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Assessments of the status of tidal flats, one of the most extensive coastal ecosystems, have been hampered by a lack of data on their global distribution and change. Here we present globally consistent, spatially-explicit data of the occurrence of tidal flats, defined as sand, rock or mud flats that undergo regular tidal inundation. More than 1.3 million Landsat images were processed to 54 composite metrics for twelve 3-year periods, spanning four decades (1984-1986 to 2017-2019). The composite metrics were used as predictor variables in a machine-learning classification trained with more than 10,000 globally distributed training samples. We assessed accuracy of the classification with 1,348 stratified random samples across the mapped area, which indicated overall map accuracies of 82.2% (80.0-84.3%, 95% confidence interval) and 86.1% (84.2-86.8%, 95% CI) for version 1.1 and 1.2 of the data, respectively. We expect these maps will provide a means to measure and monitor a range of processes that are affecting coastal ecosystems, including the impacts of human population growth and sea level rise., (© 2022. The Author(s).)

Background and Aims: Seed germination is strongly influenced by environmental temperatures. With global temperatures predicted to rise, the timing of germination for thousands of plant species could change, leading to potential decreases in fitness and ecosystem-wide impacts. The thermogradient plate (TGP) is a powerful but underutilized research tool that tests germination under a broad range of constant and alternating temperatures, giving researchers the ability to predict germination characteristics using current and future climates. Previously, limitations surrounding experimental design and data analysis methods have discouraged its use in seed biology research., Methods: Here, we have developed a freely available R script that uses TGP data to analyse seed germination responses to temperature. We illustrate this analysis framework using three example species: Wollemia nobilis, Callitris baileyi and Alectryon subdentatus. The script generates >40 germination indices including germination rates and final germination across each cell of the TGP. These indices are then used to populate generalized additive models and predict germination under current and future monthly maximum and minimum temperatures anywhere on the globe., Key Results: In our study species, modelled data were highly correlated with observed data, allowing confident predictions of monthly germination patterns for current and future climates. Wollemia nobilis germinated across a broad range of temperatures and was relatively unaffected by predicted future temperatures. In contrast, C. baileyi and A. subdentatus showed strong seasonal temperature responses, and the timing for peak germination was predicted to shift seasonally under future temperatures., Conclusions: Our experimental workflow is a leap forward in the analysis of TGP experiments, increasing its many potential benefits, thereby improving research predictions and providing substantial information to inform management and conservation of plant species globally., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Annals of Botany Company.)

Tidal wetlands are expected to respond dynamically to global environmental change, but the extent to which wetland losses have been offset by gains remains poorly understood. We developed a global analysis of satellite data to simultaneously monitor change in three highly interconnected intertidal ecosystem types-tidal flats, tidal marshes, and mangroves-from 1999 to 2019. Globally, 13,700 square kilometers of tidal wetlands have been lost, but these have been substantially offset by gains of 9700 km 2 , leading to a net change of -4000 km 2 over two decades. We found that 27% of these losses and gains were associated with direct human activities such as conversion to agriculture and restoration of lost wetlands. All other changes were attributed to indirect drivers, including the effects of coastal processes and climate change.

Non-forest ecosystems, dominated by shrubs, grasses and herbaceous plants, provide ecosystem services including carbon sequestration and forage for grazing, and are highly sensitive to climatic changes. Yet these ecosystems are poorly represented in remotely sensed biomass products and are undersampled by in situ monitoring. Current global change threats emphasize the need for new tools to capture biomass change in non-forest ecosystems at appropriate scales. Here we developed and deployed a new protocol for photogrammetric height using unoccupied aerial vehicle (UAV) images to test its capability for delivering standardized measurements of biomass across a globally distributed field experiment. We assessed whether canopy height inferred from UAV photogrammetry allows the prediction of aboveground biomass (AGB) across low-stature plant species by conducting 38 photogrammetric surveys over 741 harvested plots to sample 50 species. We found mean canopy height was strongly predictive of AGB across species, with a median adjusted R 2 of 0.87 (ranging from 0.46 to 0.99) and median prediction error from leave-one-out cross-validation of 3.9%. Biomass per-unit-of-height was similar within but different among, plant functional types. We found that photogrammetric reconstructions of canopy height were sensitive to wind speed but not sun elevation during surveys. We demonstrated that our photogrammetric approach produced generalizable measurements across growth forms and environmental settings and yielded accuracies as good as those obtained from in situ approaches. We demonstrate that using a standardized approach for UAV photogrammetry can deliver accurate AGB estimates across a wide range of dynamic and heterogeneous ecosystems. Many academic and land management institutions have the technical capacity to deploy these approaches over extents of 1-10 ha -1 . Photogrammetric approaches could provide much-needed information required to calibrate and validate the vegetation models and satellite-derived biomass products that are essential to understand vulnerable and understudied non-forested ecosystems around the globe., (© 2021 The Authors. Remote Sensing in Ecology and Conservation published by John Wiley & Sons Ltd on behalf of Zoological Society of London.)

Coral reef management and conservation stand to benefit from improved high-resolution global mapping. Yet classifications underpinning large-scale reef mapping to date are typically poorly defined, not shared or region-specific, limiting end-users' ability to interpret outputs. Here we present Reef Cover, a coral reef geomorphic zone classification, developed to support both producers and end-users of global-scale coral reef habitat maps, in a transparent and version-based framework. Scalable classes were created by focusing on attributes that can be observed remotely, but whose membership rules also reflect deep knowledge of reef form and functioning. Bridging the divide between earth observation data and geo-ecological knowledge of reefs, Reef Cover maximises the trade-off between applicability at global scales, and relevance and accuracy at local scales. Two case studies demonstrate application of the Reef Cover classification scheme and its scientific and conservation benefits: 1) detailed mapping of the Cairns Management Region of the Great Barrier Reef to support management and 2) mapping of the Caroline and Mariana Island chains in the Pacific for conservation purposes., (© 2021. The Author(s).)

Evolving capabilities in environmental data collection, sharing, and processing, are enabling unprecedented use of data from a wide range of sources. Yet data freshness, an important quality dimension associated with the age of data, is a poorly reported aspect of data quality that can lead to additional uncertainty in research findings., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Increasing human populations around the global coastline have caused extensive loss, degradation and fragmentation of coastal ecosystems, threatening the delivery of important ecosystem services 1 . As a result, alarming losses of mangrove, coral reef, seagrass, kelp forest and coastal marsh ecosystems have occurred 1-6 . However, owing to the difficulty of mapping intertidal areas globally, the distribution and status of tidal flats-one of the most extensive coastal ecosystems-remain unknown 7 . Here we present an analysis of over 700,000 satellite images that maps the global extent of and change in tidal flats over the course of 33 years (1984-2016). We find that tidal flats, defined as sand, rock or mud flats that undergo regular tidal inundation 7 , occupy at least 127,921 km 2 (124,286-131,821 km 2 , 95% confidence interval). About 70% of the global extent of tidal flats is found in three continents (Asia (44% of total), North America (15.5% of total) and South America (11% of total)), with 49.2% being concentrated in just eight countries (Indonesia, China, Australia, the United States, Canada, India, Brazil and Myanmar). For regions with sufficient data to develop a consistent multi-decadal time series-which included East Asia, the Middle East and North America-we estimate that 16.02% (15.62-16.47%, 95% confidence interval) of tidal flats were lost between 1984 and 2016. Extensive degradation from coastal development 1 , reduced sediment delivery from major rivers 8,9 , sinking of riverine deltas 8,10 , increased coastal erosion and sea-level rise 11 signal a continuing negative trajectory for tidal flat ecosystems around the world. Our high-spatial-resolution dataset delivers global maps of tidal flats, which substantially advances our understanding of the distribution, trajectory and status of these poorly known coastal ecosystems.

Vegetation cover is fundamental in the formation and maintenance of geomorphological features in dune systems. In arid Australia, increased woody shrub cover has been linked to removal of the apex predator (Dingoes, Canis dingo ) via subsequent trophic cascades. We ask whether this increase in shrubs can be linked to altered physical characteristics of the dunes. We used drone-based remote sensing to measure shrub density and construct three-dimensional models of dune morphology. Dunes had significantly different physical characteristics either side of the 'dingo-proof fence', inside which dingoes are systematically eradicated and shrub density is higher over vast spatial extents. Generalized additive models revealed that dunes with increased shrub density were higher, differently shaped and more variable in height profile. We propose that low shrub density induces aeolian and sedimentary processes that result in greater surface erosion and sediment transport, whereas high shrub density promotes dune stability. We speculate that increased vegetation cover acts to push dunes towards an alternate stable state, where climatic variation no longer has a significant effect on their morphodynamic state within the bi-stable state model. Our study provides evidence that anthropogenically induced trophic cascades can indirectly lead to large-scale changes in landscape geomorphology., (© 2018 The Author(s).)

Historical ecology can teach us valuable lessons on the processes and drivers of environmental change that can inform future monitoring priorities and management strategies. Environmental data to study environmental history, however, is often absent or of low quality. Even when studying changes occurring during the last few decades, monitoring efforts are scarce due to logistical and cost limitations, leaving large areas unassessed. The aim of this study is to evaluate the use of estuarine water colour as an indicator of historical environmental change in catchments. Water colour change was assessed in estuaries in Australia from 1987 to 2015 using satellite remote sensing. Random points were selected for each estuary and applied to the Australian Geoscience Data Cube (based on Landsat images) to obtain reflectance data through time. We propose a framework where (i) water colour is used to detect historical changes in catchments using generalised additive models, (ii) possible stressors and pressures driving those changes are evaluated using other available historical data, and (iii) lessons learned inform appropriate monitoring and management actions. This framework represents a novel approach to generate historical data for large-scale assessments of environmental change at catchment level, even in poorly studied areas., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The current set of global conservation targets requires methods for monitoring the changing status of ecosystems. Protocols for ecosystem risk assessment are uniquely suited to this task, providing objective syntheses of a wide range of data to estimate the likelihood of ecosystem collapse. Satellite remote sensing can deliver ecologically relevant, long-term datasets suitable for analysing changes in ecosystem area, structure and function at temporal and spatial scales relevant to risk assessment protocols. However, there is considerable uncertainty about how to select and effectively utilise remotely sensed variables for risk assessment. Here, we review the use of satellite remote sensing for assessing spatial and functional changes of ecosystems, with the aim of providing guidance on the use of these data in ecosystem risk assessment. We suggest that decisions on the use of satellite remote sensing should be made a priori and deductively with the assistance of conceptual ecosystem models that identify the primary indicators representing the dynamics of a focal ecosystem., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The distribution and abundance of seagrass ecosystems could change significantly over the coming century due to sea level rise (SLR). Coastal managers require mechanistic understanding of the processes affecting seagrass response to SLR to maximize their conservation and associated provision of ecosystem services. In Moreton Bay, Queensland, Australia, vast seagrass meadows supporting populations of sea turtles and dugongs are juxtaposed with the multiple stressors associated with a large and rapidly expanding human population. Here, the interactive effects of predicted SLR, changes in water clarity, and land use on future distributions of seagrass in Moreton Bay were quantified. A habitat distribution model of present day seagrass in relation to benthic irradiance and wave height was developed which correctly classified habitats in 83% of cases. Spatial predictions of seagrass and presence derived from the model and bathymetric data were used to initiate a SLR inundation model. Bathymetry was iteratively modified based on SLR and sedimentary accretion in seagrass to simulate potential seagrass habitat at 10 year time steps until 2100. The area of seagrass habitat was predicted to decline by 17% by 2100 under a scenario of SLR of 1.1 m. A scenario including the removal of impervious surfaces, such as roads and houses, from newly inundated regions, demonstrated that managed retreat of the shoreline could potentially reduce the overall decline in seagrass habitat to just 5%. The predicted reduction in area of seagrass habitat could be offset by an improvement in water clarity of 30%. Greater improvements in water clarity would be necessary for larger magnitudes of SLR. Management to improve water quality will provide present and future benefits to seagrasses under climate change and should be a priority for managers seeking to compensate for the effects of global change on these valuable habitats., (© 2013 John Wiley & Sons Ltd.)

Shape-memory polymers (SMPs) are being increasingly proposed for use in biomedical devices. This paper investigates the cytotoxicity, surface characteristics and thermomechanics of two acrylate-based SMP networks as a function of sterilization using a minimal essential media elution test, FTIR-ATR and dynamic mechanical analysis (DMA). Networks sterilized by low-temperature plasma elicited a cytotoxic response and are shown to completely destroy the cell monolayer. FTIR-ATR analysis showed evidence of surface oxidation with an increase and broadening of the absorbance peak from approximately 3500 to 3100 cm(-1), which is associated with an increase in hydroxyl groups. DMA revealed small, but statistically significant, differences in reduction of the glass transition temperatures of both networks when sterilized with gamma irradiation. One network showed an increase in rubbery modulus, which is an indication of crosslink density, after gamma irradiation. Lastly, practical sterilization concerns of SMP devices are discussed in light of the different methods.

Short-term and long-term survival of cultured neonatal foreskin melanocytes from black and white individuals were assessed following a single exposure to simulated sunlight or ultraviolet A (UVA) radiation. Melanocytes from black individuals contained significantly more melanin than melanocytes from white individuals (p less than 0.05). Black and white melanocytes had similar survival profiles following simulated sunlight exposure, whereas black melanocytes were significantly more resistant to UVA cytotoxicity than melanocytes from white subjects (p less than 0.05) at UVA doses above 15 J/cm2. There was no difference in unscheduled DNA synthesis in the black or white melanocytes following simulated sunlight exposure and no unscheduled DNA synthesis was measurable following melanocyte exposure to UVA radiation. Low-dose UVA (1 or 5 J/cm2) was mitogenic to both black and white melanocytes. By analysis of co-variance, the melanin content of melanocytes of black and white subjects was significantly (p less than 0.05) associated with susceptibility to UVA killing; melanocytes with high melanin content had high resistance to UVA cytotoxicity and those with low melanin content had low resistance to UVA cytotoxicity. From these data we suggest that the higher melanin content of melanocytes of black subjects confers increased resistance to UVA damage. This is likely to be of importance in epidermal photodamage.

Interactions of the ligand/receptor pair LFA-1(CD11a/CD18) and ICAM-1(CD54) initiate and control the cell-cell interactions of leukocytes and interactions of leukocytes with parenchymal cells in all phases of the immune response. Induction of the intercellular adhesion molecule 1 (ICAM-1) on the surface of epidermal keratinocytes has been proposed as an important regulator of contact-dependent aspects of cutaneous inflammation. Ultraviolet radiation (UVR) also modifies cutaneous inflammation, producing both up- and down-regulation of contact hypersensitivity. We have found that UVR has a biphasic effect on the induction of keratinocyte CD54. Using immunofluorescence and FACS techniques to quantitate cell-surface CD54 staining, we have shown that UVR (100 mJ/cm2 of UVB) significantly (p less than 0.01) inhibits keratinocyte CD54 induction by gamma interferon 24 h after irradiation. However, at 48, 72, and 96 h after UVR (10 to 100 mJ/cm2), CD54 expression is significantly induced (p less than 0.01 to p less than 0.001) to levels even greater than are induced by gamma interferon (20 U/ml). In addition, at 48, 72, or 96 h following UVR (30-100 mJ/cm2), the gamma-interferon-induced CD54 expression on human keratinocytes is also strongly (p less than 0.05 to p less than 0.001) enhanced. In this cell-culture system, gamma interferon and TNF-alpha are both strong CD54 inducers and are synergistic, but GM-CSF, TFG-beta, and IL-1 have no direct CD54-inducing effects. Thus the effects of UVR on CD54 induction are biphasic, producing inhibition at 24 h and induction at 48, 72, and 96 h. This effect on CD54 may contribute to the biphasic effects of UVR on delayed hypersensitivity in vivo. The early inhibition of ICAM-1 by UVR may also contribute to the therapeutic effects of UVR. We also speculate that the late induction of ICAM-1 by UVR might be an important step in the induction of photosensitive diseases such as lupus erythematosus.

Human melanocyte expression of intercellular adhesion molecule-1 (ICAM-1) with or without stimulation by interferon gamma (IFN-G), tumor necrosis factor alpha (TNF-alpha), or interleukin-1-alpha (IL-1 alpha), was measured utilizing direct immunofluorescence and fluorescence-activated cell sorting (FACS). Melanocytes grown in vitro expressed low levels of ICAM-1, which could be increased by exposing the cells to IFN-G, TNF-alpha, or IL-1 alpha. Each cytokine caused an enhancement of melanocyte ICAM-1 expression in a dose-dependent fashion. The lowest dose necessary to cause a significant increase in melanocyte ICAM-1 expression was 1 U/ml IFN-G, 0.3 ng/ml TNF-alpha, or 3 U/ml IL-1 alpha. Melanocytes were most sensitive to TNF-alpha stimulation, with the greatest levels of ICAM-1 expression following 30 ng/ml or more TNF-alpha. When IFN-G was added to melanocyte cultures in combination with TNF-alpha or IL-1 alpha, there was an additive increase in ICAM-1 expression but no synergy was noted with the combined cytokines. To our knowledge, this is the first report of melanocyte ICAM-1 induction by TNF-alpha and IL-1 alpha and by physiologically relevant doses of IFN-G. Because of the importance of ICAM-1 in the regulation of immune cell-target interactions, the study of ICAM-1 expression by melanocytes may help us to better understand immune mechanisms of melanocyte injury.

Leukotrienes are involved in diseases associated with a neutrophilic infiltrate. The role of human keratinocytes in the metabolism and inactivation of leukotrienes has not been thoroughly examined. We added exogenous radioactive leukotrienes to cultured human keratinocytes and evaluated the metabolic products using high-performance liquid chromatography. Over a 24-h period, unstimulated cultured keratinocytes convert leukotriene B4 to unidentified polar molecules. Leukotriene C4 is converted to a leukotriene D4/leukotriene E4-like product. Cultured human keratinocytes have the ability to metabolize leukotrienes and thus the keratinocyte may play a major role in the in vivo metabolism of leukotrienes produced during inflammatory dermatoses.

Sibutramine HCl, a monoamine reuptake inhibitor type of antidepressant, was administered to healthy male volunteers as either a single dose (12.5 or 50 mg) or repeated treatment (5-20 mg once daily or 15 mg twice daily). Plasma, obtained at regular intervals during and after sibutramine HCl or placebo treatment, was assayed in vitro for its ability to inhibit the uptake of [3H]-noradrenaline (NA) by rat cortical synaptosomes, [3H]-5-hydroxytryptamine (5HT) by human platelets and [14C]-dopamine (DA) by rat striatal synaptosomes. After both single and repeated sibutramine HCl administration, the rank order of uptake inhibition was [3H]-NA greater than [3H]-5HT greater than [14C]-DA. The level of monoamine uptake inhibition increased on daily administration to a plateau 4-6 days after initiation of treatment, for example, approximately 60% and 40% inhibition of [3H]-NA and [3H]-5HT, respectively, following 15 mg sibutramine HCl twice daily. The pattern of monoamine uptake inhibition following sibutramine HCl administration to man is similar to that observed in sibutramine HCl-treated rats, and probably at least partly reflects inhibition of uptake by drug metabolites in both species. The inhibition of monoamine uptake following sibutramine HCl administration to man is consistent with an antidepressant effect.

Autoantibodies to the non-histone nucleoprotein antigens SS-A/Ro, SS-B/La, and RNP are highly associated with photosensitive cutaneous lupus erythematosus (LE). In order to better understand the potential mechanisms of ultraviolet (UV) light on photosensitivity in patients with cutaneous LE, we designed immunopathologic in vitro and in vivo experiments to evaluate the effects of UV on the binding of such autoantibodies to the surface of human keratinocytes, one major target of immunologic damage in photosensitive LE. Short-term 2% paraformaldehyde fixation of suspensions of cultured human keratinocytes previously incubated with monospecific antiserum probes enabled the detection of ENA expression on the cell surface by flow-cytometry analysis. UVB light (280-320 nm) induced the binding of monospecific antibody probes for SS-A/Ro and SS-B/La on keratinocytes in a dose-dependent pattern with maximal induction observed at the dose of 200 mJ/cm2 UVB. Binding of SS-A/Ro, SS-B/La, and RNP antibody was augmented strongly, but binding of anti-Sm was very weak. In contrast, UVA (320-400 nm) light had no effect on the induction of binding of these antibody probes. Identical results were seen by standard immunofluorescence techniques. Hydroxyurea-treated keratinocytes showed similar induction of those antigens by UVB irradiation, which suggested that ENA expression on cultured keratinocytes by UVB were cell-cycle independent. Tunicamycin, an inhibitor of glycosylation of proteins, reduced UVB light effect on the SS-A/Ro and SS-B/La antigen's expression. These in vitro FACS analyses revealed that ENA augmentation on the keratinocyte cell surface was dose dependent, UVB dependent, glycosylation dependent, and cell-cycle independent. In vivo ENA augmentation on the keratinocyte surface was examined in suction blister epidermal roofs. Specific antibody probes for SS-A/Ro, SS-B/La, RNP, and Sm bound to human keratinocytes in intact suction blister epidermis following UVL irradiation in vivo. Using three different protocols, we have demonstrated that antibodies to SS-A/Ro, SS-B/La, and U1RNP bind to UVL-irradiated human keratinocytes. We speculate that this antibody binding is an important inducer of antibody dependent keratinocyte damage in photosensitive cutaneous lupus.

The reactivity of the monoclonal anti-human skin basal cell antibody (3B4-6) to cultured keratinocytes was examined by immunofluorescence techniques in order to verify the change in distribution of basal cell antigens during the in vitro differentiation of keratinocytes cultured in serum-free medium. The basal cells' antigen(s) determinants recognized by 3B4-6 were present in the cytoplasm of the cells at low concentration of Ca2+ (0.03 mM). High concentrations of Ca2+ (0.1 mM approximately 0.3 mM) induced the reactivity on the cell surface. This result was confirmed by flow cytometry analysis. The staining pattern was different from that of anti-involucrin antibody in 0.3 mM Ca2+ culture medium. This MoAb might be a useful tool for monitoring the degree of differentiation of cultured keratinocytes.

Strontium (Sr2+) can substitute for Ca2+ and stimulate a variety of functions of numerous types of cells. The purpose of this study was to investigate the details of the biologic effects of Sr2+ on human keratinocyte growth, cell cycle, viability, and differentiation and to compare these effects with Sr2+ effects on cultured skin melanocytes. Cultured keratinocytes stimulated with 1.0-3.0 mM Sr2+ showed higher viability and almost a twofold increase in cell number compared with those grown in a standard calcium concentration. Time course studies revealed that 2.0 mM Sr2+ had no effects on growth of cultured melanocytes or fibroblasts. Sr2+ increased the percentage of cultured keratinocytes in G2/M phase, with a decrease in cells in G0/G1 phase. This effect of Sr2+ on the cell cycle was not seen in cultured melanocytes or fibroblasts. A 2 mM concentration of Sr2+ produced an increase in low-density keratinocytes separated by a Percoll gradient. In addition, increased expression of human fibronectin was observed in the cytoplasm and on cell membranes of keratinocytes cultured in Sr2+. Sr2+ can be of practical benefit in the culture of human keratinocytes in serum-free medium, increasing the viability and proliferative rate and producing a more uniform population of basaloid cells with increased expression of cell surface fibronectin.

Guinea pig laryngeal fractures were used as a model to compare the ease of application and effectiveness of the fibrinogen-adhesive system with the ease of application and effectiveness of cyanoacrylate glue and control fractures stinted with contralateral gelatin film. Seven fibrin adhesive-treated and two cyanoacrylate glue-treated guinea pigs were perfused after 60 and 35 days, respectively. The larynges were serial sectioned, and the wound sites were compared. The fibrinogen adhesive system was easier to dispense than cyanoacrylate glue, did not require a completely dry surface, and stabilized within 3 minutes. Cartilage segment alignment with focal, complete fracture healing and symmetrical chondrocyte proliferation were seen in fibrogen adhesive-stinted larynges. In the cyanoacrylate glue-treated larynges, there was no alignment and minimal, asymmetrical chondrocyte proliferation. Gelatin film-stinted controls exhibited similar features. Thus, fibrogen adhesive was easier to apply and more effectively bound laryngeal fractures than cyanoacrylate glue or gelatin film.

Arachidonic acid and its metabolites (eicosanoids) are membrane-derived inflammatory mediators with a diverse set of biologic properties affecting numerous cells and organ systems, including the skin. They have been implicated in the pathogenesis of inflammatory skin disease and post-inflammatory hyperpigmentation. We have studied the ability of arachidonic acid, prostaglandin D2, prostaglandin E2, leukotriene B4, leukotriene C4, leukotriene D4, and leukotriene E4 to enhance the growth of cultured human melanocytes. Of these compounds, only leukotriene C4 and leukotriene D4 were capable of stimulating melanocyte proliferation. In addition, cultured melanocytes metabolized leukotriene C4 to leukotriene E4 with greater than 60% conversion in less than three hours. Melanocytes grown on suboptimal media (doubling time 12-20 days) respond in a dose-dependent fashion to leukotriene C4, with a significant difference from control noted at 28 days with a concentration of LTC4 of 30 nM and a doubling time of 5-8 days. We feel that leukotriene C4 and D4 could play an important role in post-inflammatory melanocyte hyperplasia.

A strong association between anti-SS-A/Ro and anti-SS-B/La antibodies and skin lesions has been well documented in subacute cutaneous lupus erythematosus and neonatal lupus erythematosis in which 70 to 80% of patients are female. In order to better understand the mechanisms of the influence of sex hormones on cutaneous lupus, we designed immunopathological in vitro experiments to evaluate the effects of estradiol and other sex steroids on the binding of SS-A/Ro- and SS-B/La-specific antibodies to cultured human keratinocytes from neonates. Cultured human keratinocytes incubated with antisera specific for SS-A/Ro or SS-B/La Ag were fixed with either acetone or paraformaldehyde and then analyzed in indirect immunofluorescent assays or by FACS analysis to detect cell surface IgG binding as an indirect measure of SS-A/Ro and SS-B/La Ag expression on the cell surface of keratinocytes. Estradiol (10(-5) to 10(-7) M) augmented binding of antiserum probes on the surface of cultured keratinocytes, with 10(-7) M estradiol showing the highest induction of cell surface binding of antisera specific for SS-A/Ro plus SS-B/La Ag (24.5% of cells were positive). In contrast, dihydrotestosterone, testosterone, and progesterone showed no augmentation. The augmentation by estradiol was partially inhibited by the antiestrogen nafoxidine. Estradiol augmented the relative incidence and absolute number of small or cuboidal cells binding antibodies specific for SS-A/Ro and SS-B/La Ag, whereas the number and incidence of larger differentiated cells binding anti-SS-A/Ro and anti-SS-B/La decreased significantly in cell cultures stimulated with estradiol. Flow cytometric analysis utilizing monospecific anti-SS-A/Ro or anti-SS-B/La sera showed that estradiol induced binding of anti-SS-A/Ro in 13.1% of cultured keratinocytes, of anti-SS-A/La in 14.4%, and of sera specific for both Ag in 21.4%. This direct association between estradiol and the augmentation of binding to the cell surface of human keratinocytes of IgG from antisera specific for SS-A/Ro and SS-B/La Ag may be a trigger factor of immunologic damage in lupus and may be important in the different sex rates observed in skin manifestation of subacute cutaneous and neonatal lupus erythematosis.

Herpes simplex virus (HSV) specific immune mediated cytotoxicity may be involved in control of HSV infections and in the tissue damage induced by HSV infection or HSV related skin disease such as herpes associated erythema multiforme. Developing an in vitro model to study this process has proved difficult due to the lack of an appropriate target cell that will express HSV antigens but is not simultaneously subject to viral induced cell death. The purpose of this study was to develop a model in which keratinocytes express cell surface HSV specific antigens but at the same time are protected from death due to viral infection. We found that keratinocytes infected with HSV in the presence of acyclovir (ACV) expressed such antigens yet remained viable for a period of time after the onset of antigen expression such that cytotoxicity studies could be successfully performed. Rabbit skin cells, a transformed keratinocyte line, or second passage human neonatal foreskin keratinocytes were grown in culture medium with or without 200 microM ACV and were infected with HSV. Examination by direct immunofluorescence with anti-HSV antibody revealed uniform HSV antigen expression by cells both with and without ACV by 8 h after infection. Cells infected without ACV exhibited marked structural abnormalities including formation of multinucleated giant cells, while cells with ACV showed fewer such changes throughout a 24-h period. An Ethidium Bromide-Acridine Orange cytotoxicity assay demonstrated significant increases in the cytotoxicity of infected cells not protected by ACV compared to that of cells with ACV (p less than .001). This in vitro model should prove useful in the investigation of HSV specific immune mediated cytotoxicity.