Efficacy and safety of enzyme replacement therapy with BMN 110 (elosulfase alfa) for Morquio A syndrome (mucopolysaccharidosis IVA): a phase 3 randomised placebo-controlled study

Objective

To assess the efficacy and safety of enzyme replacement therapy (ERT) with BMN 110 (elosulfase alfa) in patients with Morquio A syndrome (mucopolysaccharidosis IVA).

Methods

Patients with Morquio A aged ≥5 years (N?=?176) were randomised (1:1:1) to receive elosulfase alfa 2.0 mg/kg/every other week (qow), elosulfase alfa 2.0 mg/kg/week (weekly) or placebo for 24 weeks in this phase 3, double-blind, randomised study. The primary efficacy measure was 6-min walk test (6MWT) distance. Secondary efficacy measures were 3-min stair climb test (3MSCT) followed by change in urine keratan sulfate (KS). Various exploratory measures included respiratory function tests. Patient safety was also evaluated.

Results

At week 24, the estimated mean effect on the 6MWT versus placebo was 22.5 m (95 % CI 4.0, 40.9; P?=?0.017) for weekly and 0.5 m (95 % CI ?17.8, 18.9; P?=?0.954) for qow. The estimated mean effect on 3MSCT was 1.1 stairs/min (95 % CI ?2.1, 4.4; P?=?0.494) for weekly and ?0.5 stairs/min (95 % CI ?3.7, 2.8; P?=?0.778) for qow. Normalised urine KS was reduced at 24 weeks in both regimens. In the weekly dose group, 22.4 % of patients had adverse events leading to an infusion interruption/discontinuation requiring medical intervention (only 1.3 % of all infusions in this group) over 6 months. No adverse events led to permanent treatment discontinuation.

Conclusions

Elosulfase alfa improved endurance as measured by the 6MWT in the weekly but not qow dose group, did not improve endurance on the 3MSCT, reduced urine KS, and had an acceptable safety profile.     

Patterns in visual interpretation of coronary arteriograms as detected by quantitative coronary arteriography

In part 1 of a three-part study, 14 novice readers and 6 experienced cardiologists interpreted phantom images of known stenosis severity. No difference between the interpretations of experienced and novice readers was detectable. Visual estimates of "moderately" severe stenosis were 30% higher than actual percent diameter stenosis. In part 2 of the study, visual interpretation of percent diameter stenosis from 212 stenoses on 241 arteriograms was compared with quantitative coronary arteriographic assessment. The visual analysis overestimated disease severity in arteries with greater than or equal to 50% diameter stenosis (except for right coronary lesions) and underestimated severity in all arteries with less than 50% diameter stenosis. Of the 241 arteriograms, 40 had quantitative and visual analysis of all three coronary arteries for assessment of significant disease. In only 62% of the cases did visual and quantitative methods agree on the presence of severe disease; visual estimates diagnosed significantly (p less than 0.05) more three-vessel disease. In part 3 of the study, comparison of percent diameter stenosis by visual estimate with quantitative coronary arteriographic assessment before and after balloon angioplasty of 38 stenoses showed that visual interpretation significantly (p less than 0.001) overestimated initial lesion severity and underestimated stenosis severity after angioplasty.     

From the Cover: Correlating the motion of electrons and nuclei with two-dimensional electronic–vibrational spectroscopy

Multidimensional nonlinear spectroscopy, in the electronic and vibrational regimes, has reached maturity. To date, no experimental technique has combined the advantages of 2D electronic spectroscopy and 2D infrared spectroscopy, monitoring the evolution of the electronic and nuclear degrees of freedom simultaneously. The interplay and coupling between the electronic state and vibrational manifold is fundamental to understanding ensuing nonradiative pathways, especially those that involve conical intersections. We have developed a new experimental technique that is capable of correlating the electronic and vibrational degrees of freedom: 2D electronic–vibrational spectroscopy (2D-EV). We apply this new technique to the study of the 4-(di-cyanomethylene)-2-methyl-6-p-(dimethylamino)styryl-4H-pyran (DCM) laser dye in deuterated dimethyl sulfoxide and its excited state relaxation pathways. From 2D-EV spectra, we elucidate a ballistic mechanism on the excited state potential energy surface whereby molecules are almost instantaneously projected uphill in energy toward a transition state between locally excited and charge-transfer states, as evidenced by a rapid blue shift on the electronic axis of our 2D-EV spectra. The change in minimum energy structure in this excited state nonradiative crossing is evident as the central frequency of a specific vibrational mode changes on a many-picoseconds timescale. The underlying electronic dynamics, which occur on the hundreds of femtoseconds timescale, drive the far slower ensuing nuclear motions on the excited state potential surface, and serve as a excellent illustration for the unprecedented detail that 2D-EV will afford to photochemical reaction dynamics.Two-dimensional electronic spectroscopy (2D-ES) has become an incisive tool to investigate the electronic relaxation and energy transfer dynamics of molecules, molecular aggregates, and nanomaterials (1–5). These studies have been able to separate the homogenous and inhomogeneous line widths, and identify cross-peaks associated with energy transfer between excitons of biological systems or different electronic states of systems that undergo fast nonradiative transitions. Two-dimensional IR spectroscopy (2D-IR) has proved an indispensible tool for studying vibrational couplings and ground-state structures of chemical and complex biological systems (6–8). Thus far, only 1D electronic–vibrational pump-probe spectroscopy, femtosecond stimulated Raman spectroscopy, and transient 2D-IR (t-2D-IR) are able to follow the evolution of nuclei on the ground or excited states subsequent to narrowband electronic excitation (9–12). t-2D-IR has the unique capability of being able to study the evolution of couplings between vibrations on excited potential energy surfaces (PESs).All of the aforementioned experimental techniques, however, are insensitive to the correlation between the initial absorption to an electronically excited state and the ensuing evolution of the nuclear modes on the excited PES(s). The vibrational manifolds on the ground and excited states are intrinsically linked to the electronic potentials: The coupling between these degrees of freedom is what determines the vertical Franck–Condon factors and therefore the electronic structure of excited molecules, complexes, and materials. The ability to correlate the initial excitation of the electronic–vibrational manifold with the subsequent evolution of high-frequency vibrational modes opens many potential avenues of fruitful study, especially in systems where electronic–vibrational coupling is important to the functionality of a system. This principle is paramount to understand the rapid nonradiative transfer between two (or more) electronic states via conical intersections where the Born–Oppenheimer approximation is not necessarily valid (13). For example, the primary steps in vision that involve the cis–trans isomerization of rhodopsin (14), or the photoprotective mechanisms that rapidly deliver excited DNA bases back to the ground state (15). The ability to directly measure these correlations has hitherto remained unexplored. Here, we demonstrate a new experimental technique, 2D electronic–vibrational spectroscopy (2D-EV), that combines the advantages of 2D-ES and 2D-IR, providing the ability to correlate the initial electronic absorption and subsequent evolution of nuclear motions.Degenerate multidimensional spectroscopy experiments have traditionally been performed in a background-free, four-wave mixing phase-matched geometry (1). With the advent and development of pulse-shaping technology, it is now possible to take advantage of techniques routinely used in NMR, such as phase cycling, and apply them to nonlinear optical spectroscopy (16). Here, we perform 2D optical measurements in a partially collinear geometry, the so-called pump-probe geometry, as pioneered in the mid-IR and electronic regimes by the groups of Zanni and Ogilvie, respectively (17, 18) and as originally envisaged by Jonas and coworker (19). Our pulse sequence and interpulse time delays are illustrated in Fig. 1A. The first visible excitation pulse, k₁, creates a coherent superposition of the ground and excited electronic states. After a coherence time, t₁, a second pulse, k₂, converts the system into a population state, either on the ground (Fig. 1B) or excited electronic state (Fig. 1C). Following a given value of the waiting time, t₂, the mid-IR probe pulse interrogates the vibrational quantum state of the system, which subsequently emits a signal, k_sig, after the echo time, t₃. In the pump-probe geometry, k₃ and k_sig are collinear, meaning that the k₃ probe pulse self-heterodynes the emitted field. This has the significant advantage that the signal has a well defined phase relationship with respect to the heterodyne, k₃, obviating the need to phase each 2D-EV spectrum using the projection-slice theorem (20). One disadvantage of this implementation is that the signal is not background free. The k₁ and k₂ pump pulse pair are created using an acousto-optic programmable dispersive filter pulse shaper (AOPDF) (21), which affords attosecond precision over interpulse time delay, t₁, and accurate control over the relative carrier-envelope phase (ϕ₁₂). In a pump-probe geometry, we can no longer take advantage of phase-matching conditions to separate all of the relevant Liouville pathways for the third-order response of the system, namely, the pump-probe signal, rephasing and nonrephasing signals (22, 23). The sum of the latter two signals comprise the total 2D spectrum of a system: a frequency–frequency correlation map of the initial absorption with the final emission. The pump-probe signal is insensitive to the relative phase of the visible pump pulses, whereas the rephasing (photon echo) and nonrephasing (free-induction decay) signals are sensitive to this phase, and thus a 2D spectrum can be obtained by phase cycling the pair of pump pulses. Each 2D-EV spectrum is created by collecting data for a series of t₁ time delays and ϕ₁₂ relative phases for a fixed t₂ waiting time. The mid-IR emission is frequency dispersed onto an array detector, and thereby t₃ is Fourier-transformed on the detector into its conjugate, ω_IR. The data are subsequently phase-cycled (17, 18), to create a time–frequency (t₁–ω_IR) map, which is then apodized, zero-padded (24), and Fourier-transformed along the t₁ time delay to create the frequency–frequency, ω_VIS–ω_IR, 2D-EV surface. A schematic of the full experimental setup is displayed in Fig. S1.Open in a separate windowFig. 1.(A) Pulse ordering of electronic–vibrational experiments. The green k₁ and k₂ pulses represent the electronic (visible) excitation pulses, and the gray k₃ and k_sig pulses the vibrational (mid-IR) probe and vibrational echo pulses, respectively. Feynman and energy level diagrams for evolution on the (B) ground and (C) excited PESs. (D) Calculated DFT minimum energy ground-state structure of DCM dye. Schematic PESs for (E) the case where the first optically excited state undergoes a surface crossing to a CT state in near proximity to the vertical Franck–Condon region; and (F) for a two-level system where the Stokes shift arises from a large anharmonic shift on the excited state. The green arrows represent the initial absorption in E and F, the blue arrows represent vibrational relaxation or motion along a reaction coordinate, Q, and the red arrows represent the fluorescence.Two-dimensional electronic spectroscopy is a penetrating tool to observe many different pathways including population transfer, electronic coupling, and coherent superpositions of various states of a system. This has the downfall that there is a degree of ambiguity in both the manifestation of pathways in a 2D spectrum and their interpretation. Fortunately 2D-EV, like other two-color 2D experiments (18, 25), has a reduced number of pathways that can contribute to a spectrum. For excitation bandwidths that are insufficient to excite one quantum of the mid-IR vibration probed (such as the experiments detailed here), we are unable to drive any wave packets in the vibration probed. Therefore, we are only sensitive to the two pathways displayed in the Feynman diagrams and associated energy level structure in Fig. 1 B and C: vibrational evolution on the ground or excited state. Note that we have only displayed the rephasing pathway for each signal. The respective nonrephasing signals of the pathways depicted in Fig. 1 B and C, which have the conjugate evolution in the t₁ coherence, are not displayed. In 2D-EV experiments, the rephasing and nonrephasing pathways contain identical information because the period of the high-frequency vibration is far longer than that of the electronic coherence.To demonstrate this new experimental technique, we apply it to the laser dye 4-(di-cyanomethylene)-2-methyl-6-p-(dimethylamino)styryl-4H-pyran (DCM), a model push-pull emitter (26). The calculated ground-state structure of DCM is displayed in Fig. 1D. The excited-state dynamics of DCM have been extensively studied, but the role of a charge-transfer (CT) state, especially in polar solvents, has remained inconclusive. DCM exhibits a substantial solvatochromatic Stokes shift. In dimethyl sulfoxide (DMSO), the static Stokes shift (λ) is 5,200 cm⁻¹ (see Fig. S2 for the absorption and fluorescence spectra in DMSO-d₆) but is only 3,200 cm⁻¹ in n-hexane (27). This difference in Stokes shift is also accompanied by a commensurate difference in the fluorescence quantum yield, which varies by two orders of magnitude between nonpolar and polar solvents (27, 28). There are currently two models for excited-state relaxation of DCM: (i) The first electronically excited state, S₁, is a valence or locally excited (LE) state that undergoes fast nonradiative decay into a lower-lying CT state (CT state between the dimethylaniline and pyran rings) and emission from CT state dominates the fluorescence quantum yield (29–34). This case is illustrated schematically in Fig. 1E. Some studies argue that the LE → CT surface crossing is accompanied by an excited-state isomerization or twisted intermediate (29, 30, 33, 34). The other proposed model (ii), illustrated in Fig. 1F, is that the S₁ state is CT in character and therefore has an anharmonically displaced potential compared with the S₀, which gives rise to the large vibrational Stokes shift (26, 35). The one prevailing conclusion from all of these studies is that the emissive state has some CT character.Here, we demonstrate the first implementation (to our knowledge) of the new 2D-EV experimental method, tracking the evolution of the electronic excitation and simultaneously the associated changes in nuclear geometry with femtosecond time resolution. We are able to differentiate between the two proposed mechanisms leading to the observed large Stokes shift of DCM in DMSO-d₆ and propose a mechanism based on observed shifts along the electronic and visible axes of 2D-EV spectra and their respective timescales.     

Distinct roles of the photosystem II protein PsbS and zeaxanthin in the regulation of light harvesting in plants revealed by fluorescence lifetime snapshots

The photosystem II (PSII) protein PsbS and the enzyme violaxanthin deepoxidase (VDE) are known to influence the dynamics of energy-dependent quenching (qE), the component of nonphotochemical quenching (NPQ) that allows plants to respond to fast fluctuations in light intensity. Although the absence of PsbS and VDE has been shown to change the amount of quenching, there have not been any measurements that can detect whether the presence of these proteins alters the type of quenching that occurs. The chlorophyll fluorescence lifetime probes the excited-state chlorophyll relaxation dynamics and can be used to determine the amount of quenching as well as whether two different genotypes with the same amount of NPQ have similar dynamics of excited-state chlorophyll relaxation. We measured the fluorescence lifetimes on whole leaves of Arabidopsis thaliana throughout the induction and relaxation of NPQ for wild type and the qE mutants, npq4, which lacks PsbS; npq1, which lacks VDE and cannot convert violaxanthin to zeaxanthin; and npq1 npq4, which lacks both VDE and PsbS. These measurements show that although PsbS changes the amount of quenching and the rate at which quenching turns on, it does not affect the relaxation dynamics of excited chlorophyll during quenching. In addition, the data suggest that PsbS responds not only to ΔpH but also to the Δψ across the thylakoid membrane. In contrast, the presence of VDE, which is necessary for the accumulation of zeaxanthin, affects the excited-state chlorophyll relaxation dynamics.Plants regulate light harvesting by photosystem II (PSII) in response to changes in light intensity. One way that plants are able to regulate light harvesting is through turning on and off mechanisms that dissipate excess energy. This energy dissipation is assessed via nonphotochemical quenching (NPQ) measurements of chlorophyll fluorescence. Energy-dependent quenching (qE) is the NPQ process with the fastest kinetics. It turns on and off in seconds to minutes, allowing plants to respond to rapid fluctuations in light intensity, which is thought to reduce photodamage (1, 2).Illumination causes the formation of gradients of electrical potential (Δψ) and of proton concentration (ΔpH) across the thylakoid membrane. Although it has been suggested that Δψ may play a role in qE (3), only ΔpH is thought to trigger different proteins and enzymes to induce qE (4). The major known factors involved in induction of qE are the enzyme violaxanthin deepoxidase (VDE) (5) and the PSII protein PsbS (6). The mutant npq1, which lacks VDE and cannot convert violaxanthin to zeaxanthin, has a phenotype with lower qE compared with the wild type (7). Transient absorption measurements suggest that zeaxanthin may quench excited chlorophyll (8). The npq4 mutant, which lacks PsbS, shows no rapidly reversible quenching of chlorophyll fluorescence, suggesting that PsbS is required for qE in vivo (6). PsbS is pH sensitive (9) but is not thought to bind pigments, and thus is likely not the site of quenching (10). It has therefore been hypothesized that PsbS plays an indirect role in quenching, perhaps facilitating a rearrangement of proteins within the grana (11–13). In this paper, we examine the fluorescence lifetime of chlorophyll throughout the induction and relaxation of quenching in intact leaves with and without PsbS and zeaxanthin to examine whether PsbS and zeaxanthin change the type of quenching that occurs in plants.The amount and dynamics of qE are generally measured by changes in the chlorophyll fluorescence yield. One limitation of the chlorophyll fluorescence yield is that it can only inform on the amount of quenching, not on excited-state chlorophyll relaxation dynamics, which reflect how chlorophyll is quenched. Despite this issue, the amount of quenching is commonly used as a proxy for the type of quenching by separating components of quenching based on kinetics, mutants, and the effects of chemical inhibitors. By artificially increasing ΔpH in isolated chloroplasts from npq4, Johnson and Ruban (14, 15) have been able to increase the amount of quenching in npq4 plants to levels observed in wild type plants, suggesting that PsbS may catalyze qE. One potential complication with these studies is that the use of the chemical mediators of cyclic electron transport often necessitates studying isolated chloroplasts rather than intact leaves. In addition, the observation of equivalent amounts of quenching still does not prove that the type of quenching in npq4 is the same as in wild type.In contrast with fluorescence yield measurements, fluorescence lifetime measurements can be used to determine whether the relaxation dynamics of excited chlorophyll are modified by different mutations, informing on the role of a protein or molecule during quenching. The relaxation dynamics of excited chlorophyll during NPQ depends on many variables, including the distance to a quencher, the interactions between the orbitals of chlorophyll and the quencher, and the number of quenchers (16). The shape of the fluorescence lifetime decay curve can be used to determine whether two samples have similar excited chlorophyll relaxation dynamics. Our results show that, although the presence of PsbS does not alter excited chlorophyll relaxation dynamics, the absence of VDE does. These measurements are performed in intact leaves without any chemical treatments, and the data strongly suggest that PsbS plays a catalytic role in vivo.     

Regulation of photosystem I light harvesting by zeaxanthin

In oxygenic photosynthetic eukaryotes, the hydroxylated carotenoid zeaxanthin is produced from preexisting violaxanthin upon exposure to excess light conditions. Zeaxanthin binding to components of the photosystem II (PSII) antenna system has been investigated thoroughly and shown to help in the dissipation of excess chlorophyll-excited states and scavenging of oxygen radicals. However, the functional consequences of the accumulation of the light-harvesting complex I (LHCI) proteins in the photosystem I (PSI) antenna have remained unclarified so far. In this work we investigated the effect of zeaxanthin binding on photoprotection of PSI–LHCI by comparing preparations isolated from wild-type Arabidopsis thaliana (i.e., with violaxanthin) and those isolated from the A. thaliana nonphotochemical quenching 2 mutant, in which violaxanthin is replaced by zeaxanthin. Time-resolved fluorescence measurements showed that zeaxanthin binding leads to a previously unrecognized quenching effect on PSI–LHCI fluorescence. The efficiency of energy transfer from the LHCI moiety of the complex to the PSI reaction center was down-regulated, and an enhanced PSI resistance to photoinhibition was observed both in vitro and in vivo. Thus, zeaxanthin was shown to be effective in inducing dissipative states in PSI, similar to its well-known effect on PSII. We propose that, upon acclimation to high light, PSI–LHCI changes its light-harvesting efficiency by a zeaxanthin-dependent quenching of the absorbed excitation energy, whereas in PSII the stoichiometry of LHC antenna proteins per reaction center is reduced directly.In eukaryotic photosynthetic organisms, photosystem I (PSI) and photosystem II (PSII) comprise a core complex hosting cofactors involved in electron transport and an outer antenna system made of light-harvesting complexes (LHCs): Lhcas for PSI and Lhcbs for PSII. The core complexes bind chlorophyll a (Chl a) and β-carotene, whereas the outer antenna system, in addition to Chl a, binds chlorophyll b (Chl b) and xanthophylls. Despite their overall similarity, PSI and PSII differ in the rate at which they trap excitation energy at the reaction center (RC), with PSI being faster than PSII (1–9). They also differ in their structure (10–12). PSI is monomeric and carries its antenna moiety on only one side as a half-moon–shaped structure whose size is not modulated by growth conditions (13, 14). PSII, on the other hand, is found mainly as a dimeric core surrounded by an inner layer of antenna proteins (Lhcb4–6) and an outer layer of heterotrimeric LHCII complexes (Lhcb 1–3) whose stoichiometry varies depending on the growth conditions (7, 12, 13, 15). Acclimation to high irradiance leads to a lower number of trimers per PSII RC accompanied by loss of the monomeric Lhcb6. These slow acclimative responses regulate the excitation pressure on the PSII RC, preventing saturation of the electron transport chain (16) and the oxidative stress in high light (HL), leading to photoinhibition. The response to rapid changes in light level is managed by turning on some photoprotective mechanisms, such as the nonphotochemical quenching (NPQ) of the excess energy absorbed by PSII (16), which is activated by the acidification of the thylakoid lumen and protonation of the trigger protein PsbS or LhcSR. Low luminal pH also activates violaxanthin de-epoxidase (VDE), catalyzing the de-epoxidation of the xanthophyll violaxanthin to zeaxanthin (17, 18), a scavenger of reactive oxygen species (ROS) produced by excess light (9, 13). Zeaxanthin also enhances NPQ, as observed in vivo by a decrease of PSII fluorescence (19). The short-term effects of exposure to HL on PSI have been disregarded thus far. Because of its rapid photochemistry, PSI shows low fluorescence emission, implying a low ¹Chl* concentration and a low probability that chlorophyll triplet states will be formed by intersystem crossing. This characteristic suggests that the formation of oxygen singlet excited states (¹O*₂) is reduced and that NPQ phenomena in photoprotection are less relevant in PSI (20, 21). Nevertheless, several reports have shown that, especially in the cold (22–29), PSI can exhibit photo-inhibition, with its Lhca proteins being the primary target (24, 30). Upon synthesis in HL, zeaxanthin binding could be traced to two different types of binding site. One, designated “V1,” is located in the periphery of LHCII trimers (31–33). The second, designated “L2,” has an inner location in the dimeric Lhca1–4 and the monomeric Lhcb4–6 members of the LHC family (34–37). Experimental determination of the efficiency of the violaxanthin-to-zeaxanthin exchange yielded a maximal score in the Lhca3 and Lhca4 subunits (24, 25). Interestingly, Lhca1/4 and Lhca2/3 are bound to the PSI core as dimers that can be isolated in fractions identified as “LHCI-730” and “LHCI-680,” respectively, both accumulating zeaxanthin to a de-epoxidation index of ∼0.2 (20, 38). Lhca3 and Lhca4 carry low-absorption-energy chlorophyll forms known as “red forms” (39, 40) that are responsible for the red-shifted PSI emission peak at 730–740 nm at 77 K. The molecular basis for red forms is an excitonic interaction of two chromophores: chlorophylls 603 and 609 located a few angstroms from the xanthophyll in site L2, which can be either violaxanthin or zeaxanthin depending on light conditions (41, 42). It is unclear whether the binding of zeaxanthin to the PSI–LHCI complex has specific physiological function(s) or is simply a result of its common origin with Lhcb proteins.The goal of this study was to understand whether zeaxanthin plays a role in PSI–LHCI photoprotection. To investigate the role of zeaxanthin bound to Lhca proteins, we analyzed the changes in antenna size and Chl a fluorescence dynamics in PSI supercomplexes binding either violaxanthin or zeaxanthin. We found a zeaxanthin-dependent regulation of PSI antenna size and an enhanced resistance to excess light upon zeaxanthin binding. These results show that dynamic changes in the efficiency of light use and in photoprotection capacity are not exclusive to PSII, as previously thought; instead, eukaryotic photosynthetic organisms modulate the function of both photosystems in a coordinated manner.     

Predicting the risks of venous thromboembolism versus post-pancreatectomy haemorrhage: analysis of 13 771 NSQIP patients

Background

The fear of an early post-pancreatectomy haemorrhage (PPH) may prevent surgeons from prescribing post-operative venous thromboembolism (VTE) chemoprophylaxis. The primary hypothesis of this study was that the national post-pancreatectomy early PPH rate was lower than the rate of VTE. The secondary hypothesis was that patients at high risk for post-discharge VTE could be identified, potentially facilitating the selective use of extended chemoprophylaxis.

Patients and methods

All elective pancreatectomies were identified in the 2005 to 2010 American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database. Factors associated with 30-day rates of (pre-versus post-discharge) VTE, early PPH (transfusions > 4 units within 72 h) and return to the operating room (ROR) with PPH were analysed.

Results

Pancreaticoduodenectomies (PD) and distal pancreatectomies (DP) numbered 9140 (66.4%) and 4631 (33.6%) out of 13 771 pancreatectomies, respectively. Event rates included: VTE (3.1%), PPH (1.1%) and ROR+PPH (0.7%). PD and DP had similar VTE rates (P > 0.05) with 31.9% of VTE occurring post-discharge. Independent risk factors for late VTE included obesity [odds ratio (OR), 1.5], age ≥ 75 years (OR, 1.8), DP (OR, 2.4) and organ space infection (OR, 2.1) (all P < 0.02).

Conclusions

Within current practice patterns, post-pancreatectomy VTE outnumber early haemorrhagic complications, which are rare. The fear of PPH should not prevent routine and timely post-pancreatectomy VTE chemoprophylaxis. Because one-third of VTE occur post-discharge, high-risk patients may benefit from post-discharge chemoprophylaxis.     

Evaluation of circulating cathodic antigen (CCA) urine-cassette assay as a survey tool for Schistosoma mansoni in different transmission settings within Bugiri District,Uganda

Diagnosis of schistosomiasis at the point-of-care (POC) is a growing topic in neglected tropical disease research. There is a need for diagnostic tests which are affordable, sensitive, specific, user-friendly, rapid, equipment-free and delivered to those who need it, and POC is an important tool for disease mapping and guiding mass deworming. The aim of present study was to evaluate the relative diagnostic performance of two urine-circulating cathodic antigen (CCA) cassette assays, one commercially available and the other in experimental production, against results obtained using the standard Kato-Katz faecal smear method (six thick smears from three consecutive days), as a ‘gold-standard’, for Schistosoma mansoni infection in different transmission settings in Uganda. Our study was conducted among 500 school children randomly selected across 5 schools within Bugiri district, adjacent to Lake Victoria in Uganda. Considering results from the 469 pupils who provided three stool samples for the six Kato-Katz smears, 293 (76%) children had no infection, 109 (23%) were in the light intensity category, while 42 (9%) and 25 (5%) were in the moderate and heavy intensity categories respectively. Following performance analysis of CCA tests in terms of sensitivity, specificity, negative and positive predictive values, overall performance of the commercially available CCA test was more informative than single Kato-Katz faecal smear microscopy, the current operational field standard for disease mapping. The current CCA assay is therefore a satisfactory method for surveillance of S. mansoni in an area where disease endemicity is declining due to control interventions. With the recent resolution on schistosomiasis elimination by the 65th World Health Assembly, the urine POC CCA test is an attractive tool to augment and perhaps replace the Kato-Katz sampling within ongoing control programmes.     

Clinical evaluation of continuous noninvasive blood pressure monitoring: Accuracy and tracking capabilities

A continuous, noninvasive device for blood pressure measurement using pulse transit time has been recently introduced. We compared blood pressure measurements determined using this device with simultaneous invasive blood pressure measurements in 35 patients undergoing general endotracheal anesthesia. Data were analyzed for accuracy and tracking ability of the noninvasive technique, and for frequency of unavailable pressure measurements by each method. A total of 25, 133 measurements of systolic pressure, diastolic pressure, and mean arterial pressure (MAP) by each method were collected for comparison from 35 patients. Accuracy was expressed by reporting mean bias (invasive pressure minus noninvasive pressure) and limits of agreement between the two measurements. After correction for the offset found when measuring invasive and oscillometric methods of arterial pressure measurement, the mean biases for systolic, diastolic, and mean pressures by the pulse wave method were ?0.37 mm Hg, ?0.01 mm Hg, and ?0.05 mm Hg, respectively (p<0.001). The limits of agreement were: ?29.0 to 28.2 mm Hg, ?14.9 to 14.8 mm Hg, and ?19.1 to 19.0 mm Hg, respectively (95% confidence intervals). When blood pressure measured invasively changed over time by more than 10 mm Hg, the noninvasive technique accurately tracked the direction of change 67% of the time. During the entire study, 3.2% of the invasive measurements were unavailable and 12.9% of the noninvasive measurements were unavailable. The continuous noninvasive monitoring technique is not of sufficient accuracy to replace direct invasive measurement of arterial blood pressure, owing to relatively wide limits of agreement between the two methods. The continuous noninvasive method may serve as an intermediate technology between intermittent noninvasive and continuous invasive measurement of blood pressure if tracking capabilities can be improved; but, further refinement is needed before it can be recommended for routine intraoperative use.