Based on dynamical systems theory, we propose a mechanism for cell differentiation with regulation of populations of each cell type by taking simple cell models with gene expression dynamics. By incorporating several interaction kinetics, we found that the cell models with a single intracellular positive-feedback loop exhibit a cell fate switching, with a change in the total number of cells. The number of a given cell type or the population ratio of each cell type is preserved against the change in the total number of cells, depending on the form of cell-cell interaction. The differentiation is a result of

bifurcation of cell states via the intercellular Selleck Ro 61-8048 interactions, while the population regulation is explained

by self-consistent determination of the bifurcation parameter through cell-cell interactions. The relevance of this mechanism to development and differentiation in several multicellular systems is discussed. (C) 2008 Elsevier Ltd. All rights reserved.”
“The increasing incidence of melanoma and the lack of effective therapy have prompted the development of new vectors, more specific to the pigmented tumor, for early detection and treatment. Targeted agents have to exhibit a rapid, high tumor uptake, long tumor retention and rapid clearance from nontarget organs. This PSI-7977 joint work presents results obtained with a new melanoma targeting agent, [I-125]-N-(4-dipropylaminobutyl)-4-iodobenzamide or [I-125]BZ18. After labeling with a high specific

activity, the biodistribution of the compound was investigated in two animal models, the mouse and the sheep. Melanotic tumor retention was observed lasting several days. We visualized the internalization of the agent inside the melanosomes by secondary ion mass spectroscopy imaging, we measured the affinity constants of [I-125] BZ18 on a synthetic melanin model and we demonstrated a radiotoxic effect of this labeled agent on B16F0 melanoma cell Culture due to its cellular Rolziracetam internalization.

From this work, [I-125]BZ 18 appeared a promising rnelanorna targeting agent in the nuclear medicine field. (C) 2008 Elsevier Inc. All rights reserved.”
“A previously introduced degenerate diffusion-reaction model of biofilm growth and disinfection is extended to account for convective transport of oxygen and disinfectants in an aqueous environment. To achieve this in a computationally efficient manner we employ a thin-film approximation to the (Navier)-Stokes equations that can be solved analytically. In numerical experiments, we investigate how the convective transport of nutrients and disinfectants due to bulk flow hydrodynamics affects the balance between growth and disinfection processes. It is found that the development of biofilms can be significantly affected by the flow field even at extremely low Reynolds numbers.

9; 95% confidence interval, 1.01-8.52; P <

.001). The serum ET-1 level at 12 months was diagnostic for BOS (odds ratio, 3.9; 95% confidence interval, 1.42-10.80; P = .008).

Conclusions: Elevated serum ET-1 concentrations were predictive of BOS, and the assessment of circulating ET-1 might be beneficial in diagnosing and monitoring BO. (J Thorac Cardiovasc Surg 2010;140:1422-7)”
“Isolation rearing (IR), a well-established rat model of early chronic psychosocial stress, engenders marked behavioral alterations related to changes of dopamine (DA) neurotransmission in cortical and subcortical brain regions. Stress-induced shifts in gamma-aminobutyric acid (GABA)-ergic signaling have been implicated in the dysregulation buy Capmatinib of DA release. The neurosteroid 3 alpha-hydroxy-5 alpha-pregnan-20-one (allo-pregnanolone/AP), synthesized from progesterone by the action of the rate-limiting enzyme 5 alpha-reductase (5AR), is a potent positive allosteric modulator of GABA(A) receptor function. Thus, alterations of 5AR activity/expression may impact upon DA neurotransmission.

We studied the effects of IR on the 5AR expression/function and extracellular concentrations of DA and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the rat nucleus accumbens (NAcc) and medial Geneticin supplier prefrontal cortex (mPFC). Immediately after weaning, male rats were subjected to either IR or social rearing

(SR) conditions for 5-8 weeks. Compared to SR, IR rats exhibited significantly lower protein expression of 5AR isoforms (1 and 2) in both brain regions and reduced brain, but not plasma, content of AP and allotetrahydrodeoxycorticosterone, the 5 alpha-reduced metabolite of deoxycorticosterone. IR-exposed rats also exhibited higher levels of DA and DOPAC in the NAcc shell, but not in mPFC, when compared to SR rats. The 5AR inhibitor finasteride (FIN, 100 mg/kg,

i.p.) enhanced DA and DOPAC content in the NAcc shell Baf-A1 clinical trial of SR, but not IR rats. FIN, however, elicited equivalent increases in DA and DOPAC levels in the mPFC of both groups. These results show that IR induces changes in expression/activity of brain 5AR which, in a brain-region specific manner, may partially underlie the alterations in DA signaling induced by this manipulation.

This article is part of a Special Issue entitled ‘Trends in Neuropharmacology: In Memory of Erminio Costa’. (C) 2011 Elsevier Ltd. All rights reserved.”
“Neurotrophin-3 (NT-3) is produced by astrocytes, in addition to neurons, and monoamine neurotransmitters play a role in controlling NT-3 synthesis. The impact of histamine (HA) on the regulation of NT-3 synthesis in cultured astrocytes has not been studied. We evaluated the involvement of histamine receptors and intracellular mechanisms in the regulation of NT-3 production by HA.

Real-time PCR was performed to examine the expression of all known histamine receptor subtypes in cultured rat cortical astrocytes.

In Aag2 and U4.4 cells, the combined actions of the Dicer-2 and Piwi pathways triggered an efficient antiviral response permitting, among other actions, suppression of NSs filament formation and allowing establishment of persistence. In C6/36 cells, Piwi-mediated RNA interference (RNAi) appeared to be sufficient to mount an antiviral response against a secondary infection with a superinfecting virus. This study provides new insights into the role of Dicer

and Piwi in mosquito antiviral defense and the development of the antiviral response in mosquitoes.”
“Whether or not the use of maladaptive defense style is a trait, as opposed to a state dependent phenomenon, selleck products in panic disorder (PD) is a topic still very much up for debate. The aim of the study was to verify whether PD patients, both before and after treatment, used different defense style than the control group. Sixty-one PD patients (recruited from an original sample of 90 patients) and 64 healthy controls were evaluated against the Structured Clinical Interview for DSM-IV disorders, the Symptoms Check List-90, the Hamilton Rating Scales for Anxiety and for Depression and finally the Defense Style Questionnaire-40 (DSQ). The patients 3MA were treated with paroxetine or citalopram and were evaluated monthly for one year to assess

the remission. The DSQ was re-administered to the patients at the end of the study. Before treatment, PD patients used more Adenosine triphosphate neurotic and immature forms of defense than controls. After treatment, those in remission used the same defense styles as the control group, whereas non-remitters still used more immature defenses. However, all the aforementioned difference disappeared, after excluding the effect of symptom severity. Our data supports the hypothesis

that the use of maladaptive defenses might be the consequence of PD: when subjects fall ill, their capacity to use mature adaptive defenses may diminish, but when they recover their defensive style returns to a greater maturity. The present results are however limited by the dropout rate (one third of patients did not complete the study) and the use of just one questionnaire to evaluate the complexity of defense styles. (C) 2010 Elsevier Ireland Ltd. All rights reserved.”
“Chronic infection by hepatitis C virus (HCV) is a cause of the global burden of liver diseases. HCV entry into hepatocytes is a complicated and multistep process that represents a promising target for antiviral intervention. The recently reported amphipathic alpha-helical virucidal peptide (C5A) from the HCV NS5A protein suggests a new category of antiviral drug candidates. In this study, to identify C5A-like HCV inhibitors, synthetic peptides derived from the C5A-corresponding NS5 protein region of selected Flaviviridae viruses were evaluated for their anti-HCV activities. A peptide from GB virus A (GBV-A), but not other flaviviruses, demonstrated an inhibitory effect on HCV infection.

The mechanisms by which lithium exerts its activity in the central nervous system are not fully clarified: it is hypothesized that lithium

may drive acute molecular events whose activation over time triggers long-lasting modifications in critical neuronal PI3K inhibitor nets. These events are associated with long-lasting changes in the expression profile of genes in neurons that are embedded in these crucial nets. The molecular events that are acutely and chronically triggered by lithium will be reviewed here and matched with the evidence that arises from the pharmacogenetics investigations. Moreover, the pharmacogenetics reports that are not strictly associated with the mechanisms that are thought to be acutely and chronically elicited by lithium will be included in the final part of the paper. Copyright (C) 2010 S. Karger AG, Basel”
“Background Robust evidence to direct management of pregnant women with mild hypertensive disease at term is scarce. We investigated whether induction of labour in women with a singleton pregnancy complicated Epigenetics inhibitor by gestational hypertension or mild pre-eclampsia reduces severe maternal morbidity.

Methods We undertook a multicentre, parallel, open-label randomised controlled trial in six academic and 32 non-academic hospitals in the Netherlands between October, 2005, and March, 2008.

We enrolled patients with a singleton pregnancy at 36-41 weeks gestation, and who had gestational hypertension or mild pre-eclampsia. Participants were randomly allocated in a 1:1 ratio by block randomisation. with a web-based application system

to receive either induction of labour or expectant monitoring. Masking of intervention allocation was not possible. The primary outcome was a composite measure of poor maternal outcome-maternal mortality, maternal morbidity (eclampsia, HELLP syndrome, pulmonary oedema, thromboembolic disease, and placental abruption), progression to severe hypertension or proteinuria, and major post-partum haemorrhage (>1000 ml, blood loss). Analysis was by intention to treat and treatment effect is presented as relative risk. This study is registered, number ISRCTN08132825.

Findings 756 patients were allocated to receive induction of Tyrosine-protein kinase BLK labour (n=377 patients) or expectant monitoring (n=379). 397 patients refused randomisation but authorised use of their medical records. Of women who were randomised, 117 (31%) allocated to induction of labour developed poor maternal outcome compared with 166 (44%) allocated to expectant monitoring (relative risk 0.71, 95% CI 0.59-0.86, p<0.0001). No cases of maternal or neonatal death or eclampsia were recorded.

Interpretation Induction of labour is associated with improved maternal outcome and should be advised for women with mild hypertensive disease beyond 37 weeks’ gestation.

Funding ZonMw.”
“For more than half a decade, lithium has been successfully used to treat bipolar disorder. Worldwide, it is considered the first-line mood stabilizer.

These findings suggest that phonology is activated automatically for both high- and low-frequency words during Chinese sentence reading, even when the task is not focused on pronunciation. Crown Copyright (C) 2009 Published by Elsevier Ltd on behalf of IBRO. All rights

reserved.”
“We evaluated the effects or the 3 cognitive interventions fielded in the Advanced Cognitive Training for Independent and Vital Elderly study on 2 subsets of participants-1,606 without and 424 with suspected clinical depression at baseline. In the former group, only the speed of processing (vs. no-contact control) intervention had a significant effect, with its participants GSK2126458 being 38% less likely to develop suspected clinical depression at I year (adjusted odds ratio = 0.62;p <.01). None of the interventions had a significant effect on recovery from suspected clinical depression in the latter group. Although the etiological mechanism of the speed of processing’s protective effect was not isolated, it may result from successful adaptation to age-related changes through selective optimization with compensation.”
“We examined the

roles of inertial (e(3)), shoulder-centre of mass (SH-CM) and shoulder-elbow articular (SH-EL) rotation axes in the non-visual control of unconstrained 3D arm rotations. Subjects rotated the arm in elbow configurations that yielded either a constant or variable separation between these axes. We hypothesized that increasing the motion SRT1720 ic50 frequency and the task complexity would result in the limbs’ rotational axis to correspond to e(3) in order to minimize rotational resistances. Results showed two velocity-dependent profiles wherein the rotation axis coincided with the SH-EL axis for S and I velocities and then in the IF velocity shifted filipin to either a SH-CM/e(3) trade-off axis for one profile, or to no preferential axis for the other. A third profile was velocity-independent,

with the SH-CM/e(3) trade-off axis being adopted. Our results are the first to provide evidence that the rotational axis of a multi-articulated limb may change from a geometrical axis of rotation to a mass or inertia based axis as motion frequency increases. These findings are discussed within the framework of the minimum inertia tensor model (MIT), which shows that rotations about e(3) reduce the amount of joint muscle torque that must be produced by employing the interaction torque to assist movement. (C) 2009 IBRO. Published by Elsevier Ltd. All rights reserved.”
“Associations between health, control beliefs, and well-being in later life are frequently conceptualized in terms of the characteristics of individuals. However, spousal interdependencies in psychosocial characteristics are also likely to be relevant for well-being.

5 +/- 1.6 years). The blood titers of PAA were evaluated using an optimized ELISA test, expressed by a linear optical density (OD) scale. The blood samples of all participants were tested anonymously and were scored under a code number. A test recording above 1.4 OD units was predefined as positive. Results: The titers of PAA of children with schizophrenia (1.9 +/- 0.5 OD units, range: 0.7-2.44 units) were significantly selleck chemicals llc (p < 0.00001) higher than

those of the control group (1.0 +/- 0.4 OD units, range: 0.45-2.28 units). In 83% of the children with schizophrenia (24 out of the 29 patients) a positive test, i.e. OD >1.4, was detected. In contrast, in the control group, only 12% (3 of the 25 subjects) displayed a positive test, p < 0.00001. Conclusions: High titers of PAA in children with schizophrenia as compared with nonpsychotic controls may indicate an active autoimmune process in the early onset of schizophrenia. The PAA level may therefore provide a supportive diagnostic biomarker for childhood schizophrenia. Copyright (C) 2013 S. Karger AG, Basel”
“Prepulse inhibition (PPI) of startle is a measure of sensorimotor gating that is heritable and

JSH-23 concentration deficient in certain psychiatric disorders, including schizophrenia. Sprague-Dawley (SD) rats are more sensitive to PPI disruptive effects of dopamine (DA) agonists at long interstimulus intervals (60-120 ms) and less sensitive to their PPI-enhancing effects at short (10-30 ms), compared with Long-Evans (LE) rats. These heritable strain differences in sensitivity to the PPI disruptive effects of DA agonists must ultimately reflect neural changes “”downstream”" from forebrain DA receptors.

The current study evaluated the effects of the DA agonist, apomorphine (APO), on ventral pallidal (VP) gamma-aminobutyric acid (GABA) and glutamate efflux

and PPI in SD and LE rats.

PPI was tested in SD and LE rats after vehicle or APO (0.5 mg/kg, subcutaneously (s.c.)) in a within-subject design. In different SD and GNAT2 LE rats, VP dialysate was collected every 10 min for 120 min after vehicle or APO (0.5 mg/kg, s.c.) and analyzed for GABA and glutamate content by capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF).

As predicted, SD rats exhibited greater APO-induced PPI deficits at long intervals and less APO-induced PPI enhancement at short intervals compared to LE rats. APO significantly reduced VP GABA efflux in SD but not in LE rats; glutamate efflux was unaffected in both strains.

Heritable strain differences in PPI APO sensitivity in SD vs LE rats parallel, and may be mediated by, strain differences in the VP GABA efflux.”
“Feline infectious peritonitis is one of the most severe devastating diseases of the Felidae. Upon the appearance of clinical signs, a cure for the infected animal is impossible.

1 mg/ml) for 30 min. Evans blue dye leakage into the trachea induced by gaseous formaldehyde or

intravenous capsaicin was measured as an index of tachykinin NK1 receptor-mediated vascular permeability. Expression of substance P-immunoreactive nerves, tachykinin NK1 receptors, tumor necrosis factor (TNF)-alpha and NGF in the trachea was also Oligomycin A mw assessed immunohistochemically. Neurogenic plasma leakage in the trachea increased significantly between 7 and 21 days after LPS inhalation. Expression of TNF-alpha, NGF, substance P-immunoreactive nerves and tachykinin NK1 receptors was enhanced, peaking at 28 h, 7 days, 14 days and 14 days after LPS inhalation, respectively. Pretreatment with infliximab, a blocking antibody for TNF-alpha, almost completely abolished the airway changes seen after LPS inhalation. In conclusion, inhaled LPS increased innervation of sensory C-fibers and expression of tachykinin NK1 receptors in the airway, probably resulting in enhancement of neurogenic airway inflammation. These airway responses may be caused by overproduction of neurotrophins including NGF, mainly through a TNF-alpha-mediated pathway. ABT263 (C) 2011 Elsevier Inc. All rights reserved.”
“Objective: The mechanism of postangioplasty restenosis remains poorly understood. Low molecular weight (LMW) heparin has

been shown to inhibit the proliferation of vascular smooth muscle cells (VSMCs), which is the principal characteristic of restenosis. Studies have

shown that LMW heparin could bind to CD44. We hypothesized that LMW heparin might modulate CD44 expression thereby decreasing vascular remodeling.

Methods: Vascular remodeling was induced in CD44(+/+) and CD44(-/-) mice and treated with LMW heparin. The arteries were harvested for histologic assessment and determination of CD44 expression. Bone marrow transplantation was introduced Idelalisib cost to further explore the role and functional sites of CD44. Effects of LMW heparin on growth capacity, CD44 expression were further studied using the cultured mouse VSMCs.

Results: Transluminal injury induced remarkable remodeling in mouse femoral artery (sham wall thickness percentage [WT%]: 3.4 +/- 1.2% vs injury WT%: 31.8 +/- 4.7%; P < .001). LMW heparin reduced the remodeling significantly (WT%: 17.8 +/- 3.5%, P < .005). CD44(-/-) mice demonstrated considerably thicker arterial wall remodeling (WT%: 46.2 +/- 7.6%, P = .0035), and CD44-chimeric mice exhibited equal contributions of the local and circulating CD44 signal to the neointima formation. LMW heparin markedly upregulated CD44 expression in the injured femoral arteries. In vitro, LMW heparin decreased mouse VSMC growth capacity and upregulated its CD44 expression simultaneously in a dose-dependent and time-dependent manner, which could be partially blocked by CD44 inhibitor.

Conclusions: LMW heparin inhibits injury-induced femoral artery remodeling, at least partially, by upregulating CD44 expression.

Stroke patients with VaD have RO4929097 cost smaller caudate nuclei compared to those without dementia and healthy controls, with the stroke-only patients being intermediate in their caudate volume status There was preliminary evidence

of negative correlation of caudate volume with volume of deep WMH and total stroke volume, suggesting cerebrovascular disease contributes to caudate atrophy. which, in turn may disrupt fronto-subcortical circuits (C) 2009 Elsevier Ireland Ltd. All rights reserved.”
“Bone pain is one of the most common complications in cancer patients with bone metastases, and has the most significant impact on quality of life for patients. Patients with bone cancer pain may be difficult to treat due to the poor understanding of the mechanisms; therefore, selleck chemicals the mechanisms of bone cancer pain required elucidation for developing new therapeutics. Recent studies show that SCN7A/Nax channel serves as a sodium-level sensor of the body fluid that controls the Na-intake behavior by changing

the excitability of neurons. In the current study, the expression of SCN7A/Nax and the excitability of primary sensory neurons in bone cancer pain rats were examined. The analgesic effects of knockdown SCN7A/Nax channel using RNAi lentivirus intrathecal treatment were evaluated with a behavioral test. The results showed that implantation of sarcoma induced ongoing and movement-evoked pain behaviors, whereas SCN7A/Nax knockdown prevented the onset of these hyperalgesia. Immunohistochemistry showed that SCN7A/Nax was located in the medium- to large-sized neurons in dorsal root ganglions (DRGs). The proportion of SCN7A/Nax-positive cells was significantly increased in DRGs ipsilateral to sarcoma implantation. Immunostaining results were further confirmed by Western blot and MRIP real time-polymerase chain reaction (RT-PCR) analyses. Recording from primary sensory neurons in excised rat dorsal root ganglias, we found that most of SCN7A/Nax-positive neurons exhibited subthreshold oscillations, depolarized resting membrane potential and more negative threshold of action

potential. These electrophysiological changes of neurons increased ectopic spike discharge which was thought to be an important generator of chronic pain, however, the hyperexcitability was completely reversed by SCN7A/Nax knockdown. These results demonstrate that enhanced expression of SCN7A/Nax channel within distinct subpopulation of DRG neurons contributes to bone cancer pain by increasing the excitability of these neurons. These findings may lead to novel strategies for the treatment of bone cancer pain. (C) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.”
“About 10% of patients with essential thrombocythemia (ET) or myelofibrosis (MF) that lack mutations in JAK2 harbor an activating mutation in the thrombopoietin receptor, MPLW515L.

Treatment of rats with a NADPH oxidase inhibitor (apocynin) for 7 days prior to induction of status epilepticus was effective in decreasing both ROS production (by an average of 20%) and neurodegeneration (by an average of 61%). These results suggest an

involvement of ROS generated by NADPH oxidase in neuronal death in the pilocarpine model of epilepsy. check details (C) 2010 Elsevier Ireland Ltd. All rights reserved.”
“During primary infection, the number of HIV-1 particles in plasma increases rapidly, reaches a peak, and then declines until it reaches a set point level. Understanding the kinetics of primary infection, and its effect on the establishment of chronic infection, is important in defining the early pathogenesis of HIV. We studied the viral dynamics of very early HIV-1 infection in 47 subjects identified through plasma donation screening. We calculated how fast the viral LDN-193189 price load increases and how variable this parameter is among individuals. We also estimated the basic reproductive ratio, the number of new infected cells generated by an infectious cell at the start of infection when target cells are not limiting. The initial viral doubling time had a median of 0.65 days with an interquartile range of 0.56 to 0.91 days. The median basic reproductive ratio was 8.0 with an interquartile range of 4.9 to 11. In 15 patients,

we also observed the postpeak decay of plasma virus and found that the virus decay occurred at a median rate of 0.60 day(-1), corresponding to a half-life of 1.2 days. The median peak viral load was 5.8 log(10) HIV-1 RNA copies/ml, and it was reached 14 days after the virus was quantifiable with an assay, with a lower limit of detection of 50 copies/ml. These results characterize

the early plasma viral dynamics in acute HIV infection better than it has been possible thus far. They also better define the challenge that the immune response (or therapeutic intervention) has to overcome to defeat HIV at this early stage.”
“Nitric oxide (NO) is considered to be a key mediator in the pathophysiology of migraine but the localisation of NO synthesizing enzymes (NOS) throughout the pain pathways involved in migraine has not yet been fully investigated. We have used quantitative real-time PCR this website and Western blotting to measure the respective levels of mRNA and protein for nNOS and eNOS in peripheral and central tissues involved in migraine pain: dura mater, pial arteries, trigeminal ganglion (TG) trigeminal nucleus caudalis (TNC), periaqueductal grey (PAG), thalamus, hypothalamus, cortex, pituitary gland, hippocampus and cerebellum. iNOS was excluded from the present study because it was not induced. In the trigeminal vascular system we found the highest expression of nNOS mRNA in pial arteries. However, protein expression of nNOS was maximum in TNC. Among other brain structures, nNOS mRNA and protein expression was remarkably higher in the cerebellum than in any other tissues.

45) in the right hemisphere. Standardized low-resolution electromagnetic tomography analysis (sLORETA) revealed that children with DD rely more on right temporo-parietal brain areas compared to children without DD. Furthermore, in order to rule out that earlier deficient processes might influence the group differences found in the N300, we analyzed the

N170 for group differences. We did not find significant differences between children without DD and children with DD. In conclusion the results suggest deficient integration of orthographic and selleck kinase inhibitor phonological representations in dyslexia, as indexed by the N300, and further highlight how this activity is relevant for fluent reading. (C) 2012 Elsevier Ltd. All rights reserved.”
“Altered sialylation of cell surface glycoproteins and glycolipids is closely related to the malignant phenotype of cancer cells, including the metastatic potential and invasiveness. Many cancer-related antigens in clinical use contain sialic acids at the terminal position of sugar chains in the molecules. To elucidate the molecular mechanism, we focused our investigation on sialidase, which catalyzes the removal of sialic acid residues from the glycoconjugates. Four types of human sialidases identified to date behave in different manners during carcinogenesis. One of the sialidases, found in

the lysosomes, showed downregulation in cancers, promoting anchorage-independent growth, and metastatic ability, while another, found in the plasma membrane, Saracatinib showed marked upregulation, causing apoptosis suppression. It was found that estimation of the mRNA levels of sialidases by real-time PCR allowed discrimination of cancerous from noncancerous tissues and even determination of the pathological stage in some cancers. Immuno-histochemistry of cancer tissues using the antibody against the plasma membrane sialidase was useful for clinical diagnosis. This paper briefly summarizes our findings of the altered

sialidase expression in Fossariinae cancers and the possibility of their clinical application as cancer markers. Human sialidases are indeed related to malignancy and may be potential targets for cancer diagnosis and therapy.”
“During collective movement, animals display a wide variety of mechanisms to maintain cohesion. In some species, individuals rely mainly on following their direct predecessor, thereby forming spectacular processions of individuals in single file. Despite being the simplest case of following behaviour, it is largely absent from the theoretical literature on collective migrations. The objective of this study is to quantify the efficiency of following the predecessor, in terms of ensuring cohesion. The situation we consider is a sequence of individuals facing a bifurcation. The choice between left and right is influenced by the choice of the predecessor. First, we model this situation with a two-state Markov chain with a symmetric transition matrix.