Effect of pre-treatment of bentonite with sodium and calcium ions on phosphate adsorption onto zirconium-modified bentonite

To understand the influence of the pre-treatment of bentonite with Na⁺ and Ca²⁺ on the adsorption of phosphate on zirconium-modified bentonite, three kinds of adsorbent materials including zirconium-modified raw, Na⁺-pretreated and Ca²⁺-pretreated bentonites were synthesized and characterized firstly, and afterward their adsorption performance and mechanism for phosphate were studied comparatively. The phosphate adsorption ability for zirconium-modified bentonite decreased after the pre-treatment of bentonite with Na⁺, but it increased after the pre-treatment of bentonite with Ca²⁺. The maximum phosphate adsorption capacity calculated from the Langmuir isotherm model for zirconium-modified Ca²⁺-pretreated bentonites (13.4 mg P/g) was much higher than that for the zirconium-modified raw bentonite (9.06 mg P/g). The pre-treatment of bentonite with Na⁺ and Ca²⁺ did not change the interaction type between zirconium-modified bentonite and phosphate, i.e., the coordination of phosphate to zirconium. The decreased phosphate adsorption capacity for zirconium-modified bentonite induced by the Na⁺ pre-treatment could be mainly attributed to the decrease of the specific surface area and the content of exchangeable Ca. The increased phosphate adsorption capacity for zirconium-modified bentonite induced by the Ca²⁺ pre-treatment could be mainly due to the increase in the amount of exchangeable Ca. Results of this work suggest that the zirconium-modified Ca²⁺-pretreated bentonite is more suitably used as an adsorbent for the removal of phosphate from wastewater than the zirconium-modified raw and Na⁺-pretreated bentonites.

Radiographic predictors for bone mineral loss: Cortical thickness and index of the distal femur

OBJECTIVES

Researchers continue to seek easier ways to evaluate the quality of bone and screen for osteoporosis and osteopenia. Until recently, radiographic images of various parts of the body, except the distal femur, have been reappraised in the light of dual-energy X-ray absorptiometry (DXA) findings. The incidence of osteoporotic fractures around the knee joint in the elderly continues to increase. The aim of this study was to propose two new radiographic parameters of the distal femur for the assessment of bone quality.

METHODS

Anteroposterior radiographs of the knee and bone mineral density (BMD) and T-scores from DXA scans of 361 healthy patients were prospectively analyzed. The mean cortical bone thickness (CBTavg) and the distal femoral cortex index (DFCI) were the two parameters that were proposed and measured. Intra- and interobserver reliabilities were assessed. Correlations between the BMD and T-score and these parameters were investigated and their value in the diagnosis of osteoporosis and osteopenia was evaluated.

RESULTS

The DFCI, as a ratio, had higher reliability than the CBTavg. Both showed significant correlation with BMD and T-score. When compared with DFCI, CBTavg showed better correlation and was better for predicting osteoporosis and osteopenia.

CONCLUSION

The CBTavg and DFCI are simple and reliable screening tools for the prediction of osteoporosis and osteopenia. The CBTavg is more accurate but the DFCI is easier to use in clinical practice.Cite this article: Q-F. He, H. Sun, L-Y. Shu, Y. Zhu, X-T. Xie, Y. Zhan, C-F. Luo. Radiographic predictors for bone mineral loss: Cortical thickness and index of the distal femur. Bone Joint Res 2018;7:468-475. DOI: 10.1302/2046-3758.77.BJR-2017-0332.R1.

A new method to locate the radial head "safe zone" on computed tomography axial views

PURPOSE

Direct location of the "safe zone" on a CT axial view is impossible because the radial head is circular in shape. Previous "safe zone" location methods are not appropriate if the physician is unable to visualize the actual radial head. This study aims to introduce a new method to locate the "safe zone" on CT.

METHODS

CT scans were performed on 20 intact cadaveric upper limbs from 20 different corpses in full pronation and supination. The DICOM-format raw data were then re-sliced and analyzed in Mimics 17.0 (Materialise, Belgium). The radial interosseous border (IB) is shaped like a droplet on the axial view; its axis was selected as our reference line (RL). A parallel line in the radial head axial slice was created, and its position relative to the "safe zone" was studied. Deviation in RL direction was evaluated.

RESULTS

Safe-zone scope was 114.41°±11.99. The rotation angle from the RL to the safe-zone's anterior and posterior border was 215.03°±5.99 and 100.62°±8.12, respectively. Rotation direction (clockwise or anti-clockwise) depended on relative radius-ulna position. The safe zone was located by determining these two borders. The reference line's direction was stable in the upper half of the IB; its distance to the radial head fovea was 77.33° mm±6.24.

CONCLUSIONS

The radial head "safe zone" can be located on CT axial view based on the upper half of the IB using this new method. The method is clinically applicable to determine whether postoperative elbow malrotation results from plate impingement.

Relationship between the change in pacing threshold and the myocardial injury

OBJECTIVE

To investigate the effects of general conditions and past medical history of patients on the short-term pacing threshold after the implantation of active electrodes of a cardiac pacemaker, and to understand whether the application of active electrodes will cause muscle injury and the severity of the injury.

PATIENTS AND METHODS

A total of 156 patients who were treated with a cardiac pacemaker and implanted with single or double active electrodes in Cardiovascular Department of Central Hospital of Jiangjin District were enrolled, including 96 patients treated with a single active electrode and 60 patients treated with double active electrodes. Their clinical data were collected. During operation, the short-term atrial and ventricular pacing thresholds were monitored and recorded after the implantation of the active fixed electrode lead.

RESULTS

Multivariate Logistic regression analysis showed that female sex, age, smoking, drinking, coronary heart disease, diabetes mellitus and hyperlipidemia had effects on pacing thresholds in a short-term to some extent after the implantation of active fixed electrode lead of cardiac pacemaker. The levels of myocardial enzymes, myoglobin (MYO), creatine kinase (CK), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH) and cardiac troponin I (cTNI), in patients were gradually increased after the implantation of active fixed electrode lead and reached the peak at 24 h, which were higher than those before operation (p < 0.05). The levels were decreased at 72 h with statistically significant differences.

CONCLUSIONS

Female sex, age, smoking, drinking, coronary heart disease, diabetes mellitus and hyperlipidemia are independent influencing factors of pacing thresholds in a short term after the implantation of active fixed electrode lead of cardiac pacemaker. The implantation of active electrodes can raise the myocardial enzyme indexes compared with those before operation, but will fall to the preoperative levels or normal, near normal levels at 72 h after operation. The implantation of active electrodes is safe and feasible for myocardial tissues.

[Value of mDIXON-Quant sequence, diffusion-weighted imaging in quantitatively diagnosing the sacroiliitis stages]

Objective: To evaluate the value of mDIXON-Quant sequence, diffusion-weighted imaging (DWI) in quantitative diagnosing of the sacroiliitis stages in patients with ankylosing spondylitis (AS). Methods: Based on the Bath Ankylosing Spondylitis Activity Index (BASDAI) and laboratory parameters, a total of 51 patients were diagnosed with AS. They were divided into two groups as early active group (n=20) and chronic active group (n=31), and at the same time, 25 healthy people from Tianjin were included as control group. The regular MRI sequences and mDIXON-Quant sequence, DWI were obtained. The apparent diffusion coefficient (ADC) and fat-signal fraction (FF) value of bone marrow with edema of the sacroiliac joints in early active group and chronic active group and of subchondral bone marrow of sacroiliac joint in control group all were measured by ADC maps and FF maps. Mean (FF, ADC) values were compared between groups. Results: The ADC value of the early active group, chronic active group and the control group is (1.07±0.20)×10(-3)mm(2)/s, (1.00±0.22)×10(-3)mm(2)/s, (0.25±0.07)×10(-3)mm(2)/s, respectively, and the differences of ADC value between early active group and control group, chronic active group and control group were significant (P<0.01), but the difference of the ADC value between early active group and chronic active group was not significant (P=0.394). That is to say, the ADC value can't distinguish the early active group and chronic active group. The differences of FF value between groups was significant (P<0.01), and the FF value of bone marrow with edema in chronic active group were higher than that in early active group. Conclusions: The mDIXON-Quant sequence can quantitatively diagnose early active group and chronic active group, and the diagnostic value is better than DWI. Thus, it can provide guidance for clinical treatment and prognosis.

Irf8 regulates the progression of myeloproliferative neoplasm-like syndrome via Mertk signaling in zebrafish

Interferon regulatory factor (IRF)-8 is a critical transcription factor involved in the pathogenesis of myeloid neoplasia. However, the underlying mechanisms in vivo are not well known. Investigation of irf8-mutant zebrafish in this study indicated that Irf8 is evolutionarily conserved as an essential neoplastic suppressor through tight control of the proliferation and longevity of myeloid cells. Surviving irf8 mutants quickly developed a myeloproliferative neoplasm (MPN)-like disease with enhanced output of the myeloid precursors, which recurred after transplantation. Multiple molecules presented notable alteration and Mertk signaling was aberrantly activated in the hematopoietic cells in irf8 mutants. Transgenic mertk overexpression in Tg(coro1a:mertk) zebrafish recapitulated the myeloid neoplasia-like syndrome in irf8 mutants. Moreover, functional interference with Mertk, via morpholino knockdown or genetic disruption, attenuated the myeloid expansion phenotype caused by Irf8 deficiency. Therefore, Mertk signaling is a critical downstream player in the Irf8-mediated regulation of the progression of myeloid neoplasia. Our study extends the understanding of the mechanisms underlying leukemogenesis.

Effect of humic acid preloading on phosphate adsorption onto zirconium-modified zeolite

A zirconium-modified zeolite (ZrMZ) was prepared, and then, humic acid (HA) was immobilized on the ZrMZ surface to prepare HA-loaded ZrMZ (HA-ZrMZ). The obtained ZrMZ and HA-ZrMZ were characterized by energy dispersive X-ray spectroscopy, elemental analyzer, N₂ adsorption/desorption isotherms, pH at the point of zero charge, and X-ray photoelectron spectroscopy. The adsorption characteristics of phosphate on ZrMZ and HA-ZrMZ were comparatively investigated in batch mode. The adsorption mechanism of phosphate on ZrMZ and HA-ZrMZ was investigated by ionic strength effect and ³¹P nuclear magnetic resonance. The mechanism for phosphate adsorption onto ZrMZ was the formation of inner-sphere phosphate complexes at the solid/solution interface. The preloading of HA on ZrMZ reduced the phosphate adsorption capacity, and the more the HA loading amount, the lower the phosphate adsorption capacity. However, the preloading of HA on ZrMZ did not change the phosphate adsorption mechanism; i.e., the formation of inner-sphere phosphate surface complexes was still responsible for the adsorption of phosphate on HA-ZrMZ. The decreased phosphate adsorption capacity for ZrMZ after HA coating could be attributed to the fact that the coating of HA on ZrMZ reduced the amount of binding active sites available for phosphate adsorption, changed the adsorbent surface charges, and reduced the specific surface areas and pore volumes of ZrMZ.

[Unerupted first deciduous molar located higher to the first premolar: a case report]

Tooth eruption is defined as the movement of a tooth from its site of development within the alveolar process to its functional position in the oral cavity. The process of tooth eruption can be divided into different phases: pre-eruptive bone stage, alveolar bone stage, mucosal stage, preocclusal stage, occlusal stage and maturation stage. Any disturbance in these phases can lead to eruptive anomalies. The incidence of unerupted teeth is usually higher among permanent teeth than among deciduous ones. Of the primary teeth reported as unerupted, second deciduous molars are the teeth most frequently involved, followed by primary central incisors. At present almost no coverage is seen about the impaction of the first deciduous molar. In this case, a 4-year-old boy who presented with an impacted left maxillary first deciduous molar came to the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology. This tooth, located higher to the left maxillary first premolar, was well near to the maxillary sinus. The family and medical histories were noncontributory and his physical findings were within normal limits. The mother was reported as having experienced no illness or other complications and taken no medications during pregnancy. His clinical extraoral examination was noncontributory. His clinical intra-oral examination revealed that the maxillary left first primary molar was not present. No enlargement of the area was apparent visually or on palpation. The remaining primary dentition was well aligned and in good condition. His oral hygiene was good, although there were incipient occlusal carious lesions in the mandibular second primary molars. There was no history or evidence of dental trauma. A diagnosis of a left maxillary first deciduous molar was made on the basis of the clinical and radiographic evidence. Numerous local etiologic factors have been described for impacted teeth. These include anomalous teeth, malposition, fusion with adjacent or supernumerary teeth, odontoma, dentigerous cysts, tumors, underdevelopment of the jaws, keratinized epithelial lining, hereditary conditions, and trauma. In this case, the reason for impaction was not clear. After the comprehensive clinical evaluation, treatment consisted of placement of a space maintainer, the periodic examination was indicated for the follow-up, so that early interventions, such as subsequent surgical intervention and orthodontic traction could be recommended timely to manage orofacial disfigurement and to avoid consequent problems with resultant proper functioning and good periodontal health.

Modelling genome-wide topological associating domains in mouse embryonic stem cells

Chromosome conformation capture (3C)-based techniques such as chromosome conformation capture carbon copy (5C) and Hi-C revealed that the folding of mammalian chromosomes is highly hierarchical. A fundamental structural unit in the hierarchy is represented by topologically associating domains (TADs), sub-megabase regions of the genome within which the chromatin fibre preferentially interacts. 3C-based methods provide the mean contact probabilities between chromosomal loci, averaged over a large number of cells, and do not give immediate access to the single-cell conformations of the chromatin fibre. However, coarse-grained polymer models based on 5C data can be used to extract the single-cell conformations of single TADs. Here, we extend this approach to analyse around 2500 TADs in murine embryonic stem cells based on high-resolution Hi-C data. This allowed to predict the cell-to-cell variability in single contacts within genome-wide TADs and correlations between them. Based on these results, we predict that TADs are more similar to ideal chains than to globules in terms of their physical size and three-dimensional shape distribution. Furthermore, we show that their physical size and the degree of structural anisotropy of single TADs are correlated with the level of transcriptional activity of the genes that it harbours. Finally, we show that a large number of multiplets of genomic loci co-localize more often than expected by random, and these loci are particularly enriched in promoters, enhancers and CTCF-bound sites. These results provide the first genome-wide structural reconstruction of TADs using polymeric models obeying the laws of thermodynamics and reveal important universal trends in the correlation between chromosome structure and transcription.

[Predictive value of dynamic enhanced MR synovial wash in rate in progression to rheumatoid arthritis in patients with undifferentiated arthritis]

Objective: To investigate the predictive value of dynamic enhanced MR synovial wash in rate (WASHIN) in progression to rheumatoid arthritis (RA) in patients with undifferentiated arthritis (UA). Methods: The data of dynamic enhanced MR synovial WASHIN and C- reactive protein (CRP) of 33 patients with UA were analyzed between October 2014 and January 2016 from Tianjin First Center Hospital, so as to evaluate the correlation between the two indicators. According to the value of CRP, the patients were divided into two groups, the CRP>8 mg/L for CRP positive group (18 cases), CRP≤8 mg/L for CRP negative group (15 cases). Ranked sum test was used to compare the difference of WASHIN between two groups. The ROC curve analysis was carried out to test the diagnostic power of WASHIN. Results: In 33 patients with UA, the correlation between WASHIN and CRP was positive, r=0.767, P<0.01; as for the WASHIN, there was significant difference between CRP positive group(49.51±19.79)/s and CRP negative group(19.90±14.51)/s (P<0.01). 9 cases were clinically diagnosed with RA during follow-up, of which 8 cases for CRP positive group and 1 case for CRP negative group. The biggest area under the ROC curve of synovial WASHIN was 0.944, the biggest Youden index was 0.85, sensitivity was 100.0%, specificity was 87.5%. 2 cases were clinically diagnosed with osteoarthrosis during follow-up, synovial WASHIN respectively of 18.42 and 21.48 /s. Conclusion: Synovial WASHIN can improve the sensitivity and specificity to predict the prognosis from UA to RA, and can provide certain guiding significance for clinical work.

Looping probability of random heteropolymers helps to understand the scaling properties of biopolymers

Random heteropolymers are a minimal description of biopolymers and can provide a theoretical framework to the investigate the formation of loops in biophysical experiments. The looping probability as a function of polymer length was observed to display in some biopolymers, like chromosomes in cell nuclei or long RNA chains, anomalous scaling exponents. Combining a two-state model with self-adjusting simulated-tempering calculations, we calculate numerically the looping properties of several realizations of the random interactions within the chain. We find a continuous set of exponents upon varying the temperature, which arises from finite-size effects and is amplified by the disorder of the interactions. We suggest that this could provide a simple explanation for the anomalous scaling exponents found in experiments. In addition, our results have important implications notably for the study of chromosome folding as they show that scaling exponents cannot be the sole criteria for testing hypothesis-driven models of chromosome architecture.