Potential therapeutic approaches for modulating expression and accumulation of defective lamin A in laminopathies and age-related diseases

Senescence Rejuvenation through Reduction in Mitochondrial Reactive Oxygen Species Generation by Polygonum cuspidatum Extract: In Vitro Evidence

Oxidative stress caused by reactive oxygen species (ROS) is one of the major causes of senescence. Strategies to reduce ROS are known to be important factors in reversing senescence, but effective strategies have not been found. In this study, we screened substances commonly used as cosmetic additives to find substances with antioxidant effects. Polygonum cuspidatum (P. cuspidatum) extract significantly reduced ROS levels in senescent cells. A novel mechanism was discovered in which P. cuspidatum extract reduced ROS, a byproduct of inefficient oxidative phosphorylation (OXPHOS), by increasing OXPHOS efficiency. The reduction in ROS by P. cuspidatum extract restored senescence-associated phenotypes and enhanced skin protection. Then, we identified polydatin as the active ingredient of P. cuspidatum extract that exhibited antioxidant effects. Polydatin, which contains stilbenoid polyphenols that act as singlet oxygen scavengers through redox reactions, increased OXPHOS efficiency and subsequently restored senescence-associated phenotypes. In summary, our data confirmed the effects of P. cuspidatum extract on senescence rejuvenation and skin protection through ROS reduction. This novel finding may be used as a treatment in senescence rejuvenation in clinical and cosmetic fields.

Recent Advancement in Elimination Strategies and Potential Rejuvenation Targets of Senescence

Cellular senescence is a state of exiting the cell cycle, resisting apoptosis, and changing phenotype. Senescent cells (SCs) can be identified by large, distorted morphology and irreversible inability to replicate. In early development, senescence has beneficial roles like tissue patterning and wound healing, where SCs are cleared by the immune system. However, there is a steep rise in SC number as organisms age. The issue with SC accumulation stems from the loss of cellular function, alterations of the microenvironment, and secretions of pro-inflammatory molecules, consisting of cytokines, chemokines, matrix metalloproteinases (MMPs), interleukins, and extracellular matrix (ECM)-associated molecules. This secreted cocktail is referred to as the senescence-associated secretory phenotype (SASP), a hallmark of cellular senescence. The SASP promotes inflammation and displays a bystander effect where paracrine signaling turns proliferating cells into senescent states. To alleviate age-associated diseases, researchers have developed novel methods and techniques to selectively eliminate SCs in aged individuals. Although studies demonstrated that selectively killing SCs improves age-related disorders, there are drawbacks to SC removal. Considering favorable aspects of senescence in the body, this paper reviews recent advancements in elimination strategies and potential rejuvenation targets of senescence to bring researchers in the field up to date.

Targeting Mitochondrial Oxidative Stress as a Strategy to Treat Aging and Age-Related Diseases

Mitochondria are one of the organelles undergoing rapid alteration during the senescence process. Senescent cells show an increase in mitochondrial size, which is attributed to the accumulation of defective mitochondria, which causes mitochondrial oxidative stress. Defective mitochondria are also targets of mitochondrial oxidative stress, and the vicious cycle between defective mitochondria and mitochondrial oxidative stress contributes to the onset and development of aging and age-related diseases. Based on the findings, strategies to reduce mitochondrial oxidative stress have been suggested for the effective treatment of aging and age-related diseases. In this article, we discuss mitochondrial alterations and the consequent increase in mitochondrial oxidative stress. Then, the causal role of mitochondrial oxidative stress on aging is investigated by examining how aging and age-related diseases are exacerbated by induced stress. Furthermore, we assess the importance of targeting mitochondrial oxidative stress for the regulation of aging and suggest different therapeutic strategies to reduce mitochondrial oxidative stress. Therefore, this review will not only shed light on a new perspective on the role of mitochondrial oxidative stress in aging but also provide effective therapeutic strategies for the treatment of aging and age-related diseases through the regulation of mitochondrial oxidative stress.

Sex Differences in Molecular Mechanisms of Cardiovascular Aging

Cardiovascular disease (CVD) is still the leading cause of illness and death in the Western world. Cardiovascular aging is a progressive modification occurring in cardiac and vascular morphology and physiology where increased endothelial dysfunction and arterial stiffness are observed, generally accompanied by increased systolic blood pressure and augmented pulse pressure. The effects of biological sex on cardiovascular pathophysiology have long been known. The incidence of hypertension is higher in men, and it increases in postmenopausal women. Premenopausal women are protected from CVD compared with age-matched men and this protective effect is lost with menopause, suggesting that sex-hormones influence blood pressure regulation. In parallel, the heart progressively remodels over the course of life and the pattern of cardiac remodeling also differs between the sexes. Lower autonomic tone, reduced baroreceptor response, and greater vascular function are observed in premenopausal women than men of similar age. However, postmenopausal women have stiffer arteries than their male counterparts. The biological mechanisms responsible for sex-related differences observed in cardiovascular aging are being unraveled over the last several decades. This review focuses on molecular mechanisms underlying the sex-differences of CVD in aging.

The emerging role of cellular senescence in complications of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has triggered a sudden global change in healthcare systems. Cancer patients have a higher risk of death from COVID-19 in comparison to patients without cancer. Many studies have stated that various factors, such as older age, frequent exposure to healthcare, and higher smoking rates are responsible for the complications of COVID-19. We hypothesize that side effects of chemotherapy, such as cellular senescence, could worsen COVID-19. Given this situation, in this review, we highlight the updated findings of research investigating the impact of cellular senescence on COVID-19 complications and explored potential therapeutic targets for eliminating senescent cells during the COVID-19 pandemic.

Down-Regulation of Lnc-CYP7A1-1 Rejuvenates Aged Human Mesenchymal Stem Cells to Improve Their Efficacy for Heart Repair Through SYNE1

Background

Several long non-coding RNAs (lncRNAs) have been associated with cell senescence, termed senescence-associated lncRNAs (SAL-RNAs). However, the mechanisms involved for SAL-RNAs in aging are not fully elucidated. In the present study, we investigated the effects of SAL-RNAs on aged human bone marrow-derived mesenchymal stem cells (hBM-MSCs), and the possible means to counteract such effects to improve the regenerative capacity of aged hBM-MSCs.

Methods

By comparing the lncRNAs expression of hBM-MSCs derived from young and old individuals, lnc-CYP7A1-1 was identified as being significantly increased with age. Using predictive software, the expression of Spectrin Repeat Containing Nuclear Envelope Protein 1 (SYNE1), was found to be decreased with age. Next, through lentiviral constructs, we downregulated the expression of lnc-CYP7A1-1 or SYNE1 in hBM-MSCs separately. Additionally, hBM-MSCs proliferation, survival, migration, and senescence were investigated in vitro. In vivo, lnc-CYP7A1-1 downregulated aged hBM-MSCs were implanted into infarcted mouse hearts after myocardial infarction (MI), and cardiac function was measured. Through lentivirus-mediated downregulation of lnc-CYP7A1-1 in aged hBM-MSCs, we revealed that cell senescence was decreased, whereas cell proliferation, migration, and survival were increased. On the other hand, downregulation of SYNE1, the target gene of lnc-CYP7A1-1, in young hBM-MSCs increased cell senescence, yet decreased cell proliferation, migration, and survival. Downregulation of lnc-CYP7A1-1 in aged hBM-MSCs induced cell rejuvenation, yet this effect was attenuated by repression of SYNE1. In vivo, transplantation of lnc-CYP7A1-1 downregulated old hBM-MSCs improved cardiac function after MI.

Conclusion

Down-regulation of lnc-CYP7A1-1 rejuvenated aged hBM-MSCs and improved cardiac function when implanted into the infarcted mouse hearts, possibly through its target gene SYNE1.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

Molecular therapies delaying cardiovascular aging: disease- or health-oriented approaches

Regenerative medicine is a new therapeutic modality that aims to mend tissue damage by encouraging the reconstitution of physiological integrity. It represents an advancement over conventional therapies that allow reducing the damage but result in disease chronicization. Age-related decline in spontaneous capacity of repair, especially in organs like the heart that have very limited proliferative capacity, contributes in reducing the benefit of conventional therapy. ncRNAs are emerging as key epigenetic regulators of cardiovascular regeneration. Inhibition or replacement of miRNAs may offer reparative solutions to cardiovascular disease. The first part of this review article is devoted to illustrating novel therapies emerging from research on miRNAs. In the second part, we develop new therapeutic concepts emerging from genetics of longevity. Prolonged survival, as in supercentenarians, denotes an exceptional capacity to repair and cope with risk factors and diseases. These characteristics are shared with offspring, suggesting that the regenerative phenotype is heritable. New evidence indicates that genetic traits responsible for prolongation of health span in humans can be passed to and benefit the outcomes of animal models of cardiovascular disease. Genetic studies have also focused on determinants of accelerated senescence and related druggable targets. Evolutionary genetics assessing the genetic basis of adaptation and comparing successful and unsuccessful genetic changes in response to selection within populations represent a powerful basis to develop novel therapies aiming to prolong cardiovascular and whole organism health.

Suppression of myopathic lamin mutations by muscle-specific activation of AMPK and modulation of downstream signaling

Laminopathies are diseases caused by dominant mutations in the human LMNA gene encoding A-type lamins. Lamins are intermediate filaments that line the inner nuclear membrane, provide structural support for the nucleus and regulate gene expression. Drosophila melanogaster models of skeletal muscle laminopathies were developed to investigate the pathological defects caused by mutant lamins and identify potential therapeutic targets. Human disease-causing LMNA mutations were modeled in Drosophila Lamin C (LamC) and expressed in indirect flight muscle (IFM). IFM-specific expression of mutant, but not wild-type LamC, caused held-up wings indicative of myofibrillar defects. Analyses of the muscles revealed cytoplasmic aggregates of nuclear envelope (NE) proteins, nuclear and mitochondrial dysmorphology, myofibrillar disorganization and up-regulation of the autophagy cargo receptor p62. We hypothesized that the cytoplasmic aggregates of NE proteins trigger signaling pathways that alter cellular homeostasis, causing muscle dysfunction. In support of this hypothesis, transcriptomics data from human muscle biopsy tissue revealed misregulation of the AMP-activated protein kinase (AMPK)/4E-binding protein 1 (4E-BP1)/autophagy/proteostatic pathways. Ribosomal protein S6K (S6K) messenger RNA (mRNA) levels were increased and AMPKα and mRNAs encoding downstream targets were decreased in muscles expressing mutant LMNA relative controls. The Drosophila laminopathy models were used to determine if altering the levels of these factors modulated muscle pathology. Muscle-specific over-expression of AMPKα and down-stream targets 4E-BP, Forkhead box transcription factors O (Foxo) and Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), as well as inhibition of S6K, suppressed the held-up wing phenotype, myofibrillar defects and LamC aggregation. These findings provide novel insights on mutant LMNA-based disease mechanisms and identify potential targets for drug therapy.

Roles of long noncoding RNAs in aging and aging complications

Aging is a universal and time dependent complex biological process, characterized by a progressive physiological dysfunction and an increased vulnerability to death. Though the physiological process of aging is still not fully understood, several cellular and molecular mechanisms have been identified. Long noncoding RNAs is a class of regulatory ncRNAs with transcript lengths >200 nucleotides. Discovery of this vast pool of regulators in mammalian genome supplies a new dimension to study and explore the aging process. In this review, we discuss the contribution of lncRNAs in aging and aging complications, and raise interest of serving lncRNAs as biomarkers and potential therapeutic targets to prolong health and ameliorate age-associated diseases. We hope understanding the roles of these high specificity and low conservation regulators in generating age-associated phenotypes might benefit human lifespan.

Are parents of children with Cockayne syndrome manifesting features of the disorder?: Case reports

RATIONALE

Postnatal growth failure and progressive neurologic dysfunction and increasing multiorgan involvement are the main clinical features of Cockayne syndrome (CS). CS is a rare autosomal recessive disorder of the group of DNA repair diseases. Usually, genetic carriers, such as parents of patients, are not at risk for developing the disease.

PATIENT CONCERNS

A series of 14 family subjects (6 children with age range from 6 months to 4 years with CS) and 9 parents (aged from 23 to 34 years) from consanguineous families is reported.

DIAGNOSES

Ultraviolet irradiation studies were performed on these children and were indicative of CS.

INTERVENTIONS

Cells of skin fibroblast from these children with the disease showed a symmetrical accumulation of chromosomal aberrations and the nuclear lamina aberrations. Our results showed a significant and simultaneous increase of percent of blebbs and invaginations of the nuclear lamina in all cases CS. The pronounced changes in 12.6 times at atypical form (girl); in 8.5 times at severe form (boy) and in 5.6 times at light form (boy). Percentage of metaphases with chromosomal aberration is significantly higher in CS cells: in 4 times at atypical form, in 3 times at hard form, and in 2 times at light form. The parents of these families (consanguineous families) were intellectually variable between normal/borderline intelligence, though most manifested a constellation of skeletal and extraskeletal abnormalities and notably, the characteristic cachectic facial appearance. The parents were considered as manifesting the mild type of CS, because they showed no abnormalities of DNA repair.

OUTCOMES

Clinical manifestations in heterozygote carriers of an autosomal recessive disorders is a rare phenomenon as carriers are usually healthy.

LESSONS

The interesting finding of the families studied is that there appeared to be a multitude of carriers manifesting with normal to borderline intelligence but with a wide spectrum of skeletal and extraskeletal abnormalities.

Chemical screening identifies ROCK as a target for recovering mitochondrial function in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) constitutes a genetic disease wherein an aging phenotype manifests in childhood. Recent studies indicate that reactive oxygen species (ROS) play important roles in HGPS phenotype progression. Thus, pharmacological reduction in ROS levels has been proposed as a potentially effective treatment for patient with this disorder. In this study, we performed high-throughput screening to find compounds that could reduce ROS levels in HGPS fibroblasts and identified rho-associated protein kinase (ROCK) inhibitor (Y-27632) as an effective agent. To elucidate the underlying mechanism of ROCK in regulating ROS levels, we performed a yeast two-hybrid screen and discovered that ROCK1 interacts with Rac1b. ROCK activation phosphorylated Rac1b at Ser71 and increased ROS levels by facilitating the interaction between Rac1b and cytochrome c. Conversely, ROCK inactivation with Y-27632 abolished their interaction, concomitant with ROS reduction. Additionally, ROCK activation resulted in mitochondrial dysfunction, whereas ROCK inactivation with Y-27632 induced the recovery of mitochondrial function. Furthermore, a reduction in the frequency of abnormal nuclear morphology and DNA double-strand breaks was observed along with decreased ROS levels. Thus, our study reveals a novel mechanism through which alleviation of the HGPS phenotype is mediated by the recovery of mitochondrial function upon ROCK inactivation.

All-trans retinoic acid and rapamycin normalize Hutchinson Gilford progeria fibroblast phenotype

Hutchinson Gilford progeria syndrome is a fatal disorder characterized by accelerated aging, bone resorption and atherosclerosis, caused by a LMNA mutation which produces progerin, a mutant lamin A precursor. Progeria cells display progerin and prelamin A nuclear accumulation, altered histone methylation pattern, heterochromatin loss, increased DNA damage and cell cycle alterations. Since the LMNA promoter contains a retinoic acid responsive element, we investigated if all-trans retinoic acid administration could lower progerin levels in cultured fibroblasts. We also evaluated the effect of associating rapamycin, which induces autophagic degradation of progerin and prelamin A. We demonstrate that all-trans retinoic acid acts synergistically with low-dosage rapamycin reducing progerin and prelamin A, via transcriptional downregulation associated with protein degradation, and increasing the lamin A to progerin ratio. These effects rescue cell dynamics and cellular proliferation through recovery of DNA damage response factor PARP1 and chromatin-associated nuclear envelope proteins LAP2α and BAF. The combined all-trans retinoic acid-rapamycin treatment is dramatically efficient, highly reproducible, represents a promising new approach in Hutchinson-Gilford Progeria therapy and deserves investigation in ageing-associated disorders.

Aging Chart: a community resource for rapid exploratory pathway analysis of age-related processes

Aging research is a multi-disciplinary field encompassing knowledge from many areas of basic, applied and clinical research. Age-related processes occur on molecular, cellular, tissue, organ, system, organismal and even psychological levels, trigger the onset of multiple debilitating diseases and lead to a loss of function, and there is a need for a unified knowledge repository designed to track, analyze and visualize the cause and effect relationships and interactions between the many elements and processes on all levels. Aging Chart (http://agingchart.org/) is a new, community-curated collection of aging pathways and knowledge that provides a platform for rapid exploratory analysis. Building on an initial content base constructed by a team of experts from peer-reviewed literature, users can integrate new data into biological pathway diagrams for a visible, intuitive, top-down framework of aging processes that fosters knowledge-building and collaboration. As the body of knowledge in aging research is rapidly increasing, an open visual encyclopedia of aging processes will be useful to both the new entrants and experts in the field.

Anti-Proliferative Effect of Rosmarinus officinalis L. Extract on Human Melanoma A375 Cells

Rosemary (Rosmarinus officinalis L.) has been used since ancient times in traditional medicine, while nowadays various rosemary formulations are increasingly exploited by alternative medicine to cure or prevent a wide range of health disorders. Rosemary’s bioproperties have prompted scientific investigation, which allowed us to ascertain antioxidant, anti-inflammatory, cytostatic, and cytotoxic activities of crude extracts or of pure components. Although there is a growing body of experimental work, information about rosemary’s anticancer properties, such as chemoprotective or anti-proliferative effects on cancer cells, is very poor, especially concerning the mechanism of action. Melanoma is a skin tumor whose diffusion is rapidly increasing in the world and whose malignancy is reinforced by its high resistance to cytotoxic agents; hence the availability of new cytotoxic drugs would be very helpful to improve melanoma prognosis. Here we report on the effect of a rosemary hydroalcoholic extract on the viability of the human melanoma A375 cell line. Main components of rosemary extract were identified by liquid chromatography coupled to tandem mass spectrometry (LC/ESI-MS/MS) and the effect of the crude extract or of pure components on the proliferation of cancer cells was tested by MTT and Trypan blue assays. The effect on cell cycle was investigated by using flow cytometry, and the alteration of the cellular redox state was evaluated by intracellular ROS levels and protein carbonylation analysis. Furthermore, in order to get information about the molecular mechanisms of cytotoxicity, a comparative proteomic investigation was performed.

Lamins at the crossroads of mechanosignaling

The intermediate filament proteins, A- and B-type lamins, form the nuclear lamina scaffold adjacent to the inner nuclear membrane. Lamins also contribute to chromatin regulation and various signaling pathways affecting gene expression. In this review, Osmanagic-Myers et al. focus on the role of nuclear lamins in mechanosensing and also discuss how disease-linked lamin mutants may impair the response of cells to mechanical stimuli and influence the properties of the extracellular matrix.

The intermediate filament proteins, A- and B-type lamins, form the nuclear lamina scaffold adjacent to the inner nuclear membrane. B-type lamins confer elasticity, while A-type lamins lend viscosity and stiffness to nuclei. Lamins also contribute to chromatin regulation and various signaling pathways affecting gene expression. The mechanical roles of lamins and their functions in gene regulation are often viewed as independent activities, but recent findings suggest a highly cross-linked and interdependent regulation of these different functions, particularly in mechanosignaling. In this newly emerging concept, lamins act as a “mechanostat” that senses forces from outside and responds to tension by reinforcing the cytoskeleton and the extracellular matrix. A-type lamins, emerin, and the linker of the nucleoskeleton and cytoskeleton (LINC) complex directly transmit forces from the extracellular matrix into the nucleus. These mechanical forces lead to changes in the molecular structure, modification, and assembly state of A-type lamins. This in turn activates a tension-induced “inside-out signaling” through which the nucleus feeds back to the cytoskeleton and the extracellular matrix to balance outside and inside forces. These functions regulate differentiation and may be impaired in lamin-linked diseases, leading to cellular phenotypes, particularly in mechanical load-bearing tissues.

Longevity expectations in the pension fund, insurance, and employee benefits industries

Considerable progress has been made in many areas of biomedical science since the 1960s, suggesting likely increases in life expectancy and decreases in morbidity and mortality in the adult population. These changes may pose substantial risks to the pensions and benefits industries. While there is no significant statistical evidence demonstrating rapid decreases in mortality rates, there are conflicting opinions among demographers and biogerontologists on the biological limits of the human lifespan and trends in life expectancy. We administered a survey of the International Employee Benefits Association (IEBA), a large, international industry group. Industry professionals employed by consulting (35%), insurance (24%), pension (14%), and other (27%) companies responded to 32 questions. Respondents showed reasonably conservative views on the future of longevity and retirement, including that for women. The respondents formed their personal longevity expectations based on their family history and, to a lesser degree, on the actuarial life tables. Most of the sample expressed no desire to life past age 100 years, even if the enabling technologies required to maintain a healthy youthful state were available, and only a few respondents in the sample expressed a desire to live for the maximum period (at least) offered by the survey question. The majority of the respondents would not undergo any invasive procedures, and only 56% of the respondents would opt for noninvasive therapies to extend their healthy lifespans to 150 years of age if these were available.

Genetics and epigenetics of aging and longevity

Evolutionary theories of aging predict the existence of certain genes that provide selective advantage early in life with adverse effect on lifespan later in life (antagonistic pleiotropy theory) or longevity insurance genes (disposable soma theory). Indeed, the study of human and animal genetics is gradually identifying new genes that increase lifespan when overexpressed or mutated: gerontogenes. Furthermore, genetic and epigenetic mechanisms are being identified that have a positive effect on longevity. The gerontogenes are classified as lifespan regulators, mediators, effectors, housekeeping genes, genes involved in mitochondrial function, and genes regulating cellular senescence and apoptosis. In this review we demonstrate that the majority of the genes as well as genetic and epigenetic mechanisms that are involved in regulation of longevity are highly interconnected and related to stress response.

Signaling pathway cloud regulation for in silico screening and ranking of the potential geroprotective drugs

The major challenges of aging research include absence of the comprehensive set of aging biomarkers, the time it takes to evaluate the effects of various interventions on longevity in humans and the difficulty extrapolating the results from model organisms to humans. To address these challenges we propose the in silico method for screening and ranking the possible geroprotectors followed by the high-throughput in vivo and in vitro validation. The proposed method evaluates the changes in the collection of activated or suppressed signaling pathways involved in aging and longevity, termed signaling pathway cloud, constructed using the gene expression data and epigenetic profiles of young and old patients' tissues. The possible interventions are selected and rated according to their ability to regulate age-related changes and minimize differences in the signaling pathway cloud. While many algorithmic solutions to simulating the induction of the old into young metabolic profiles in silico are possible, this flexible and scalable approach may potentially be used to predict the efficacy of the many drugs that may extend human longevity before conducting pre-clinical work and expensive clinical trials.

Open access integrated therapeutic and diagnostic platforms for personalized cardiovascular medicine

It is undeniable that the increasing costs in healthcare are a concern. Although technological advancements have been made in healthcare systems, the return on investment made by governments and payers has been poor. The current model of care is unsustainable and is due for an upgrade. In developed nations, a law of diminishing returns has been noted in population health standards, whilst in the developing world, westernized chronic illnesses, such as diabetes and cardiovascular disease have become emerging problems. The reasons for these trends are complex, multifactorial and not easily reversed. Personalized medicine has the potential to have a significant impact on these issues, but for it to be truly successful, interdisciplinary mass collaboration is required. We propose here a vision for open-access advanced analytics for personalized cardiac diagnostics using imaging, electrocardiography and genomics.