RESUMEN
To clarify the detailed molecular mechanisms underlying the development of asthma, we assessed the potential immune effects of prenatal osteoprotegerin (OPG) inhibition in the pathogenesis of asthma. The effects of OPG deficiency on the development of asthma were evaluated using an ovalbumin-induced asthma model in OPG knockout mice. Histological analysis demonstrated that OPG was mainly detected in airway epithelial cells in wild type mice. After ovalbumin sensitization and challenge, accumulation of inflammatory cells, gene expression of T helper 2-related cytokines and mucus hypersecretion in lung tissues were inhibited by OPG deficiency. Importantly, the serum level of IgE was not increased in OPG KO mice after ovalbumin sensitization and challenge. Based on these findings, OPG knockout mice were protected against methacholine-induced airway hyperresponsiveness. OPG expression is thought to be essential for induction of the allergic immune response in asthma.
Asunto(s)
Asma , Hipersensibilidad , Osteoprotegerina , Animales , Asma/genética , Líquido del Lavado Bronquioalveolar , Citocinas/metabolismo , Modelos Animales de Enfermedad , Hipersensibilidad/patología , Pulmón/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Osteoprotegerina/genética , OvalbúminaRESUMEN
BACKGROUND: To establish a method to prevent and manage fatigue caused by psychological and physical stress in young females, early detection factors, such as understanding of fatigue and causes of psychological and physical stress, as well as a review of early management of psychiatric disease, are important. With increasing knowledge regarding the diverse causes of stress, it is important to select biomarkers with consideration of the types of stress burden and mechanisms underlying the development of physical symptoms. The methods used to search for stress characteristics is an issue that needs to be addressed. However, consensus regarding objective assessment methods for impaired mental health is lacking. METHODS: We examined the effects of an objective structured clinical examination (OSCE), considered to be a uniform source of psychological and physical stress, on biomarkers of oxidative stress and fatigue in 16 third-year female medical university students (21.3 ± 2.1 years old) in Japan with a normal menstrual cycle. A self-administered questionnaire consisting of Zung's Self-rating Depression Scale (SDS) and State-Trait Anxiety Inventory (STAI) was used to assess subjective stress. Furthermore, stress-related biomarkers (urinary 8-hydroxy-2'-deoxyguanosine [u-8-OHdG], urinary 5-hydroxytryptamine [u-5-HT], and salivary human herpesvirus-6 [s-HHV-6]) were examined at 1 month, 1 week, and 1 day before, and 1 week after the OSCE. RESULTS: The results indicated that the OSCE did not have effects on u-8-OHdG, a biomarker of oxidative stress. However, u-5-HT and s-HHV-6 were found to be elevated in examinations performed prior to the OSCE. CONCLUSIONS: The present findings suggest that u-5-HT and s-HHV-6 levels can be used for objective assessment of mental and physical fatigue in young females, including that produced not only by knowledge regarding an upcoming OSCE, but also by skill and attitude aspects related to that examination.
RESUMEN
To study the temperature dependence of magnetic properties of permanent magnets, methods of treating the thermal fluctuation causing the thermal activation phenomena must be established. To study finite-temperature properties quantitatively, we need atomistic energy information to calculate the canonical distribution. In the present review, we report our recent studies on the thermal properties of the Nd2Fe14B magnet and the methods of studying them. We first propose an atomistic Hamiltonian and show various thermodynamic properties, for example, the temperature dependences of the magnetization showing a spin reorientation transition, the magnetic anisotropy energy, the domain wall profiles, the anisotropy of the exchange stiffness constant, and the spectrum of ferromagnetic resonance. The effects of the dipole-dipole interaction (DDI) in large grains are also presented. In addition to these equilibrium properties, the temperature dependence of the coercivity of a single grain was studied using the stochastic Landau-Lifshitz-Gilbert equation and also by the analysis of the free energy landscape, which was obtained by Monte Carlo simulation. The upper limit of coercivity at room temperature was found to be about 3 T at room temperature. The coercivity of a polycrystalline magnet, that is, an ensemble of interactinve grains, is expected to be reduced further by the effects of the grain boundary phase, which is also studied. Surface nucleation is a key ingredient in the domain wall depinning process. Finally, we study the effect of DDI among grains and also discuss the distribution of properties of grains from the viewpoint of first-order reversal curve.
RESUMEN
First-principles calculation based on density functional theory is a powerful tool for understanding and designing magnetic materials. It enables us to quantitatively describe magnetic properties and structural stability, although further methodological developments for the treatment of strongly correlated 4f electrons and finite-temperature magnetism are needed. Here, we review recent developments of computational schemes for rare-earth magnet compounds, and summarize our theoretical studies on Nd2Fe14B and RFe12-type compounds. Effects of chemical substitution and interstitial dopants are clarified. We also discuss how data-driven approaches are used for studying multinary systems. Chemical composition can be optimized with fewer trials by the Bayesian optimization. We also present a data-assimilation method for predicting finite-temperature magnetization in wide composition space by integrating computational and experimental data.
RESUMEN
Existing data-driven approaches for exploring high-entropy alloys (HEAs) face three challenges: numerous element-combination candidates, designing appropriate descriptors, and limited and biased existing data. To overcome these issues, here we show the development of an evidence-based material recommender system (ERS) that adopts Dempster-Shafer theory, a general framework for reasoning with uncertainty. Herein, without using material descriptors, we model, collect and combine pieces of evidence from data about the HEA phase existence of alloys. To evaluate the ERS, we compared its HEA-recommendation capability with those of matrix-factorization- and supervised-learning-based recommender systems on four widely known datasets of up-to-five-component alloys. The k-fold cross-validation on the datasets suggests that the ERS outperforms all competitors. Furthermore, the ERS shows good extrapolation capabilities in recommending quaternary and quinary HEAs. We experimentally validated the most strongly recommended Fe-Co-based magnetic HEA (namely, FeCoMnNi) and confirmed that its thin film shows a body-centered cubic structure.
RESUMEN
New Nd-Fe-B crystal structures can be formed via the elemental substitution of LA-T-X host structures, including lanthanides (LA), transition metals (T) and light elements, X = B, C, N and O. The 5967 samples of ternary LA-T-X materials that are collected are then used as the host structures. For each host crystal structure, a substituted crystal structure is created by substituting all lanthanide sites with Nd, all transition metal sites with Fe and all light-element sites with B. High-throughput first-principles calculations are applied to evaluate the phase stability of the newly created crystal structures, and 20 of them are found to be potentially formable. A data-driven approach based on supervised and unsupervised learning techniques is applied to estimate the stability and analyze the structure-stability relationship of the newly created Nd-Fe-B crystal structures. For predicting the stability for the newly created Nd-Fe-B structures, three supervised learning models: kernel ridge regression, logistic classification and decision tree model, are learned from the LA-T-X host crystal structures; the models achieved maximum accuracy and recall scores of 70.4 and 68.7%, respectively. On the other hand, our proposed unsupervised learning model based on the integration of descriptor-relevance analysis and a Gaussian mixture model achieved an accuracy and recall score of 72.9 and 82.1%, respectively, which are significantly better than those of the supervised models. While capturing and interpreting the structure-stability relationship of the Nd-Fe-B crystal structures, the unsupervised learning model indicates that the average atomic coordination number and coordination number of the Fe sites are the most important factors in determining the phase stability of the new substituted Nd-Fe-B crystal structures.
RESUMEN
There is no proven medical therapy to inhibit the progression of abdominal aortic aneurysm (AAA) in the clinical setting. To develop a novel therapeutic approach for the treatment of AAA, we focused on vaccination targeting Ang II (angiotensin II) and assessed the effect of an Ang II peptide vaccine on the progression of AAA using a rat model. Ang II peptide was conjugated with KLH (keyhole limpet hemocyanin) carrier protein to induce a sufficient immune response. Male rats were subcutaneously immunized with Ang II-KLH with an adjuvant on days 0, 14, and 28. Aortic dilatation was induced by intraluminal incubation with elastase on day 35. Treatment with Ang II vaccine successfully induced the production of a high titer of anti-Ang II antibodies. Immunization with Ang II vaccine resulted in a significant reduction in expansion of the aortic diameter compared with control rats, without a blood pressure-lowering effect. Four weeks after operation, the increase in Ang II in the aneurysm wall was significantly inhibited by treatment with Ang II vaccine. Inhibition of Ang II action led to suppression of the inflammatory response in the AAA wall through attenuation of the NFκB (nuclear factor kappa B) and c-jun N-terminal kinase signaling cascades. Treatment with Ang II vaccine inhibited accumulation of macrophages in the AAA wall. In addition, expression of TNF-α (tumor necrosis factor alpha) and activation of MMP (matrix metalloproteinase)-2 and MMP-9 were also inhibited by treatment with Ang II vaccine, resulting in protection against the destruction of elastic fibers. This vaccine therapy could become a potent therapeutic option to treat patients with AAA.
Asunto(s)
Angiotensina II/inmunología , Aneurisma de la Aorta Abdominal/prevención & control , Modelos Animales de Enfermedad , Vacunas de Subunidad/administración & dosificación , Animales , Aneurisma de la Aorta Abdominal/inmunología , Aneurisma de la Aorta Abdominal/patología , Progresión de la Enfermedad , Hemocianinas/inmunología , Inmunoconjugados/administración & dosificación , Inmunoconjugados/inmunología , Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Macrófagos/metabolismo , Masculino , Metaloproteinasa 2 de la Matriz/inmunología , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/inmunología , Metaloproteinasa 9 de la Matriz/metabolismo , FN-kappa B/inmunología , FN-kappa B/metabolismo , Ratas Wistar , Transducción de Señal/efectos de los fármacos , Transducción de Señal/inmunología , Vacunas de Subunidad/inmunologíaRESUMEN
In this study, we investigate the structure-stability relationship of hypothetical Nd-Fe-B crystal structures using descriptor-relevance analysis and the t-SNE dimensionality reduction method. 149 hypothetical Nd-Fe-B crystal structures are generated from 5967 LA-T-X host structures in the Open Quantum Materials Database by using the elemental substitution method, with LA denoting lanthanides, T denoting transition metals, and X denoting light elements such as B, C, N, and O. By borrowing the skeletal structure of each of the host materials, a hypothetical crystal structure is created by substituting all lanthanide sites with Nd, all transition metal sites with Fe, and all light element sites with B. High-throughput first-principle calculations are applied to evaluate the phase stability of these structures. Twenty of them are found to be potentially formable. As the first investigative result, the descriptor-relevance analysis on the orbital field matrix (OFM) materials' descriptor reveals the average atomic coordination number as the essential factor in determining the structure stability of these substituted Nd-Fe-B crystal structures. 19 among 20 hypothetical structures that are found potentially formable have an average coordination number larger than 6.5. By applying the t-SNE dimensionality reduction method, all the local structures represented by the OFM descriptors are integrated into a visible space to study the detailed correlation between their characteristics and the stability of the crystal structure to which they belong. We discover that unstable substituted structures frequently carry Nd and Fe local structures with two prominent points: low average coordination numbers and fully occupied B neighboring atoms. Moreover, there are only three popular forms of B local structures appearing on all potentially formable substituted structures: cage networks, planar networks, and interstitial sites. The discovered relationships are promising to speed up the screening process for the new formable crystal structures.
RESUMEN
Recent progress in understanding the electronic band topology and emergent topological properties encourage us to reconsider the band structure of well-known materials including elemental substances. Controlling such a band topology by external field is of particular interest from both fundamental and technological viewpoints. Here we report possible signatures of the pressure-induced topological phase transition from a semiconductor to a Weyl semimetal in elemental tellurium probed by transport measurements. Pressure variation of the periods of Shubnikov-de Haas oscillations, as well as oscillation phases, shows an anomaly around the pressure theoretically predicted for topological phase transition. This behavior is consistent with the pressure-induced band deformation and resultant band-crossing effect. Moreover, effective cyclotron mass is reduced toward the critical pressure, potentially reflecting the emergence of massless linear dispersion. The present result paves the way for studying the electronic band topology in well-known compounds and topological phase transition by the external field.
RESUMEN
We calculate positron annihilation parameters, namely the S and W parameters from the Doppler broadening spectroscopy and the positron lifetime [Formula: see text], for defect-free states as well as cation mono-vacancies and vacancy complexes in nitride semiconductor alloys Al0.5Ga0.5N, In0.5Ga0.5N and Al0.5In0.5N. The obtained distributions of these parameters differ from compound to compound. Especially, the S-W relation for In0.5Ga0.5N is very different from that for Al0.5Ga0.5N. For the cation mono-vacancies, introducing local structural parameters, their correlations with S, W and [Formula: see text] are investigated. The S and [Formula: see text] variations are well described with the size distributions of the vacancies while the W variation is related to the presence of localized d electrons. For the vacancy complexes as well as the cation mono-vacancies, multiple-linear-regression models to describe S, W and [Formula: see text] are successfully constructed using the local structural parameters as descriptors. The S-W and S-[Formula: see text] relations are also compared with those for AlN, GaN and InN.
RESUMEN
Abdominal aortic aneurysm (AAA) is considered to be a potent life-threatening disorder in elderly individuals. Although many patients with a small AAA are detected during routine abdominal screening, there is no effective therapeutic option to prevent the progression or regression of AAA in the clinical setting. Recent advances in molecular biology have led to the identification of several important molecules, including microRNA and transcription factor, in the process of AAA formation. Regulation of these factors using nucleic acid drugs is expected to be a novel therapeutic option for AAA. Nucleic acid drugs can bind to target factors, mRNA, microRNA, and transcription factors in a sequence-specific fashion, resulting in a loss of function of the target molecule at the transcriptional or posttranscriptional level. Of note, inhibition of a transcription factor using a decoy strategy effectively suppresses experimental AAA formation, by regulating the expression of several genes associated with the disease progression. This review focuses on recent advances in molecular therapy of using nucleic acid drugs to treat AAA.
RESUMEN
The pyrochlore oxides [Formula: see text]O7 exhibit a complex interplay between geometrical frustration, electronic correlations, and spin-orbit coupling (SOC), due to the lattice structure and active charge, spin, and orbital degrees of freedom. Understanding the properties of these materials is a theoretical challenge, because their intricate nature depends on material-specific details and quantum many-body effects. Here we review our recent studies based on first-principles calculations and quantum many-body theories for 4d and 5d pyrochlore oxides with B = Mo, Os, and Ir. In these studies, the SOC and local electron correlations are treated within the local density approximation (LDA) + U and LDA + dynamical mean-field theory formalisms. We also discuss the technical aspects of these calculations.
RESUMEN
The mosquito, Aedes baisasi, which inhabits brackish mangrove swamps, is known to feed on fish. However, its host assemblage has not been investigated at the species level. We amplified and sequenced the cytochrome oxidase subunit I barcoding regions as well as some other regions from blood-fed females to identify host assemblages in the natural populations from four islands in the Ryukyu Archipelago. Hosts were identified from 230 females. We identified 15 host fish species belonging to eight families and four orders. Contrary to expectations from previous observations, mudskippers were detected from only 3% of blood-engorged females. The dominant host was a four-eyed sleeper, Bostrychus sinensis (Butidae, Gobiiformes), in Iriomote-jima Island (61%), while it was a snake eel, Pisodonophis boro (Ophichthidae, Anguilliformes), in Amami-oshima and Okinawa-jima islands (78% and 79%, respectively). Most of the identified hosts were known as air-breathing or amphibious fishes that inhabit mangroves or lagoons. Our results suggest that A. baisasi females locate the bloodmeal hosts within the mangrove forests and sometimes in the adjacent lagoons and land on the surface of available amphibious or other air-breathing fishes exposed in the air to feed on their blood.
Asunto(s)
Sangre/parasitología , Culicidae/fisiología , Conducta Alimentaria/fisiología , Peces/parasitología , Aedes/fisiología , Animales , Femenino , Hábitos , Especificidad del Huésped/fisiologíaRESUMEN
INTRODUCTION: New treatments to inhibit neointimal formation after percutaneous transluminal angioplasty (PTA) are needed for patients undergoing chronic hemodialysis (HD). We compared the efficacy and safety of AMG0102, a balloon catheter containing nuclear factor κB (NF-κB) decoy oligodeoxynucleotide (ODN) with the PTA balloon catheter (control group) for arteriovenous fistula (AVF) stenosis. METHODS: In total, 175 patients (age ≥20 years, undergoing HD, with venous stenosis at the anastomotic region) were registered in this prospective open-label, randomized study. Patients were followed postoperatively for 36 weeks. The duration of primary patency on the targeted venous stenosis site (primary endpoint) was estimated by the Kaplan-Meier method. RESULTS: A lower restenosis risk was observed for the AMG0102 group, but it was not statistically significant (stratified log-rank test P = 0.250, hazard ratio [HR] 0.774; 95% confidence interval [CI]: 0.500-1.198). The median duration of primary patency was 245 days and 172 days in the AMG0102 and control groups, respectively. After stratification based on the status of diabetes complications, the HR was 0.666 (95% CI: 0.366-1.212; P = 0.183) and the median duration of primary patency was prolonged by 108 days in the AMG0102 group with diabetes complications (245 days) compared with the control group (137 days). Adverse event (AE) incidence up to 36 postoperative weeks did not differ between groups. Four device failures occurred in 3 patients (AMG0102 group), but none resulted in AEs. CONCLUSION: Further modifications to enhance NF-κB decoy ODN uptake and efficacy are necessary to show its clinical utility for AVF stenosis in chronic HD.
RESUMEN
In many flowering plants, floral scents are a significant trait for visitors, playing an important role in attracting pollinators and/or detracting herbivores. The evolution of flowering plants from hermaphroditism to dioecy is often accompanied by sexual dimorphism in floral scent. In this study, floral scents emitted by different sexual morphs of the subdioecious shrub Eurya japonica Thunb. were collected using a dynamic headspace method, and sexual and temporal variations were evaluated by gas chromatography-mass spectrometry (GC-MS). Two volatiles, α-pinene and linalool, were identified as the major components of floral scents in females, hermaphrodites, and males. The males emit higher amounts of floral scents, particularly α-pinene, compared to females or hermaphrodites. Floral scents emitted by males generally decrease as flowers enter senescence, whereas those from females or hermaphrodites do not significantly differ. Intraspecific variations in floral scents of subdioecious species provided by this study would contribute to better understanding of sexual dimorphism in floral scent.
RESUMEN
We have developed a descriptor named Orbital Field Matrix (OFM) for representing material structures in datasets of multi-element materials. The descriptor is based on the information regarding atomic valence shell electrons and their coordination. In this work, we develop an extension of OFM called OFM1. We have shown that these descriptors are highly applicable in predicting the physical properties of materials and in providing insights on the materials space by mapping into a low embedded dimensional space. Our experiments with transition metal/lanthanide metal alloys show that the local magnetic moments and formation energies can be accurately reproduced using simple nearest-neighbor regression, thus confirming the relevance of our descriptors. Using kernel ridge regressions, we could accurately reproduce formation energies and local magnetic moments calculated based on first-principles, with mean absolute errors of 0.03 µB and 0.10 eV/atom, respectively. We show that meaningful low-dimensional representations can be extracted from the original descriptor using descriptive learning algorithms. Intuitive prehension on the materials space, qualitative evaluation on the similarities in local structures or crystalline materials, and inference in the designing of new materials by element substitution can be performed effectively based on these low-dimensional representations.
RESUMEN
Transactivation of inflammatory and immune mediators in asthma is tightly regulated by nuclear factor κB (NF-κB) and signal transducer and activator of transcription 6 (STAT6). Therefore, we investigated the efficacy of simultaneous inhibition of NF-κB and STAT6 using a chimeric decoy strategy to prevent asthma exacerbation. The effects of decoy oligodeoxynucleotides were evaluated using an ovalbumin-induced mouse asthma model. Ovalbumin-sensitized mice received intratracheal administration of decoy oligodeoxynucleotides 3 days before ovalbumin challenge. Fluorescent-dye-labeled decoy oligodeoxynucleotides could be detected in lymphocytes and macrophages in the lung, and activation of NF-κB and STAT6 was inhibited by chimeric decoy oligodeoxynucleotide transfer. Consequently, treatment with chimeric or NF-κB decoy oligodeoxynucleotides protected against methacholine-induced airway hyperresponsiveness, whereas the effect of chimeric decoy oligodeoxynucleotides was significantly greater than that of NF-κB decoy oligodeoxynucleotides. Treatment with chimeric decoy oligodeoxynucleotides suppressed airway inflammation through inhibition of overexpression of interleukin-4 (IL-4), IL-5, and IL-13 and inflammatory infiltrates. Histamine levels in the lung were reduced via suppression of mast cell accumulation. A significant reduction in mucin secretion was observed due to suppression of MUC5AC gene expression. Interestingly, the inhibitory effects on IL-5, IL-13, and histamine secretion were achieved by transfer of chimeric decoy oligodeoxynucleotides only. This novel therapeutic approach could be useful to treat patients with various types of asthma.
RESUMEN
We propose a novel representation of materials named an 'orbital-field matrix (OFM)', which is based on the distribution of valence shell electrons. We demonstrate that this new representation can be highly useful in mining material data. Experimental investigation shows that the formation energies of crystalline materials, atomization energies of molecular materials, and local magnetic moments of the constituent atoms in bimetal alloys of lanthanide metal and transition-metal can be predicted with high accuracy using the OFM. Knowledge regarding the role of the coordination numbers of the transition-metal and lanthanide elements in determining the local magnetic moments of the transition-metal sites can be acquired directly from decision tree regression analyses using the OFM.
RESUMEN
Angiotensin II is thought to participate in aneurysm formation, because of its ability to induce and perpetuate inflammation in the aortic wall. Because activation of renin is the first step of the renin-angiotensin system, renin inhibition could inhibit all components of this system effectively. Therefore, we examined the hypothesis that direct inhibition of renin activity could decrease the expansion of aortic aneurysm using a rabbit model. Aortic dilatation was induced by incubation with elastase around the rabbit abdominal aorta. Continuous administration of a direct renin inhibitor, aliskiren, was started at 1 week before incubation with elastase and continued for 5 weeks. Treatment with aliskiren markedly inhibited tissue renin activation and resulted in a significant reduction in angiotensin I and II production in the aneurysm wall. Consequently, the inhibition of renin activity prevented the expansion of experimental aortic aneurysm associated with preservation of the medial layer, independent of its blood pressure-lowering effect. Administration of aliskiren led to the inhibition of activation of NF-κB (nuclear factor-κB), AP-1 (activator protein-1), and CREB (cAMP response element-binding protein), which are thought to cooperatively regulate the inflammatory gene expression profile associated with aneurysm formation. As a result, treatment with aliskiren inhibited macrophage accumulation through suppression of MCP-1 (monocyte chemoattractant protein-1) and CCL4 (C-C motif chemokine ligand 4) expression, and TNF-α (tumor necrosis factor-α) production and activation of MMP-2 (matrix metalloproteinase-2) and MMP-9 (matrix metalloproteinase-9) were also suppressed in the aneurysm wall. In addition, inhibition of (pro)renin receptor elevation was also observed after treatment with aliskiren. Direct inhibition of renin activity using aliskiren prevented the progression of aortic aneurysm, suggesting it as a therapeutic option to treat abdominal aortic aneurysm.
Asunto(s)
Amidas/farmacología , Aorta Abdominal/diagnóstico por imagen , Aneurisma de la Aorta Abdominal/tratamiento farmacológico , Fumaratos/farmacología , ARN/genética , Renina/antagonistas & inhibidores , Animales , Aneurisma de la Aorta Abdominal/diagnóstico , Aneurisma de la Aorta Abdominal/genética , Western Blotting , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Regulación de la Expresión Génica/efectos de los fármacos , Técnicas para Inmunoenzimas , Inmunohistoquímica , Conejos , Reacción en Cadena en Tiempo Real de la Polimerasa , Renina/genética , Renina/metabolismo , Sistema Renina-Angiotensina/genética , UltrasonografíaRESUMEN
A band gap for electronic states in crystals governs various properties of solids, such as transport, optical, and magnetic properties. Its estimation and control have been an important issue in solid-state physics. The band gap can be controlled externally by various parameters, such as pressure, atomic compositions, and external field. Sometimes, the gap even collapses by tuning some parameter. In the field of topological insulators, this closing of the gap at a time-reversal invariant momentum indicates a band inversion, that is, it leads to a topological phase transition from a normal insulator to a topological insulator. We show, through an exhaustive study on possible space groups, that the gap closing in inversion-asymmetric crystals is universal, in the sense that the gap closing always leads either to a Weyl semimetal or to a nodal-line semimetal. We consider three-dimensional spinful systems with time-reversal symmetry. The space group of the system and the wave vector at the gap closing uniquely determine which possibility occurs and where the gap-closing points or lines lie in the wave vector space after the closing of the gap. In particular, we show that an insulator-to-insulator transition never happens, which is in sharp contrast to inversion-symmetric systems.