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Boosting algorithms, especially AdaBoost, have attracted great attention in computer vision. In the early version of boosting algorithms, the weak classifier selection and the strong classifier learning are linked together. It has been demonstrated that decoupling of these two processes can provide more flexibility for training a better classifier. In these studies, linear discriminant analysis (LDA) has been adopted to select weak classifiers independently based on class separability rather than a training error that occurs normally in AdaBoost. It is observed that LDA is successful only if a large number of labeled training samples is available. However, a large-scale labeled training set is not always available in many computer vision applications such as object classification. To tackle this problem, this paper proposes semisupervised subspace learning combined with a boosting framework for object classification, through which unlabeled data can participate in the boosting training to compensate for the lack of enough labeled data. With the proposed framework, this paper develops three various approaches that utilize unlabeled data in different ways. According to the experiments on several public image data sets, the proposed methods achieve superior performance over AdaBoost and existing semisupervised algorithms. [ABSTRACT FROM PUBLISHER]

Nonmuscle myosin light-chain kinase (MYLK) mediates increased lung vascular endothelial permeability in lipopolysaccharide-induced lung inflammatory injury, the chief cause of the acute respiratory distress syndrome. In a lung injury model, we demonstrate here that MYLK was also essential for neutrophil transmigration, but that this function was mostly independent of myosin II regulatory light chain, the only known substrate of MYLK. Instead, MYLK in neutrophils was required for the recruitment and activation of the tyrosine kinase Pyk2, which mediated full activation of β2 integrins. Our results demonstrate that MYLK-mediated activation of β2 integrins through Pyk2 links β2 integrin signaling to the actin motile machinery of neutrophils. [ABSTRACT FROM AUTHOR]

ABSTRACT To tackle the challenge of non‐destructively analyzing complex oxide layers formed by atmospheric corrosion on active metals, we investigate the potential of inverse spatially offset Raman spectroscopy (inverse‐SORS) to detect corrosion products and elucidate how the spectroscopic features of SORS vary. This study explores the utilization of inverse‐SORS technology for longitudinal structural analysis of opaque CeO2/La2O3 laminates, which serve as a proxy for corrosion products. Through a combination of experimental measurements and Monte Carlo simulation, it demonstrates the feasibility of inverse‐SORS in non‐destructively elucidating the layered structure of these laminates. With increasing the spatial offset of this technology, the Raman intensity ratio of La2O3‐to‐CeO2 increases from 0.23 to 3.2 and then decreases to 0.27 for the CeO2/La2O3 sample with a 34‐μm‐thick CeO2 layer under 532‐nm excitation, whereas the bottom La2O3 layer is hardly detected when the thickness of the upper La2O3 layer increases to 225 μm. The results reveal that a thinner CeO2 layer facilitates the escape and detection of Raman signals originating from the bottom La2O3 layer, leading to an enhanced La2O3‐to‐CeO2 signal ratio and a reduced offset at the characteristic peak. The research also sheds light on the intricate interplay among multiple variables, such as spatial offset, laser wavelength, the corresponding absorption factor, the thickness of the oxide layer, and the compactness. These insights suggest that SORS is a valuable and non‐destructive approach for dissecting the structures of highly turbid composites of metallic compounds and semi‐quantitatively deducing their thickness. [ABSTRACT FROM AUTHOR]

Objective: Leukocyte parameters are associated with cardiovascular diseases. The aim of the present study was to investigate the role of leukocyte parameters in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI) with high thrombus burden (HTB)., Methods: A total of 102 consecutive STEMI patients with HTB who underwent PPCI within 12 h from the onset of symptoms between June 2020 and September 2021 were enrolled in this study. In addition, 101 age- and sex-matched STEMI patients with low thrombus burden (LTB) who underwent PPCI within 12 h from the onset of symptoms were enrolled as controls. Leukocyte parameters, such as neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and monocyte to lymphocyte ratio (MLR), were calculated at the time of admission., Results: The value of NLR and MLR were significantly higher in the HTB group than in the LTB group (6.24 ± 4.87 vs. 4.65 ± 3.47, p  = 0.008; 0.40 ± 0.27 vs. 0.33 ± 0.20, p  = 0.038). A cutoff value of >5.38 for NLR had a sensitivity and specificity of 53.9% and 74.3%, respectively, and MLR >0.29 had a sensitivity and specificity of 60.8% and 55.4%, respectively, for determining the STEMI patients with HTB [area under the receiver operating characteristic curve (AUC): 0.603, 95% confidence interval (CI): 0.524-0.681, p  = 0.012; AUC: 0.578, 95% CI: 0.499-0.656, p  = 0.046]. There was no significant difference of all-cause mortality rate and major adverse cardiac events (MACEs) between the STEMI patients with HTB or with LTB (3.92% in HTB group vs. 2.97% in LTB group, p  = 0.712; 10.78% in HTB group vs. 8.91% in LTB group, p  = 0.215). Compared with the HTB patients in the low NLR group, C-reactive protein, baseline troponin I, baseline brain natriuretic peptide, and leukocyte parameters, such as white blood cell, neutrophil, lymphocyte, NLR, PLR, and MLR, were also significantly higher in the high NLR group in STEMI patients who underwent PPCI with HTB (18.94 ± 19.06 vs. 35.23 ± 52.83, p  = 0.037; 10.99 ± 18.07 vs. 21.37 ± 19.64, p  = 0.007; 199.39 ± 323.67 vs. 430.72 ± 683.59, p  = 0.028; 11.55 ± 3.56 vs. 9.31 ± 2.54, p  = 0.001; 9.77 ± 3.17 vs. 5.79 ± 1.97, p  = 0.000; 1.16 ± 0.44 vs. 2.69 ± 1.23, p  = 0.000; 9.37 ± 4.60 vs 1.31 ± 2.58, p  = 0.000; 200.88 ± 89.90 vs. 97.47 ± 50.99, p  = 0.000; 0.52 ± 0.29 vs. 0.26 ± 0.14, p  = 0.000, respectively). MACEs and heart failure in the high NLR group were significantly higher than that in the low NLR group of STEMI patients who underwent PPCI with HTB (20.45% vs. 4.25%, p  = 0.041; 10.91% vs. 2.13%, p  = 0.038)., Conclusion: The value of NLR and MLR were higher in STEMI patients who underwent PPCI with HTB. In STEMI patients who underwent PPCI with HTB, a raised NLR could effectively predict the occurrence of MACEs and heart failure., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Wang, Li, Yu, Xu and Xu.)

The closed-open digital microfluidic (DMF) system offers a versatile and powerful platform for various applications by combining the advantages of both closed and open structures. The current closed-open DMF system faces challenges in scaling up due to electrode structural differences between closed and open regions. Here we developed an adjustable closed-open DMF platform by utilizing the modified slippery liquid-infused porous surfaces (SLIPS) with asymmetric electrowetting on dielectric (AEWOD) as a hydrophobic dielectric layer. The consistent electrode structures of the bottom printed circuit board (PCB) electrode array on both the closed and open regions, and the utilization of a transparent acrylic with floating potential as the top plate allow a low-cost and easily scalable closed-open DMF system to be achieved. The impacts of applied voltage, parallel plate spacing, electrode switching interval, and electrode driving strategies on various droplet manipulations were investigated. The results show that the optimal plate spacings range from 340-510 μm within the closed region. Meanwhile, we also studied the influence of the thickness, geometry, and position of the top plate on the droplet movement at the closed-open boundary. Through force analysis and experimentation, it is found that a thin top plate and a bevel of ∼4° can effectively facilitate the movement of droplets at the boundary. Finally, we successfully achieved protein staining experiments on this platform and developed a customized smartphone application for the accurate detection of protein concentration. This innovative closed-open DMF system provides new possibilities for future applications in real-time biological sample processing and detection.

Potassium efflux via the two-pore K + channel TWIK2 is a requisite step for the activation of NLRP3 inflammasome, however, it remains unclear how K + efflux is activated in response to select cues. Here, we report that during homeostasis, TWIK2 resides in endosomal compartments. TWIK2 is transported by endosomal fusion to the plasmalemma in response to increased extracellular ATP resulting in the extrusion of K + . We showed that ATP-induced endosomal TWIK2 plasmalemma translocation is regulated by Rab11a. Deleting Rab11a or ATP-ligated purinergic receptor P2X7 each prevented endosomal fusion with the plasmalemma and K + efflux as well as NLRP3 inflammasome activation in macrophages. Adoptive transfer of Rab11a-depleted macrophages into mouse lungs prevented NLRP3 inflammasome activation and inflammatory lung injury. We conclude that Rab11a-mediated endosomal trafficking in macrophages thus regulates TWIK2 localization and activity at the cell surface and the downstream activation of the NLRP3 inflammasome. Results show that endosomal trafficking of TWIK2 to the plasmalemma is a potential therapeutic target in acute or chronic inflammatory states., Competing Interests: LH, MA, JX, BZ, PT, YK, AD, AM No competing interests declared, (© 2023, Huang et al.)

We aimed to explore whether the cuff/arm (C/A) circumference ratio within the suggested range (> 80%) affects the accuracy of mercury cuff blood pressure (BP) measurement (cuff BP) using intrabrachial BP (IABP) as a reference.A total of 253 patients aged 62.42 ± 9.70 years were included. After coronary angiography, the catheter in the right arm was gradually withdrawn toward the cubital fossa, and the IABP was continuously recorded. The cuff BP of the right arm was measured based on the artery blood flow using a special method similar to the traditional mercury method. The cuff was replaced using another C/A ratio after one minute, and the test was performed again. We used three different cuffs for each participant to meet the C/A ratios of 80%-84%, 85%-89%, and 90%-100%. We calculated the percentage deviation degree (DD) between the cuff BP and IABP values: DD = difference/IABP × 100%. The agreement between the values was evaluated using the Bland-Altman method.The IABP values were 138.52 ± 16.89/79.67 ± 9.81 mmHg. The DD of the systolic BP (SBP), with a ratio of 80%-84% (3.06%), was the smallest. The DD of the diastolic BP (DBP) was lowest at a ratio of 85%-89% (2.47%). Men and women had the lowest DD of the SBP at a C/A ratio of 80%-84% and the lowest DD of the DBP at a C/A ratio of 85%-89%. Regardless of whether the participants had coronary heart disease, the DD of the SBP at a C/A ratio of 80%-84% was the lowest, and the DD of the DBP at a C/A ratio of 85%-89% was the lowest.Even in the suggested range of > 80%, when the C/A ratio was 80%-84%, the difference in the SBP between the cuff and IABP was the lowest, but when the C/A ratio was 85%-89%, the difference in the DBP was the lowest.

A flexible adhesive tape decorated with SERS-active silver nanorods (AgNRs) in the form of an array nanostructure is described. The tape was constructed by transferring the AgNRs nanostructures from silicon to the transparent tape by a "paste & peel off" procedure. The transparent, sticky, and flexible properties of commercial tapes allow almost any SERS-inactive irregular surface to be detected in-situ by pasting the SERS tape onto the position to be analyzed. Three examples for an analytical application are presented, viz. determination of (a) tetramethylthiuram disulfide and thiabendazole (two pesticides), (b) colorants in the gel of a writing pen, and (c) the fluorophore Rhodamine B. The tetramethylthiuram disulfide on apple surface was rapidly detected with a LOD of 28.8 ng·cm -2 . The AgNRs effectively quenched the fluorescence of the matrix and fluorophores, this enabling the colorants and Rhodamine B to be identified. The results demonstrated that the SERS tape can be used for versatile in-situ detection. Conceivably, it may find applications in food analysis, non-invasive identification, environmental monitoring, and in other areas of daily life. Graphic abstract A flexible and adhesive SERS active tape decorated with silver nanorods (AgNRs) arrays was constructed through a "paste & peel off" method. It can be used as a versatile in situ analysis platform for various applications.

Sufficient training data normally is required to train deeply learned models. However, due to the expensive manual process for labelling large number of images (i.e., annotation), the amount of available training data (i.e., real data) is always limited. To produce more data for training a deep network, Generative Adversarial Network (GAN) can be used to generate artificial sample data (i.e., generated data). However, the generated data usually does not have annotation labels. To solve this problem, in this paper, we propose a virtual label called Multi-pseudo Regularized Label (MpRL) and assign it to the generated data. With MpRL, the generated data will be used as the supplementary of real training data to train a deep neural network in a semi-supervised learning fashion. To build the corresponding relationship between the real data and generated data, MpRL assigns each generated data a proper virtual label which reflects the likelihood of the affiliation of the generated data to predefined training classes in the real data domain. Unlike the traditional label which usually is a single integral number, the virtual label proposed in this work is a set of weight-based values each individual of which is a number in (0,1] called multi-pseudo label and reflects the degree of relation between each generated data to every pre-defined class of real data. A comprehensive evaluation is carried out by adopting two state-of-the-art convolutional neural networks (CNNs) in our experiments to verify the effectiveness of MpRL. Experiments demonstrate that by assigning MpRL to generated data, we can further improve the person re-ID performance on five re-ID datasets, i.e., Market-1501, DukeMTMC-reID, CUHK03, VIPeR, and CUHK01. The proposed method obtains +6.29%, +6.30%, +5.58%, +5.84%, and +3.48% improvements in rank-1 accuracy over a strong CNN baseline on the five datasets respectively, and outperforms state-of-the-art methods.

Long-term heart rate (HR) control is a management strategy for patients with chronic atrial fibrillation (AF). Nevertheless, the optimal target HR of AF patients is debatable. Our aim was to study HR at rest, during, and after a 6-minute walk test (6MWT) in AF patients, compared with controls with sinus rhythm (SR). Consecutive matched patients with AF (n = 186) or SR (n = 172) were recruited, and 6MWT was performed. HRs at rest, during 6MWT, and recovery periods were recorded. All subjects were divided into 5 subgroups (<80 beats/min, 80 to 89 beats/min, 90 to 99 beats/min, 100 to 109 beats/min, and ≥110 beats/min) according to the HR at rest. No statistical difference was observed in baseline HR at rest, between AF and SR groups (p = 0.30). The exercise HR increase percentage was significantly higher in overall AF patients compared with those in SR (40 ± 15% vs 14 ± 7%, p <0.001). Even with similar mean baseline HRs at rest, the 5 AF subgroups all showed significantly higher mean exercise HR, maximal exercise HR, and maximal exercise HR increase percentage compared with their respective SR subgroups, especially the subgroups with HR at rest >90 beats/min. Unlike the SR patients, the 4 AF subgroups with HR >80 beats/min at the fifth minute after 6MWT did not recover to at rest levels. In conclusion, HR increased excessively during 6MWT and HR recovery was delayed after 6MWT in AF patients, especially when HR at rest is >90 beats/min. The optimal initial HR at rest for AF patients should perhaps be <90 beats/min., (Copyright © 2018. Published by Elsevier Inc.)

Objective: To evaluate whether an association exists between an inter-arm systolic blood pressure difference (sIAD) and all-cause and cardiovascular mortality., Methods: We searched for cohort studies that evaluated the association of a sIAD and all-cause or cardiovascular mortality in the electronic databases Medline/PubMed and Embase (August 2014). Random effects models were used to calculate pooled hazard ratios (HRs) and 95% confidence intervals (CIs)., Results: Nine cohort studies (4 prospective and 5 retrospective) enrolling 15,617 participants were included. The pooled HR of all-cause mortality for a sIAD of ≥ 10 mm Hg was 1.53 (95% CI 1.14-2.06), and that for a sIAD of ≥ 15 mm Hg was 1.46 (1.13-1.88). Pooled HRs of cardiovascular mortality were 2.21 (95% CI 1.52-3.21) for a sIAD of ≥ 10mm Hg, and 1.89 (1.32-2.69) for a sIAD of ≥ 15 mm Hg. In the patient-based cohorts including hospital- and diabetes-based cohorts, both sIADs of ≥ 10 and ≥ 15 mm Hg were associated with increased all-cause (pooled HR 1.95, 95% CI 1.01-3.78 and 1.59, 1.06-2.38, respectively) and cardiovascular mortality (pooled HR 2.98, 95% CI 1.88-4.72 and 2.10, 1.07-4.13, respectively). In the community-based cohorts, however, only a sIAD of ≥ 15 mm Hg was associated with increased cardiovascular mortality (pooled HR 1.94, 95 % CI 1.12-3.35)., Conclusions: In the patient populations, a sIAD of ≥ 10 or of ≥ 15 mm Hg could be a useful indictor for increased all-cause and cardiovascular mortality, and a sIAD of ≥ 15 mm Hg might help to predict increased cardiovascular mortality in the community populations., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Objective: This study aimed to investigate the role of inducible costimulatory molecule (ICOS) pathway in the rejection reaction of mice undergoing allogeneic tracheal transplantation., Methods: The bronchus was separated from wide-type (WT) BalB/c mice and transplanted into WT BalB/c mice, C57 mice and icos(-/-) mice to prepare the obliterative bronchiolitis (OB) animal model. The transplanted bronchus was pathologically examined; flow cytometry was done to detect the T cell subsets and activity of the bronchus and spleen of recipient mice., Results: 21 d after transplantation, evident rejection reaction was observed and the proportion of Th2 and Th17 cells increased significantly in the bronchus and spleen in C57 mice receiving allogeneic tracheal transplantation when compared with mice with autologous transplantation, but the proportion of Treg cells was comparable between them. When compared with WT BalB/c mice, the proportion of Th2, Th17 and Treg cells reduced markedly and rejection reaction was attenuated in icos(-/-) mice receiving tracheal transplantation, although rejection reaction was still noted., Conclusion: icos knockout may delay the rejection reaction after tracheal transplantation, which might be ascribed to the imbalance among Th2, Th17 and Treg cells.

Excessive reactive oxygen/nitrogen species have been associated with the onset, progression, and outcome of sepsis, both in preclinical and clinical studies. However, the signaling pathways regulating oxidative/nitrative stress in the pathogenesis of sepsis-induced acute lung injury and acute respiratory distress syndrome are not fully understood. Employing the novel mouse model with genetic deletions of both caveolin-1 (Cav1) and adiponectin (ADPN) [double knockout (DKO) mice], we have demonstrated the critical role of Cav1 and ADPN signaling cross talk in regulating oxidative/nitrative stress and resulting inflammatory lung injury following LPS challenge. In contrast to the inhibited inflammatory lung injury in Cav1(-/-) mice, we observed severe lung inflammation and markedly increased lung vascular permeability in DKO mice in response to LPS challenge. Accordingly, the DKO mice exhibited an 80% mortality rate following a sublethal dose of LPS challenge. At basal state, loss of Cav1 and ADPN resulted in a drastic increase of oxidative stress and resultant nitrative stress in DKO lungs. Scavenging of superoxide by pretreating the DKO mice with MnTMPYP (a superoxide dismutase mimetic) restored the inflammatory responses to LPS challenge including reduced lung myeloperoxidase activity and vascular permeability. Thus oxidative/nitrative stress collectively modulated by Cav1 and ADPN signalings is a critical determinant of inflammatory lung injury in response to LPS challenge.

The postural change of pulse pressure (PP) in the persons with orthostatic hypertension (OHT) is unclear. This study included 2849 (65.0 ± 9.3 years) community participants. Blood pressures (BPs) in supine and standing positions were measured. The differences between upright and supine BP and PP were recorded as ΔBP and ΔPP. The criteria for OHT was ΔBP ≥10 mm Hg, for orthostatic hypotension (OH) was ≤-10 mm Hg and for orthostatic normotension (ONT) was -9 to 9 mm Hg. Fasting blood lipids and glucose were measured. The supine SBP of the sOHT group were similar to that of sONT group (140.9 ± 20.2 mm Hg vs 138.2 ± 19.7 mm Hg), but significantly lower than that of sOH group (151.9 ± 19.2 mm Hg; P < .05). Their PPs were 65.3 ± 15.9, 62.8 ± 14.7, and 71.1 ± 15.1 mm Hg, respectively, and with the similar group difference like SBP. When the position changed from supine to standing, the sOHT group showed PP rise, while sOH and sONT groups showed PP reduction (3.8 ± 7.1 mm Hg vs -17.0 ± 8.5 mm Hg and -5.8 ± 6.6 mm Hg; both P < .05). Thus, the standing PP in the sOHT group was significantly higher than in the sONT (69.1 ± 18.0 mm Hg vs 57.0 ± 15.8 mm Hg; P < .05) and in the sOH (54.2 ± 15.2 mm Hg; P < .05) groups. The postural PP profile varies with the postural responses of SBP. The sOHT group has obviously increased PP and significantly higher standing PP compared with the sONT group., (Copyright © 2014 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.)

Many types of embryos' bodyplans exhibit consistently oriented laterality of the heart, viscera, and brain. Errors of left-right patterning present an important class of human birth defects, and considerable controversy exists about the nature and evolutionary conservation of the molecular mechanisms that allow embryos to reliably orient the left-right axis. Here we show that the same mutations in the cytoskeletal protein tubulin that alter asymmetry in plants also affect very early steps of left-right patterning in nematode and frog embryos, as well as chirality of human cells in culture. In the frog embryo, tubulin α and tubulin γ-associated proteins are required for the differential distribution of maternal proteins to the left or right blastomere at the first cell division. Our data reveal a remarkable molecular conservation of mechanisms initiating left-right asymmetry. The origin of laterality is cytoplasmic, ancient, and highly conserved across kingdoms, a fundamental feature of the cytoskeleton that underlies chirality in cells and multicellular organisms.

In neutrophils, the phosphoinositide 3-kinase/Akt signaling cascade is involved in migration, degranulation, and O(2)(-) production. However, it is unclear whether the Akt kinase isoforms have distinct functions in neutrophil activation. Here we report functional differences between the 2 major Akt isoforms in neutrophil activation on the basis of studies in which we used individual Akt1 and Akt2 knockout mice. Akt2(-/-) neutrophils exhibited decreased cell migration, granule enzyme release, and O(2)(-) production compared with wild-type and Akt1(-/-) neutrophils. Surprisingly, Akt2 deficiency and pharmacologic inhibition of Akt also abrogated phorbol ester-induced O(2)(-) production, which was unaffected by treatment with the phosphoinositide 3-kinase inhibitor LY294002. The decreased O(2)(-) production in Akt2(-/-) neutrophils was accompanied by reduced p47(phox) phosphorylation and its membrane translocation, suggesting that Akt2 is important for the assembly of phagocyte nicotinamide adenine dinucleotide phosphate oxidase. In wild-type neutrophils, Akt2 but not Akt1 translocated to plasma membrane upon chemoattractant stimulation and to the leading edge in polarized neutrophils. In the absence of Akt2, chemoattractant-induced Akt protein phosphorylation was significantly reduced. These results demonstrate a predominant role of Akt2 in regulating neutrophil functions and provide evidence for differential activation of the 2 Akt isoforms in neutrophils.

Nonmuscle myosin light-chain kinase (MYLK) mediates increased lung vascular endothelial permeability in lipopolysaccharide-induced lung inflammatory injury, the chief cause of the acute respiratory distress syndrome. In a lung injury model, we demonstrate here that MYLK was also essential for neutrophil transmigration, but that this function was mostly independent of myosin II regulatory light chain, the only known substrate of MYLK. Instead, MYLK in neutrophils was required for the recruitment and activation of the tyrosine kinase Pyk2, which mediated full activation of beta(2) integrins. Our results demonstrate that MYLK-mediated activation of beta(2) integrins through Pyk2 links beta(2) integrin signaling to the actin motile machinery of neutrophils.

Like blood neutrophils, dHL60 cells respond to a uniform concentration of attractant by polarizing in apparently random directions. How each cell chooses its own direction is unknown. We now find that an arrow drawn from the center of the nucleus of an unpolarized cell to its centrosome strongly predicts the subsequent direction of attractant-induced polarity: Of 60 cells that polarized in response to uniform f-Met-Leu-Phe (fMLP), 42 polarized to the left of this arrow, 6 polarized to the right, and 12 polarized directly toward or away from the centrosome. To investigate this directional bias we perturbed a regulatory pathway, downstream of Cdc42 and partitioning-defective 6 (Par6), which controls centrosome orientation relative to polarity of other cells. Dominant negative Par6 mutants block polarity altogether, as previously shown for disrupting Cdc42 activity. Cells remain able to polarize, but without directional bias, if their microtubules are disrupted with nocodazole, or they express mutant proteins that interfere with activities of PKCzeta or dynein. Expressing constitutively active glycogen synthase kinase 3beta (GSK3beta) causes cells to polarize preferentially to the right. Distributions of most of these polarity regulators localize to the centrosome but show no left-right asymmetry before polarization. Together, these findings suggest that an intrinsically chiral structure, perhaps the centrosome, serves as a template for directing polarity in the absence of spatial cues. Such a template could help to determine left-right asymmetry and planar polarity in development.

How do microtubules, which maintain and direct polarity of many eukaryotic cells, regulate polarity of blood neutrophils? In sharp contrast to most cells, disrupting a neutrophil's microtubule network with nocodazole causes it to polarize and migrate [Niggli, V. (2003) J. Cell Sci. 116, 813-822]. Nocodazole induces the same responses in differentiated HL-60 cells, a model neutrophil cell line, and reduces their chemotactic prowess by causing them to pursue abnormally circuitous paths in migrating toward a stationary point source of an attractant, f-Met-Leu-Phe (fMLP). The chemotactic defect stems from dramatic nocodazole-induced imbalance between the divergent, opposed fMLP-induced "backness" and "frontness" signals responsible for neutrophil polarity. Nocodazole (i) stimulates backness by increasing Rho- and actomyosin-dependent contractility, as reported by Niggli, and also (ii) impairs fMLP-dependent frontness: pseudopods are flatter, contain less F-actin, and show decreased membrane translocation of PH-Akt-GFP, a fluorescent marker for 3'-phosphoinositide lipids. Inhibiting backness with a pharmacologic inhibitor of a Rho-dependent kinase substantially reverses nocodazole's effects on chemotaxis, straightness of migration paths, morphology, and PH-Akt-GFP translocation. Thus, microtubules normally balance backness vs. frontness signals, preventing backness from reducing the strength of pseudopods and from impairing directional migration.