Effects of Dermatan Sulfate from Marine Invertebrate Styela plicata in the Wound Healing Pathway: A Natural Resource Applied to Regenerative Therapy.

Acute and chronic dermatological injuries need rapid tissue repair due to the susceptibility to infections. To effectively promote cutaneous wound recovery, it is essential to develop safe, low-cost, and affordable regenerative tools. Therefore, we aimed to identify the biological mechanisms involved in the wound healing properties of the glycosaminoglycan dermatan sulfate (DS), obtained from ascidian Styela plicata, a marine invertebrate, which in preliminary work from our group showed no toxicity and promoted a remarkable fibroblast proliferation and migration. In this study, 2,4-DS (50 µg/mL)-treated and control groups had the relative gene expression of 84 genes participating in the healing pathway evaluated. The results showed that 57% of the genes were overexpressed during treatment, 16% were underexpressed, and 9.52% were not detected. In silico analysis of metabolic interactions exhibited overexpression of genes related to: extracellular matrix organization, hemostasis, secretion of inflammatory mediators, and regulation of insulin-like growth factor transport and uptake. Furthermore, in C57BL/6 mice subjected to experimental wounds treated with 0.25% 2,4-DS, the histological parameters demonstrated a great capacity for vascular recovery. Additionally, this study confirmed that DS is a potent inducer of wound-healing cellular pathways and a promoter of neovascularization, being a natural ally in the tissue regeneration strategy.

Acute graft thrombosis in patients who underwent renal transplant and received anticoagulant or antiplatelet agents. A systematic review and meta-analysis.

OBJECTIVES: Thrombosis is a major cause of early allograft loss in renal transplantation. Herein, we assessed the frequency of acute graft thrombosis in patients who underwent renal transplant and received anticoagulant or antiplatelet agents. METHODS: We performed a systematic review of all available case series studies of anticoagulant and/or antiplatelet prophylaxis of thrombosis in renal transplantation. The data were pooled in a proportional meta-analysis. RESULTS: Twenty-one case series were identified from 7,160 retrieved titles. A total of 3,246 patients were analyzed (1,718 treated with antiplatelet and/or anticoagulant agents and 1,528 non-treated control subjects). Allograft thrombosis occurred in 7.24% (95% CI 3.45 to 12.27%) of the patients receiving no intervention compared with 3.38% (95% CI 1.45 to 6.1%), 1.2% (95% CI 0.6 to 2.1%) and 0.47% (95% CI 0.001 to 1.79%) of the patients in the anticoagulant, aspirin, and aspirin + anticoagulant groups, respectively. The bleeding complication rate for anticoagulants was significantly higher than in the other groups. CONCLUSIONS: Our data suggests that anticoagulants, and aspirin, either alone or in association with an anticoagulant, seem to have a low frequency of acute allograft thrombosis after kidney transplantation. Higher hemorrhagic complication rates might occur when anticoagulants are used.

Fasting and 24-h urine pH in patients with urolithiasis using potassium citrate.

PURPOSE: To evaluate the correlation between the pH readings in 24-h urine and the random fasting specimen in patients with urolithiasis using 2 methods. METHODS: A total of 114 patients with urinary lithiasis using potassium citrate were prospectively analyzed. All patients collected 24-h urine and an additional sample, after nocturnal fasting, collected on the day they brought the 24-h sample at the lab. Two different methods (test strip and digital meter) were used to determine pH values. RESULTS: The pH analysis using strips in the 24-h urine presented a mean value similar to the one obtained in the fasting sample (6.07 ± 0.74 vs. 6.02 ± 0.82, respectively; P > 0.05). The same behavior was seen considering the readings with a digital pH meter (5.8 ± 0.78 vs. 5.75 ± 0.83; P > 0.05). However, readings conducted in the same specimen with pH meter and test strip were dissonant (P < 0.05), suggesting that the colorimetric method is not reliable in the assessment of urinary pH in this population. CONCLUSION: pH assessment in a random urinary specimen proved as efficient as the 24-h urine standard method to monitor patients with kidney stones in the use of potassium citrate. Classical test strip analysis is not sensitive enough to evaluate the urine pH in this population and digital pH meter reading is preferred.

Impact of Time-Zero Biopsy on the Outcome of Transplanted Kidneys.

BACKGROUND: A low supply of donated organs led to the expansion of criteria for kidney transplantation (KT), and the impact on late glomerular function rates (eGFR) is still uncertain. This study aimed to correlate the histologic findings at time-zero biopsy (TzB) with the final eGFR, to identify criteria that could help achieve a more thorough preimplantation evaluation of the organ. METHODS: Records from 395 adult deceased KTs were reviewed. TzBs were analyzed considering histologic criteria by compartment (vascular, interstitial, tubular, and inflammatory) and correlated with the eGFR after 1 year. RESULTS: Among donors, 56.9% were men (mean age 39 years), with the main causes of death being brain trauma (44.2%) and stroke (46.0%). Histologic analysis of TzB revealed 6.0% of glomerulosclerosis; 18.8% presenting vascular alterations; interstitial fibrosis in 54.6%; tubular changes in 76.9%, and nonspecific inflammatory infiltrate in 2.3%. Linear regression analysis showed that the main histologic findings that had impact in the eGFR were interstitial fibrosis (P = .000), followed by tubular alterations (P = .036) and glomerulosclerosis (P = .008). CONCLUSIONS: Histologic variables like interstitial fibrosis and tubular alterations show the most significant negative correlation with final eGFR. The effect of glomerulosclerosis may not be as important as formerly suggested in the literature.

Random Close Packing as a Dynamical Phase Transition.

Sphere packing is an ancient problem. The densest packing is known to be a face-centered cubic (FCC) crystal, with space-filling fraction ϕ_{FCC}=π/sqrt[18]≈0.74. The densest "random packing," random close packing (RCP), is yet ill defined, although many experiments and simulations agree on a value ϕ_{RCP}≈0.64. We introduce a simple absorbing-state model, biased random organization (BRO), which exhibits a Manna class dynamical phase transition between absorbing and active states that has as its densest critical point ϕ_{c_{max}}≈0.64≈ϕ_{RCP} and, like other Manna class models, is hyperuniform at criticality. The configurations we obtain from BRO appear to be structurally identical to RCP configurations from other protocols. This leads us to conjecture that the highest-density absorbing state for an isotropic biased random organization model produces an ensemble of configurations that characterizes the state conventionally known as RCP.

Interstitial fluid velocity is decreased around cortical bone vascular pores and depends on osteocyte position in a rat model of disuse osteoporosis.

Muscle paralysis induced with botulinum toxin (Botox) injection increases vascular porosity and reduces osteocyte lacunar density in the tibial cortical bone of skeletally mature rats. These morphological changes potentially affect interstitial fluid flow in the lacunar-canalicular porosity, which is thought to play a role in osteocyte mechanotransduction. The aim of this study was to investigate the effects of disuse-induced morphological changes on interstitial fluid velocity around osteocytes in the bone cortex. Micro-CT images from a previous study that quantified the effects of Botox-induced muscle paralysis on bone microarchitecture in skeletally mature rats were used to create high-resolution, animal-specific finite element models that included the vascular pores and osteocyte lacunae within the tibial metaphysis of Botox-injected (BTX, n = 8) and saline-injected control (CTRL, n = 8) groups. To quantify fluid flow, lacunar and canalicular porosities were modeled as fluid-saturated poroelastic materials, and boundary conditions were applied to simulate physiological loading. This modeling approach allowed a detailed quantification of the fluid flow velocities around osteocytes in a relatively large volume of bone tissue. The analysis demonstrated that interstitial fluid velocity at the vascular pore surfaces was significantly lower in BTX compared to CTRL because of the decreased vascular canal separation. No significant differences in average fluid velocity were observed at the osteocyte lacunae and no correlation was found between the fluid velocity and the lacunar density, which was significantly lower in BTX. Instead, the lacunar fluid velocity was dependent on the osteocyte's specific position in the bone cortex and its proximity to a vascular pore.

Pelvic floor muscle strength is correlated with sexual function.

PURPOSE: Sexual performance is related to proprioception and pelvic floor muscle strength (PFMS). The aim of this study was to correlate sexual activity and orgasm with PFMS. MATERIALS AND METHODS: A total of 140 healthy continent female were prospectively distributed into 4 groups according to age: Group 1 (G1), 30-40; Group 2 (G2), 41-50; Group 3 (G3), 51-60; Group 4 (G4), over 60 years old. Evaluated parameters were: frequency of sexual activity and orgasm achievement; body mass index (BMI) and objective evaluation of PFMS using perineometer and surface electromyography. RESULTS: BMI was higher in G4 compared to G1 (p=0.042). Women who reported sexual activity was significantly higher in G1 compared to G3 and G4 (94.1% vs. 66.7% and 37.5%, respectively; p=0.001). Orgasm was more frequently in G1 compared to G3 and G4 (91.2% vs. 63.9% and 28.1%, respectively; p=0.001), demonstrating that sexual activity and orgasm decrease after age 51. The duration of PFM contraction was significantly higher in women who had sexual intercourse (p=0.033) and orgasm (p=0.018). CONCLUSIONS: Although the frequency of sexual intercourse and orgasm may decrease with aging, a relationship between sexual activity and PFMS remains apparent, once both sexually active women and those who have orgasms showed better PFM endurance than non-sexually active ones.

Challenges and Future Directions of Big Data and Artificial Intelligence in Education.

We discuss the new challenges and directions facing the use of big data and artificial intelligence (AI) in education research, policy-making, and industry. In recent years, applications of big data and AI in education have made significant headways. This highlights a novel trend in leading-edge educational research. The convenience and embeddedness of data collection within educational technologies, paired with computational techniques have made the analyses of big data a reality. We are moving beyond proof-of-concept demonstrations and applications of techniques, and are beginning to see substantial adoption in many areas of education. The key research trends in the domains of big data and AI are associated with assessment, individualized learning, and precision education. Model-driven data analytics approaches will grow quickly to guide the development, interpretation, and validation of the algorithms. However, conclusions from educational analytics should, of course, be applied with caution. At the education policy level, the government should be devoted to supporting lifelong learning, offering teacher education programs, and protecting personal data. With regard to the education industry, reciprocal and mutually beneficial relationships should be developed in order to enhance academia-industry collaboration. Furthermore, it is important to make sure that technologies are guided by relevant theoretical frameworks and are empirically tested. Lastly, in this paper we advocate an in-depth dialog between supporters of "cold" technology and "warm" humanity so that it can lead to greater understanding among teachers and students about how technology, and specifically, the big data explosion and AI revolution can bring new opportunities (and challenges) that can be best leveraged for pedagogical practices and learning.

Hyperuniform Structures Formed by Shearing Colloidal Suspensions.

In periodically sheared suspensions there is a dynamical phase transition, characterized by a critical strain amplitude γ_{c}, between an absorbing state where particle trajectories are reversible and an active state where trajectories are chaotic and diffusive. Repulsive nonhydrodynamic interactions between "colliding" particles' surfaces have been proposed as a source of this broken time reversal symmetry. A simple toy model called random organization qualitatively reproduces the dynamical features of this transition. Random organization and other absorbing state models exhibit hyperuniformity, a strong suppression of density fluctuations on long length scales quantified by a structure factor S(q→0)∼q^{α} with α>0, at criticality. Here we show experimentally that the particles in periodically sheared suspensions organize into structures with anisotropic short-range order but isotropic, long-range hyperuniform order when oscillatory shear amplitudes approach γ_{c}.

Lindemann Unjamming of Emulsions.

We study the bulk and shear elastic properties of barely-compressed, "athermal" emulsions and find that the rigidity of the jammed solid fails at remarkably large critical osmotic pressures. The minuscule yield strain and similarly small Brownian particle displacement of solid emulsions close to this transition suggests that this catastrophic failure corresponds to a plastic-entropic instability: the solid becomes too soft and weak to resist the thermal agitation of the droplets that compose it and fails. We propose a modified Lindemann stability criterion to describe this transition and derive a scaling law for the critical osmotic pressure that agrees quantitatively with experimental observations.

Effects of tadalafil to prevent injury on corpus cavernosum after vascular or nervous peri-prostatic bundle injury. Experimental model in rats.

PURPOSE: To evaluate the effects of tadalafil (TD) in preventing histological alterations of the corpus cavernosum caused by isolated lesions of cavernous nerve (ILCN) and artery (ILCA) in rats. METHODS: Fifty male Wistar rats were randomly assigned in five groups: G1: control; G2: bilateral ILCN; G3: bilateral ILCA; G4: ILCN+TD; G5: ILCA+TD. The cavernous bodies were submitted to histomorphometry, immunohistochemistry and biochemical analysis. RESULTS: Nerve density was significantly higher in G2 and G4 compared to control (22.62±2.84 and 19.53±3.47 vs. 15.72±1.82; respectively, p<0.05). Smooth muscle density was significantly lower in G2 and G3 in comparison to G1 (12.87±1.90 and 18.93±1.51 vs. 21.78±1.81, respectively; p<0.05). A significant decrease in the sinusoidal lumen area was observed in G2 compared to controls (5.01±1.62 vs. 9.88±3.66, respectively; p<0.05) and the blood vessel density was increased in G2 and G3 (29.32±4.13 e 20.80±2.47 vs. 10.13±2.71, p<0.05). Collagen density was higher in G3 compared to G1 (93.76±15.81 vs. 64.59±19.25; p<0.05). CONCLUSIONS: Histomorphometric alterations caused by ILCN were more intense than those produced by vascular injury, but the collagen analyses showed more fibrosis in animals with ILCA. TD was effective in preventing the majority of the alterations induced by the periprostatic bundle injury.

Sujetos cerebrales: repertorios interpretativos de los usos de la neurociencia en las políticas públicas de infancia temprana en el Chile actual / Brain Subjects: Interpretative repertoires of the uses neuroscience in early childhood policies in current Chile / Sujeitos cerebrais: repertorios interpretativos dos usos da neurociência nas políticas pública da infância no Chile atual

Resumen: Se presentan algunos resultados de una investigación más amplia, dirigida a conocer los discursos de la infancia y su cuidado de un dispositivo de intervención de la infancia temprana en Chile. Utilizando el recurso del análisis de repertorios interpretativos (Potter y Wetherell, 1987; Wetherell y Potter 1996) se analizó un corpus textual conformado por 12 documentos institucionales. De los múltiples repertorios identificados, aquí presentamos aquellos que nos permitieron captar de forma singular las relaciones entre neurociencias, política pública e infancia: el cerebro como actor social; el riesgo como alteración; y la intervención como optimización. Concluimos, que estos repertorios colaboran a la conformación de representaciones de la infancia altamente biologizadas y fuertemente vinculadas a modelos de capital humano y representaciones tradicionales del género y la maternidad. Si bien los hallazgos de la neurociencia se plantean como promesa para superar la desigualdad social, se trataría más bien de un optimismo cruel (Edwards, Gillies y Horsley, 2015) que ocultaría las profundas desigualdades de género y sociales en nuestro país y el posicionamiento de las madres pobres como responsables de los riesgos, así como del desarrollo cerebral de sus hijos.

Abstract: Some results of a broader investigation are presented, aimed at knowing the speeches of childhood and their care of an intervention device of early childhood in Chile. Using the resource of interpretive repertoire analysis (Potter and Wetherell, 1987, Wetherell and Potter, 1996), a textual corpus consisting of 12 institutional documents was analyzed. From the multiple repertories identified, we present those that allow us to capture in a singular way the relationships between neurosciences, public policy and childhood: the brain as a social actor; the risk as alteration; and the intervention as optimization. We conclude that these repertoires collaborate in the conformation of representations of childhood that are highly biologized and strongly linked to models of human capital and traditional representations of gender and motherhood. Although the findings of neuroscience are seen as a promise to overcome social inequality, it would be rather a cruel optimism (Edwards et al., 2015) that would hide the deep gender and social inequalities in our country and the positioning of poor mothers as responsible for the risks, as well as the brain development of their children.

Resumo: São apresentados alguns resultados de uma investigação mais ampla, dirigida a conhecer os discursos da infância e seu cuidado de um dispositivo de intervencao da primeira infancia temprana no Chile. Utilizando o análise de recursos de repertórios interpretativos (Potter e Wetherer, 1987) analisou-se se um corpus textual composto de 12 documentos institucionais. Dos vários repertórios identificados, apresentamos aqueles que nos permitem captar de forma singular as relações entre neurociências, políticas públicas e infancia: o cérebro como ator social; o risco como alteração; e a intervenção como otimização. Concluímos que esses repertórios colaboram com as representações da infância altamente biologizadas e fortemente ligadas aos modelos de capital humano e representações tradicionais do gênero e maternidade. Enquanto as descobertas da neurociência surgem como uma promessa para superar a desigualdade social, mais bem tratar-se-ia de um cruel otimismo (Edwards et al., 2015) que ocultaría as profundas desigualdades de gênero e sociais em nosso país, e o posicionamento das mães pobres como responsáveis pelos riscos, bem como o desenvolvimento cerebral de seus filhos.

Self-faceting of emulsion droplets as a route to solid icosahedra and other polyhedra.

HYPOTHESIS: Temperature-controlled self-faceting of liquid droplets has been recently discovered in surfactant-stabilized alkane-in-water emulsions. We hypothesize that similar self-faceting may occur in emulsion droplets of UV-polymerizable linear hydrocarbons. We further hypothesize that the faceted droplet shapes can be fixed by UV-initiated polymerization, thus providing a new route towards the production of solid polyhedra. EXPERIMENTS: Temperature-induced shape variations were studied by optical microscopy in micron-size emulsion droplets of UV-polymerizable alkyl acrylate. When polymerized, the resultant solid particles' 3D shape and internal structure were determined by combined scanning electron microscopy (SEM) and focused ion beam (FIB) slicing. The SEM and FIB nanoscale resolution provided a far greater detail imaging than that achievable for the liquid droplets, which could only be studied by optical microscopy, severely limiting their 3D shape determination. FINDINGS: We demonstrate the formation of solid icosahedra, polyhedral platelets, and rods of hitherto-unreported sizes, well below the 3D-printing resolution (∼20µm). The presence of icosahedral shapes and the absence of any resolvable internal structure at sub-µm length scales, are in line with the surface-freezing-driven mechanism proposed for the faceting phenomenon. Further development of the method presented here may allow large-quantity production of shaped micron- to nano- sized colloidal building blocks for 3D metamaterials and other applications.

Impact of vulvovaginal atrophy on pelvic floor muscle strength in healthy continent women.

OBJECTIVES: To assess the correlation between hormonal status and pelvic floor muscle strength. METHODS: A total of 140 continent women were prospectively evaluated, and divided into four groups according to age: group 1 (n = 34) aged 30-40 years; group 2 (n = 38) aged 41-50 years; group 3 (n = 35) aged 51-60; and group 4 (n = 33) aged >60 years. The following parameters were evaluated: demographic data using clinical questionnaire; hypermobility of the bladder neck using swab test; vaginal trophism by gynecological examination; hormonal status of the vagina by cytology; and pelvic floor muscle strength using a perineometer and electromyography. RESULTS: There were no statistical differences between pelvic floor muscle strength, demographic characteristics, vaginal trophism and hypermobility of the bladder neck between groups (P > 0.05). There was a larger number of women with vaginal atrophy among those aged >60 years. Vaginal trophism assessed by pelvic examination was highly consistent with the findings of colpocytology (kappa test = 0.888). Electromyography showed that women with hypermobility had lower muscle resistance (endurance) when compared with those without hypermobility. CONCLUSIONS: Although vaginal atrophy is more intense in women aged >60 years, no difference can be found in the pelvic floor muscle strength during the physiological aging process in continent women. As a consequence, trophism is not the only factor related to pelvic floor muscle strength, and it should not preclude the selection of patients who are referred to prophylaxis.

Effects of tadalafil to prevent injury on corpus cavernosum after vascular or nervous peri-prostatic bundle injury. Experimental model in rats

Abstract Purpose: To evaluate the effects of tadalafil (TD) in preventing histological alterations of the corpus cavernosum caused by isolated lesions of cavernous nerve (ILCN) and artery (ILCA) in rats. Methods: Fifty male Wistar rats were randomly assigned in five groups: G1: control; G2: bilateral ILCN; G3: bilateral ILCA; G4: ILCN+TD; G5: ILCA+TD. The cavernous bodies were submitted to histomorphometry, immunohistochemistry and biochemical analysis. Results: Nerve density was significantly higher in G2 and G4 compared to control (22.62±2.84 and 19.53±3.47 vs. 15.72±1.82; respectively, p<0.05). Smooth muscle density was significantly lower in G2 and G3 in comparison to G1 (12.87±1.90 and 18.93±1.51 vs. 21.78±1.81, respectively; p<0.05). A significant decrease in the sinusoidal lumen area was observed in G2 compared to controls (5.01±1.62 vs. 9.88±3.66, respectively; p<0.05) and the blood vessel density was increased in G2 and G3 (29.32±4.13 e 20.80±2.47 vs. 10.13±2.71, p<0.05). Collagen density was higher in G3 compared to G1 (93.76±15.81 vs. 64.59±19.25; p<0.05). Conclusions: Histomorphometric alterations caused by ILCN were more intense than those produced by vascular injury, but the collagen analyses showed more fibrosis in animals with ILCA. TD was effective in preventing the majority of the alterations induced by the periprostatic bundle injury.

Perfil dos agravos e local das lesões do paciente adulto atendido na sala amarela de um hospital público do Distrito Federal / Profile of grievers and location of adult patient injuries attended in the yellow room of the Federal District public hospital

Objetivo: identificar quais são os mecanismos de trauma e os tipos de lesões mais frequentes nos pacientes de 30 a 49 anos atendidos na sala amarela do centro de trauma de um hospital público do Distrito Federal. Método: estudo epidemiológico descritivo transversal sobre o perfil, epidemiológico e clínico. Os critérios de inclusão foram: admissões primárias, faixa-etárias 30 a 49 anos, ambos os sexos e vítima trauma, totalizando amostra com 697 admissões. Resultados: foi evidenciado que nesta faixa etária, prevaleceram os motociclistas traumatizados com 27,7%( n= 193), seguido de ocupante de automóvel traumatizado com 17,5%( n= 122) e queda da própria altura com 11,04%( n=77). Conclusão: o trabalho evidencia a necessidade das equipes componentes dos sistemas hospitalares e demais unidades que atuam diretamente ou indiretamente, com pacientes traumáticos, a necessidade de se aperfeiçoarem, na tentativa de se conhecer melhor o perfil de pacientes que buscam tratamentos nesta unidade, além de poder proporcionar uma assistência de melhor qualidade.

Objective: to identify the mechanisms of trauma and the most frequent types of injuries in patients aged 30 to 49 attended of the Federal District Public Hospital trauma center, specifically in the yellow room. Method: This is a cross-sectional descriptive epidemiological study on the epidemiological and clinical profile. ). Inclusion criteria were: primary admissions, age range 30 to 49 years, both sexes and trauma victim. The sample was composed for 697 admissions. Results: Among the injuries, it was evidenced that in this age bracket, traumatic motorcyclists prevailed with 27.7% (n = 193), followed by a traumatic motor vehicle occupant with 17.5% (n = 122) and fall of the height itself with 11.04 % (n = 77). Conclusion: This work evidences the need of the hospital system components teams and other units that act directly or indirectly, with trauma patients, the need to improve themselves, in an attempt to better understand the profile of patients who seek treatment in these units, besides being able to provide assistance.

Circulating Plasma MicroRNA-208a as Potential Biomarker of Chronic Indeterminate Phase of Chagas Disease.

Chagas cardiomyopathy is the most severe clinical manifestation of chronic Chagas disease. The disease affects most of the Latin American countries, being considered one of the leading causes of morbidity and death in the continent. The pathogenesis of Chagas cardiomyopathy is very complex, with mechanisms involving parasite-dependent cytopathy, immune-mediated myocardial damage and neurogenic disturbances. These pathological changes eventually result in cardiac myocyte hypertrophy, arrhythmias, congestive heart failure and stroke during chronic infection phase. Herein, we show that miR-208a, a microRNA that is a key factor in promoting cardiovascular dysfunction during cardiac hypertrophy processes of heart failure, has its circulating levels increased during chronic indeterminate phase when compared to cardiac (CARD) clinical forms in patients with Chagas disease. In contrast, we have not found altered serum levels of miR-34a, a microRNA known to promote pro-apoptotic role in myocardial infarction during degenerative process of cardiac injuries thus indicating intrinsic differences in the nature of the mechanisms underlying the heart failure triggered by Trypanosoma cruzi infection. Our findings support that the chronic indeterminate phase is a progressive phase involved in the genesis of chagasic cardiopathy and point out the use of plasma levels of miR-208a as candidate biomarker in risk-prediction score for the clinical prognosis of Chagas disease.

Freezing on a sphere.

The best understood crystal ordering transition is that of two-dimensional freezing, which proceeds by the rapid eradication of lattice defects as the temperature is lowered below a critical threshold. But crystals that assemble on closed surfaces are required by topology to have a minimum number of lattice defects, called disclinations, that act as conserved topological charges-consider the 12 pentagons on a football or the 12 pentamers on a viral capsid. Moreover, crystals assembled on curved surfaces can spontaneously develop additional lattice defects to alleviate the stress imposed by the curvature. It is therefore unclear how crystallization can proceed on a sphere, the simplest curved surface on which it is impossible to eliminate such defects. Here we show that freezing on the surface of a sphere proceeds by the formation of a single, encompassing crystalline 'continent', which forces defects into 12 isolated 'seas' with the same icosahedral symmetry as footballs and viruses. We use this broken symmetry-aligning the vertices of an icosahedron with the defect seas and unfolding the faces onto a plane-to construct a new order parameter that reveals the underlying long-range orientational order of the lattice. The effects of geometry on crystallization could be taken into account in the design of nanometre- and micrometre-scale structures in which mobile defects are sequestered into self-ordered arrays. Our results may also be relevant in understanding the properties and occurrence of natural icosahedral structures such as viruses.