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1.
Sci Rep ; 12(1): 2907, 2022 02 21.
Article in English | MEDLINE | ID: mdl-35190584

ABSTRACT

Physical activity (PA) helps prevention and aftercare of sporadic breast cancer (BC), cardiopulmonary fitness (CPF) being an age-independent predictor of tumor-specific mortality. Therefore, we wanted to identify predictors of CPF (represented by peak oxygen uptake: VO2peak) in BRCA1/2 mutation carriers whose risk of developing BC is high. We used cross-sectional data from 68 BRCA1/2 germline mutation carrying women participating in the randomized, prospective, controlled clinical study LIBRE-1. Assessments included cardiopulmonary exercise testing, medical and lifestyle history plus socioeconomic status. Additionally, the participants completed a psychological questionnaire regarding their attitude, subjective norms, perceived behavior control and intention towards PA. A multivariate logistic regression model was used to identify predictors for participants reaching their age- and sex-adjusted VO2peak reference values. 22 participants (median age: 40 years, interquartile range (IQR) 33-46) were cancer-unaffected and 46 cancer-affected (median age: 44 years, IQR 35-50). The strongest predictor for reaching the reference VO2peak value was attitude towards PA (Odds Ratio 3.0; 95% Confidence Interval 1.3-8.4; p = 0.021). None of the other predictors showed a significant association. A positive attitude towards PA seems to be associated with VO2peak, which should be considered in developing therapeutic and preventive strategies.Trial registrations: NCT02087592; DRKS00005736.


Subject(s)
Attitude to Health , BRCA1 Protein/genetics , BRCA2 Protein/genetics , Breast Neoplasms/genetics , Breast Neoplasms/prevention & control , Exercise Test , Exercise/psychology , Germ-Line Mutation , Oxygen Consumption , Adult , Breast Neoplasms/etiology , Breast Neoplasms/psychology , Cross-Sectional Studies , Female , Heterozygote , Humans , Middle Aged , Prospective Studies , Surveys and Questionnaires
2.
Ultrasound Obstet Gynecol ; 53(3): 367-375, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30014562

ABSTRACT

OBJECTIVES: The soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) ratio is generally elevated some time before and at the clinical onset of pre-eclampsia. The PROGNOSIS study validated a sFlt-1/PlGF ratio cut-off of ≤ 38 to rule out the onset of pre-eclampsia within 1 week of testing in women with suspected disease. The aim of this study was to assess the predictive value of the sFlt-1/PlGF ratio to rule out the onset of pre-eclampsia for up to 4 weeks, and to assess the value of repeat measurements. METHODS: This was an exploratory post-hoc analysis of data from the PROGNOSIS study performed in pregnant women aged ≥ 18 years with suspected pre-eclampsia, who were at 24 + 0 to 36 + 6 weeks' gestation at their first clinic visit. Serum samples were collected at the first visit and weekly thereafter. sFlt-1 and PlGF levels were measured using Elecsys® sFlt-1 and PlGF immunoassays. Whether the sFlt-1/PlGF ratio cut-off of ≤ 38 used to rule out the onset of pre-eclampsia within 1 week could predict the absence of pre-eclampsia 2, 3, and 4 weeks post-baseline was assessed. The value of repeat sFlt-1/PlGF testing was assessed by examining the difference in sFlt-1/PlGF ratio 2 and 3 weeks after the first measurement in women with, and those without, pre-eclampsia or adverse fetal outcome. RESULTS: On analysis of 550 women, sFlt-1/PlGF ratio ≤ 38 ruled out the onset of pre-eclampsia 2 and 3 weeks post-baseline with high negative predictive values (NPV) of 97.9% and 95.7%, respectively. The onset of pre-eclampsia within 4 weeks was ruled out with a high NPV (94.3%) and high sensitivity and specificity (66.2% and 83.1%, respectively). Compared with women who did not develop pre-eclampsia, those who developed pre-eclampsia had significantly larger median increases in sFlt-1/PlGF ratio at 2 weeks (∆, 31.22 vs 1.45; P < 0.001) and at 3 weeks (∆, 48.97 vs 2.39; P < 0.001) after their initial visit. Women who developed pre-eclampsia and/or adverse fetal outcome compared with those who did not had a significantly greater median increase in sFlt-1/PlGF ratio over the same period (∆, 21.22 vs 1.40; P < 0.001 at 2 weeks; ∆, 34.95 vs 2.30; P < 0.001 at 3 weeks). CONCLUSION: The Elecsys® immunoassay sFlt-1/PlGF ratio can help to rule out the onset of pre-eclampsia for 4 weeks in women with suspected pre-eclampsia. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.


Subject(s)
Placenta Growth Factor/blood , Pre-Eclampsia/diagnosis , Prenatal Diagnosis/methods , Vascular Endothelial Growth Factor Receptor-1/blood , Adult , Biomarkers/metabolism , Female , Fetus , Gestational Age , Humans , Pre-Eclampsia/blood , Pre-Eclampsia/epidemiology , Pre-Eclampsia/mortality , Predictive Value of Tests , Pregnancy , Prognosis , Prospective Studies , Retrospective Studies
3.
Phys Rev Lett ; 110(4): 048103, 2013 Jan 25.
Article in English | MEDLINE | ID: mdl-25166204

ABSTRACT

We develop a generic description of thin active films that captures key features of flow and rotation patterns emerging from the activity of chiral motors which introduce torque dipoles. We highlight the role of the spin rotation field and show that fluid flows can occur in two ways: by coupling of the spin rotation rate to the velocity field via a surface or by spatial gradients of the spin rotation rate. We discuss our results in the context of patches of bacteria on solid surfaces and groups of rotating cilia. Our theory could apply to active chiral processes in the cell cytoskeleton and in epithelia.


Subject(s)
Models, Biological , Models, Chemical , Actins/chemistry , Actins/physiology , Bacterial Adhesion/physiology , Cilia/chemistry , Cilia/physiology , Cytoskeleton/chemistry , Cytoskeleton/physiology , Myosins/chemistry , Myosins/physiology , Torque
4.
Eur Phys J E Soft Matter ; 35(9): 89, 2012 Sep.
Article in English | MEDLINE | ID: mdl-23001784

ABSTRACT

Active processes in biological systems often exhibit chiral asymmetries. Examples are the chirality of cytoskeletal filaments which interact with motor proteins, the chirality of the beat of cilia and flagella as well as the helical trajectories of many biological microswimmers. Here, we derive constitutive material equations for active fluids which account for the effects of active chiral processes. We identify active contributions to the antisymmetric part of the stress as well as active angular momentum fluxes. We discuss four types of elementary chiral motors and their effects on a surrounding fluid. We show that large-scale chiral flows can result from the collective behavior of such motors even in cases where isolated motors do not create a hydrodynamic far field.


Subject(s)
Hydrodynamics , Models, Molecular , Actin Cytoskeleton/chemistry , Actin Cytoskeleton/metabolism , Kinetics , Molecular Conformation , Torque
5.
Neurology ; 78(13): 998-1006, 2012 Mar 27.
Article in English | MEDLINE | ID: mdl-22422897

ABSTRACT

OBJECTIVE: The Methods of Optimal Depression Detection in Parkinson's Disease (MOOD-PD) study compared the psychometric properties of 9 depression scales to provide guidance on scale selection in Parkinson disease (PD). METHODS: Patients with PD (n = 229) from community-based neurology practices completed 6 self-report scales (Beck Depression Inventory [BDI]-II, Center for Epidemiologic Studies Depression Rating Scale-Revised [CESD-R], 30-item Geriatric Depression Scale [GDS-30], Inventory of Depressive Symptoms-Patient [IDS-SR], Patient Health Questionnaire-9 [PHQ-9], and Unified Parkinson's Disease Rating Scale [UPDRS]-Part I) and were administered 3 clinician-rated scales (17-item Hamilton Depression Rating Scale [HAM-D-17], Inventory of Depressive Symptoms-Clinician [IDS-C], and Montgomery-Åsberg Depression Rating Scale [MADRS] and a psychiatric interview. DSM-IV-TR diagnoses were established by an expert panel blinded to the self-reported rating scale data. Receiver operating characteristic curves were used to estimate the area under the curve (AUC) of each scale. RESULTS: All scales performed better than chance (AUC 0.75-0.85). Sensitivity ranged from 0.66 to 0.85 and specificity ranged from 0.60 to 0.88. The UPDRS Depression item had a smaller AUC than the BDI-II, HAM-D-17, IDS-C, and MADRS. The CESD-R also had a smaller AUC than the MADRS. The remaining AUCs were statistically similar. CONCLUSIONS: The GDS-30 may be the most efficient depression screening scale to use in PD because of its brevity, favorable psychometric properties, and lack of copyright protection. However, all scales studied, except for the UPDRS Depression, are valid screening tools when PD-specific cutoff scores are used.


Subject(s)
Depression/diagnosis , Depression/psychology , Parkinson Disease/diagnosis , Parkinson Disease/psychology , Psychiatric Status Rating Scales/standards , Self Report/standards , Surveys and Questionnaires/standards , Aged , Depression/epidemiology , Female , Humans , Male , Middle Aged , Parkinson Disease/epidemiology
6.
Eur Phys J E Soft Matter ; 33(2): 99-103, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20852912

ABSTRACT

Cell sorting is a widespread phenomenon pivotal to the early development of multicellular organisms. In vitro cell sorting studies have been instrumental in revealing the cellular properties driving this process. However, these studies have as yet been limited to two-dimensional analysis of three-dimensional cell sorting events. Here we describe a method to record the sorting of primary zebrafish ectoderm and mesoderm germ layer progenitor cells in three dimensions over time, and quantitatively analyze their sorting behavior using an order parameter related to heterotypic interface length. We investigate the cell population size dependence of sorted aggregates and find that the germ layer progenitor cells engulfed in the final configuration display a relationship between total interfacial length and system size according to a simple geometrical argument, subject to a finite-size effect.


Subject(s)
Cell Separation/methods , Animals , Cell Aggregation , Ectoderm/cytology , Mesoderm/cytology , Stem Cells/cytology , Zebrafish/embryology
7.
Phys Rev E Stat Nonlin Soft Matter Phys ; 81(3 Pt 1): 030904, 2010 Mar.
Article in English | MEDLINE | ID: mdl-20365690

ABSTRACT

The initial stages of transcription by RNA polymerase are frequently marked by pausing and stalling events. These events have been linked to an inactive backtracked state in which the polymerase diffuses along the template DNA. We investigate theoretically the influence of RNA secondary structure in confining this diffusion. The effective confinement length peaks at transcript lengths commensurate with early stalling. This finite-size effect accounts for slow progress at the beginning of transcription, which we illustrate via stochastic hopping models for backtracking polymerases.


Subject(s)
DNA-Directed RNA Polymerases/chemistry , DNA-Directed RNA Polymerases/genetics , Models, Chemical , Models, Genetic , RNA/chemistry , RNA/genetics , Transcription, Genetic/genetics , Binding Sites , DNA-Directed RNA Polymerases/ultrastructure , Enzyme Activation , Models, Molecular , Nucleic Acid Conformation , Protein Binding , Protein Structure, Secondary , RNA/ultrastructure , Structure-Activity Relationship
8.
Eur Phys J E Soft Matter ; 30(4): 439-47, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19856004

ABSTRACT

We calculate the first-passage time distribution for diffusion through a cylindrical pore with sticky walls. A particle diffusively explores the interior of the pore through a series of binding and unbinding events with the cylinder wall. Through a diagrammatic expansion we obtain first-passage time statistics for the particle's exit from the pore. Connections between the model and nucleocytoplasmic transport in cells are discussed.


Subject(s)
Diffusion , Biological Transport , Models, Chemical , Porosity , Probability , Time Factors
9.
J Eur Acad Dermatol Venereol ; 23(1): 52-7, 2009 Jan.
Article in English | MEDLINE | ID: mdl-18702624

ABSTRACT

BACKGROUND: Dermatology in a penitentiary environment is an under-researched field. OBJECTIVES: To study the prison population seeking medical advice for skin diseases and to assess among detainees the life impact of these diseases, an approach that to the best of our knowledge has not previously been reported. METHODS: This prospective study was carried out in the male population of two penal institutions in the region of Toulouse, south-western France. RESULTS: One hundred seventy-eight men were seen, for a total of 234 diagnoses and 281 consultations. The five most frequent diagnoses, in order of decreasing frequency, were disorders of the pilosebaceous follicle, fungal diseases, benign skin tumours, warts and eczemas, which are common skin diseases. However, 72% of inmates believed their skin disease was directly related to detention. This belief was related to the conditions of life in prison (seclusion and its effects) and to frequent psychological problems. CONCLUSIONS: The disorders observed were generally benign skin conditions that could be expected in a population of young men living in a closed community. They led to a high demand for care and treatment: skin diseases represented the largest specialist consultation in our institutions. Skin problems can easily be managed in an outpatient unit, which confirms the usefulness of a dedicated dermatology clinic within the outpatient consultation units of penal institutions in order to provide care of equivalent quality to that available in a free environment. The dermatologist can have an important role in the medical management and the health education of prisoners.


Subject(s)
Prisoners , Skin Diseases/epidemiology , Adult , France/epidemiology , Humans , Male , Middle Aged , Prospective Studies , Skin Diseases/classification
10.
J Radiol ; 88(9 Pt 2): 1261-3, 2007 Sep.
Article in French | MEDLINE | ID: mdl-17878872

ABSTRACT

The daily practice of radiologists has evolved and radiologists are increasingly being directly involved with patient care and treatment. Consequently, radiologists have become a part of the therapeutic team available to patients. This active role, in hospital based or out-patient practices, does not only have an impact on the radiologist's professional activities. New liabilities related to interventional procedures or treatments are now added to already existing professional liability from diagnostic activities. Therefore, musculoskeletal radiologists performing interventional procedures must be aware and familiar with their obligations towards patients, including the requirement to provide adequate information to patients and documenting that informed consent was obtained.


Subject(s)
Bone Diseases/therapy , Disclosure/legislation & jurisprudence , Informed Consent/legislation & jurisprudence , Liability, Legal , Muscular Diseases/therapy , Radiology, Interventional/legislation & jurisprudence , Ambulatory Care/legislation & jurisprudence , Consent Forms/legislation & jurisprudence , France , Humans , Medical Staff, Hospital/legislation & jurisprudence , Patient Care Team/legislation & jurisprudence
11.
Neurology ; 63(2): 293-300, 2004 Jul 27.
Article in English | MEDLINE | ID: mdl-15277623

ABSTRACT

OBJECTIVE: To determine the prevalence and impact of comorbid psychiatric disturbances in Parkinson disease (PD) patients with psychosis. METHODS: Subject data were derived from a research database of 116 PD patients participating in standardized motor, cognitive, psychiatric, and caregiver assessments. RESULTS: There were 25 patients (22%) with psychosis manifest as hallucinations (n = 9), delusions (n = 1), or hallucinations and delusions (n = 15) and 25 patients (22%) who had no current or past psychiatric comorbidities (PDN). In the psychotic group, 44% had psychosis only (PSY), and 56% had psychosis plus at least one other comorbid psychiatric disturbance (PSY+), including depressive disorders (71%), anxiety disorders (21%), apathetic syndromes (14%), and delirium (14%). There were no differences in age, sex, education, or age onset or duration of PD among the PSY, PSY+, and PDN groups. Both psychotic groups had greater motor, functional, and frontal cognitive deficits and increased caregiver burden scores relative to PDN. PSY+ showed greater global and selective cognitive deficits compared to PDN. Psychosis was a primary predictor of caregiver burden, whereas depressive symptoms indirectly enhanced motor impairments. CONCLUSIONS: Nonpsychotic psychiatric disturbances, especially affective disturbances, are common comorbidities in PD patients with psychosis and warrant clinical attention to reduce morbidity and caregiver distress.


Subject(s)
Mental Disorders/epidemiology , Parkinson Disease/epidemiology , Psychotic Disorders/epidemiology , Activities of Daily Living , Aged , Anxiety Disorders/epidemiology , Caregivers/psychology , Cognition Disorders/epidemiology , Comorbidity , Databases, Factual , Delusions/epidemiology , Female , Hallucinations/epidemiology , Humans , Longitudinal Studies , Male , Middle Aged , Mood Disorders/epidemiology , Prevalence , Severity of Illness Index , Surveys and Questionnaires
12.
Novartis Found Symp ; 237: 164-75; discussion 176-81, 2001.
Article in English | MEDLINE | ID: mdl-11444042

ABSTRACT

Cell division during development in many cases generates daughter cells that differ not only in fate, but also in size. We investigate the mechanisms that ensure proper spindle positioning during such asymmetric divisions using the one-cell stage Caenorhabditis elegans embryo as a model system. We utilized a UV laser microbeam as an in vivo microtubule-severing device to probe the forces driving spindle positioning. Our results indicate that extra-spindle pulling forces acting on the spindle poles dictate spindle position along the anterior-posterior embryonic axis. Importantly, forces acting on the posterior spindle pole appear more extensive than those acting on the anterior one, thus explaining the overall posterior spindle displacement that leads to the asymmetric division of the wild-type one-cell stage embryo. In separate work, we analysed a locus called zyg-8, which plays a key role in ensuring proper spindle positioning. Our data show that zyg-8 is required to promote microtubule growth and/or stability during anaphase. We identified the molecular nature of the zyg-8 locus in the course of a large-scale RNAi-based functional genomics screen. ZYG-8 harbours two notable protein domains: a Ca2+/calmodulin-dependent kinase domain, and a domain related to doublecortin, a human microtubule-associated protein involved in neuronal migration.


Subject(s)
Caenorhabditis elegans/embryology , Cell Division/physiology , Cell Polarity/physiology , Embryo, Nonmammalian/physiology , Microtubule-Associated Proteins , Spindle Apparatus/metabolism , Animals , Caenorhabditis elegans/physiology , Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans Proteins/metabolism , Doublecortin Domain Proteins , Embryo, Nonmammalian/cytology , Lasers , Microtubules/metabolism , Neuropeptides/metabolism , Oocytes/physiology
13.
J Bacteriol ; 183(11): 3499-505, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11344158

ABSTRACT

Based on the complementarity of the initial coding region (downstream box [db]) of several bacterial and phage mRNAs to bases 1469 to 1483 in helix 44 of 16S rRNA (anti-downstream box [adb]), it has been proposed that db-adb base pairing enhances translation in a way that is similar to that of the Shine-Dalgarno (SD)/anti-Shine-Dalgarno (aSD) interaction. Computer modeling of helix 44 on the 30S subunit shows that the topography of the 30S ribosome does not allow a simultaneous db-adb interaction and placement of the initiation codon in the ribosomal P site. Thus, the db-adb interaction cannot substitute for the SD-aSD interaction in translation initiation. We have always argued that any contribution of the db-adb interaction should be most apparent on mRNAs devoid of an SD sequence. Here, we show that 30S ribosomes do not bind to leaderless mRNA in the absence of initiator tRNA, even when the initial coding region shows a 15-nucleotide complementarity (optimal fit) with the putative adb. In addition, an optimized db did not affect the translational efficiency of a leaderless lambda cI-lacZ reporter construct. Thus, the db-adb interaction can hardly serve as an initial recruitment signal for ribosomes. Moreover, we show that different leaderless mRNAs are translated in heterologous systems although the sequence of the putative adb's within helix 44 of the 30S subunits of the corresponding bacteria differ largely. Taken our data together with those of others (M. O'Connor, T. Asai, C. L. Squires, and A. E. Dahlberg, Proc. Natl. Acad. Sci. USA 96:8973-8978, 1999; A. La Teana, A. Brandi, M. O'Connor, S. Freddi, and C. L. Pon, RNA 6:1393-1402, 2000), we conclude that the db does not base pair with the adb.


Subject(s)
Protein Biosynthesis , RNA, Messenger/metabolism , RNA, Ribosomal, 16S/metabolism , Base Pairing , Base Sequence , Escherichia coli/genetics , Escherichia coli/metabolism , Models, Molecular , Molecular Sequence Data , Nucleic Acid Conformation , RNA, Messenger/chemistry , RNA, Messenger/genetics , RNA, Ribosomal, 16S/chemistry , RNA, Ribosomal, 16S/genetics , Thermus thermophilus/genetics , Thermus thermophilus/metabolism
14.
Mol Biol Cell ; 12(5): 1481-98, 2001 May.
Article in English | MEDLINE | ID: mdl-11359937

ABSTRACT

To quantitatively investigate the trafficking of the transmembrane lectin VIP36 and its relation to cargo-containing transport carriers (TCs), we analyzed a C-terminal fluorescent-protein (FP) fusion, VIP36-SP-FP. When expressed at moderate levels, VIP36-SP-FP localized to the endoplasmic reticulum, Golgi apparatus, and intermediate transport structures, and colocalized with epitope-tagged VIP36. Temperature shift and pharmacological experiments indicated VIP36-SP-FP recycled in the early secretory pathway, exhibiting trafficking representative of a class of transmembrane cargo receptors, including the closely related lectin ERGIC53. VIP36-SP-FP trafficking structures comprised tubules and globular elements, which translocated in a saltatory manner. Simultaneous visualization of anterograde secretory cargo and VIP36-SP-FP indicated that the globular structures were pre-Golgi carriers, and that VIP36-SP-FP segregated from cargo within the Golgi and was not included in post-Golgi TCs. Organelle-specific bleach experiments directly measured the exchange of VIP36-SP-FP between the Golgi and endoplasmic reticulum (ER). Fitting a two-compartment model to the recovery data predicted first order rate constants of 1.22 +/- 0.44%/min for ER --> Golgi, and 7.68 +/- 1.94%/min for Golgi --> ER transport, revealing a half-time of 113 +/- 70 min for leaving the ER and 1.67 +/- 0.45 min for leaving the Golgi, and accounting for the measured steady-state distribution of VIP36-SP-FP (13% Golgi/87% ER). Perturbing transport with AlF(4)(-) treatment altered VIP36-SP-GFP distribution and changed the rate constants. The parameters of the model suggest that relatively small differences in the first order rate constants, perhaps manifested in subtle differences in the tendency to enter distinct TCs, result in large differences in the steady-state localization of secretory components.


Subject(s)
Carrier Proteins/metabolism , Endoplasmic Reticulum/metabolism , Golgi Apparatus/metabolism , Mannose-Binding Lectins , Membrane Proteins/metabolism , Membrane Transport Proteins , Protein Transport , Secretory Vesicles/metabolism , Animals , Biomarkers , Brefeldin A/pharmacology , COS Cells , Cycloheximide/pharmacology , Humans , Kinetics , Luminescent Proteins/metabolism , Microscopy, Confocal , Microscopy, Video , Protein Synthesis Inhibitors/pharmacology , Protein Transport/drug effects , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Secretory Vesicles/chemistry , Time Factors
15.
FEBS Lett ; 495(3): 167-71, 2001 Apr 27.
Article in English | MEDLINE | ID: mdl-11334885

ABSTRACT

Sequence determinants and structural features of the RNA govern mRNA-ribosome interaction in bacteria. However, ribosomal recruitment to leaderless mRNAs, which start directly with the AUG start codon and do not bear a Shine-Dalgarno sequence like canonical mRNAs, does not appear to rely on 16S rRNA-mRNA interactions. Here, we have studied the effects of translation initiation factors IF2 and IF3 on 30S initiation at a 5'-terminal AUG and at a competing downstream canonical ribosome binding site. We show that IF2 affects the forward kinetics of 30S initiation complex formation at the 5'-terminal AUG as well as the stability of these complexes. Moreover, the IF2:IF3 molar ratio was found to play a decisive role in translation initiation of a leaderless mRNA both in vitro and in vivo indicating that the translational efficiency of an mRNA is not only intrinsically determined but can be altered depending on the availability of components of the translational machinery.


Subject(s)
Codon, Initiator , Peptide Initiation Factors/pharmacology , Protein Biosynthesis , Ribosomes/metabolism , Escherichia coli/genetics , Eukaryotic Initiation Factor-3 , Genes, Reporter , Macromolecular Substances , Peptide Initiation Factors/metabolism , Prokaryotic Initiation Factor-2 , RNA, Transfer, Met/metabolism , Transformation, Genetic
16.
Nature ; 409(6820): 630-3, 2001 Feb 01.
Article in English | MEDLINE | ID: mdl-11214323

ABSTRACT

Cell divisions that create daughter cells of different sizes are crucial for the generation of cell diversity during animal development. In such asymmetric divisions, the mitotic spindle must be asymmetrically positioned at the end of anaphase. The mechanisms by which cell polarity translates to asymmetric spindle positioning remain unclear. Here we examine the nature of the forces governing asymmetric spindle positioning in the single-cell-stage Caenorhabditis elegans embryo. To reveal the forces that act on each spindle pole, we removed the central spindle in living embryos either physically with an ultraviolet laser microbeam, or genetically by RNA-mediated interference of a kinesin. We show that pulling forces external to the spindle act on the two spindle poles. A stronger net force acts on the posterior pole, thereby explaining the overall posterior displacement seen in wild-type embryos. We also show that the net force acting on each spindle pole is under control of the par genes that are required for cell polarity along the anterior-posterior embryonic axis. Finally, we discuss simple mathematical models that describe the main features of spindle pole behaviour. Our work suggests a mechanism for generating asymmetry in spindle positioning by varying the net pulling force that acts on each spindle pole, thus allowing for the generation of daughter cells with different sizes.


Subject(s)
Caenorhabditis elegans/embryology , Cell Polarity , Spindle Apparatus/physiology , Animals , Biomechanical Phenomena , Caenorhabditis elegans/cytology , Cell Division , Embryo, Nonmammalian/cytology , Embryo, Nonmammalian/physiology , Models, Biological
17.
Antimicrob Agents Chemother ; 44(12): 3278-84, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11083627

ABSTRACT

beta-L-5-Iododioxolane uracil was shown to have potent anti-Epstein-Barr virus (EBV) activity (50% effective concentration = 0.03 microM) with low cytotoxicity (50% cytotoxic concentration = 1,000 microM). It exerts its antiviral activity by suppressing replicative EBV DNA and viral protein synthesis. This compound is phosphorylated in cells where the EBV is replicating but not in cells where the EBV is latent. EBV-specific thymidine kinase could phosphorylate beta-L-5-iododioxolane uracil to the monophosphate metabolite. The K(m) of beta-L-5-iododioxolane uracil with EBV thymidine kinase was estimated to be 5.5 microM, which is similar to that obtained with thymidine but about fivefold higher than that obtained with 2' fluoro-5-methyl-beta-L-arabinofuranosyl uracil, the first L-nucleoside analogue discovered to have anti-EBV activity. The relative V(max) is seven times higher than that of thymidine. The anti-EBV activity of beta-L-5-iododioxolane uracil and its intracellular phosphorylation could be inhibited by 5'-ethynylthymidine, a potent EBV thymidine kinase inhibitor. The present study suggests that beta-L-5-iododioxolane uracil exerts its action after phosphorylation; therefore, EBV thymidine kinase is critical for the antiviral action of this drug.


Subject(s)
Antiviral Agents/pharmacology , Dioxolanes/pharmacology , Herpesvirus 4, Human/drug effects , Thymidine Kinase/metabolism , Thymidine/analogs & derivatives , Uracil/pharmacology , Antiviral Agents/metabolism , Dioxolanes/metabolism , Drug Interactions , Enzyme Inhibitors/pharmacology , Humans , Substrate Specificity , Thymidine/pharmacology , Thymidine Kinase/antagonists & inhibitors , Tumor Cells, Cultured , Uracil/analogs & derivatives , Uracil/metabolism , Virus Replication/drug effects
18.
Mol Pharmacol ; 58(5): 1109-14, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11040060

ABSTRACT

A nonnaturally occurring L-configuration nucleoside analog, L-beta-5-bromovinyl-(2-hydroxymethyl)-1,3-(dioxolanyl)uracil (L-BVOddU) selectively inhibited varicella-zoster virus growth in human embryonic lung (HEL) 299 cell culture with an EC(50) of 0.055 microM, whereas no inhibition of CEM and HEL 299 cell growth or mitochondrial DNA synthesis was observed at concentrations up to 200 microM. L-BVOddU was phosphorylated by viral thymidine kinase but not by human cytosolic thymidine kinase, and the antiviral activity of this compound is dependent on the viral thymidine kinase. Unlike other D-configuration bromovinyl deoxyuridine analogs, such as E-5-(2-bromovinyl)-2'-deoxyuridine and 1-beta-arabinofuranosyl-E-5-(2-bromovinyl)uracil, this compound was metabolized only to its monophosphate metabolite. The di- or triphosphate metabolites were not detected. This suggested that the inhibitory mechanism may be unique and different from other anti-herpesvirus nucleoside analogs.


Subject(s)
Antiviral Agents/pharmacology , Herpesvirus 3, Human/drug effects , Nucleosides/pharmacology , Prodrugs/metabolism , Thymidine Kinase/metabolism , Uracil/pharmacology , Acyclovir/metabolism , Acyclovir/pharmacology , Antiviral Agents/metabolism , Cells, Cultured , Herpesvirus 3, Human/enzymology , Humans , Kinetics , Nucleosides/metabolism , Phosphorylation , Uracil/analogs & derivatives , Uracil/metabolism
19.
EMBO J ; 19(15): 4101-10, 2000 Aug 01.
Article in English | MEDLINE | ID: mdl-10921890

ABSTRACT

Translation initiation in bacteria involves a stochastic binding mechanism in which the 30S ribosomal subunit first binds either to mRNA or to initiator tRNA, fMet-tRNA(f)(Met). Leaderless lambda cI mRNA did not form a binary complex with 30S ribosomes, which argues against the view that ribosomal recruitment signals other than a 5'-terminal start codon are essential for translation initiation of these mRNAs. We show that, in Escherichia coli, translation initiation factor 2 (IF2) selectively stimulates translation of lambda cI mRNA in vivo and in vitro. These experiments suggest that the start codon of leaderless mRNAs is recognized by a 30S-fMet-tRNA(f)(Met)-IF2 complex, an intermediate equivalent to that obligatorily formed during translation initiation in eukaryotes. We further show that leaderless lambda cI mRNA is faithfully translated in vitro in both archaebacterial and eukaryotic translation systems. This suggests that translation of leaderless mRNAs reflects a fundamental capability of the translational apparatus of all three domains of life and lends support to the hypothesis that the translation initiation pathway is universally conserved.


Subject(s)
Biological Evolution , DNA-Binding Proteins , Peptide Chain Initiation, Translational , Peptide Initiation Factors/metabolism , RNA, Messenger/metabolism , Ribosomes/metabolism , 3' Untranslated Regions , Animals , Bacterial Outer Membrane Proteins/genetics , Binding, Competitive , Codon, Initiator , Models, Genetic , Prokaryotic Initiation Factor-2 , RNA, Transfer, Met/metabolism , Rabbits , Repressor Proteins/genetics , Reticulocytes/metabolism , Sulfolobus/genetics , Viral Proteins , Viral Regulatory and Accessory Proteins
20.
J Med Chem ; 43(13): 2538-46, 2000 Jun 29.
Article in English | MEDLINE | ID: mdl-10891113

ABSTRACT

A series of (E)-5-(2-bromovinyl)uracil analogues and related nucleosides was synthesized, and their antiviral activities were evaluated. (E)-5-(2-Bromovinyl)-2'-deoxy-L-uridine (L-BVDU, 2), 1-(beta-L-arabinofuranosyl)-(E)-5-(2-bromovinyl)uracil (L-BVAU, 4), (E)-5-(2-bromovinyl)-1-(2-deoxy-2-fluoro-beta-L-ribofuranosyl)uracil (L-FBVRU, 8) and (E)-5-(2-bromovinyl)-1-(2-deoxy-2-fluoro-beta-L-arabinofuranosyl)urac il (L-FBVAU, 10) were synthesized via appropriate 5-iodouracil analogues from L-arabinose. D- and L-Oxathiolane and -dioxolane derivatives 13, 16, 20, 21, and 29-34 were prepared by glycosylation reaction of the oxathiolane and dioxolane intermediates with silylated uracil analogues using TMSI as the coupling agent. The synthesized compounds were evaluated in cell cultures infected with the following viruses: varicella zoster virus (VZV), Epstein Barr virus (EBV), and herpes simplex virus types 1 and 2 (HSV-1 and HSV-2). Among the tested compounds, beta-L-CV-OddU (29), beta-L-BV-OddU (31), and beta-L-IV-OddU (33) exhibited potent in vitro antiviral activity against VZV with EC(50) values of 0.15, 0. 07, and 0.035 microM, respectively, and against EBV with EC(50) values of 0.49, 0.59, and 3.91 microM, respectively.


Subject(s)
Antiviral Agents/chemical synthesis , Dioxolanes/chemical synthesis , Herpesviridae/drug effects , Pyrimidine Nucleosides/chemical synthesis , Uracil/analogs & derivatives , Uracil/chemical synthesis , Vinyl Compounds/chemical synthesis , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Cell Division/drug effects , Cell Line , Dioxolanes/chemistry , Dioxolanes/pharmacology , Herpesvirus 1, Human/drug effects , Herpesvirus 2, Human/drug effects , Herpesvirus 3, Human/drug effects , Herpesvirus 4, Human/drug effects , Humans , Pyrimidine Nucleosides/chemistry , Pyrimidine Nucleosides/pharmacology , Structure-Activity Relationship , Uracil/chemistry , Uracil/pharmacology , Vinyl Compounds/chemistry , Vinyl Compounds/pharmacology
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