Intracellular morphogenesis of diatom silica is guided by local variations in membrane curvature.

Silica cell-wall formation in diatoms is a showcase for the ability of organisms to control inorganic mineralization. The process of silicification by these unicellular algae is tightly regulated within a membrane-bound organelle, the silica deposition vesicle (SDV). Two opposing scenarios were proposed to explain the tight regulation of this intracellular process: a template-mediated process that relies on preformed scaffolds, or a template-independent self-assembly process.

Accuracy tradeoffs between individual bone and joint-level statistical shape models of knee morphology.

Statistical shape models (SSMs) are useful tools in evaluating variation in bony anatomy to assess pathology, plan surgical interventions, and inform the design of orthopaedic implants and instrumentation. Recently, by considering multiple bones spanning a joint or the whole lower extremity, SSMs can support studies investigating articular conformity and joint mechanics. The objective of this study was to assess tradeoffs in accuracy between SSMs of the femur or tibia individually versus a combined joint-level model.

Exocytosis of the silicified cell wall of diatoms involves extensive membrane disintegration.

Diatoms are unicellular algae characterized by silica cell walls. These silica elements are known to be formed intracellularly in membrane-bound silica deposition vesicles and exocytosed after completion. How diatoms maintain membrane homeostasis during the exocytosis of these large and rigid silica elements remains unknown.

Efficient gene replacement by CRISPR/Cas-mediated homologous recombination in the model diatom Thalassiosira pseudonana.

CRISPR/Cas enables targeted genome editing in many different plant and algal species including the model diatom Thalassiosira pseudonana. However, efficient gene targeting by homologous recombination (HR) to date is only reported for photosynthetic organisms in their haploid life-cycle phase. Here, a CRISPR/Cas construct, assembled using Golden Gate cloning, enabled highly efficient HR in a diploid photosynthetic organism.

Complex morphologies of biogenic crystals emerge from anisotropic growth of symmetry-related facets.

Directing crystal growth into complex morphologies is challenging, as crystals tend to adopt thermodynamically stable morphologies. However, many organisms form crystals with intricate morphologies, as exemplified by coccoliths, microscopic calcite crystal arrays produced by unicellular algae. The complex morphologies of the coccolith crystals were hypothesized to materialize from numerous crystallographic facets, stabilized by fine-tuned interactions between organic molecules and the growing crystals.

Structural evidence for extracellular silica formation by diatoms.

The silica cell wall of diatoms, a widespread group of unicellular microalgae, is an exquisite example for the ability of organisms to finely sculpt minerals under strict biological control. The prevailing paradigm for diatom silicification is that this is invariably an intracellular process, occurring inside specialized silica deposition vesicles that are responsible for silica precipitation and morphogenesis. Here, we study the formation of long silicified extensions that characterize many diatom species.

In situ electron microscopy characterization of intracellular ion pools in mineral forming microalgae.

The formation of coccoliths, intricate calcium carbonate scales that cover the cells of unicellular marine microalgae, is a highly regulated biological process. For decades, scientists have tried to elucidate the cellular, chemical, and structural mechanisms that control the precise mineralogy and shape of the inorganic crystals. Transmission electron microscopy was pivotal in characterizing some of the organelles that orchestrate this process.

A Krebs Cycle Component Limits Caspase Activation Rate through Mitochondrial Surface Restriction of CRL Activation.

How cells avoid excessive caspase activity and unwanted cell death during apoptotic caspase-mediated removal of large cellular structures is poorly understood. We investigate caspase-mediated extrusion of spermatid cytoplasmic contents in Drosophila during spermatid individualization. We show that a Krebs cycle component, the ATP-specific form of the succinyl-CoA synthetase β subunit (A-Sβ), binds to and activates the Cullin-3-based ubiquitin ligase (CRL3) complex required for caspase activation in spermatids.

The unconventional myosin CRINKLED and its mammalian orthologue MYO7A regulate caspases in their signalling roles.

Caspases provide vital links in non-apoptotic regulatory networks controlling inflammation, compensatory proliferation, morphology and cell migration. How caspases are activated under non-apoptotic conditions and process a selective set of substrates without killing the cell remain enigmatic. Here we find that the Drosophila unconventional myosin CRINKLED (CK) selectively interacts with the initiator caspase DRONC and regulates some of its non-apoptotic functions.

The "midsulcus line" as a landmark for tibial resection during total knee arthroplasty.

Background: Proper tibial alignment is an important goal of total knee arthroplasty. Most surgeons agree that tibial coronal alignment should be within three degrees of neutral mechanical alignment. The "midsulcus line" is a line drawn along the sulcus of the tibial spines, and then the line is continued in the sagittal plane and extended onto the anterior tibia where it intersects the tibial tubercle approximately 3 to 4mm lateral to the tubercle's medial border.

Variability in Distal Femoral Anatomy in Patients Undergoing Total Knee Arthroplasty: Measurements on 13,546 Computed Tomography Scans.

Proper mechanical and rotational alignment plays an important role in achieving the success of the total knee arthroplasty (TKA). The purpose of the present study was to retrospectively determine with computed tomography (CT) the distal femoral valgus angle (DFVA) and femoral rotation angle (FRA). Our cohort included 13,546 CT scans of patients undergoing TKA.

Tibial Slope is Highly Variable in Patients Undergoing Primary Total Knee Arthroplasty: Analysis of 13,546 Computed Tomography Scans.

The purpose of this study was to retrospectively measure with computed tomography (CT) the posterior tibial slope (PTS) to establish the average anatomy and the incidence of outliers in patients undergoing total knee arthroplasty (TKA). Our cohort included 13,546 arthritic patients: 8241 (61%) female; 5305 (39%) male. The average PTS angle was 7.

Tibial base design and patient morphology affecting tibial coverage and rotational alignment after total knee arthroplasty.

Purpose: To understand interactions between total knee arthroplasty tibial base design attributes, variations in tibial morphology, and the resulting tibial coverage and rotational alignment.

Methods: Tibial anthropometric measurements, including aspect ratio (medial-lateral width/anterior-posterior length) and tibial asymmetry, were taken for 14,791 total knee arthroplasty patients and compared with the ability of four different commercial tibial base designs to cover the resected plateau. The anthropometric measurements were also compared with the resulting tibial base rotation, which occurred when rotating the base to maximize coverage.

Sporoptosis: sowing the seeds of nuclear destruction.

What are the origins of programmed cell death (PCD)? In this issue of Developmental Cell, Eastwood et al. (2012) uncover an ancient developmental program of nuclear destruction in yeast, implying that some PCD mechanisms could have emerged from nonlethal processes before the divergence of fungi and metazoan.

Apoptosis is regulated by the VDAC1 N-terminal region and by VDAC oligomerization: release of cytochrome c, AIF and Smac/Diablo.

Mitochondria, central to basic life functions due to their generation of cellular energy, also serve as the venue for cellular decisions leading to apoptosis. A key protein in mitochondria-mediated apoptosis is the voltage-dependent anion channel (VDAC), which also mediates the exchange of metabolites and energy between the cytosol and the mitochondria. In this study, the functions played by the N-terminal region of VDAC1 and by VDAC1 oligomerization in the release of cytochrome c, Smac/Diablo and apoptosis-inducing factor (AIF) and subsequent apoptosis were addressed.

VDAC1 cysteine residues: topology and function in channel activity and apoptosis.

The VDAC (voltage-dependent anion channel) is proposed to control metabolic cross-talk between mitochondria and the cytosol, as well as apoptotic cell death. It has been suggested that apoptosis is modulated by the oxidation state of VDAC. Since cysteine residues are the major target for oxidation/reduction, we verified whether one or both VDAC1 cysteine residues are involved in VDAC1-mediated transport or apoptosis activities.

Study of micromotion in modular acetabular components during gait and subluxation: a finite element investigation.

Polyethylene wear after total hip arthroplasty may occur as a result of normal gait and as a result of subluxation and relocation with impact. Relocation of a subluxed hip may impart a moment to the cup creating sliding as well as compression at the cup liner interface. The purpose of the current study is to quantify, by a validated finite element model, the forces generated in a hip arthroplasty as a result of subluxation relocation and compare them to the forces generated during normal gait.

Experimental and analytical validation of a modular acetabular prosthesis in total hip arthroplasty.

A finite element model has been developed to predict in vivo micro motion between a modular acetabular cup and liner after cement less total hip arthroplasty. The purpose of this study is to experimentally validate the model. Six LVDT sensors were used to monitor the micromotion of the liner when subjected to loading conditions ranging from 250 N to 5000 N.

Active warming of critically ill trauma patients during intrahospital transfer: a prospective, randomized trial.

Objective: Hypothermia in trauma victims is a frequently observed phenomenon in acute care. Known complications of hypothermia are impaired wound healing, cardiac complications, hemodynamic instability, impaired immune function and increased blood loss. We compared active warming versus passive warming in hypothermia in critical-care patients undergoing intrahospital transfer from ICU to computer tomography (CT).

Environmental monitoring of sevoflurane and nitrous oxide using the cuffed oropharyngeal airway.

Unlabelled: We compared exposure to sevoflurane (SEV) and nitrous oxide (N(2)O) during ventilation using the cuffed oropharyngeal airway (COPA) with waste gas exposure using a conventional face mask (FM) without any additional airways or face straps and with the laryngeal mask airway (LMA). Trace concentrations of SEV and N(2)O were assessed by using a direct reading spectrometer during 33 surgical procedures under general anesthesia. Measurements were made at the patients' mouths and in the anesthesiologists' breathing zones.

Tunneled epidural catheters for prolonged analgesia in pediatric patients.

Unlabelled: We conducted this retrospective study to document the efficacy and safety, and demonstrate the spectrum of indications for subcutaneously tunneled epidural catheters in the management of prolonged pain in pediatric patients. The charts of 25 patients with prolonged pain that was unresponsive to conventional opioid therapy (10: end stage malignancy, 8: extensive abdominal surgery, 7: trauma, etc.) and who received thoracic, lumbar, or caudal tunneled epidural catheters between 1995 and 1999 were reviewed for efficacy and catheter-related complications (infection or bleeding at the insertion site, toxicity related to local anesthetics, tachyphylaxis and respiratory depression).