Zero Thermal Expansion in Magnetic and Metallic Tb(Co,Fe)2 Intermetallic Compounds

Due to the advantage of invariable length with temperatures, zero thermal expansion (ZTE) materials are intriguing but very rare especially for the metals based compounds. Here, we report a ZTE in the magnetic intermetallic compounds of Tb(Co,Fe)₂ over a wide temperature range (123-307 K). A negligible coefficient of thermal expansion (α_l = 0.48 × 10^-6 K^-1) has been found in Tb(Co_1.9Fe_0.1). Tb(Co,Fe)₂ exhibits ferrimagnetic structure, in which the moments of Tb and Co/Fe are antiparallel alignment along the c axis. The intriguing ZTE property of Tb(Co,Fe)₂ is formed due to the balance between the negative contribution from the Tb magnetic moment induced spontaneous magnetostriction and the positive role from the normal lattice expansion. The present ZTE intermetallic compounds are also featured by the advantages of wide temperature range, high electrical conductivity, and relatively high thermal conductivity.

Negative thermal expansion in molecular materials

Some mechanisms resulting in negative thermal expansion in molecular materials are summarized.

Structure and excellent visible light catalysis of Prussian blue analogues BiFe(CN)6·4H2O

BiFe(CN)₆·4H₂O, which exhibited a layered structure of FeC₆ and BiN₆ coordination polyhedra, was synthesised and exhibited excellent visible light catalytic activity.

Defect dipole-induced domain reorientation of NdFeO3–PbTiO3 thin films

The increasing temperature induces the realignment of the defect dipoles in NdFeO₃–PbTiO₃ thin films, which further reorients the domains.

Large spontaneous polarization in polar perovskites of PbTiO3–Bi(Zn1/2Ti1/2)O3

With the substitution of Bi(Zn_0.5Ti_0.5)O₃, a continuously enhanced spontaneous polarization up to 112 μC cm⁻² has been observed in (1 − x)PbTiO₃–xBi(Zn_0.5Ti_0.5)O₃.

3D negative thermal expansion in orthorhombic MIL-68(In)

Rare three-dimensional negative thermal expansion (NTE) has been found in a low symmetry compound, orthorhombic MIL-68(In).

Correction to: Gene mutation spectrum and genotype-phenotype correlation in a cohort of Chinese osteogenesis imperfecta patients revealed by targeted next generation sequencing

In Table 2:Family 6 should be c.643-13_662delCTATCTTTTCTAGGGTCCCATGGGTCCCCGAGG instead of c.643-13_662delCTATCTTTTCTAGGGTCCCATGGGTCCCC.Family 33 should be c.271_279dupGCCCTCTCG instead of c.271_279dupGCCCTCT.In the 2nd para. of the Molecular diagnosis, section t(5;8)(q32;q21) should be t(5;7)(q32;q21).

Local Chemical Ordering and Negative Thermal Expansion in PtNi Alloy Nanoparticles

An atomic insight into the local chemical ordering and lattice strain is particular interesting to recent emerging bimetallic nanocatalysts such as PtNi alloys. Here, we reported the atomic distribution, chemical environment, and lattice thermal evolution in full-scale structural description of PtNi alloy nanoparticles (NPs). The different segregation of elements in the well-faceted PtNi nanoparticles is convinced by extended X-ray absorption fine structure (EXAFS). Atomic pair distribution function (PDF) study evidences the coexistence of the face-centered cubic and tetragonal ordering parts in the local environment of PtNi nanoparticles. Further reverse Monte Carlo (RMC) simulation with PDF data obviously exposed the segregation as Ni and Pt in the centers of {111} and {001} facets, respectively. Layer-by-layer statistical analysis up to 6 nm for the local atomic pairs revealed the distribution of local tetragonal ordering on the surface. This local coordination environment facilitates the distribution of heteroatomic Pt-Ni pairs, which plays an important role in the negative thermal expansion of Pt₄₁Ni₅₉ NPs. The present study on PtNi alloy NPs from local short-range coordination to long-range average lattice provides a new perspective on tailoring physical properties in nanomaterials.

Colossal Volume Contraction in Strong Polar Perovskites of Pb(Ti,V)O3

The unique physical property of negative thermal expansion (NTE) is not only interesting for scientific research but also important for practical applications. Chemical modification generally tends to weaken NTE. It remains a challenge to obtain enhanced NTE from currently available materials. Herein, we successfully achieve enhanced NTE in Pb(Ti_1-xV_x)O₃ by improving its ferroelectricity. With the chemical substitution of vanadium, lattice tetragonality (c/a) is highly promoted, which is attributed to strong spontaneous polarization, evidenced by the enhanced covalent interaction in the V/Ti-O and Pb-O2 bonds from first-principles calculations. As a consequence, Pb(Ti_0.9V_0.1)O₃ exhibits a nonlinear and much stronger NTE over a wide temperature range with a volumetric coefficient of thermal expansion α_V = -3.76 × 10^-5/°C (25-550 °C). Interestingly, an intrinsic giant volume contraction (∼3.7%) was obtained at the composition of Pb(Ti_0.7V_0.3)O₃ during the ferroelectric-to-paraelectric phase transition, which represents the highest value ever reported. Such volume contraction is well correlated to the effect of spontaneous volume ferroelectrostriction. The present study extends the scope of the NTE family and provides an effective approach to explore new materials with large NTE, such as through adjusting the NTE-related ferroelectric property in the family of ferroelectrics.

Gene mutation spectrum and genotype-phenotype correlation in a cohort of Chinese osteogenesis imperfecta patients revealed by targeted next generation sequencing

The achievement of more accurate diagnosis would greatly benefit the management of patients with osteogenesis imperfecta (OI). In this study, we present the largest OI sample in China as screened by next generation sequencing. In particular, we successfully identified 81 variants, which included 45 novel variants. We further did a genotype-phenotype analysis, which helps make a better understanding of OI.

INTRODUCTION

This study aims to reveal the gene mutation spectrum and the genotype-phenotype relationship among Chinese OI patients by next generation sequencing (NGS).

METHODS

We developed a NGS-based panel for targeted sequencing of all exons of 14 genes related to OI, and performed diagnostic gene sequencing for a cohort of 103 Chinese OI patients from 101 unrelated families. Mutations identified by NGS were further confirmed by Sanger sequencing and co-segregation analysis.

RESULTS

Of the 103 patients from 101 unrelated OI families, we identified 79 mutations, including 43 novel mutations (11 frameshift, 17 missense, 5 nonsense, 9 splice site, and 1 chromosome translocation) in 90 patients (87.4%). Mutations in genes encoding type I collagen, COL1A1 (n = 37), and COL1A2 (n = 29) accounts for 73.3% of all molecularly diagnosed patients, followed by IFITM5 (n = 9, 10%), SERPINF1 (n = 4, 4.4%), WNT1 (n = 4, 4.4%), FKBP10 (n = 3, 3.3%), TMEM38B (n = 3, 3.3%), and PLOD2 (n = 1, 1.1%). This corresponds to 75 autosomal dominant inherited (AD) OI patients and 15 autosomal recessive (AR) inherited patients. Compared with AD inherited OI patients, AR inherited patients had lower bone mineral density (BMD) at spine (P = 0.05) and less frequent blue sclera (P = 0.001). Patients with type I collagen qualitative defects had lower femoral neck BMD Z-score (P = 0.034) and were shorter compared with patients with type I collagen quantitative defects (P = 0.022).

CONCLUSION

We revealed the gene mutation spectrum in Chinese OI patients, and novel mutations identified here expanded the mutation catalog and genotype and phenotype relationships among OI patients.

Isotropic Zero Thermal Expansion and Local Vibrational Dynamics in (Sc,Fe)F3

Scandium fluoride (ScF₃) exhibits a pronounced negative thermal expansion (NTE), which can be suppressed and ultimately transformed into an isotropic zero thermal expansion (ZTE) by partially substituting Sc with Fe in (Sc_0.8Fe_0.2)F₃ (Fe20). The latter displays a rather small coefficient of thermal expansion of -0.17 × 10^-6/K from 300 to 700 K. Synchrotron X-ray and neutron pair distribution functions confirm that the Sc/Fe-F bond has positive thermal expansion (PTE). Local vibrational dynamics based on extended X-ray absorption fine structure indicates a decreased anisotropy of relative vibration in the Sc/Fe-F bond. Combined analysis proposes a delicate balance between the counteracting effects of the chemical bond PTE and NTE from transverse vibration. The present study extends the scope of isotropic ZTE compounds and, more significantly, provides a complete local vibrational dynamics to shed light on the ZTE mechanism in chemically tailored NTE compounds.

A novel large fragment deletion in PLS3 causes rare X-linked early-onset osteoporosis and response to zoledronic acid

We identified a novel large fragment deletion from intron 9 to 3'UTR in PLS3 (E10-E16del) in one Chinese boy with X-linked early-onset osteoporosis and vertebral fractures, which expanded the pathogenic spectrum of X-linked early-onset osteoporosis. Treatment with zoledronic acid was beneficial for increasing BMD and reshaping the vertebral bodies of this patient.

INTRODUCTION

X-linked early-onset osteoporosis is a rare disease, which is characterized by low bone mineral density (BMD), vertebral compression fractures (VCFs), and/or long bone fractures. We aimed to detect the phenotype and the underlying pathogenic mutation of X-linked early-onset osteoporosis in a boy from a nonconsanguineous Chinese family.

METHODS

We investigated the pathogenic mutation of the patient with X-linked early-onset osteoporosis by targeted next-generation sequencing and confirmed it by Sanger sequencing. We also observed the effects of zoledronic acid on fracture frequency and BMD of the patient.

RESULTS

Low BMD and multiple VCFs were the main phenotypes of X-linked early-onset osteoporosis. We identified a total of 12,229 bp deletion in PLS3, involving intron 9 to the 3'UTR (E10-E16 del). This large fragment deletion might be mediated by Alu repeats and microhomology of 26 bp at each breakpoint junction. Zoledronic acid treatment could significantly increase the Z-score of BMD and reshape the compressed vertebral bodies.

CONCLUSION

We identified a large fragment deletion mutation in PLS3 for the first time and elucidated the possible mechanism of the deletion, which led to X-linked early-onset osteoporosis and multiple vertebral fractures. Our findings would enrich the etiology spectrum of this rare disease.

Vertebral fracture in postmenopausal Chinese women: a population-based study

In a random sample of postmenopausal Chinese women, the prevalence of radiographic vertebral fractures increased from 13% between ages 50 and 59 to over 50% after age 80 years. A model with seven clinical risk factors predicted the probability of vertebral fractures as well with as without BMD and better than a model with only three risk factors. More than half an hour of outdoor activity per day might correlate with lower risk of vertebral fracture in this population.

INTRODUCTION

We aimed to describe the prevalence and develop a model for prediction of radiographic vertebral fractures in a large random sample of postmenopausal Chinese women.

METHODS

We enrolled 1760 women from an age-stratified random sample of postmenopausal women in Beijing, China. The presence of vertebral fracture was assessed by semi-quantitative grading of lateral thoracolumbar radiographs, risk factors by interview, bone mineral density (BMD) of the proximal femur and lumbar spine by dual x-ray absorptiometry (DXA), and markers of bone turnover from a fasting blood sample. Associations of these factors were analyzed in logistic models and discrimination by areas of receiver operating characteristics curves (AUC).

RESULTS

The prevalence of vertebral fracture, ranged from 13.4% ages 50 to 59 years old to 58.1% at age 80 years or older. Older age, a history of non-vertebral fracture, lower femoral neck BMD T-score, body mass index (BMI), height loss, housework, and less than half an hour of outdoor activity were significantly associated with increased probability of having a vertebral fracture. A model with those seven factors had a similar AUC with or without BMD and performed better than a simple model with three factors.

CONCLUSION

This study is from a true random sample of postmenopausal women in urban China with high response rate. The prevalence of vertebral fractures in postmenopausal women in Beijing increases from 13% under age 60 to over 50% by age 80 years. A model with seven clinical risk factors with or without BMD is better than simple models and may guide the use of spine x-rays to identify women with vertebral fractures. More than half an hour of outdoor activity might correlate with lower risk of vertebral fracture in this population.

Association between bone mineral density, muscle strength, and vitamin D status in patients with myasthenia gravis: a cross-sectional study

Myasthenia gravis (MG) patients had low proximal hip BMD, which could be explained by reduced muscle strength, elevated bone resorption markers, vitamin D deficiency, and increased PTH levels in those with MG compared to controls.

INTRODUCTION

Muscle strength is closely correlated with bone mineral density (BMD) and vitamin D status. Here, we evaluated muscle strength, BMD, and vitamin D status in a large sample of Chinese patients with MG.

METHODS

In this cross-sectional survey, 86 patients with MG without glucocorticoid treatment and 86 healthy controls were included. Serum levels of 25-hydroxyvitamin D [25OHD], parathyroid hormone (PTH), bone turnover markers (BTMs), and BMD were measured and compared between the two groups. Grip strength and one-leg standing time (OLST) were also assessed in MG patients.

RESULTS

Low grip strength and short OLST were found in 11 (12.8%) and 12 (14.0%) MG patients, respectively. There were 3 (3.5%) MG patients with low bone mass for chronological age. Serum beta C-terminal telopeptide and PTH levels were higher (p < 0.001 and p = 0.001, respectively), and BMD at the femoral neck and trochanter were lower in MG patients (p < 0.001 and p < 0.001, respectively) compared to healthy controls. In patients with MG, grip strength was positively correlated with BMD. Serum 25OHD levels were lower in MG patients than in healthy controls (17.36 ± 6.64 vs. 22.11 ± 7.28 ng/ml, p < 0.001).

CONCLUSION

Grip strength was positively correlated with BMD in Chinese patients with MG. MG patients tended to have low proximal hip BMD, which may partially be explained by reduced muscle strength, vitamin D deficiency, increased PTH levels, and elevated bone resorption markers compared to controls.

Critical Role of Monoclinic Polarization Rotation in High-Performance Perovskite Piezoelectric Materials

High-performance piezoelectric materials constantly attract interest for both technological applications and fundamental research. The understanding of the origin of the high-performance piezoelectric property remains a challenge mainly due to the lack of direct experimental evidence. We perform in situ high-energy x-ray diffraction combined with 2D geometry scattering technology to reveal the underlying mechanism for the perovskite-type lead-based high-performance piezoelectric materials. The direct structural evidence reveals that the electric-field-driven continuous polarization rotation within the monoclinic plane plays a critical role to achieve the giant piezoelectric response. An intrinsic relationship between the crystal structure and piezoelectric performance in perovskite ferroelectrics has been established: A strong tendency of electric-field-driven polarization rotation generates peak piezoelectric performance and vice versa. Furthermore, the monoclinic M_{A} structure is the key feature to superior piezoelectric properties as compared to other structures such as monoclinic M_{B}, rhombohedral, and tetragonal. A high piezoelectric response originates from intrinsic lattice strain, but little from extrinsic domain switching. The present results will facilitate designing high-performance perovskite piezoelectric materials by enhancing the intrinsic lattice contribution with easy and continuous polarization rotation.

Zero Thermal Expansion and Semiconducting Properties in PbTiO3-Bi(Co, Ti)O3 Ferroelectric Solid Solutions

Zero thermal expansion (ZTE) behavior is rare but important for both fundamental studies and practical applications of functional materials. Until now, most available ZTE materials are either electrical insulating oxides or conductive metallic compounds. Very few ZTE materials exhibit the semiconductor feature. Here we report a ZTE in a semiconducting ferroelectric of 0.6PbTiO₃-0.4Bi(Co_0.55Ti_0.45)O_3-δ. Its unit cell volume exhibits a negligible change over a broad temperature range from room temperature to 500 °C. The ZTE is supposed to be correlated with the spontaneous volume ferroelectronstriction. Intriguingly, the present ZTE material also exhibits the semiconducting characteristic accompanied by negative temperature coefficient of resistance. The mechanism of electric conduction is attributed to the electronic hopping from one ion (Ti³⁺) to another (Ti⁴⁺). The semiconductor nature has also been confirmed by the noticeable visible-light absorption with the relatively lower band gap (E_g) value of 1.5 eV, while the ferroelectric property can be well-maintained with large polarization. The first-principles calculations reveal that the drastically narrowed E_g is related to the Co-Ti substitution. The present multifunctional material containing ZTE, semiconducting, and ferroelectric properties is suggested to enable new applications such as the substrate for solar conversion devices.

Composite Yttrium-Carbonaceous Spheres Templated Multi-Shell YVO4 Hollow Spheres with Superior Upconversion Photoluminescence

Complex oxide YVO₄ multi-shell hollow spheres with uniform morphologies and controllable shell numbers are successfully prepared by using a newly developed and general composite yttrium-carbonaceous sphere templated approach. The prominent upconversion luminous intensity of the YVO₄ :Yb³⁺ /Er³⁺ hollow spheres might be attributed to the enhanced near-infrared excitation light harvesting efficiency originated from the multiple reflections.

Tunable thermal expansion in framework materials through redox intercalation

Thermal expansion properties of solids are of fundamental interest and control of thermal expansion is important for practical applications but can be difficult to achieve. Many framework-type materials show negative thermal expansion when internal cages are empty but positive thermal expansion when additional atoms or molecules fill internal voids present. Here we show that redox intercalation offers an effective method to control thermal expansion from positive to zero to negative by insertion of Li ions into the simple negative thermal expansion framework material ScF₃, doped with 10% Fe to enable reduction. The small concentration of intercalated Li ions has a strong influence through steric hindrance of transverse fluoride ion vibrations, which directly controls the thermal expansion. Redox intercalation of guest ions is thus likely to be a general and effective method for controlling thermal expansion in the many known framework materials with phonon-driven negative thermal expansion.

The positive thermal expansion exhibited by most materials at increased temperatures is a severe issue for many high precision applications. Here, Xing and co-workers show that redox intercalation of Li ions into a ScF₃ framework offers effective control of the thermal expansion for this simple material.

Anomalous dispersion X-ray diffraction study of Pb/Bi ordering/disordering states in PbTiO3-based perovskite oxides

Synchrotron radiation-based anomalous dispersion X-ray powder diffraction (ADSPD) was carried out to reveal the Pb/Bi ordering/disordering states in a series of PbTiO₃-based negative thermal expansion materials (1 - x)PbTiO₃ - xBiFeO₃ (x = 0.1, 0.3, 0.5) and (1 - x)PbTiO₃ - xBi(Zn_1/2Ti_1/2)O₃ (x = 0.1, 0.2, 0.3). It gives strong evidence of the disordered Pb/Bi distributions in these compositions, which is consistent with electron diffraction studies. Combined with binding energy calculation, we show that the disordered nature of Pb/Bi distributions is likely to be attributed to the similar electron configurations of Pb²⁺ and Bi³⁺ as well as their comparable coordinate environments in perovskite structures. The results of this study may be helpful to better understand the structure-property relationship in Pb/Bi-containing perovskites and are useful for further developing underlying physics in relevant materials.

Spring-like motion caused large anisotropic thermal expansion in nonporous M(eim)2(M = Zn, Cd)

Spring-like thermal motion caused large anisotropic thermal expansion in nonporous coordination polymers.

Local structure and controllable thermal expansion in the solid solution (Mn1−xNix)ZrF6

Controllable thermal expansion in the cubic solid solutions of (Mn_1−xNi_x)ZrF₆through atomic linkage flexibility.

Preparation and characterization of high Curie-temperature piezoelectric ceramics in a new Bi-based perovskite of (1 − x)PbTiO3-xBi(Zn1/2Hf1/2)O3

The increasing trend of T_C is non-monotonic, which corresponds well with that of c/a in the (1 − x)PbTiO₃-xBi(Zn_1/2Hf_1/2)O₃ solid solutions.

PbTiO3-based perovskite ferroelectric and multiferroic thin films

Ferroelectric thin films, especially PbTiO₃-based perovskite thin films which possess robust spontaneous electrical polarization, are widely investigated and applied in various devices.

Local Structural Distortion Induced Uniaxial Negative Thermal Expansion in Nanosized Semimetal Bismuth

The corrugated layer structure bismuth has been successfully tailored into negative thermal expansion along c axis by size effect. Pair distribution function and extended X-ray absorption fine structure are combined to reveal the local structural distortion for nanosized bismuth. The comprehensive method to identify the local structure of nanomaterials can benefit the regulating and controlling of thermal expansion in nanodivices.

Giant Polarization and High Temperature Monoclinic Phase in a Lead-Free Perovskite of Bi(Zn0.5Ti0.5)O3-BiFeO3

Lead-free piezoelectrics have attracted increasing attention because of the awareness of lead toxicity to the environment. Here, a new bismuth-based lead-free perovskite, (1 - x)Bi(Zn_0.5Ti_0.5)O₃-xBiFeO₃, has been synthesized via a high-pressure and high-temperature method. It exhibits interesting properties of giant polarization, morphotropic phase boundary (MPB), and monoclinic phase. In particular, large tetragonality (c/a = 1.228) and giant spontaneous polarization of 110 μC/cm² has been obtained in 0.6 Bi(Zn_0.5Ti_0.5)O₃-0.4BiFeO₃, which is much higher than most available lead-free materials and conventional Pb(Zr,Ti)O₃. MPB is clearly identified to be constituted of tetragonal and monoclinic phases at x = 0.5. Notably, a single monoclinic phase has been observed at x = 0.6, which exhibits an intriguing high-temperature property. The present results are helpful to explore new lead-free MPB systems in bismuth-based compounds.

Near-Zero Thermal Expansion and High Ultraviolet Transparency in a Borate Crystal of Zn4 B6 O13

Intrinsic isotropic near-zero thermal expansion is discovered in borate crystal Zn₄ B₆ O₁₃ with high transparency in the ultraviolet region. First-principles calculations demonstrate that the very low thermal expansion originates mainly from the invariability of the solid [B₂₄ O₄₈ ] truncated octahedra that are fixed by the [Zn₄ O₁₃ ] clusters in the ZBO structure.

Thermal Expansion Anomaly in TTB Ferroelectrics: The Interplay between Framework Structure and Electric Polarization

Tetragonal tungsten bronze (TTB) makes up a large family of functional materials with fascinating dielectric, piezoelectric, or ferroelectric properties. Understanding the thermal expansion mechanisms associated with their physical properties is important for their practical applications as well as theoretical investigations. Fortunately, the appearance of anomalous thermal expansion in functional materials offers a chance to capture the physics behind them. Herein, we report an investigation of the thermal expansion anomalies in TTBs that are related to ferroelectric transitions and summarize recent progress in this field. The special role of Pb(2+) cation is elucidated. The interplay between the thermal expansion anomaly, electric polarization, and framework structure provides new insight into the structure-property relationships in functional materials.

Large negative thermal expansion in non-perovskite lead-free ferroelectric Sn2P2S6

Functional materials showing both negative thermal expansion (NTE) and physical performance, such as ferroelectricity and magnetism, have been extensively explored in the past decade. However, among ferroelectrics a remarkable NTE was only found in perovskite-type PbTiO3-based compounds. In this work, a large NTE of -4.7 × 10(-5) K(-1) is obtained in the non-perovskite lead-free ferroelectric Sn2P2S6 from 243 K to TC (338 K). Structure refinements and first-principle calculations reveal the effects of the Sn(ii) 5s-S 3p interaction on spontaneous polarization and its correlation with NTE. Then the mechanism of spontaneous volume ferroelectrostriction (SVFS) is verified and it could well elucidate the nature of NTE in ferroelectric Sn2P2S6. This is the first case to demonstrate the unusual NTE behavior by SVFS in a non-perovskite lead-free ferroelectric material.

Hydration and Thermal Expansion in Anatase Nanoparticles

A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface hydration. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a hydrated surface and is positive without a hydrated surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific hydrated surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.

Association of a type 2 diabetes genetic risk score with insulin secretion modulated by insulin sensitivity among Chinese Hans

Type 2 diabetes (T2D) is characterized by insulin resistance and impaired insulin secretion. The present study aimed to identify the influence of insulin sensitivity on the genetic risk of impaired insulin secretion among a Chinese Han population. For 3229 controls and 1994 treatment-naïve T2D, single nucleotide polymorphisms (SNPs) from 24 T2D-related genomic loci were genotyped and a genetic risk score (GRS) was constructed. Results showed that GRS was associated with insulin secretion and disposition indices in both controls and treatment-naïve T2Ds. Upon stratifying the participants into tertiles by the Matsuda index, we observed an inhibitory relationship between the GRS and insulin secretion in low insulin sensitive but not in high insulin sensitive controls and treatment-naïve T2Ds. Moreover, low insulin sensitive individuals exhibited more severe impairment in insulin secretion and beta cell response to insulin sensitivity with an increase in risk alleles. Our findings identified that the association of GRS with insulin secretion was strongly modulated by insulin sensitivity in both controls and T2Ds of Chinese Han. It indicates that insulin sensitization should be emphasized in prevention and treatment of T2D for beta cell protection.

Establishment of a normal reference value of parathyroid hormone in a large healthy Chinese population and evaluation of its relation to bone turnover and bone mineral density

A normal reference value of parathyroid hormone (PTH) was established for the first time in a large sample of healthy Chinese subjects by completely excluding interference of vitamin D deficiency. A high PTH level correlated significantly with an elevated bone turnover and a reduced bone mineral density (BMD).

INTRODUCTION

The aims of this study are to establish a normal reference value for serum PTH and to evaluate the effect of parathyroid gland status on bone turnover and BMD.

METHODS

Our cross-sectional study included 1436 healthy individuals from 5 different Chinese cities. Concentrations of serum PTH, 25-hydroxyvitamin D (25OHD), procollagen I N-terminal peptide (P1NP, a bone formation marker), and carboxyl-terminal telopeptide of type I collagen (β-CTX, a bone resorption marker) were measured by electrochemiluminescence immunoassay. BMD was measured by dual-energy X-ray absorptiometry. The relation of PTH concentration to age, gender, height, and weight was examined. Reference values of PTH were established for all subjects and for subjects categorized by serum 25OHD concentrations. Correlations of PTH levels with bone turnover biomarkers and BMD were statistically analyzed.

RESULTS

Reference values of PTH were 8.84-69.95 pg/mL in all the subjects and 7.48-60.73 and 5.83-56.78 pg/mL in the subjects with serum 25OHD concentrations of ≥20 and ≥30 ng/mL, respectively. Serum PTH showed a negative linear correlation with 25OHD, and the breakpoint was 18.21 ng/mL, below which the PTH level rapidly increased. The increase in PTH levels with age showed a positive linear correlation with P1NP and β-CTX concentrations and a negative linear correlation with BMD at the lumbar spines and the femoral neck.

CONCLUSIONS

A reference value of PTH was established in a large sample of healthy Chinese subjects according to 25OHD status, gender, and age. A high PTH level correlated significantly with an elevated bone turnover and a reduced BMD.

Novel mutations of CLCN7 cause autosomal dominant osteopetrosis type II (ADO-II) and intermediate autosomal recessive osteopetrosis (IARO) in Chinese patients

SUMMARY

Osteopetrosis is a group of genetic bone disorders. Mutations in the chloride channel 7 gene (CLCN7) lead to chloride channel defect, which results in autosomal dominant osteopetrosis type II (ADO-II), autosomal recessive osteopetrosis (ARO), and intermediate autosomal recessive osteopetrosis (IARO). In the present study, we identified seven novel mutations of the CLCN7 gene and reported the first case of IARO with compound heterozygous mutation in Chinese population.

INTRODUCTION

Osteopetrosis is a heritable bone disorder due to the deficiency of or function defect in osteoclasts. Mutations in the CLCN7 lead to chloride channel defects, which result in osteopetrosis with diverse severity ranging from asymptomatic or relatively mild symptoms in ADO-II to the very severe phenotype in ARO. Heterozygous mutations in CLCN7 are associated to ADO-II, while homozygous and compound heterozygous mutations in CLCN7 may result in ARO and IARO. To date, a total of 24 mutations in CLCN7 were identified in ADO-II, and only 3 mutations were identified in IARO. In the present study, we reported seven unrelated ADO-II patients and one IARO patient from Chinese population and elucidated the characteristics of CLCN7 gene mutations in these patients.

METHODS

All 25 CLCN7 exons and exon-intron boundaries from genomic DNA were amplified and sequenced in eight affected individuals suffering from ADO-II/IARO. The clinical, biochemical, and radiographic analysis were evaluated to compare the differences between ADO-II and IARO both in genotype and phenotype.

RESULTS

The results showed that there were seven novel CLCN7 mutations identified in these ADO-II/IARO patients, including six heterozygous missense mutations (p.L224R, p.S290Y, p.R326G, p.G347R, p.S473N, and p.L564P) and a novel splice mutation (p.K691FS).

CONCLUSIONS

The compound heterozygous mutations (p.L224R and p.K691FS) were firstly observed in one IARO patient. The present study would enrich the database of CLCN7 mutations and improve our understanding of this heritable bone disorder.