Pulmonary Embolism as a Cause of Death in Psychiatric Inpatients: a Case Series

We report four cases of fatal pulmonary embolism confirmed by autopsy among inpatients in a Hong Kong psychiatric hospital from 2010 to 2014. None of the four patients had a medical or premorbid condition associated with vascular thromboembolism or causing prolonged immobilisation. Only two patients were taking long-term antipsychotic medication, but all were physically restrained shortly before the event.

Dynamics from noisy data with extreme timing uncertainty

Imperfect knowledge of the times at which 'snapshots' of a system are recorded degrades our ability to recover dynamical information, and can scramble the sequence of events. In X-ray free-electron lasers, for example, the uncertainty--the so-called timing jitter--between the arrival of an optical trigger ('pump') pulse and a probing X-ray pulse can exceed the length of the X-ray pulse by up to two orders of magnitude, marring the otherwise precise time-resolution capabilities of this class of instruments. The widespread notion that little dynamical information is available on timescales shorter than the timing uncertainty has led to various hardware schemes to reduce timing uncertainty. These schemes are expensive, tend to be specific to one experimental approach and cannot be used when the record was created under ill-defined or uncontrolled conditions such as during geological events. Here we present a data-analytical approach, based on singular-value decomposition and nonlinear Laplacian spectral analysis, that can recover the history and dynamics of a system from a dense collection of noisy snapshots spanning a sufficiently large multiple of the timing uncertainty. The power of the algorithm is demonstrated by extracting the underlying dynamics on the few-femtosecond timescale from noisy experimental X-ray free-electron laser data recorded with 300-femtosecond timing uncertainty. Using a noisy dataset from a pump-probe experiment on the Coulomb explosion of nitrogen molecules, our analysis reveals vibrational wave-packets consisting of components with periods as short as 15 femtoseconds, as well as more rapid changes, which have yet to be fully explored. Our approach can potentially be applied whenever dynamical or historical information is tainted by timing uncertainty.

Single-particle structure determination by X-ray free-electron lasers: Possibilities and challenges

Single-particle structure recovery without crystals or radiation damage is a revolutionary possibility offered by X-ray free-electron lasers, but it involves formidable experimental and data-analytical challenges. Many of these difficulties were encountered during the development of cryogenic electron microscopy of biological systems. Electron microscopy of biological entities has now reached a spatial resolution of about 0.3 nm, with a rapidly emerging capability to map discrete and continuous conformational changes and the energy landscapes of biomolecular machines. Nonetheless, single-particle imaging by X-ray free-electron lasers remains important for a range of applications, including the study of large "electron-opaque" objects and time-resolved examination of key biological processes at physiological temperatures. After summarizing the state of the art in the study of structure and conformations by cryogenic electron microscopy, we identify the primary opportunities and challenges facing X-ray-based single-particle approaches, and possible means for circumventing them.

High-resolution structure of viruses from random diffraction snapshots

The advent of the X-ray free-electron laser (XFEL) has made it possible to record diffraction snapshots of biological entities injected into the X-ray beam before the onset of radiation damage. Algorithmic means must then be used to determine the snapshot orientations and thence the three-dimensional structure of the object. Existing Bayesian approaches are limited in reconstruction resolution typically to 1/10 of the object diameter, with the computational expense increasing as the eighth power of the ratio of diameter to resolution. We present an approach capable of exploiting object symmetries to recover three-dimensional structure to high resolution, and thus reconstruct the structure of the satellite tobacco necrosis virus to atomic level. Our approach offers the highest reconstruction resolution for XFEL snapshots to date and provides a potentially powerful alternative route for analysis of data from crystalline and nano-crystalline objects.

Conformations of macromolecules and their complexes from heterogeneous datasets

We describe a new generation of algorithms capable of mapping the structure and conformations of macromolecules and their complexes from large ensembles of heterogeneous snapshots, and demonstrate the feasibility of determining both discrete and continuous macromolecular conformational spectra. These algorithms naturally incorporate conformational heterogeneity without resort to sorting and classification, or prior knowledge of the type of heterogeneity present. They are applicable to single-particle diffraction and image datasets produced by X-ray lasers and cryo-electron microscopy, respectively, and particularly suitable for systems not easily amenable to purification or crystallization.

Structure of isolated biomolecules obtained from ultrashort x-ray pulses: exploiting the symmetry of random orientations

Amongst the promised capabilities of fourth-generation x-ray sources currently under construction is the ability to record diffraction patterns from individual biological molecules. One version of such an experiment would involve directing a stream of molecules into the x-ray beam and sequentially recording the scattering from each molecule of a short, but intense, pulse of radiation. The pulses are sufficiently short that the diffraction pattern is that due to scattering from identical molecules 'frozen' in random orientations. Each diffraction pattern may be thought of as a section through the 3D reciprocal space of the molecule, of unknown, random, orientation. At least two algorithms have been proposed for finding the relative orientations from just the measured diffraction data. The 'common-line' method, also employed in 3D electron microscopy, appears not best suited to the very low mean photon count per diffraction pattern pixel expected in such experiments. A manifold embedding technique has been used to reconstruct the 3D diffraction volume and hence the electron density of a small protein at the signal level expected of the scattering of an x-ray free electron laser pulse from a 500 kD biomolecule. In this paper, we propose an alternative algorithm which raises the possibility of reconstructing the 3D diffraction volume of a molecule without determining the relative orientations of the individual diffraction patterns. We discuss why such an algorithm may provide a practical and computationally convenient method of extracting information from very weak diffraction patterns. We suggest also how such a method may be adapted to the problem of finding the variations of a structure with time in a time-resolved pump-probe experiment.

Phase and amplitude recovery and diffraction image generation method: structure of Sb/Au(110)–√3 × √3R54.7° from surface X-ray diffraction

The discovery that the phase problem of diffraction from non-periodic objects may be solved by oversampling the diffraction intensities in reciprocal space with respect to a Nyquist criterion has opened up new vistas for structure determination by diffraction methods. A similar principle may be applied to the problem of surface X-ray diffraction (SXRD), where, owing to the breaking of a crystal periodicity normal to its surface, diffraction data consist of a set of superstructure rods (SRs) due to scattering from the parts of the surface whose structure is different from that of the truncated bulk and of crystal truncation rods (CTRs), formed by interfering contributions from the surface and the bulk. A phase and amplitude recovery and diffraction image generation method (PARADIGM) is described that provides a prescription for finding the unmeasured amplitudes and phases of the surface contributions to the CTRs in addition to the phases of the SRs, directly from the diffraction data. The resulting ;diffraction image' is the basis of a determination of the previously unknown multidomain structure of Sb/Au(110)-radical3xradical3R54.7 degrees.

Multimerin processing by cells with and without pathways for regulated protein secretion

Multimerin is a massive, soluble, homomultimeric, factor V-binding protein found in platelet alpha-granules and in vascular endothelium. Unlike platelets, endothelial cells contain multimerin within granules that lack the secretory granule membrane protein P-selectin, and in culture, they constitutively secrete most of their synthesized multimerin. To further evaluate multimerin's posttranslational processing and storage, we expressed human endothelial cell prepromultimerin in a variety of cell lines, with and without pathways for regulated secretion. The recombinant multimerin produced by these different cells showed variations in its glycosylation, proteolytic processing, and multimer profile, and human embryonic kidney 293 cells recapitulated multimerin's normal processing for constitutive secretion by human endothelial cells. When multimerin was expressed in a neuroendocrine cell line capable of regulated protein secretion, it was efficiently targeted for regulated secretion. However, the multimerin stored in these cells was proteolyzed more extensively than normally occurs in platelets, suggesting that endoproteases similar to those expressed by megakaryocytes are required to produce platelet-type multimerin. The impact of the tissue-specific differences in multimerin's posttranslational processing on its functions is not yet known. Multimerin's sorting and targeting for regulated secretion may be important for its functions and its association with factor V in secretion granules.

Characterization of a novel trypanosome lytic factor from human serum

Natural resistance of humans to the cattle pathogen Trypanosoma brucei brucei has been attributed to the presence in human serum of nonimmune factors that lyse the parasite. Normal human serum contains two trypanosome lytic factors (TLFs). TLF1 is a 500-kDa lipoprotein, which is reported to contain apolipoprotein A-I (apoA-I), haptoglobin-related protein (Hpr), hemoglobin, paraoxonase, and apoA-II, whereas TLF2 is a larger, poorly characterized particle. We report here a new immunoaffinity-based purification procedure for TLF2 and TLF1, as well as further characterization of the components of each purified TLF. Immunoaffinity-purified TLF1 has a specific activity 10-fold higher than that of TLF1 purified by previously described methods. Moreover, we find that TLF1 is a lipoprotein particle that contains mainly apoA-I and Hpr, trace amounts of paraoxonase, apoA-II, and haptoglobin, but no detectable hemoglobin. Characterization of TLF2 reveals that it is a 1,000-kDa protein complex containing mainly immunoglobulin M, apoA-I, and Hpr but less than 1% detectable lipid.

Studies of multimerin in human endothelial cells

Multimerin is a novel, massive, soluble protein that resembles von Willebrand factor in its repeating, homomultimeric structure. Both proteins are expressed by megakaryocytes and endothelial cells and are stored in the region of platelet alpha-granules resembling Weibel-Palade bodies. These findings led us to study the distribution of multimerin within human endothelial cells. Multimerin was identified in vascular endothelium in situ. In cultured endothelial cells, multimerin was identified within round to rod-shaped, dense-core granules, some of which contained intragranular, longitudinally arranged tubules and resembled Weibel-Palade bodies. However, multimerin was found primarily in different structures than the Weibel-Palade body proteins von Willebrand factor and P-selectin. After stimulation with secretagogues, multimerin was observed to redistribute from intracellular structures to the external cellular membrane, without detectable accompanied secretion of multimerin into the culture media. In early passage endothelial cell cultures, multimerin was associated with extensive, fibrillary, extracellular matrix structures, in a different distribution than fibronectin. Although multimerin and von Willebrand factor are stored together in platelets, they are mainly found within different structures in endothelial cells, indicating that there are tissue-specific differences in the sorting of these soluble, multimeric proteins.

Application of optical cross talk to switching between bistable soliton states

The dynamics of bistable soliton propagation and switching in a fiber whose intensity-dependent refractive index is described by the linear plus smooth-step model is numerically investigated under conditions where the fiber is evanescently coupled to an identical, initially empty, parallel fiber. The initially empty fiber can perform a number of useful operations on solitons in the first fiber, which could be of interest in optical device design.

Review of cyanoacrylate tissue glues with emphasis on their otorhinolaryngological applications

Cyanoacrylates were first synthesized by Ardis in 1949. However, it was not until Coover in 1959 discovered their adhesive properties that an interest arose in using these substances in surgical procedures. Over the past two decades the use of cyanoacrylates has been varied and widespread among the surgical specialties. methyl 2-cyanoacrylate (Eastman 910 Monomer), Isobutyl-cyanoacrylate (Bucrylate), and 2-cyano-butyl-acrylate (Histoacryl) were the most widely used. Because of its tissue toxicity methyl 2-cyanoacrylate was discarded. The consensus of various investigators was that the higher homologues, in particular Histoacryl could be safely used in human applications. The authors thought it would be important to ascertain how the academic departments of Otolaryngology perceived the role of cyanoacrylates within their specialty. A questionnaire was distributed to 115 academic centers: 47% of the departments responded and, of those, 34% indicated a current working knowledge of the cyanoacrylates. This response confirmed a very active interest in these tissue adhesives despite a lack of F.D.A. approval. The otologic applications of these adhesives has been well documented, but the literature is devoid of studies using cyanoacrylates in other aspects of Otolaryngology. The authors feel that these adhesives (in particular Histoacryl) have a role as an adjunctive technique in facial reconstructive and cosmetic surgery for autogenous cartilage grafting. A study using rabbits was designed to determine if Histoacryl could be used safely to overcome the technical difficulties (graft migration during healing and cartilage fracture during suturing) often encountered when performing autogenous onlay cartilage grafting. On the left ear of each rabbit, a cartilage graft was harvested and reimplanted at a second site on the same ear by suturing the perichondrium of the graft to the perichondrium of the donor site. On the right ear the graft was secured to the donor site with Histoacryl. The histological analysis of the rabbits' ears sacrificed at weekly intervals from 1 week to 1 month failed to demonstrate cartilage damage or tissue toxicity in the ears where Histoacryl was used. In conclusion, the authors contend that a role exists for the use of Histoacryl as an adjunctive technique in facial reconstructive and cosmetic surgery. The study will be continued to assess the long-term results of using Histoacryl for autogenous onlay cartilage grafting.

ABO blood groups in Chilean and Peruvian mummies. II. Results of agglutination-inhibition technique

ABO blood groups of Peruvian and Chilean mummies were determined with the agglutination-inhibition method. In Peru all ABO blood groups were found in the period from 3000 B.C. to 1400 A.D.; from this period to 1650 only A and O were seen. In Chile no B or AB was noted either in pre-Columbian or Colonial mummies. This confirms the archeological concept that the Chilean Indian was culturally as well as genetically different from the Peruvian Indian. Further studies using other genetic markers are in order, as well as changing certain preconceived notions on blood groups of American Indians.