Stable Patches Research Articles

Follicular unit extraction as a therapeutic option for Vitiligo

Follicular unit extraction (FUE) is a surgical procedure, which can be used to transplant follicular units into vitiliginous areas. Such follicular unit transplant has been recently used to repigment stable vitiligo patches. FUE was done for a 12-year-old female with a stable vitiligo patch with leukotrichia on the eyebrow. Repigmentation was noted in 6 weeks and complete pigmentation seen at 12 weeks. Leukotrichia resolved over a period of 6 months. No recurrence was noted at the end of 6 months follow-up with excellent colour match. This case is presented to highlight the simplicity, safety and effectiveness of FUE in stable vitiligo patches with leukotrichia.

The diversity and host specificity of mites associated with ants: the roles of ecological and life history traits of ant hosts

Ant nests are stable resource patches that can be utilized by myrmecophiles (organisms living in association with ants). Mites are the most abundant guests in ant nests and are frequently observed in phoretic relationships with ants. Little is known about the effects of ecological and life history characteristics of ant hosts on mite species richness. Previous work focused on mite descriptions and provided little ecological information. Phoretic mites were surveyed for 43 ant species in 273 colonies in Ohio. Mite collections totaled 151 species including representatives of the cohorts Astigmatina and Heterostigmatina, and the suborder Mesostigmata. Most mite species had specific host species and attachment sites on the ants. Statistical analyses showed mite species richness to be highest in colonies of ant species that are (1) populous, (2) large bodied, (3) in the genus Lasius, and (4) established through social parasitism. The species richness was higher for ant species with social parasitism or the genus Lasius, but the relative importance of other host ecological and life history variables differed among mite taxa. Prevalence was greater for female ant alates than workers or males and was positively influenced by (1) host size, (2) social parasitism, and (3) the genus Lasius. These results suggest that greater ant diversity also supports a greater diversity of associated mites, but that mite diversity is disproportionately higher in ant species with greater resource availability within nests or those that may facilitate the exchange of mite assemblages among ant nests.

Landscape Heterogeneity of Shrub Expansion in Arctic Alaska

The expansion of shrubs into tundra areas is a key terrestrial change underway in the Arctic in response to elevated temperatures during the twentieth century. Repeat photography permits a glimpse into greening satellite pixels, and it shows that, since 1950, some shrub patches have increased rapidly (hereafter expanding), while others have increased little or not at all (hereafter stable). We characterized and compared adjacent expanding and stable shrub patches across Arctic Alaska by sampling a wide range of physical and chemical soil and vegetation properties, including shrub growth rings. Expanding patches of Alnus viridis ssp. fruticosa (Siberian alder) contained shrub stems with thicker growth rings than in stable patches. Alder growth in expanding patches also showed strong correlation with spring and summer warming, whereas alder growth in stable patches showed little correlation with temperature. Expanding patches had different vegetation composition, deeper thaw depth, higher mean annual ground temperature, higher mean growing season temperature, lower soil moisture, less carbon in mineral soil, and lower C:N values in soils and shrub leaves. Expanding patches—higher resource environments—were associated with floodplains, stream corridors, and outcrops. Stable patches—lower resource environments—were associated with poorly drained tussock tundra. Collectively, we interpret these differences as implying that preexisting soil conditions predispose parts of the landscape to a rapid response to climate change, and we therefore expect shrub expansion to continue penetrating the landscape via dendritic floodplains, streams, and scattered rock outcrops.

Silver-Assisted Colloidal Synthesis of Stable, Plasmon Resonant Gold Patches on Silica Nanospheres

Patchy particles possessing heterogeneous surface composition show great promise as self-organizing building blocks for new classes of hierarchical functional structures. A major hurdle is the scalable synthesis of stable patches on nanosized core particles with arbitrarily defined patch number and coverage. So far, few methods have been reported which could be expected to meet these challenges. Recently, we described the heterogeneous nucleation and growth of silver patches on silica nanospheres via a template free colloidal route. The patches produced, although tunable in size and number and showing interesting plasmon resonant properties, were rather unstable and degraded rapidly during attempts to process them further. In the present work, therefore, we set out to explore if related approaches can be employed to produce patchy particles involving gold, which is known to be more stable. The differences between typical patch precursors Ag(+) and [AuCl(x)(OH)(4-x)](-) and their respective interactions with amorphous silica make this a significant challenge. We show that preformed small silver patches in addition to the presence of a reducing agent are necessary for the formation of gold patches conformal to the silica nanosphere surface. Systematic study of the process parameters and their influence on the patchy particle morphology as well as in-depth analytical transmission electron microscopy investigation of the patch composition reveal that patches spread over the silica surface via a cycle of galvanic dissolution and redeposition of silver. The resulting gold patchy particles remain stable during subsequent storage or washing and display tunable plasmon resonances within the visible and near-IR spectrum.

Membrane Compartment Occupied by Can1 (MCC) and Eisosome Subdomains of the Fungal Plasma Membrane

Studies on the budding yeast Saccharomyces cerevisiae have revealed that fungal plasma membranes are organized into different subdomains. One new domain termed MCC/eisosomes consists of stable punctate patches that are distinct from lipid rafts. The MCC/eisosome domains correspond to furrows in the plasma membrane that are about 300 nm long and 50 nm deep. The MCC portion includes integral membrane proteins, such as the tetraspanners Sur7 and Nce102. The adjacent eisosome includes proteins that are peripherally associated with the membrane, including the BAR domains proteins Pil1 and Lsp1 that are thought to promote membrane curvature. Genetic analysis of the MCC/eisosome components indicates these domains broadly affect overall plasma membrane organization. The mechanisms regulating the formation of MCC/eisosomes in model organisms will be reviewed as well as the role of these plasma membrane domains in fungal pathogenesis and response to antifungal drugs.

The floodplain large-wood cycle hypothesis: A mechanism for the physical and biotic structuring of temperate forested alluvial valleys in the North Pacific coastal ecoregion

A ‘floodplain large-wood cycle’ is hypothesized as a mechanism for generating landforms and influencing river dynamics in ways that structure and maintain riparian and aquatic ecosystems of forested alluvial river valleys of the Pacific coastal temperate rainforest of North America. In the cycle, pieces of wood large enough to resist fluvial transport and remain in river channels initiate and stabilize wood jams, which in turn create alluvial patches and protect them from erosion. These stable patches provide sites for trees to mature over hundreds of years in river valleys where the average cycle of floodplain turnover is much briefer, thus providing a future source of large wood and reinforcing the cycle. Different tree species can function in the floodplain large-wood cycle in different ecological regions, in different river valleys within regions, and within individual river valleys in which forest composition changes through time. The cycle promotes a physically complex, biodiverse, and self-reinforcing state. Conversely, loss of large trees from the system drives landforms and ecosystems toward an alternate stable state of diminished biogeomorphic complexity. Reestablishing large trees is thus necessary to restore such rivers. Although interactions and mechanisms may differ between biomes and in larger or smaller rivers, available evidence suggests that large riparian trees may have similarly fundamental roles in the physical and biotic structuring of river valleys elsewhere in the temperate zone.

Preventing formation of dry patches in seawater falling film evaporators

When a liquid film is falling across a heated surface, the film structure results in a variation of heat transfer and interface temperature thus facilitating the film rupture. The variation of heat transfer lefts behind a thermal topology on the heating surface that may suffice to initiate formation of vapour bubbles. Once formed, vapour bubbles grow and act on the film flow as obstacles, disturb the film and may cause film rupture with stable dry patches and salt deposition on the heating surface. Even if the liquid film remains continuous, any growing bubble results in salt deposition on the heating surface in the bubble foot region, and in both cases the heat transfer in the film becomes deteriorated. Consequently, bubble formation in evaporating falling films is to be prevented in the praxis. In the present contribution first the conditions of bubble nucleation in an evaporating falling film are formulated. From these conditions the minimum heating surface temperature required for nucleate boiling in ...

Stability of DNA-Tethered Lipid Membranes with Mobile Tethers

We recently introduced two approaches for tethering planar lipid bilayers as membrane patches to either a supported lipid bilayer or DNA-functionalized surface using DNA hybridization (Chung, M.; Lowe, R. D.; Chan, Y-H. M.; Ganesan, P. V.; Boxer, S. G. J. Struct. Biol.2009, 168, 190-9). When mobile DNA tethers are used, the tethered bilayer patches become unstable, while they are stable if the tethers are fixed on the surface. Because the mobile tethers between a patch and a supported lipid bilayer offer a particularly interesting architecture for studying the dynamics of membrane-membrane interactions, we have investigated the sources of instability, focusing on membrane composition. The most stable patches were made with a mixture of saturated lipids and cholesterol, suggesting an important role for membrane stiffness. Other factors such as the effect of tether length, lateral mobility, and patch membrane edge were also investigated. On the basis of these results, a model for the mechanism of patch destruction is developed.

Impact of induced chlorine-poisoning on the catalytic behaviour of Ce0.5Zr0.5O2 and Ce0.15Zr0.85O2 in the gas-phase oxidation of chlorinated VOCs

The main scope of this work is to evaluate the catalytic stability of two Ce/Zr mixed oxides, namely Ce0.5Zr0.5O2 and Ce0.15Zr0.85O2, in the gas-phase oxidation of 1,2-dichloroethane as a model reaction for chlorinated VOC abatement. In order to simulate an accelerated Cl-poisoning of the catalysts the samples were submitted to a chlorination step with an aqueous solution of HCl at room temperature followed by calcination or by reduction and calcination at mild temperature (550°C). For comparative purposes pure CeO2 and ZrO2 catalysts were also investigated. It was found that chlorination led to remarkable changes in surface area, acidity and redox properties, as revealed by EDX, N2-physisorption, XRD, Raman spectroscopy, adsorption of pyridine followed by IR, NH3-TPD, H2-TPR and oxygen storage capacity. Interestingly, the balance between negative (significant decrease in surface area, and lower overall acidity and reducibility) and positive (promoted redox properties due to the formation of stable CeOCl patches and generation of new acid sites related to Cl− ions adsorbed on Ce4+ and Zr4+ cations) changes introduced by chlorine incorporation appeared to be effectively counterbalanced. As a result the catalytic behaviour of chlorinated samples was not markedly affected when compared with the corresponding parent samples. Hence, a slightly lower activity was found for CeO2 and Ce0.5Zr0.5O2 while catalytic conversion was somewhat promoted for Ce0.15Zr0.85O2 and ZrO2. Anyway, after chlorination both Ce0.5Zr0.5O2 and Ce0.15Zr0.85O2 exhibited an adequate catalytic performance not only in terms of low-temperature conversion, but also of stability during extended periods of time on stream.

Plant species extinction debt in a temperate biodiversity hotspot: Community, species and functional traits approaches

Destruction and fragmentation of (semi-) natural habitats are considered the main causes of biodiversity loss worldwide. Plant species may exhibit a slow response to fragmentation, resulting in the development of an extinction debt in fragmented plant communities. The detection of extinction debt is of primary importance in habitat conservation strategies. We applied two different approaches proposed in the literature to identify extinction debt in South-East Belgium calcareous grasslands. The first method compared species richness between stable and fragmented habitat patches. The second explored correlations between current species richness and current and past landscape configurations using multiple regression analyses. We subsequently examined results generated by both methods. In addition, we proposed techniques to identify species that are more likely to support extinction debt and associated functional traits. We estimated a respective extinction debt of approximately 28% and 35% of the total and specialist species richness. Similar results were obtained from both methods. We identified 15 threatened specialist species under the current landscape configuration. It is likely the landscape configuration no longer supports the species habitat requirements. We demonstrated that non-clonal species are most threatened, as well as taxa that cannot persist in degraded habitats and form only sparsely distributed populations. We discussed our results in light of other studies in similar habitats, and the overall implications for habitat conservation.

Patchy bed disturbance and fish predation independently influence the distribution of stream invertebrates and algae

1. The identification of factors determining the patchy distribution of organisms in space and time is a central concern of ecology. Predation and abiotic disturbance are both well-known drivers of this patchiness, but their interplay is still poorly understood, especially for communities dominated by mobile organisms in frequently disturbed ecosystems. 2. We investigated the separate and interactive influences of bed disturbance by floods and predation by fish on the benthic community in a flood-prone stream. Electric fields excluded fish predators from half of 48 stream bed patches (area 0·49 m(2) ) with contrasting disturbance treatments. Three types of bed disturbance were created by either scouring or filling patches to a depth of 15-20 cm or by leaving the patches undisturbed, thus mimicking the mosaic of scour and fill caused by a moderate flood. Benthic invertebrates and algae were sampled repeatedly until 57 days after the disturbance. 3. Disturbance influenced all ten investigated biological response variables, whereas predation affected four variables. Averaged across time, invertebrate taxon richness and total abundance were highest in stable patches. Algal biomass and densities of five of the seven most common invertebrate taxa (most of which were highly mobile) were higher in fill than in scour patches, whereas two taxa were more abundant in scour and stable than in fill patches. Furthermore, two common invertebrate grazers were more abundant and algal biomass tended to be reduced in fish exclusion patches, suggesting a patch-scale trophic cascade from fish to algae. 4. Our results highlight the importance of patchy physical disturbance for the microdistribution of mobile stream organisms and indicate a notable, but less prevalent, influence of fish predation at the patch scale in this frequently disturbed environment. Disturbance and predation treatments interacted only once, suggesting that the observed predation effects were largely independent of local bed disturbance patterns.

The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells.

BackgroundThe leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal) cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear.ResultsWe developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions.ConclusionsPavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells.

The Candida albicans Sur7 Protein Is Needed for Proper Synthesis of the Fibrillar Component of the Cell Wall That Confers Strength

The Candida albicans plasma membrane plays important roles in interfacing with the environment, morphogenesis, and cell wall synthesis. The role of the Sur7 protein in cell wall structure and function was analyzed, since previous studies showed that this plasma membrane protein is needed to prevent abnormal intracellular growth of the cell wall. Sur7 localizes to stable patches in the plasma membrane, known as MCC (membrane compartment occupied by Can1), that are associated with eisosome proteins. The sur7Δ mutant cells displayed increased sensitivity to factors that exacerbate cell wall defects, such as detergent (SDS) and the chitin-binding agents calcofluor white and Congo red. The sur7Δ cells were also slightly more sensitive to inhibitors that block the synthesis of cell wall chitin (nikkomycin Z) and β-1,3-glucan (caspofungin). In contrast, Fmp45, a paralog of Sur7 that also localizes to punctate plasma membrane patches, did not have a detectable role in cell wall synthesis. Chemical analysis of cell wall composition demonstrated that sur7Δ cells contain decreased levels of β-glucan, a glucose polymer that confers rigidity on the cell wall. Consistent with this, sur7Δ cells were more sensitive to lysis, which could be partially rescued by increasing the osmolarity of the medium. Interestingly, Sur7 is present in static patches, whereas β-1,3-glucan synthase is mobile in the plasma membrane and is often associated with actin patches. Thus, Sur7 may influence β-glucan synthesis indirectly, perhaps by altering the functions of the cell signaling components that localize to the MCC and eisosome domains.

Sequence composition and environment effects on residue fluctuations in protein structures

Structure fluctuations in proteins affect a broad range of cell phenomena, including stability of proteins and their fragments, allosteric transitions, and energy transfer. This study presents a statistical-thermodynamic analysis of relationship between the sequence composition and the distribution of residue fluctuations in protein-protein complexes. A one-node-per-residue elastic network model accounting for the nonhomogeneous protein mass distribution and the interatomic interactions through the renormalized inter-residue potential is developed. Two factors, a protein mass distribution and a residue environment, were found to determine the scale of residue fluctuations. Surface residues undergo larger fluctuations than core residues in agreement with experimental observations. Ranking residues over the normalized scale of fluctuations yields a distinct classification of amino acids into three groups: (i) highly fluctuating-Gly, Ala, Ser, Pro, and Asp, (ii) moderately fluctuating-Thr, Asn, Gln, Lys, Glu, Arg, Val, and Cys, and (iii) weakly fluctuating-Ile, Leu, Met, Phe, Tyr, Trp, and His. The structural instability in proteins possibly relates to the high content of the highly fluctuating residues and a deficiency of the weakly fluctuating residues in irregular secondary structure elements (loops), chameleon sequences, and disordered proteins. Strong correlation between residue fluctuations and the sequence composition of protein loops supports this hypothesis. Comparing fluctuations of binding site residues (interface residues) with other surface residues shows that, on average, the interface is more rigid than the rest of the protein surface and Gly, Ala, Ser, Cys, Leu, and Trp have a propensity to form more stable docking patches on the interface. The findings have broad implications for understanding mechanisms of protein association and stability of protein structures.

A hierarchical model for analysing the stability of vegetation patterns created by grazing in temperate pastures

Questions: Does vegetation structure display any stability over the grazing season and in two successive years, and is there any correlation between the stability of these spatial patterns and local sward composition? Location: An upland grassland in the French Massif Central. Method: The mosaic of short and tall vegetation stands considered as grazed and ungrazed patches respectively is modeled as the realization of a Boolean process. This method does not require any arbitrarily set sward-height thresholds to discriminate between grazed and ungrazed areas, or the use of additional variables such as defoliation indexes. The model was validated by comparing empirical and simulated sward-height distributions and semi-variograms. Results: The model discriminated between grazed and ungrazed patches at both a fine (1 m2) and a larger (500 m2) scale. Selective grazing on legumes and forbs and avoidance of reproductive grass could partly explain the stability of fine-scale grazing patterns in lightly grazed plots. In these plots, the model revealed an inter-annual stability of large-scale grazing patterns at the time peak biomass occurred. At the end of the grazing season, lightly grazed plots showed fluctuating patch boundaries while heavily grazed plots showed a certain degree of patch stability. Conclusion: The model presented here reveals that selective grazing at the bite scale could lead to the creation of relatively stable patches within the pasture. Locally maintaining short cover heights would result in divergent within-plot vegetation dynamics, and thus favor the functional diversity of vegetation.

Structure Fluctuations in Proteins and their Relationship to Amino Acid Propensities

The spectrum and scale of fluctuations in protein structures affect the range of cell phenomena, including stability of protein structures or their fragments, allosteric transitions and energy transfer. The study presents a statistical-thermodynamic analysis of relationship between the sequence composition and the distribution of residue fluctuations in protein-protein complexes [1]. A one-node-per-residue elastic network model accounting for the nonhomogeneous protein mass distribution and the inter-atomic interactions through the renormalized inter-residue potential is developed. Two factors, a protein mass distribution and a residue environment, were found to determine the scale of residue fluctuations. Surface residues undergo larger fluctuations than core residues, showing agreement with experimental observations. Ranking residues over the normalized scale of fluctuations yields a distinct classification of amino acids into three groups: (i) highly fluctuating - Gly, Ala, Ser, Pro and Asp, (ii) moderately fluctuating - Thr, Asn, Gln, Lys, Glu, Arg, Val and Cys (iii) weakly fluctuating - Ile, Leu, Met, Phe, Tyr, Trp and His. The structural instability in proteins possibly relates to the high content of the highly fluctuating residues and a deficiency of the weakly fluctuating residues in irregular secondary structure elements (loops), chameleon sequences and disordered proteins. Strong correlation between residue fluctuations and the sequence composition of protein loops supports this hypothesis. Comparing fluctuations of binding site residues (interface residues) with other surface residues shows that, on average, the interface is more rigid than the rest of the protein surface and Gly, Ala, Ser, Cys, Leu and Trp have a propensity to form more stable docking patches on the interface. The findings have broad implications for understanding mechanisms of protein association and stability of protein structures.1. A.M. Ruvinsky and I.A. Vakser. arXiv:0907.5021v1

First evidences of fast creeping on a long-lasting quiescent earthquake normal-fault in the Mediterranean

SUMMARY A key issue in our understanding of the earthquake cycle and seismic hazard is the behaviour of an active fault during the interseismic phase. Locked and creeping faults represent two end-members of mechanical behaviours that are given two extreme rupturing hazard levels, that is, high and low, respectively. Geophysical and space geodetic analyses are carried out over the Pollino Range, an extensional environment within the Africa–Eurasia plate boundary, to disclose the behaviour of the long-lasting quiescent Castrovillari normal fault. Fault trenching evidenced at least four large earthquakes (6.5–7.0 Mw) in the past and an elapsed time of 1200 yr since the last event. Inversion of Differential Interferometric Synthetic Aperture Radar and Global Positioning System over a decade shows fast creeping at all depths of the fault plane. The velocity-strengthening creeping zone reaches maximum rates 20 mm yr −1 against an average rate of about 3–9 mm yr −1 . It limits the southern-weakening locked part of the fault. An essential condition for the generation of a large earthquake on the Castrovillari fault, as has occurred in the past, is a rupture through the velocity-strengthening zone. The Castrovillari fault yields the best evidence for being both a strong and weak fault during its earthquake cycle. Creeping at rates faster than its tectonically driven ones, it must thus consist of a mix of unstable and conditionally stable patches ready to sustain a sizeable earthquake. Quantifying and mapping the slip rate over the fault plane is important because they influence fault moment budget estimate and helps to constrain constitutive laws of fault zones. Aseismic slip also redistributes stress in the crust, thereby affecting the locations of future earthquakes.

DNA-tethered membranes formed by giant vesicle rupture

We have developed a strategy for preparing tethered lipid bilayer membrane patches on solid surfaces by DNA hybridization. In this way, the tethered membrane patch is held at a controllable distance from the surface by varying the length of the DNA used. Two basic strategies are described. In the first, single-stranded DNA strands are immobilized by click chemistry to a silica surface, whose remaining surface is passivated to prevent direct assembly of a solid supported bilayer. Then giant unilamellar vesicles (GUVs) displaying the antisense strand, using a DNA-lipid conjugate developed in earlier work [Chan, Y.-H.M., van Lengerich, B., et al., 2008. Lipid-anchored DNA mediates vesicle fusion as observed by lipid and content mixing. Biointerphases 3 (2), FA17-FA21], are allowed to tether, spread and rupture to form tethered bilayer patches. In the second, a supported lipid bilayer displaying DNA using the DNA-lipid conjugate is first assembled on the surface. Then GUVs displaying the antisense strand are allowed to tether, spread and rupture to form tethered bilayer patches. The essential difference between these methods is that the tethering hybrid DNA is immobile in the first, while it is mobile in the second. Both strategies are successful; however, with mobile DNA hybrids as tethers, the patches are unstable, while in the first strategy stable patches can be formed. In the case of mobile tethers, if different length DNA hybrids are present, lateral segregation by length occurs and can be visualized by fluorescence interference contrast microscopy making this an interesting model for interactions that occur in cell junctions. In both cases, lipid mobility is high and there is a negligible immobile fraction. Thus, these architectures offer a flexible platform for the assembly of lipid bilayers at a well-defined distance from a solid support.

The Sur7 protein resides in punctate membrane subdomains and mediates spatial regulation of cell wall synthesis in Candida albicans

The eukaryotic plasma membrane is organized into distinct domains that contribute to its function. One new type of plasma membrane domain was identified by studies on the Sur7 protein, which was discovered in the yeast S. cerevisiae to localize into stable punctate patches known as MCC or eisosomes. Sur7 shares similarities with Claudin proteins that form tight junction domains in animal cells, suggesting common roles for these tetraspanning membrane proteins. Recent analysis of C. albicans revealed broad new roles for Sur7; a sur7Δ mutant mislocalized septins and actin and was defective in morphogenesis. Strikingly, cell wall synthesis was very abnormal, including long projections of chitin-rich cell wall into the cytoplasm. Some phenotypes of the sur7Δ mutant are similar to the effects of inhibiting cell wall β-glucan synthesis. This suggests that the abnormal cell wall structures are related to the increased chitin synthesis commonly seen under cell wall stress conditions, which could be mediated in part by the altered septin localization. Altogether, these results identify new roles for Sur7 and MCC/eisosomes in plasma membrane organization and coordination of the different aspects of cell wall synthesis.

Evaluation of safety and efficacy of topical prostaglandin E2in treatment of vitiligo

Prostaglandin E2 (PGE2) has stimulant and immunomodulatory effects on melanocytes and regulates their proliferation. To study the efficacy and safety of topical PGE2 in treating stable vitiligo patches involving <5% body surface area. Fifty-six consecutive patients with clinically diagnosed stable vitiligo of types vulgaris, focal, segmental, lip and genital applied a translucent PGE2 (0.25 mg g(-1)) gel twice daily for 6 months. Evaluation was fortnightly for 3 months and monthly thereafter up to 6 months. Assessment was based on degree of repigmentation in treated patches ranging from 0% (no change) to 100% (complete repigmentation). Overall response was graded as: poor, 1-25% repigmentation; moderate, 26-50%; good, 51-75%; excellent, >75%. Vitiligo vulgaris was the most common type (n=22; 39%), followed by focal and lip vitiligo, with lesions being mostly on the face (25%) and lips. Repigmentation was seen in 40 of 56 patients (71%), with mean onset at 2 months. Patients with disease duration of 6 months or less repigmented best, with face and scalp responding earliest (1-1.5 months). Complete clearance occurred in eight of 40 patients, six of the eight having face lesions. Excellent response was seen in 22 of 40 patients. All neck, scalp and trunk lesions, 33% genital, 29% lip vitiligo, 100% segmental and 63% focal patches showed moderate to excellent response. Incidence of side-effects was 18%, mainly a transient burning sensation especially on the lips. The efficacy and safety of topical PGE2 make it a promising therapy for localized stable vitiligo.