A new method based on dispersive solid phase microextraction with commercial MOFs coupled to LC-MS/MS for the determination of isoflavones in soy drinks.

For the first time, a method based on dispersive solid phase microextraction (D-µSPE) using commercial metal-organic frameworks coupled to liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS) has been proposed for the determination of isoflavones in soy drinks. The use of commercial sorbents simplifies the sample treatment procedure and allows their application to routine analysis. Optimization of the parameters involved in the microextraction process was carried out using a Box-Behnken experimental design. Under the optimized conditions, the limits of detection ranged between 2 and 7 µg L-1; the intra-day and inter-day precision were <10 and 20%, respectively, and the recoveries were in the range of 61-120%. No significant matrix effect was found, which allowed the use of external standard calibration method. The method was successfully applied to the determination of isoflavones in commercial soy milk samples.

Comparative MRI analysis of the forebrain of three sauropsida models.

The study of the brain by magnetic resonance imaging (MRI) allows to obtain detailed anatomical images, useful to describe specific encephalic structures and to analyze possible variabilities. It is widely used in clinical practice and is becoming increasingly used in veterinary medicine, even in exotic animals; however, despite its potential, its use in comparative neuroanatomy studies is still incipient. It is a technology that in recent years has significantly improved anatomical resolution, together with the fact that it is non-invasive and allows for systematic comparative analysis. All this makes it particularly interesting and useful in evolutionary neuroscience studies, since it allows for the analysis and comparison of brains of rare or otherwise inaccessible species. In the present study, we have analyzed the prosencephalon of three representative sauropsid species, the turtle Trachemys scripta (order Testudine), the lizard Pogona vitticeps (order Squamata) and the snake Python regius (order Squamata) by MRI. In addition, we used MRI sections to analyze the total brain volume and ventricular system of these species, employing volumetric and chemometric analyses together. The raw MRI data of the sauropsida models analyzed in the present study are available for viewing and downloading and have allowed us to produce an atlas of the forebrain of each of the species analyzed, with the main brain regions. In addition, our volumetric data showed that the three groups presented clear differences in terms of total and ventricular brain volumes, particularly the turtles, which in all cases presented distinctive characteristics compared to the lizards and snakes.

Controlling systemic corruption through group size and salary dispersion of public servants.

We investigate an agent-based model for the emergence of corruption in public contracts. There are two types of agents: business people and public servants. Both business people and public servants can adopt two strategies: corrupt or honest behavior. Interactions between business people and public servants take place through defined payoff rules. Either type of agent can switch between corrupt or honest strategies by comparing their payoffs after interacting. We measure the level of corruption in the system by the fractions of corrupt and honest agents for asymptotic times. We study the effects of the group size of the interacting agents, the dispersion with respect to the average salary of the public servants, and a parameter representing the institutional control of corruption. We characterize the fractions of honest and corrupt agents as functions of these variables. We construct phase diagrams for the level of corruption in the system in terms of these variables, where three collective states can be distinguished: i) a phase where corruption dominates; ii) a phase where corruption remains in less than 50% of the agents; and iii) a phase where corruption disappears. Our results indicate that a combination of large group sizes of interacting servants and business people and small dispersion of the salaries of public servants, contributes to the decrease of systemic corruption in public contracts.

An Adiponectin Receptor Agonist Reduces Type 2 Diabetic Periodontitis.

Periodontitis is twice as prevalent in diabetics as in nondiabetics, and type 2 diabetes (T2D)-associated periodontitis is severe in many cases due to the altered and aberrant functions of bone cells in hyperglycemic conditions. Therefore, developing an effective method to halt the disease process, as well as restore and regenerate lost alveolar bone to reserve the natural teeth in diabetics, is critically important. In the current study, we applied a newly discovered adiponectin receptor agonist AdipoRon (APR) in experimental periodontitis in diabetic animal models and demonstrated the underlying molecular mechanisms. We found that when APR systemically quenched the blood sugar level in diet-induced obesity (DIO) diabetic mice, it reduced osteoclast numbers and alveolar bone loss significantly due to APR's inhibition on osteoclast differentiation shown in our in vitro studies. APR also decreased the production of proinflammatory molecules CC chemokine ligand 2 and interleukin 6 in diseased gingival tissues. On the other hand, APR promoted alveolar bone regeneration through enhancing osteogenic differentiation and decreasing stromal cell-derived factor 1 in the bone marrow that facilitates stem cell migration. Same results were achieved by APR treatment of periodontitis induced in adiponectin (APN) knockout mice, indicating the ability of APR to activate the endogenous APN receptors to exert osteoanabolic effects. In summary, our study supports the notion that APR could be used as an effective multipronged approach to target T2D-associated periodontitis.

Effect of flower orientation on the male and female traits of Myrtillocactus geometrizans (Cactaceae).

Intra-individual variation in the production and size of reproductive traits has been documented in columnar cacti, being higher in equator-facing flowers. Such variation is attributed to the high amount of PAR intercepted by stems oriented towards the equator. Most studies focused on this phenomenon have documented the existence of intra-individual variation on traits associated with the female function; however, its impact on traits associated with the male function has been neglected. We tested the hypothesis that equator-facing flowers of Myrtillocactus geometrizans exhibit higher values on traits associated with both male and female functions than flowers facing against it. Number and size of anthers and ovaries, pollen:ovule ratio and number and quality of pollen grains (diameter, germinability, viability and pollen tube length) were estimated from reproductive structures facing north and south, and compared with t-tests between orientations. Number of anthers per flower, number of pollen grains per anther and per floral bud; pollen size, viability and germinability; pollen tube length; ovary length and pollen:ovule ratio were significantly higher in reproductive structures oriented towards the south (i.e. equator). These findings suggest that intra-individual variation in floral traits of M. geometrizans might be associated with different availability of resources in branches with contrasting orientation. Our results provide new evidence of the existence of a response to an orientation-dependent extrinsic gradient. To our knowledge, this is the first study documenting the existence of intra-individual variation on pollen quality and P:O ratio in Cactaceae species.

Changes in floral biology and inbreeding depression in native and invaded regions of Datura stramonium.

Plant populations invading new environments might compromise their fitness contribution to the next generation, because of the lack of native specialist pollinators and/or potential mates. Thus, changes in plant mating system and traits linked to it are expected in populations colonising new environments where selection would favour selfing and floral traits that maximise reproductive output. To test this, we studied native (Mexico) and non-native (Spain) populations of the obligate sexual reproducing annual weed Datura stramonium. Flower size, herkogamy, total number of seeds per plant, number of visits by and type of pollinators, and inbreeding depression were assessed in native and non-native populations. Finally, we measured phenotypic selection on corolla size and herkogamy in each population. Flower size and herkogamy showed wide and similar variation in both ranges. However, the largest average flower size was found in one non-native population whereas the highest average positive herkogamy was detected in one native population. On average, flowers in the native range received more visits by pollinators. Hawkmoths were the main visitors in the native populations while only bees were observed visiting flowers in Spain's populations. Only in the native range was inbreeding depression detected. Selection to reduce herkogamy was found only in one native population. Absence of both inbreeding depression and selection on floral traits suggest a change in mating system of D. stramonium in a new range where generalist pollinators may be promoting high reproductive success. Selection against deleterious alleles might explain the reduction of inbreeding depression, promoting the evolution of selfing.

Photosynthetically active radiation and carbon gain drives the southern orientation of Myrtillocactus geometrizans fruits.

The equatorial orientation of reproductive structures is known in some columnar cacti from extratropical deserts. It has been hypothesised that photosynthetically active radiation (PAR) interception is the main reason for this orientation, because of its key effect on nocturnal CO2 uptake. However, there are no studies addressing both the effect of PAR and its consequence, carbon gain, on fruit orientation. Accordingly, we tested whether PAR and carbon gain could explain the southern fruit orientation of Myrtillocactus geometrizans, an inter-tropical columnar cactus. We studied three populations of M. geometrizans in Mexico. For each population, azimuth of fruits, total daily PAR, nocturnal acid accumulation (NAA) and fruit production were measured. The relationships between rib orientation and number of fruits, as well as total daily PAR, were evaluated using periodic regressions. The effect of total daily PAR and NAA on number of fruits was assessed using generalised linear models. During spring, mean fruit orientation had a south azimuth for three populations. Likewise, rib orientation had a significant effect on fruit production, with the south-facing ribs having the maximum number of fruits. Total daily PAR was highest in the south-facing ribs, at least for those in the northern and central populations. Furthermore, during spring, there was a significant positive effect of total daily PAR and NAA on fruit production. Our results provide strong evidence that the higher carbon gain in equatorial ribs, through a highest interception of PAR, would be the responsible factor for equatorial orientation of fruits in an inter-tropical columnar cactus.

Recurrent acute thermal lesion induces esophageal hyperproliferative premalignant lesions in mice esophagus.

Hot beverage consumption is a risk factor for esophageal squamous cell carcinoma, but the underlying mechanisms are still unknown. We developed an experimental mouse model to understand the mechanism of thermal lesion to esophageal carcinogenesis. Female BALB/c mice were treated by gavage with water at different temperatures three times a week and nitrosamines in the drinking water. Water at 70°C, but not at lower temperatures, initially induced an esophageal necrosis that healed and became resistant to necrosis after further administrations. However, when 70°C water was associated with N-nitrosodiethylamine at doses above 1 ppm, there was interference in epithelial regeneration, allowing recurrent thermal injury and inflammation. Recurrent thermal injury resulted in hyper proliferative premalignant lesions being induced earlier (at 4 weeks) and at a higher frequency (4-fold increase at 16 weeks) when compared to mice treated with NDEA only. Ki-67 immunostaining revealed that recurrent thermal injury induced basal cell proliferation resulting in the expansion of epithelial basal cells, confirmed by the increase in cytokeratin 14 positive cells with concomitant reduction of differentiated cytokeratin 5 positive cells. We conclude that recurrent thermal lesion may act as a tumor promoter though a strong proliferation stimulus of esophageal epithelial basal cells.

Quaternary origin and genetic divergence of the endemic cactus Mammillaria pectinifera in a changing landscape in the Tehuacán Valley, Mexico.

The endemic Mexican cactus, Mammillaria pectinifera, shows low dispersal capabilities and isolated populations within the highly dissected landscape of Tehuacán Valley. These characteristics can restrict gene flow and act upon the genetic divergence and speciation in arid plants. We conducted a phylogeographic study to determine if the origin, current distribution, and genetic structure of M. pectinifera were driven by Quaternary geomorphic processes. Sequences of the plastids psbA-trnH and trnT-trnL obtained from 66 individuals from seven populations were used to estimate genetic diversity. Population differentiation was assessed by an analysis of molecular variance. We applied a stepwise phylogenetic calibration test to determine whether species origin and genetic divergence among haplotypes were temporally concordant with recognizable episodes of geomorphic evolution. The combination of plastid markers yielded six haplotypes, with high levels of haplotype diversity (h = 0.622) and low nucleotide diversity (π = 0.00085). The populations were found to be genetically structured (F(ST) = 0.682; P < 0.00001), indicating that geographic isolation and limited dispersal were the primary causes of genetic population differentiation. The estimated origin and divergence time among haplotypes were 0.017-2.39 and 0.019-1.237 mya, respectively, which correlates with Pleistocene tectonics and erosion events, supporting a hypothesis of geomorphically-driven geographical isolation. Based on a Bayesian skyline plot, these populations showed long term demographic stability, indicating that persistence in confined habitats has been the main response of this species to landscape changes. We conclude that the origin and haplotype divergence of M. pectinifera were a response to local Quaternary geomorphic evolution.

[Limits of therapeutic effort. Professional opinions]. / Limitación del esfuerzo terapéutico. Opinión de los profesionales.

INTRODUCTION: In our clinical practice we find the need to care for patients with irreversible conditions, due to advanced age or underlying chronic disease, and a change in the types of disease currently facing the health workforce.The objective of this research was to study the ethical assessment of health professionals in our Hospital on extraordinary life support measures. MATERIAL AND METHODS: Prospective descriptive study conducted at the Hospital General Universitario de Ciudad Real during the months of April to August 2010. The convenience sample consisted of 189 professionals from different categories working in our hospital during the study period.It included a questionnaire adapted for use in hospitals, comprising 18 items with dichotomous responses.Informed consent was requested and the confidentiality of information ensured. RESULTS: A sample of 189 professionals, of whom 21.7% were male and 78.3% were female. The mean age was 40.39 years SD + 10, with a mode of 31 years.The professionals involved were doctors, nurses and nursing assistants, with an average experience of 15.8% ± 10.4 SD years.A total of 79.9% were in favour of euthanasia, 93.6% against dysthanasia, 92.6% for antidysthanasia, and 99.5% for orthotonasia. The medical group was the one most against the use of euthanasia P=.0001. Differences were found between religious practice and the ethical situations at the end of life. CONCLUSIONS: Most participants took into account the patient's decision to limit extraordinary measures in terminal disease situations.The study reveals that the effectiveness and usefulness of our clinical practice should include an ethical evaluation by professionals with the patient. It became clear that the majority of the sample of professionals is against over-aggressive treatment, and for a dignified death.

Pharmacotherapies to manage bone loss-associated diseases: a quest for the perfect benefit-to-risk ratio.

In this review, benefits and side-effects of current and emerging therapies to treat and prevent pathological bone loss are described. Bisphosphonates are the antiresorptive compounds most widely used in the treatment of bone-loss associated diseases. They are generally well-tolerated although have recently been associated with osteonecrosis of the jaw and other complications. Therapies modulating estrogen receptor activation are indicated in the prevention and treatment of either breast cancer or osteoporosis in postmenopausal women. Thus, hormone replacement therapy is effective in prevention of osteoporosis, but its long-term use can increase the risk of breast cancer, stroke and embolism. Tamoxifen benefits all stages of breast cancer, but its use may lead to uterine cancer and thromboembolism. Raloxifene is approved in prevention of breast cancer and treatment of postmenopausal osteoporosis, but its use can increase the risk of fatal stroke. Aromatase inhibitors are superior to tamoxifen at advanced stages of disease and as adjuvants, but their use increase fracture incidence. Fulvestrant is as effective as aromatase inhibitors in the treatment of advanced breast cancer and does not cause bone fractures. Another antiresorptive available for the treatment of postmenopausal osteoporosis, Paget's disease and hypercalcemia is calcitonin, which also exhibits analgesic effects. A promising antiresorptive agent currently in clinical trials is denosumab. Aditional therapies for osteoporosis that decrease fracture risk consist of PTH-like anabolic agents and the dual action bone agent strontium ranelate. Antiseptics and antibiotics are used extensively in periodontal disease intervention to target bacterial biofilm, although host-directed therapies are also being developed.

Phenotypic analysis of Dlx5 overexpression in post-natal bone.

Dlx5 plays an important role in the embryonic development of mineralized tissues. We hypothesized that Dlx5 also functions in regulating post-natal bone formation in mice. To prove this hypothesis, we infected 5-day-old bone sialoprotein (BSP)/avian retroviral receptor gene (TVA) transgenic mice with replication-competent retroviral vectors expressing wild-type Dlx5 (RCAS-Dlx5WT) and mutated Dlx5 at arginine (R) 31 of its homeodomain (RCAS-Dlx5RH). Immunohistochemistry indicated that RCAS-Dlx5WT increased BSP and osteopontin (OPN) expression, whereas it decreased that of osteocalcin (OC). RCAS-Dlx5RH mediated opposite effects. Semi-quantitative RT-PCR confirmed these results. Ex vivo overexpression of RCAS-Dlx5WT in BSP/TVA calvarial cells promoted, whereas that of RCAS-Dlx5RH inhibited, mineralized nodule formation as compared with that in control cells. Our results suggest that Dlx5 promotes expression of early markers of osteogenic differentiation and increases mineralization post-natally.

Percepciones, actitudes y conductas de médicos gineco-obstetras, respecto al uso actual de terapia de reemlazo hormonal / Perceptions, attitudes, and behavior of obstetrician-gynecologists for the use of hormonal replacement therapy

Resultados de una encuesta con preguntas específicas contestadas por el 97,6 por ciento de los gineco-obstetras del Departamento de Obstetricia y Ginecología de Clínica Alemana de Santiago, para establecer un diagnóstico de situación sobre el uso de terapia de reemplazo hormonal (TRH). Se enfatizan preguntas sobre la aceptabilidad de las futuras usuarias tanto de TRH como de terapias alternativas; sobre la percepción de los eventuales beneficios desde un punto de vista general, o específicamente cardiovascular; así como las preferencias de hormonas a usar y predilecciones por las vías de administración; las asociaciones del uso y cáncer mamario; las variaciones sobre el uso de TRH pos publicación del Women Health Iniciative Study; los factores que inciden en la discontinuación del tratamiento; la importancia de edad para el uso, factores relacionados con los costos de las terapias y la preferencia o no de productos originales de investigación. Conclusión: Es necesaria una mayor capacitación sobre el uso de TRH en la actualidad tanto de los ginecólogos especialistas en climaterio y menopausia, como de los que no lo son. A falta de información concluyente sobre esta temática en el momento actual se sugiere que el manejo de este tipo de pacientes sea efectuado por los equipos médicos especializados.

In order to set a diagnosis about the use of hormonal replacement therapy (HRT) in peri and postmenopausal women by the obstetricians and gynecologists members of our staff, we did a survey that was answered by 97.6 percent of them. Questions about the future patients desire related to use of HRT or use of natural or alternative medicines were included. There were also questions related to the "risk-benefit" relationship on the use of HRT from an overall point of view as well as from a cardiovascular point of view. The preference of medical doctors (MD) on choice of hormone type in HRT use, in respect to the administration, were also asked. Among others, questions were asked in order to know MD opinions on the relationship with breast cancer, the changes on acceptability use after the WHI study, reasons for the treatment discontinuation, the importance of women's age and the cost of pharmaceuticals produces on HRT use. Conclusions: Are focused on a need of a solid educational program on use of HRT addressed to gynecologists, as well as to general practitioners, cardiologists, oncologists and others related. Educational programs are also quite beneficial to future users as well as women that are currently under treatment. In the absence of conclusive information available at the present moment, we advise that patients considering HRT should seek the counsel of medical teams whose specialties include menopause.

[New caretakers for the elderly, how to prepare them?]. / Nuevas cuidadoras para los mayores. Cómo formarlas?

The appearance at the homes of our elderly of a new caretaker who is foreign to the family unit and in need of preparation justifies the creation of a multidisciplinary Formative Course at the local level. Groups were captured at civic and social centers in the town. A theoretical-practical methodology was used, dealing with diverse themes ranging from the elderly's general hygiene needs to social resources of interest to the groups. The participants' cultural diversity permitted a continuous flow of information among the participants, enriching the contents with personal anecdotes which will prove to be of great use for the application of treatment. Although 50% of the participants were non-Spanish speakers, the practical nature of the workshops proved of great usefulness since it facilitated the participation and integration of the group.

Impact of the endorectal ultrasound probe on uroflow parameters in males.

OBJECTIVES: The aim of this study was to test the null hypothesis that the presence in the rectum of an endorectal ultrasound probe during transrectal voiding ultrasonography (TRVUS) would have no significant effect on uroflowmetry parameters. PATIENTS AND METHODS: We studied 43 randomly selected men undergoing TRVUS of the prostate for non-neurogenic lower urinary tract symptoms. Uroflowmetry was performed immediately before and during the TRVUS. Results were compared with a paired Student's t test; the null hypothesis was confirmed by p values >0.05. RESULTS: Forty patients were able to void with the endorectal probe inserted, and 95% described this micturition as representative of their usual voiding behavior. No significant statistical difference was found between uroflowmetry parameters before and during TRVUS, confirming our null hypothesis. CONCLUSION: Our data suggest that uroflowmetry in combination with TRVUS can be a reliable tool for evaluating disorders of micturition in males, at least in selected cases.

Results from two years of field studies to determine Mancozeb based spray programmes with minimal impact on predatory mites in European vine cultivation.

Mancozeb is a dithiocarbamate fungicide with contact activity against a wide range of economically important fungal diseases. Its multi-site mode of action means that to date there have been no recorded incidences of resistance developing despite many years of use on high risk diseases. One such disease, Grape downy mildew (Plasmopara viticola) has developed resistance to a wide range of important oomycete specific fungicides following their introduction onto the market. The role of Mancozeb either as a mixing or alternation partner in helping to manage these resistance situations remains critically important. Historical use patterns for mancozeb in tree and vine crops involved many applications of product at high use rates. Although this gave excellent disease control, a negative impact on predatory mites was often reported by researchers. This has lead to the development of mancozeb spray programmes in vines and other crops with a much reduced impact on predatory mites. A range of field studies was conducted over two years in France, Germany, Italy, Portugal and Spain where 2, 3 or 4 applications of mancozeb containing products were made per season at different spray timings. In this paper findings from field studies over two years in five different vine growing regions in Europe indicated that two to four applications of mancozeb at 1.6 kg a.i./ha as part of a spray programme caused minimal impact on naturally occurring populations of predatory mites which in turn was compatible with Integrated Pest Management programmes and the conservation of predatory mites.

Selectivity of the ubiquitin pathway for oxidatively modified proteins: relevance to protein precipitation diseases.

There is now consensus that the accumulation of oxidatively modified proteins is cytotoxic and causally related to several age-related diseases, including the amyloid diseases and age-related cataracts. There is also general agreement that proteolytic pathways provide a quality control mechanism to limit accumulation of damaged proteins. Although many researchers assume that the ubiquitin pathway is involved in recognition and proteolytic removal of oxidatively modified proteins, which are produced upon cellular stress, there has been no direct evidence to support this hypothesis. In this work, we used a novel proteolysis-resistant ubiquitin variant to demonstrate that ubiquitin conjugates isolated from oxidatively stressed mammalian cells are enriched 3.3-15-fold for oxidatively modified proteins and that failure to execute ubiquitin-dependent proteolysis renders various cell types more susceptible to oxidative stress-related cytotoxicity. These results were corroborated using several inhibitors of the ubiquitin proteasome pathway, including PS-341, an anticancer drug in clinical use. Taken together the data indicate that the ubiquitin proteolytic pathway recognizes and removes oxidatively modified proteins, and that failure of this system, as occurs upon aging or stress, may be involved in and exacerbate cytotoxicity and age-related syndromes in which accumulation of ubiquitinated and oxidatively modified proteins has an etiologic role.

Potassium channel-blockers as therapeutic agents to interfere with bone resorption of periodontal disease.

UNLABELLED: Inflammatory lesions of periodontal disease contain all the cellular components, including abundant activated/memory T- and B-cells, necessary to control immunological interactive networks and to accelerate bone resorption by RANKL-dependent and -independent mechanisms. Blockade of RANKL function has been shown to ameliorate periodontal bone resorption and other osteopenic disorders without affecting inflammation. Development of therapies aimed at decreasing the expression of RANKL and pro-inflammatory cytokines by T-cells constitutes a promising strategy to ameliorate not only bone resorption, but also inflammation. Several reports have demonstrated that the potassium channels Kv1.3 and IKCa1, through the use of selective blockers, play important roles in T-cell-mediated events, including T-cell proliferation and the production of pro-inflammatory cytokines. More recently, a potassium channel-blocker for Kv1.3 has been shown to down-regulate bone resorption by decreasing the ratio of RANKL-to-OPG expression by memory-activated T-cells. In this article, we first summarize the mechanisms by which chronically activated/memory T-cells, in concert with B-cells and macrophages, trigger inflammatory bone resorption. Then, we describe the main structural and functional characteristics of potassium channels Kv1.3 and IKCa1 in some of the cells implicated in periodontal disease progression. Finally, this review elucidates some recent advances in the use of potassium channel-blockers of Kv1.3 and IKCa1 to ameliorate the clinical signs or side-effects of several immunological disorders and to decrease inflammatory bone resorption in periodontal disease. ABBREVIATIONS: AICD, activation-induced cell death; APC, antigen-presenting cells; B(K), large conductance; CRAC, calcium release-activated calcium channels; DC, dendritic cell; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; IFN-gamma, interferon-gamma; IP(3), inositol (1,4,5)-triphosphate; (K)ir, inward rectifier; JNK, c-Jun N-terminal kinase; I(K), intermediate conductance; LPS, lipopolysaccharide; L, ligand; MCSF, macrophage colony-stimulating factor; MHC, major histocompatibility complex; NFAT, nuclear factor of activated T-cells; RANK, receptor activator of nuclear factor-kappaB; T(CM), central memory T-cells; T(EM), effector memory T-cells; TNF, tumor necrosis factor; TRAIL, TNF-related apoptosis-inducing ligand; OPG, osteoprotegerin; Omp29, 29-kDa outer membrane protein; PKC, protein kinase C; PLC, phospholipase C; RT-PCR, reverse-transcriptase polymerase chain-reaction; S(K), small conductance; TCR, T-cell receptor; and (K)v, voltage-gated.

Role of Gas6/Axl signaling in lens epithelial cell proliferation and survival.

Axl is a receptor tyrosine kinase that is activated by Gas6, a growth factor that belongs to the vitamin K-dependent protein family. Although Gas6 binding to Axl has been shown to transmit mitogenic and/or antiapoptotic signals to a variety of cell types, the role of the Axl-Gas6 system in normal and pathological lens biology is not known. We demonstrate for the first time that Axl protein is expressed in normal rat and bovine lens and that its ligand, Gas6, is present in bovine aqueous humor. In addition, we have detected tyrosine-phosphorylated Axl in normal rat and bovine lens epithelial tissues. We further show that human recombinant Gas6 is able to act as a growth factor in cultured human lens epithelial cells by activating Axl and then the AKT signaling pathway. Gas6 mediates a survival and anti-apoptotic response in cultured human lens epithelial cells subjected to serum-starvation (48-72hr), or treated with transforming growth factor beta1 (5 ng ml(-1), 48hr) or tumor necrosis alpha (100 ng ml(-1), 48hr), as demonstrated by increased number of viable cells, and decreased DNA condensation or caspase-3 activity. In contrast, Gas6 is not able to block apoptosis induced by staurosporin (1microM, 5-24hr) in human lens epithelial cells. Taken together, these data suggest that the Gas6/Axl signaling plays an important role in the control of lens epithelial cell growth and survival and hence in the maintenance of lens homeostasis.