studies. A direct measurement of both the translational and rotational diffusion coefficients of water along the 400 K isotherm up to 3 GPa, corresponding to the melting point of ice VII, is provided and compared with molecular dynamics simulations. The translational diffusion is observed to strongly decrease with pressure, though its variation slows down for pressures higher than 1 GPa and decouples from that of the shear viscosity. The rotational diffusion turns out to be insensitive to pressure. Through comparison with structural data and molecular dynamics simulations, we show that this is a consequence of the rigidity of the first neighbors shell and of the invariance of the number of hydrogen bonds of a water molecule under high pressure. These results show the inadequacy of the Stokes-Einstein-Debye equations to predict the self-diffusive behavior of water at high temperature and high pressure, and challenge the usual description of hot dense water behaving as a simple liquid.

The outcome of allogeneic HSCT in older AML patients is determined by disease biology and not by the donor type: an analysis of 96 allografted AML patients ≥ 50 years from the Czech acute leukaemia clinical register (alert).

Older patients with AML have poor prognosis after chemotherapy and allo-SCT was historically limited to the young patients. In the multicentre retrospective study we analyzed 96 consecutive AML patients ≥ 50 years allografted with related (n=59) or unrelated (n=37) donor. The 2- year OS and DFS rates were 45 % and 42 % for the whole group. The corresponding figures for related patients were 48% and 42% whereas for unrelated 42% and 42%, respectively (OS p=0,721, DFS p= 0,896). The cumulative incidences of relapse (28% of all patients) and NRM mortality (26%) were low with no significant differences among related and unrelated cohorts. Multivariate analysis revealed the only major independent variables associated with an inferior OS were unfavourable cytogenetics (RR 3.36; CI 1.66-6.83; p=0.001) and advanced disease status (RR 2.30; CI 1.21-4.37; p=0.011). Unfavourable cytogenetics (RR 3.00; CI 1.50-5.99; p=0.002) and advanced disease at SCT (RR 2.27; CI 1.22-4.22; p=0.009) were also the only independent variables associated with inferior DFS. In conclusion, our analysis indicates that outcomes of allografted AML patients aged ≥ 50 years are determined by cytogenetic risk category and disease status at transplantation and not by the type of donor.

Observation of a superfluid component within solid helium.

We demonstrate by neutron scattering that a localized superfluid component exists at high pressures within solid helium in aerogel. Its existence is deduced from the observation of two sharp phonon-roton spectra which are clearly distinguishable from modes in bulk superfluid helium. These roton excitations exhibit different roton gap parameters than the roton observed in the bulk fluid at freezing pressure. One of the roton modes disappears after annealing the samples. Comparison with theoretical calculations suggests that the model that reproduces the observed data best is that of superfluid double layers within the solid and at the helium-substrate interface.

Dynamics of apomyoglobin in the alpha-to-beta transition and of partially unfolded aggregated protein.

Changes of molecular dynamics in the alpha-to-beta transition associated with amyloid fibril formation were explored on apomyoglobin (ApoMb) as a model system. Circular dichroism, neutron and X-ray scattering experiments were performed as a function of temperature on the protein, at different solvent conditions. A significant change in molecular dynamics was observed at the alpha-to-beta transition at about 55 degrees C, indicating a more resilient high temperature beta structure phase. A similar effect at approximately the same temperature was observed in holo-myoglobin, associated with partial unfolding and protein aggregation. A study in a wide temperature range between 20 and 360 K revealed that a dynamical transition at about 200 K for motions in the 50 ps time scale exists also for a hydrated powder of heat-denatured aggregated ApoMb.

Self- and interdiffusion in dilute liquid germanium-based alloys.

Self- and inter-diffusion coefficients in liquid Ge and dilute Ge-based Ge-Si, Ge-Au, Ge-In, Ge-Ce and Ge-Gd alloys-containing 2 at% additions, respectively, are measured using a comprehensive approach of measuring techniques: quasi-elastic neutron scattering, in situ long-capillary experiments combined with x-ray radiography, and a long-capillary experiment under microgravity conditions. Resulting inter- and Ge self-diffusion coefficients are equal within error bars for each investigated alloy. The interdiffusion coefficients are smaller for the alloys containing Ce and Gd, However, no dependence of the atomic mass of the minor additions, that varies by about a factor of seven between Si and Au, on the diffusion coefficients could be observed. This demonstrates that in a loosely-packed metallic liquid with fast diffusive dynamics the diffusion mechanism is highly collective in nature.

Absence of a long-range ordered magnetic ground state in Pr3Rh4Sn13 studied through specific heat and inelastic neutron scattering.

Signatures of absence of a long-range ordered magnetic ground state down to 0.36 K are observed in magnetic susceptibility, specific heat, thermal/electrical transport and inelastic neutron scattering data of the quasi-skutterudite compound Pr3Rh4Sn13 which crystallizes in the Yb3Rh4Sn13-type structure with a cage-like network of Sn atoms. In this structure, Pr3+ occupies a lattice site with D 2d point symmetry having a ninefold degeneracy corresponding to J = 4. The magnetic susceptibility of Pr3Rh4Sn13 shows only a weak temperature dependence below 10 K; otherwise remaining paramagnetic-like in the range, 10 K-300 K. From the inelastic neutron scattering intensity of Pr3Rh4Sn13 recorded at different temperatures, we identify excitations at 4.5(7) K, 5.42(6) K, 10.77(5) K, 27.27(5) K, 192.28(4) K and 308.33(3) K through a careful peak analysis. However, no signatures of long-range magnetic order are observed in the neutron data down to 1.5 K, which is also confirmed by the specific heat data down to 0.36 K. A broad Schottky-like peak is recovered for the magnetic part of the specific heat, C 4f, which suggests the role of crystal electric fields of Pr3+ . A crystalline electric field model consisting of 7 levels was applied to C 4f which leads to the estimation of energy levels at 4.48(2) K, 6.94(4) K, 11.23(8) K, 27.01(5) K, 193.12(6) K and 367.30(2) K. The CEF energy levels estimated from the heat capacity analysis are in close agreement with the excitation energies seen in the neutron data. The Sommerfeld coefficient estimated from the analysis of magnetic specific heat is [Formula: see text] mJ K-2 mol-Pr which suggests the formation of heavy itinerant quasi-particles in Pr3Rh4Sn13. Combining inelastic neutron scattering results, analysis of the specific heat data down to 0.36 K, magnetic susceptibility and, electrical and thermal transport, we establish the absence of long-range ordered magnetic ground state in Pr3Rh4Sn13.

Inelastic neutron scattering study of the lattice dynamics in the clathrate compound BaGe5.

We report inelastic neutron scattering (INS) measurements on the polycrystalline oP60-type clathrate BaGe5, whose crystal structure is related to the type-I clathrate Ba8Ge43□3 and to the cP124-clathrate Ba6Ge25. Our results show that BaGe5 exhibits a similar phonon density of states (PDOS) in the energy range 0-40 meV with respect to Ba8Ge43□3. The low-energy region of the PDOS spectrum (0-10 meV) consists of two peaks at 4.1 and 6.2 meV likely related to Ba-weighted modes. Compared to Ba8Ge43□3, the low-energy region of the phonon spectrum of BaGe5 shows a more complex structure, likely reflecting the presence of three distinct crystallographic sites for Ba. The specific heat data of BaGe5, reexamined in light of the INS results, indicate that the Ba-weighted modes dominate the low-temperature behavior of Cp.

Flow cytometric evaluation of platelet activation by ionic or nonionic contrast media and modulation by heparin and recombinant hirudin.

RATIONALE AND OBJECTIVES: The purpose of this study was to investigate the platelet activation properties of ionic and nonionic contrast media in native heparinized or hirudinized human blood using flow cytometric analysis techniques. MATERIALS AND METHODS: Freshly drawn human blood samples were incubated at 37 degrees C with ionic (Hexabrix and Angiovist) and non-ionic (Isovue and Omnipaque) contrast media for varying periods of time. Using fluorescent monoclonal antibodies to platelet surface receptors glycoprotein IIIa and with granule membrane protein-140, platelet activation was measured in whole blood using flow cytometry. Platelet factor 4 and thromboxane B2 levels also were measured. RESULTS: Dose- and time-dependent platelet activation was observed in nonionic, but not in ionic, contrast media (P < 0.05). Whole blood drawn into heparin or hirudin showed reduced platelet activation in the presence of contrast media compared with nonanticoagulated whole blood. Platelet factor 4 and thromboxane B2 levels showed similar results. Significant platelet activation was seen by flow cytometry in high (2000 mOsmol/kg), but not in lower osmolality (800 mOsmol/kg) controls for ionic and nonionic contrast media, respectively (P < 0.001). CONCLUSION: This study suggests that nonionic contrast media use is associated with significant levels of platelet activation, and that heparin or recombinant hirudin (where heparin is contraindicated) is preferable for use with nonionic contrast media, as these anticoagulants reduce contrast media induced platelet activation.

Urinary tract infection following instrumentation for urodynamic testing.

After identifying a temporal cluster of urinary tract infections in patients who had undergone urodynamic procedures, we examined the techniques within the urodynamic laboratory and retrospectively reviewed charts of all 155 patients tested in the previous six months. The rate of acquired urinary tract infections was 18.7%. Risk factors for infection included undergoing cystometrograms and being subject to the first procedure performed in a day. Technical errors in the performance of the urodynamic studies included failure to completely disassemble the apparatus upon completion of a procedure, failure to use sterile components, and lapses in aseptic technique. Bacteria implicated in the outbreak were isolated from tubing, transducers, and flush solutions. After the institution of appropriate technique, all patients tested in the subsequent six months were followed. The rate of acquired urinary tract infection dropped to 5%. Urodynamic apparatus should be completely disassembled following the completion of a procedure; reassembly using sterile components should occur immediately prior to the next procedure; aseptic technique should be maintained; and patients should undergo routine urine screening before a procedure. Surveillance of urodynamic procedures may reveal correctable flaws in technique.

Aprotinin modulation of platelet activation in patients undergoing cardiopulmonary bypass operations.

BACKGROUND: Aprotinin significantly decreases postoperative blood loss, yet its exact mechanism of action remains unproven. METHODS: To study the cytoprotective effect on platelets, we collected blood samples from patients during cardiopulmonary bypass (CPB) operations performed with or without aprotinin. Analysis included whole-blood flow cytometry. RESULTS: The highest percentages of activated platelets (positive for GMP-140 expression) were bound to leukocytes and erythrocytes in all CPB patients. Platelet-platelet activation did not reveal any marked differences between groups. However, in the platelet-cell bound region, increased ristocetin-stimulated platelet activation was observed from 30 minutes on CPB to 90 minutes after CPB with aprotinin (11.9% +/- 5.1% to 33.1% +/- 8.6%; p < 0.05), but not without aprotinin (17.5% +/- 0.1% to 17.9% +/- 2.3%). Platelet autoactivation increased more in the untreated group with time on CPB. CONCLUSIONS: This study demonstrates that in the presence of aprotinin, platelets remain unstimulated during CPB and the von Willebrand GPIb-mediated activatability of platelets is preserved, thus maintaining a viable platelet population. Most important, this study reveals that these mechanisms are more related to platelet-leukocyte than to platelet-platelet interactions.

Efficacy of aprotinin with various anticoagulant agents in cardiopulmonary bypass.

BACKGROUND: Aprotinin has recently been approved for clinical use in cardiopulmonary bypass. Although unfractionated heparin has been the only anticoagulant widely used for cardiopulmonary bypass, disadvantages involving heparin have led to ongoing investigations of alternative anticoagulant agents. METHODS: The objective of this study was to evaluate the efficacy of aprotinin in combination with other anticoagulant agents, specifically low molecular weight heparin and recombinant hirudin, using a dog model of cardiopulmonary bypass. RESULTS: The blood conservation resulting from the use of aprotinin was observed only with unfractionated heparin. Efficacy of anticoagulation as measured by protein deposits in the bypass circuit filter revealed an unexpected reduction in the quantity of deposits when aprotinin was used in combination with low molecular weight heparin. CONCLUSIONS: As alternative anticoagulant agents are sought, the potential benefits of aprotinin in the reduction of operative blood loss must be evaluated independently for each anticoagulant agent.

Evaluation of CGP 39393 as the anticoagulant in cardiopulmonary bypass operation in a dog model.

Recombinant desulphatohirudin HV1 (CGP 39393), a specific and potent peptidic inhibitor of thrombin, was evaluated as the sole anticoagulant in a dog model of cardiopulmonary bypass. CGP 39393 was administered as a bolus plus infusion for a 1-hour pump period at doses of 1.0 mg/kg + 0.75 mg.kg-1.h-1, 1.0 mg/kg + 1.50 mg.kg-1.h-1, 1.0 mg/kg + 2.25 mg.kg-1.h-1, or 1.0 mg/kg + 3.0 mg.kg-1.h-1 (n = 5 per group). The lowest dose was ineffective, as a high degree of clot formation (314 +/- 160 mg) occurred as determined by quantitation of protein deposits in the pump line filter. The three higher doses inhibited clot formation (35 to 44 mg) but did not reveal a dose-dependent effect (p = 0.308 between groups). All four doses produced the same amount of postoperative blood loss (6.5 to 10 g/kg over 2 hours; p = 0.215 between groups) and no oozing of blood from cut tissues (sternum, muscle, skin) during or after operation. No adverse hemodynamic or hematologic effects were observed. Animals were physiologically stable coming off pump, requiring minimal fluid replacement or other cardiovascular supportive measures. The chromogenic anti-IIa assay could be used to monitor CGP 39393. Some activated partial thromboplastin time and all activated clotting time values were off scale on pump, but they fell immediately after cardiopulmonary bypass, typically reaching near-normal levels within 30 to 60 minutes. No reversal of CGP 39393 was used, as blood levels declined rapidly after cessation of the infusion. This study in a dog model shows that CGP 39393 administered as a bolus plus infusion (minimum dose, 1.0 mg/kg + 1.50 mg.kg-1.h-1) can be used safely and effectively during cardiopulmonary bypass for cardiac operation.

Studies on the pharmacokinetics and pharmacodynamics of recombinant hirudin (rHV2-Lys 47) after intravenous and subcutaneous administration in dogs.

In recent years, the pharmacological and biochemical characterization of hirudins has taken a major upswing due to the availability of this natural polypeptide in recombinant form. Despite this, the current knowledge on the pharmacokinetics and pharmacodynamics of recombinant hirudin (rH) appears to be incomplete. The present study was designed to investigate the relationship between plasma concentrations of rH with corresponding antithrombin responses after intravenous (i.v.) and subcutaneous (s.c.) administration in dogs. Four male, Mongrel dogs were each injected with an i.v. (bolus) dose (1 mg/kg) of one specific variant of rH, i.e. rH with a lysine residue in position 47 (rHV2-Lys 47). The dogs were injected with a s.c. dose (1 mg/kg) of rHV2-Lys 47 after one week. After each dose, blood was collected at different time intervals, plasma separated and stored at -70 degrees C. Plasma concentrations of rHV2-Lys 47 were determined using an enzyme-linked immunosorbent assay (ELISA) method and pharmacokinetic parameters were determined using standard non-compartmental methods. The ex vivo antithrombin activity of the drug was measured using activated partial thromboplastin time (APTT), calcium-thrombin time (Ca++TT) and a chromogenic anti-IIa assay. The results from this study indicate that the pharmacokinetic behavior of rHV2-Lys 47 is strongly influenced by the route of administration. In all three functional assays used, a significant correlation was obtained after i.v. administration between plasma concentrations and corresponding responses over the time period of the study when compared to s.c. administration. The results are indicative of a probable structural and functional modification of this rH variant after s.c. administration which may be responsible for the altered pharmacokinetics and pharmacodynamics after s.c. dosing.

Flow cytometric evaluation of the effect of various thrombin inhibitors on platelet activation in whole blood.

In an in vitro study the effect of various thrombin inhibitors (argatroban, efegatran, DuP 714, recombinant hirudin and PEG-hirudin) on platelet activation in whole blood was investigated. Blood was drawn from normal human volunteers using the double syringe technique without use of a tourniquet to avoid autoaggregation of platelets. Blood was anticoagulated with either argatroban, efegatran, DuP 714, hirudin or PEG-hirudin at final concentrations of 10 micrograms/ml. Blood samples were then incubated at 37 degrees C either with saline, r-tissue factor, arachidonic acid, adenosine diphosphate or collagen. At definite times (1, 2.5, 5, 10 min) aliquots were taken and after various steps of fixative procedure the percentage of platelet activation was measured using fluorescent monoclonal antibodies to platelet surface receptors GPIIIa (CD-61) and P-selectin (CD-62). Flow cytometric analysis showed a platelet activation after all agonists used. All thrombin inhibitors studied caused a nearly complete inhibition of r-tissue factor-mediated platelet activation. In contrast, after activation with the other agonists an increased percent CD-62 expression was found with a maximum after 2.5 to 5 min. The results show that in whole blood thrombin inhibitors are effective in preventing platelet activation induced by r-tissue factor. The formation of active serine proteases including thrombin may be effectively inhibited by these agents. The observations further suggest that while thrombin inhibitors may control serine proteases, these agents do not inhibit the activation of platelets mediated by other agonists.

Alteration of pharmacokinetics and pharmacodynamics of recombinant hirudin (rHV2-Lys 47) after repeated intravenous administration in dogs.

Native hirudin is a heterogenous polypeptide obtained from the medicinal leech, Hirudo medicinalis. Recent advances in molecular biological techniques have led to the availability of large amounts of hirudin in the recombinant form. Recombinant hirudins (rH) are currently being investigated for potential use in the prophylaxis and treatment of deep venous thrombosis (DVT), in disseminated intravascular coagulation (DIC) and during cardiovascular bypass surgery. In this study, one specific variant of rH with a lysine residue in position 47 (rHV2-Lys 47) was administered in dogs in a multiple dose regimen of 2 mg/kg (i.v. bolus) for three weeks with a dosing interval of one week. After each dose, blood samples were collected at regular time intervals, plasma separated and stored at -4 degrees C. Concentrations of rHV2-Lys 47 in each sample were determined using an enzyme-linked immunosorbent assay (ELISA). Ex vivo antithrombin responses measured included activated partial thromboplastin time (APTT), calcium-thrombin time (Ca++TT-10 NIH units/ml) and a chromogenic anti-IIa assay. It was the purpose of this study to detect any sensitization or desensitization of antithrombin responses when rHV2-Lys 47 is used in a repeated fashion such as would be expected in the prophylaxis of DVT. The results indicated that there was no attenuation in the responses; however, there was a sensitization of response as measured by the Ca++TT (10 NIH units/ml). These findings could have major implications in the clinical use of rH where this drug is expected to be used in a multiple dose regimen.