Cilia and centrosomes: Ultrastructural and mechanical perspectives.

Cilia and centrosomes of eukaryotic cells play important roles in cell movement, fluid transport, extracellular sensing, and chromosome division. The physiological functions of cilia and centrosomes are generated by their dynamics, motions, and forces controlled by the physical, chemical, and biological environments. How an individual cilium achieves its beat pattern and induces fluid flow is governed by its ultrastructure as well as the coordination of associated molecular motors. Thus, a bottom-up understanding of the physiological functions of cilia and centrosomes from the molecular to tissue levels is required. Correlations between the structure and motion can be understood in terms of mechanics. This review first focuses on cilia and centrosomes at the molecular level, introducing their ultrastructure. We then shift to the organelle level and introduce the kinematics and mechanics of cilia and centrosomes. Next, at the tissue level, we introduce nodal ciliary dynamics and nodal flow, which play crucial roles in the organogenetic process of left-right asymmetry. We also introduce respiratory ciliary dynamics and mucous flow, which are critical for protecting the epithelium from drying and exposure to harmful particles and viruses, i.e., respiratory clearance function. Finally, we discuss the future research directions in this field.

Rsph4a is essential for the triplet radial spoke head assembly of the mouse motile cilia.

Motile cilia/flagella are essential for swimming and generating extracellular fluid flow in eukaryotes. Motile cilia harbor a 9+2 arrangement consisting of nine doublet microtubules with dynein arms at the periphery and a pair of singlet microtubules at the center (central pair). In the central system, the radial spoke has a T-shaped architecture and regulates the motility and motion pattern of cilia. Recent cryoelectron tomography data reveal three types of radial spokes (RS1, RS2, and RS3) in the 96 nm axoneme repeat unit; however, the molecular composition of the third radial spoke, RS3 is unknown. In human pathology, it is well known mutation of the radial spoke head-related genes causes primary ciliary dyskinesia (PCD) including respiratory defect and infertility. Here, we describe the role of the primary ciliary dyskinesia protein Rsph4a in the mouse motile cilia. Cryoelectron tomography reveals that the mouse trachea cilia harbor three types of radial spoke as with the other vertebrates and that all triplet spoke heads are lacking in the trachea cilia of Rsph4a-deficient mice. Furthermore, observation of ciliary movement and immunofluorescence analysis indicates that Rsph4a contributes to the generation of the planar beating of motile cilia by building the distal architecture of radial spokes in the trachea, the ependymal tissues, and the oviduct. Although detailed mechanism of RSs assembly remains unknown, our results suggest Rsph4a is a generic component of radial spoke heads, and could explain the severe phenotype of human PCD patients with RSPH4A mutation.

[Discordant lymphoma of diffuse large B-cell lymphoma and peripheral T-cell lymphoma, not otherwise specified in a human T-cell leukemia virus type-I carrier].

A 69-year-old man was diagnosed with diffuse large B-cell lymphoma (DLBCL) negative for Epstein-Barr virus-encoded small nuclear RNA 1 (EBER-1) in October 2011, when he was also diagnosed as having a human T-cell leukemia virus type-I (HTLV-1) carrier. He achieved complete response after six courses of R-CHOP therapy. In February 2015, the patient had high fever and markedly elevated serum lactate dehydrogenase (LDH) level. Bone marrow examination revealed infiltration of CD4-positive T-cell malignancy. Based on the tentative diagnosis of adult T-cell leukemia/lymphoma, modified LSG15 therapy was initiated. His symptoms and serum LDH level quickly improved after the start of treatment. During the treatment, HTLV-1 proviral DNA integration was reported negative, allowing his final diagnosis to be peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). Despite discontinuation of chemotherapy in the middle of the second course due to the patient's preference, complete remission was reached. He remains in clinical remission at 28 months after the treatment discontinuation. Discordant lymphoma of DLBCL and PTCL-NOS in HTLV-1 carrier has not been well characterized and will be discussed with a literature review.

Intravenous itraconazole compared with liposomal amphotericin B as empirical antifungal therapy in patients with neutropaenia and persistent fever.

BACKGROUND: Fungal infections are a major complication of neutropaenia following chemotherapy. Their early diagnosis is difficult, and empirical antifungal treatment is widely used, and uses of less toxic drugs that reduce breakthrough infection are required. OBJECTIVE: We conducted a multicentre, open-label, randomised, non-inferiority trial to compare the safety and efficacy of intravenous itraconazole (ivITCZ) and liposomal amphotericin B (LAmB) as empirical antifungal therapy in patients with haematological malignancies with neutropaenia and persistent fever. METHODS: Patients with haematological malignancies who developed fever refractory to broad-spectrum antibacterial agents under neutropaenia conditions were enrolled. Patients were randomised for treatment with LAmB (3.0 mg/kg/d) or ivITCZ (induction: 400 mg/d, maintenance: 200 mg/d). RESULTS: Observed overall favourable response rates of 17/52 (32.7%) and 18/50 (36.0%) in the LAmB and ivITCZ groups, with a model-based estimate of a 4% difference (90% CI, -12% to 20%), did not fulfil the statistical non-inferiority criterion. In the LAmB group, there were two cases of breakthrough infection and five cases of probable invasive fungal disease, whereas in the itraconazole group, neither breakthrough infection nor probable invasive fungal disease occurred. Patients in the ivITCZ group had significantly fewer grade 3-4 hypokalaemia-related events than LAmB group patients (P < .01). The overall incidence of adverse events tended to be lower in the ivITCZ group (P = .07). CONCLUSION: ivITCZ showed similar efficacy and safety as LAmB as empirical antifungal therapy in haematological malignancy patients with febrile neutropaenia, although the small sample size and various limitations prevented demonstration of its non-inferiority.

[Occurrence of acquired factor V inhibitor during antibiotic therapy for a surgical wound infection].

Acquired factor V (FV) inhibitor is a rare disorder. Herein we report a case of an 82-year-old Japanese woman with FV inhibitor exhibiting a pseudo decline in the activities of the multiple coagulation factors. After rectal cancer surgery, she received antibiotic therapy for wound infection. As prothrombin and activated partial thromboplastin time was prolonged, heparin for atrial fibrillation was discontinued without improvement. Coagulation factor activity assays revealed deficiencies in II, V, VII, VIII, IX, X, XI, and XII factor activities; in particular, the FV activity was markedly decreased to <1%. The cross-mixing test findings revealed an inhibitor pattern, and multiple coagulation factor inhibitors were positive. The FV inhibitor level was high at 62 Bethesda U/ml. The patient exhibited no bleeding tendency with the prolonged wound infection without immunosuppressive therapy. The inhibitor disappeared four months after the onset.

Clinical impact of pretransplant use of multiple tyrosine kinase inhibitors on the outcome of allogeneic hematopoietic stem cell transplantation for chronic myelogenous leukemia.

Tyrosine kinase inhibitors (TKIs) are widely used to treat patients with chronic myelogenous leukemia in the chronic phase (CML-CP), and outcomes of TKI treatment for patients with CML-CP have been excellent. Since multiple TKIs are currently available, second-line or third-line TKI therapy is considered for patients who are intolerant of or resistant to the previous TKI treatment. Therefore, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered only for patients with disease progression or for patients after treatment failure with multiple TKIs. To reflect the current clinical situation of patients with CML-CP, we tried to clarify whether prior TKI treatment affects the outcome of allo-HSCT. Data from 237 patients for whom the number of pretransplant TKIs varied from one to three were used for analysis. Before allo-HSCT, 153 patients were treated with one TKI, 49 patients were treated with two TKIs and 35 patients were treated with three TKIs. In addition to conventional risk factors, i.e., disease status at transplantation and patient's age, the use of three TKIs before transplantation was identified as a significant adverse factor for prognosis. Nonrelapse mortality rate was higher in patients treated with three TKIs than in patients treated with one or two TKIs. Our results suggest that allo-HSCT could be considered for young patients with CML-CP who manifest resistance to second-line TKI therapy and who have an appropriate donor.

[Relapsed/refractory multiple myeloma with CD138 shedding and formation of extramedullary disease in the common bile duct region presenting as obstructive jaundice].

A 56-year-old man was diagnosed with immunoglobulin (Ig) A-κ multiple myeloma in July 2007. After three courses of vincristine, adriamycin, and dexamethasone (VAD) chemotherapy, autologous peripheral blood stem cell transplantation was performed and achieved a very good partial response. In February 2010, an increase in the M-protein concentration and plasmacytoma in the L3/4 lumbar vertebrae were observed, and radiation treatment was performed. This was followed by administrations of bortezomib, lenalidomide, and thalidomide, none of which achieved a good response. In November 2011, the patient presented with obstructive jaundice, and imaging tests revealed tumorous lesions in the lower bile duct region and bilateral kidneys. Plasmacytoma was diagnosed from biopsy of the right renal mass. Radiotherapy to the common bile duct tumor resulted in jaundice amelioration, but the patient died despite subsequent treatment efforts. Autopsy revealed multiple extramedullary lesions in the abdominal cavity and in the region around the common bile duct. CD138 shedding was observed in the myeloma cells. We include a discussion of the literature on CD138 shedding and 38 reports of obstructive jaundice associated with extramedullary disease.

Fluctuation of cilia-generated flow on the surface of the tracheal lumen.

Although we inhale air that contains many harmful substances, including, for example, dust and viruses, these small particles are trapped on the surface of the tracheal lumen and transported towards the larynx by cilia-generated flow. The transport phenomena are affected not only by the time- and space-average flow field but also by the fluctuation of the flow. Because flow fluctuation has received little attention, we investigated it experimentally in mice. To understand the origin of flow fluctuation, we first measured the distribution of ciliated cells in the trachea and individual ciliary motions. We then measured the detailed flow field using a confocal micro-PTV system. Strong flow fluctuations were observed, caused by the unsteadiness of the ciliary beat and the spatial inhomogeneity of ciliated cells. The spreading of particles relative to the bulk motion became diffusive if the time scale was sufficiently larger than the beat period. Finally, we quantified the effects of flow fluctuation on bulk flow by evaluating the Peclet number of the system, which indicated that the directional transport was an order of magnitude larger than the isotropic diffusion. These results are important in understanding transport phenomena in the airways on a cellular scale.

Bioimaging of glucose analogs labeled at the C-1 or C-2 position with a fluorescent dansylamino group.

Glucose is the most important energy source in all organisms; however, our understanding of the pathways and mechanisms underlying glucose transportation and localization in living cells is incomplete. Here, we prepared two glucose analogs labeled with a dansylamino group at the C-1 (1-Dansyl) or C-2 (2-Dansyl) position; the dansyl group is a highly fluorescent moiety that is characterized by a large Stokes shift between its excitation and emission wavelengths. We then examined the cytotoxicity of the two glucose analogs in mammalian fibroblast cells and in the ciliated protozoan Tetrahymena thermophila. In both cell types, 2-Dansyl had no negative effects on cell growth. The specificity of cellular uptake of glucose analogs was confirmed using an inhibitor of glucose transporter in NIH3T3 cells. In NIH3T3 cells and T. thermophila, fluorescence microscopy revealed that the glucose analogs localized throughout the cytoplasm, but especially at the periphery of the nucleus. In T. thermophila, we also found that swimming speed was comparable in media containing non-labeled glucose or one of the glucose analogs, which provided more evidence not only that the analogs were not cytotoxic in these cells but also that the analogs had no negative effect on the ciliary motion. Together, the present results suggest that the glucose analogs have low toxicity and will be useful for bioimaging of glucose-related systems.

Isolation of ependymal cilia from mouse brain.

BACKGROUND: Ependymal cilia play a major role in the circulation of cerebrospinal fluid. Although isolation of cilia is an essential technique for investigating ciliary structure, to the best of our knowledge, no report on the isolation and structural analysis of ependymal cilia from mouse brain is available. NEW METHOD: We developed a novel method for isolating ependymal cilia from mouse brain ventricles. We isolated ependymal cilia by partially opening the lateral ventricles and gently applying shear stress, followed by pipetting and ultracentrifugation. RESULTS: Using this new method, we were able to observe cilia separately. The results demonstrated that our method successfully isolated intact ependymal cilia with preserved morphology and ultrastructure. In this procedure, the ventricular ependymal cell layer was partially detached. COMPARISON WITH EXISTING METHODS: Compared to existing methods for isolating cilia from other tissues, our method is meticulously tailored for extracting ependymal cilia from the mouse brain. Designed with a keen understanding of the fragility of the ventricular ependyma, our method prioritizes minimizing tissue damage during the isolation procedure. CONCLUSIONS: We isolated ependymal cilia from mouse brain by applying shear stress selectively to the ventricles. Our method can be used to conduct more detailed studies on the structure of ependymal cilia.

[Rapid improvement of fluid retention with lenalidomide plus low-dose dexamethasone for POEMS syndrome relapsed after autologous peripheral blood stem cell transplantation].

We report a 53-year-old male with POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome who relapsed after autologous peripheral stem cell transplantation (ASCT), but responded extremely well to lenalidomide (LEN) plus low dose dexamethasone (Ld) therapy. The patient had been diagnosed with POEMS syndrome in November 2006, and underwent ASCT in February 2007. In July 2011, he developed respiratory distress, generalized edema, and massive bilateral pleural effusion. Plasma vascular endothelial growth factor (VEGF) and M protein were increased, strongly indicating a relapse. Ld therapy was remarkably effective for these symptoms, resulting in complete remission with M-protein becoming undetectable by immunofixation. Since completing 11 courses of therapy with an every 4 weeks regimen, he has remained in clinical remission. The patient's activities of daily living have also markedly improved from total physical incapacity to being able to stand with slight assistance. LEN is associated with a lower incidence of peripheral neuropathy than other new drugs. Although LEN has occasionally been given to patients with POEMS syndrome in recent years, there are still few reports on its use for patients with recurrent disease after ASCT. Our successful management of this patient suggests that Ld therapy is not only relatively safe but also a promising option for POEMS syndrome relapsing after ASCT.

Inertial migration of cancer cells in blood flow in microchannels.

The circulating tumor cell test is used to evaluate the condition of breast cancer patients by counting the number of cancer cells in peripheral blood samples. Although microfluidic systems to detect or separate cells using the inertial migration effect may be applied to this test, the hydrodynamic forces acting on cancer cells in high hematocrit blood flow are incompletely understood. In the present study, we investigated the inertial migration of cancer cells in high hematocrit blood flow in microchannels. The maximum hematocrit used in this study was about 40%. By measuring the cell migration probability, we examined the effects of cell-cell interactions, cell deformability, and variations in cell size on the inertial migration of cancer cells in blood. The results clearly illustrate that cancer cells can migrate towards equilibrium positions up to a hematocrit level of 10%. We also performed simple scaling analysis to explain the differences in migration length between rigid particles and cancer cells as well as the effect of hematocrit on cancer cell migration. These results will be important for the design of microfluidic devices for separating cells from blood.

Mouse respiratory cilia with the asymmetric axonemal structure on sparsely distributed ciliary cells can generate overall directional flow.

Mucociliary clearance on the surface of the tracheal lumen is an important component of lung defense against dust mites and viruses. However, the axonemal structure that achieves effective ciliary motion, and the mechanisms by which discretely distributed ciliary cells generate directional flow are unknown. In this study, we examined individual ciliary motion with 7- to 9-nm spatial precision by labeling the ciliary tip with quantum dots and detected an asymmetric beating pattern. Cryo-electron tomography revealed that the densities of two inner dynein arms were missing from at least 2 doublet microtubules in the axonemal structure. Although the flow directions generated by individual ciliated cells were unsteady and diverse, the time- and space-averaged velocity field was found to be directional. These results indicate that the asymmetric ciliary motion is driven by the asymmetric axonemal structure, and it generates overall directional flow from the lungs to the oropharynx on sparsely distributed ciliated cells. FROM THE CLINICAL EDITOR: The authors of this study utilized quantum dots in determining the kinetics of ciliary motion in mouse respiratory cilia with 7- to 9-nm spatial precision.

Effect of cilia-induced surface velocity on cerebrospinal fluid exchange in the lateral ventricles.

Ciliary motility disorders are known to cause hydrocephalus. The instantaneous velocity of cerebrospinal fluid (CSF) flow is dominated by artery pulsation, and it remains unclear why ciliary dysfunction results in hydrocephalus. In this study, we investigated the effects of cilia-induced surface velocity on CSF flow using computational fluid dynamics. A geometric model of the human ventricles was constructed using medical imaging data. The CSF produced by the choroid plexus and cilia-induced surface velocity were given as the velocity boundary conditions at the ventricular walls. We developed healthy and reduced cilia motility models based on experimental data of cilia-induced velocity in healthy wild-type and Dpcd-knockout mice. The results indicate that there is almost no difference in intraventricular pressure between healthy and reduced cilia motility models. Additionally, it was found that newly produced CSF from the choroid plexus did not spread to the anterior and inferior horns of the lateral ventricles in the reduced cilia motility model. These findings suggest that a ciliary motility disorder could delay CSF exchange in the anterior and inferior horns of the lateral ventricles.

Dominant negative mutant actins identified in flightless Drosophila can be classified into three classes.

Strongly dominant negative mutant actins, identified by An and Mogami (An, H. S., and Mogami, K. (1996) J. Mol. Biol. 260, 492-505), in the indirect flight muscle of Drosophila impaired its flight, even when three copies of the wild-type gene were present. Understanding how these strongly dominant negative mutant actins disrupt the function of wild-type actin would provide useful information about the molecular mechanism by which actin functions in vivo. Here, we expressed and purified six of these strongly dominant negative mutant actins in Dictyostelium and classified them into three groups based on their biochemical phenotypes. The first group, G156D, G156S, and G268D actins, showed impaired polymerization and a tendency to aggregate under conditions favoring polymerization. G63D actin of the second group was also unable to polymerize but, unlike those in the first group, remained soluble under polymerizing conditions. Kinetic analyses using G63D actin or G63D actin.gelsolin complexes suggested that the pointed end surface is defective, which would alter the polymerization kinetics of wild-type actin when mixed and could affect formation of thin filament structures in indirect flight muscle. The third group, R95C and E226K actins, was normal in terms of polymerization, but their motility on heavy meromyosin surfaces in the presence of tropomyosin-troponin indicated altered sensitivity to Ca(2+). Cofilaments in which R95C or E226K actins were copolymerized with a 3-fold excess of wild-type actin also showed altered Ca(2+) sensitivity in the presence of tropomyosin-troponin.

Asymmetry of blood flow and cancer cell adhesion in a microchannel with symmetric bifurcation and confluence.

Bifurcations and confluences are very common geometries in biomedical microdevices. Blood flow at microchannel bifurcations has different characteristics from that at confluences because of the multiphase properties of blood. Using a confocal micro-PIV system, we investigated the behaviour of red blood cells (RBCs) and cancer cells in microchannels with geometrically symmetric bifurcations and confluences. The behaviour of RBCs and cancer cells was strongly asymmetric at bifurcations and confluences whilst the trajectories of tracer particles in pure water were almost symmetric. The cell-free layer disappeared on the inner wall of the bifurcation but increased in size on the inner wall of the confluence. Cancer cells frequently adhered to the inner wall of the bifurcation but rarely to other locations. Because the wall surface coating and the wall shear stress were almost symmetric for the bifurcation and the confluence, the result indicates that not only chemical mediation and wall shear stress but also microscale haemodynamics play important roles in the adhesion of cancer cells to the microchannel walls. These results provide the fundamental basis for a better understanding of blood flow and cell adhesion in biomedical microdevices.

Dynein pulls microtubules without rotating its stalk.

Dynein is a microtubule motor that powers motility of cilia and flagella. There is evidence that the relative sliding of the doublet microtubules is due to a conformational change in the motor domain that moves a microtubule bound to the end of an extension known as the stalk. A predominant model for the movement involves a rotation of the head domain, with its stalk, toward the microtubule plus end. However, stalks bound to microtubules have been difficult to observe. Here, we present the clearest views so far of stalks in action, by observing sea urchin, outer arm dynein molecules bound to microtubules, with a new method, "cryo-positive stain" electron microscopy. The dynein molecules in the complex were shown to be active in in vitro motility assays. Analysis of the electron micrographs shows that the stalk angles relative to microtubules do not change significantly between the ADP.vanadate and no-nucleotide states, but the heads, together with their stalks, shift with respect to their A-tubule attachments. Our results disagree with models in which the stalk acts as a lever arm to amplify structural changes. The observed movement of the head and stalk relative to the tail indicates a new plausible mechanism, in which dynein uses its stalk as a grappling hook, catching a tubulin subunit 8 nm ahead and pulling on it by retracting a part of the tail (linker).

Importance of Compliance With Guidelines for the Prevention of Varicella-Zoster Virus Reactivation in Multiple Myeloma.

BACKGROUND/AIM: The importance of compliance with National Comprehensive Cancer Network (NCCN) guidelines for preventing varicella-zoster virus reactivation (VZVr) in multiple myeloma (MM) in a clinical setting has not been well investigated. PATIENTS AND METHODS: We retrospectively studied the clinical characteristics and outcomes of 118 patients with MM treated with proteasome inhibitors. RESULTS: Thirty-nine episodes of VZVr were observed in 37 patients (VZVr group). The proportion of prophylactic antiviral prescriptions and compliance with antiviral prophylaxis based on the NCCN Clinical Practice guidelines was 76% and 30% in the VZVr group, and 88% and 74% in the non-VZVr group, respectively. Multivariate analysis showed that compliance with the NCCN guidelines was the only independent risk factor for VZVr (p=0.0017). CONCLUSION: It is important that prophylactic antivirals are prescribed for an appropriate duration of time to prevent the reactivation of VZV in compliance with existing guidelines.

Screening of novel dominant negative mutant actins using glycine targeted scanning identifies G146V actin that cooperatively inhibits cofilin binding.

A number of studies suggested that the structure of actin filaments changes by interaction with actin-binding proteins such as cofilin and myosin, and that the conformational changes of the actin subunits within a filament are cooperative. To understand the functions of these cooperative conformational changes induced by actin-binding proteins, we sought to obtain dominant negative mutant actins impaired in cooperative conformational changes. A series of mutant actin genes in which glycine residues in actin were systematically substituted by valine residues were constructed, and were expressed individually in yeast cells that carry a wild-type endogenous actin gene. Six dominant negative actin mutations were identified on the basis of growth inhibition. Among them, G146V mutation was chosen for further biochemical analysis because the Gly146 residue is located at the strategic hinge position connecting the large and small domains of an actin molecule. We found that G146V actin filaments hardly bind cofilin, consistent with a previous suggestion that cofilin binding causes conformational changes of actin around Gly146 (Galkin et al. [3]). Notably, copolymer that consists of 1:10 mixture of the mutant and wild-type actin molecules showed significantly reduced affinity for cofilin, suggesting that G146V mutant actin affects the conformation of neighboring wild-type actin within a filament, and inhibits cofilin binding.

Safety and Effectiveness of Ixazomib Dose-escalating Strategy in Ixazomib-Lenalidomide-Dexamethasone Treatment for Relapsed/Refractory Multiple Myeloma.

BACKGROUND/AIM: Gastrointestinal toxicity is common in patients receiving common therapy of ixazomib with lenalidomide and low-dose dexamethasone (IRd) for relapsed/refractory multiple myeloma. Here, we investigated the safety and effectiveness of ixazomib dosing schedules. PATIENTS AND METHODS: We retrospectively evaluated 17 consecutive patients treated with IRd (10 patients on ixazomib dose-escalation strategy (2.3 mg starting dose); seven patients on standard dose). RESULTS: The incidence of grade 3 or more haematological and grade 2 or more non-haematological adverse events was lower in the dose-escalation group than in the standard-dose group, and only that of diarrhoea was significantly lower. The median time to treatment interruption was significantly longer in the dose-escalation group than in the standard-dose group. There was no significant difference in the overall response rate (20% vs. 43%) and disease control rate (70% vs. 86%). CONCLUSION: A dose-escalation strategy to optimise ixazomib dosing may reduce treatment interruption due to adverse events without compromising its antitumor activity.