Can zinc protect cells from the cytotoxic effects of cobalt ions and nanoparticles derived from metal-on-metal joint arthroplasties?

Objectives

Recently, high failure rates of metal-on-metal (MOM) hip implants have raised concerns of cobalt toxicity. Adverse reactions occur to cobalt nanoparticles (CoNPs) and cobalt ions (Co²⁺) during wear of MOM hip implants, but the toxic mechanism is not clear.

Methods

To evaluate the protective effect of zinc ions (Zn²⁺), Balb/3T3 mouse fibroblast cells were pretreated with 50 μM Zn²⁺ for four hours. The cells were then exposed to different concentrations of CoNPs and Co²⁺ for four hours, 24 hours and 48 hours. The cell viabilities, reactive oxygen species (ROS) levels, and inflammatory cytokines were measured.

Results

CoNPs and Co²⁺ can induce the increase of ROS and inflammatory cytokines, such as tumour necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). However, Zn pretreatment can significantly prevent cytotoxicity induced by CoNPs and Co²⁺, decrease ROS production, and decrease levels of inflammatory cytokines in Balb/3T3 mouse fibroblast cells.

Conclusion

These results suggest that Zn pretreatment can provide protection against inflammation and cytotoxicity induced by CoNPs and Co²⁺ in Balb/3T3 cells.

Cite this article: Y. Liu, H. Zhu, H. Hong, W. Wang, F. Liu. Can zinc protect cells from the cytotoxic effects of cobalt ions and nanoparticles derived from metal-on-metal joint arthroplasties? Bone Joint Res 2017;6:649–655. DOI: 10.1302/2046-3758.612.BJR-2016-0137.R2.

One-step purification and immobilization of extracellularly expressed sortase A by magnetic particles to develop a robust and recyclable biocatalyst

Sortase A (SrtA) is a transpeptidase widely used to site-specifically modify peptides and proteins and shows promise for industrial applications. In this study, a novel strategy was developed for constructing immobilized-SrtA as a robust and recyclable enzyme via direct immobilization of extracellularly expressed SrtA in the fermentation supernatant using magnetic particles. Efficient extracellular SrtA expression was achieved in Escherichia coli through molecular engineering, including manipulation of the protein transport pathway, codon optimization, and co-expression of molecular chaperones to promote expressed SrtA secretion into the medium at high levels. Subsequently, a simple one-step protocol was established for the purification and immobilization of SrtA containing a His-tag from the fermentation supernatant onto a nickel-modified magnetic particle. The immobilized SrtA was proved to retain full enzymatic activity for peptide-to-peptide ligation and protein modification, and was successfully reused for five cycles without obvious activity loss.

Head-shaft angle changes during internal and external shoulder rotations: 2-D angulation in 3-D space

INTRODUCTION

Restoration of native head-shaft angle (HSA) is critical for treatment of proximal humerus fracture. However, HSA has not been properly investigated according to the humeral rotation. This study was designed to analyze the relationship between the humeral rotation and the HSA at 1° increments, and clarify its serial changing pattern according to the humeral rotation.

HYPOTHESIS

The angulation of HSA would be undervalued when the humerus is being rotated externally and it would be overvalued when it is being rotated internally.

MATERIALS AND METHODS

Eight dried cadaveric normal humeri were CT scanned. They were analyzed using computer-aided design with a standardized neutral position. HSA was the angle between the humeral shaft axis (SA) and the humeral head axis (HA). SA and HA were the best-fit lines through center of all the best-fitting circles in every cross section along the humeral shaft and within the humeral head, respectively. Each 3D model was rotated 30° internally and 45° externally relatives to the SA at 1° increments with the camera was fixed at antero-posterior view of neutral position. Angulation of HSA in every rotational degree was documented as ratio relatives to the angulation of HSA in neutral position.

RESULTS

The average HSA at neutral position was 133±1.93°. HSA was underestimated by 8±1.9% and it was overestimated by 20±5.1% at the maximum external rotation (ER) and internal rotation (IR), respectively. HSA was underestimated by 1% in every 5.8° of ER and overestimated by 1% in every 1.5° of IR. Rotational misalignments within 10° of IR and 18° of ER could be tolerated (P>.05).

CONCLUSIONS

HSA was underestimated at ER and was overestimated at IR. This information could be useful for surgeons in restoring the native HSA for treatment of proximal humerus fracture.

TYPE OF STUDY

Basic research study.

New potent and selective αvβ3 integrin ligands: Macrocyclic peptides containing RGD motif synthesized by sortase A-mediated ligation

Three 14-mer macrocyclic peptides 1-3 containing mono-, di- and tri-RGD structure motif were designed and synthesized by sortase A-mediated ligation in good yields. The results of in intro cell-based biological assays indicated that linear peptide 5 and macrocyclic peptide 1, containing di-RGD and mono-RGD motif respectively, showed remarkable potency and selectivity to α_vβ₃ integrin.

Efficient expression of sortase A from Staphylococcus aureus in Escherichia coli and its enzymatic characterizations

Background

Sortase A (SrtA) is a transpeptidase found in Staphylococcus aureus, which is widely used in site-specific protein modification. However, SrtA was expressed in Escherichia coli (E. coli) in rather low level (ranging from several milligrams to 76.9 mg/L at most). The present study aims to optimize fermentation conditions for improving SrtA expression in E. coli.

Results

Under the optimized media (0.48 g/L glycerol, 1.37 g/L tryptone, 0.51 g/L yeast extract, MOPS 0.5 g/L, PBS buffer 180 mL/L) and condition (30 °C for 8 h) in a 7-L fermentor, the enzyme activity and the yield of SrtA reached 2458.4 ± 115.9 U/mg DCW and 232.4 ± 21.1 mg/L, respectively, which were higher by 5.8- and 4.5-folds compared with initial conditions, respectively. The yield of SrtA also represented threefold increase than the previously reported maximal level. In addition, the enzymatic characterizations of SrtA (optimal temperature, optimal pH, the influence of metal irons, and tolerance to water-soluble organic solvents) were determined.

Conclusions

Enhanced expression of SrtA was achieved by optimization of medium and condition. This result will have potential application for production levels of SrtA on an industry scale. Moreover, the detailed enzymatic characterizations of SrtA were examined, which will provide a useful guide for its future application.

Electronic supplementary material

The online version of this article (doi:10.1186/s40643-017-0143-y) contains supplementary material, which is available to authorized users.

[The clinical and imaging features of 118 patients with spontaneous cerebral arterial dissections presenting with ischemic stroke]

OBJECTIVE

To investigate the clinical and radiologic features of patients with spontaneous cerebral arterial dissections (CADs) presenting with ischemic stroke and to explore the effect of gender and age on those features.

METHODS

Patients admitted to our stroke center diagnosed as ischemic stroke secondary to CADs from August 2008 to April 2015 were prospectively registered. Patients aged between 15 to 80 years old, who had acute brain infarcts within the territory of a major cerebral artery affected by a dissection confirmed by the neuroradiological examinations, were enrolled in the study. The followings were the exclusion criteria: (1) there were any potential causes for the brain infarcts other than CADs; (2) CADs were the results of a definite cause; (3) the clinical data were incomplete.

RESULTS

A total of 118 patients were enrolled in the study with the mean age of (44.2±12.8) years old. There were 87 men (73.7%) and 67 patients (56.8%) aged under 45 years old. Smoking (41.5%), hypertension (25.4%) and hypercholesterolemia (21.2%) were the three leading risk factors for stroke. Hypercholesterolemia was more common in the male patients (25.3% vs 9.7%, P=0.021), whereas hypertension (39.2% vs 14.9%, P=0.005) and diabetes (25.5% vs 4.5%, P=0.002) were more common in the patients aged 45 years or older. Headache or neck pain before or at the onset of stroke was more common in the female patients (67.7% vs 34.5%, P=0.002). A total of 71 patients were found with CADs of the anterior circulation, while 47 patients with that of the posterior circulation. The involvement of the intra and extracranial arteries were documented in 59 and 59 patients, respectively. The middle cerebral artery (MCA) was the most common site in the intracranial dissection and more MCA dissections were observed in the male patients (46.3% vs 11.1%, P=0.016). The dissection of intracranial carotid artery was more common in patients aged under 45 years old (38.7% vs 0, P<0.001). Lumen status of CADs often presented as stenosis (43.2%) and occlusion (41.2%), while less aneurysm (5.9%) and aneurysm with stenosis (9.3%) were observed. Aneurysm was found to be more common in patients aged 45 years or older (11.8% vs 1.5%, P=0.042).

CONCLUSION

Chinese patients with spontaneous CADs presenting with ischemic stroke have unique clinical and imaging features, which correlated with age and gender.

Sortase A-mediated on-resin peptide cleavage and in situ ligation: an efficient one-pot strategy for the synthesis of functional peptides and proteins

A one-pot approach combining Sortase A mediated on-resin peptide cleavage, activation and in situ ligation was developed and was employed to synthesize dual functional peptides, modify peptides with lipid, biotin and PEG, as well as protein N-terminal labeling in high efficiency.

Selective inhibition of metabotropic glutamate type 1 alpha receptor (mGluR1α) reduces cell proliferation and migration following status epilepticus in early development

The present study examined whether a single or multiple episode(s) of status epilepticus induced with kainic acid (KA) during the first 3 weeks of postnatal (P) development would aberrantly stimulate proliferation zones that alters migration to potentially injured areas and whether they would be blocked by selective Group I mGluR antagonists. mGluR1α (LY367385) and mGluR5 (MPEP) antagonists were administered 2h following KA-induced status epilepticus and animals were examined after 7days. Proliferating cells of the subventricular zone (SVZ), third ventricle, hippocampus, amygdala cortical complex were analyzed with the proliferative marker, Ki67; and two complementary retrograde dye tracers. Proliferation increased in extrahippocampal limbic structures when KA was administered on P13 or P20 which correlated with number of injured cells at the older age. LY367385 post-treatment caused striking decreases in proliferation in all limbic structures in the presence and absence of injury, whereas a reduction with MPEP was observed only within the amygdala cortical complex (Amg/ERcx) in the presence of multiple seizures (3×KA). After 3×KA and LY367385 post-treatments, diminished co-staining of dye tracers with Ki67 was observed within the Amg/ERcx despite high levels of progenitors marked by the retrograde tracers in this region. This indicates that not only was local proliferation within the SVZ and distant structures inhibited, but also that migration itself was reduced indirectly since there were less cells to migrate from the SVZ. Co-labeling with biomarkers provided evidence for neuronal differentiation suggesting potential aberrant integration may occur in distant locations, and that targeting of mGluR1α receptors may be a potential therapeutic strategy for future development.

Characterization of Staphylococcus aureus faecal isolates associated with food-borne disease in Korea

AIMS

To characterize Staphylococcus aureus faecal isolates from people suspected to be infected with food poisoning by using antimicrobial susceptibility testing and molecular techniques.

METHODS AND RESULTS

A total of 340 Staph. aureus isolates from 6226 people suspected to be infected with food poisoning were identified and characterized by biochemical methods, antimicrobial susceptibility testing and PCR. Samples were obtained from January 2006 to December 2008 from the National Notifiable Diseases Surveillance System at the Research Institute of Public Health and Environment in Seoul Metropolitan, Korea. All strains carried at least one of the eight staphylococcal enterotoxin (se) genes tested and a total of 27 se profiles were produced; the most frequent se profile was seg-sei and the next was sea. Among the total isolates, 36 methicillin-resistant Staphylococcus aureus (MRSAs) isolates were further analysed by multilocus sequence typing (MLST), Staphylococcal cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE) and PCR detection for pvl. ST72-SCCmec type IV was the most predominant clone (27 isolates, 75%) followed by ST1-SCCmec type IV (five isolates, 13·8%), ST20-SCCmec type IV (one isolate, 2·8%), ST493-SCCmec type IV (one isolate, 2·8%), ST903-SCCmec type IV (one isolate, 2·8%) and ST5-SCCmec type II (one isolate, 2·8%). By PFGE typing, MRSAs isolated during the same period were grouped together although they were isolated from different regions. None of MRSAs had PVL gene and nine MRSAs were multidrug resistant.

CONCLUSIONS

Analysis of MRSAs by MLST, SCCmec typing, PFGE and pvl detection showed that the majority of strain associated with food-borne diseases belonged to a Korean community-acquired (CA) MRSA clone with ST72-SCCmec type IV-PVL negative-SEG/SEI and its variations while one strain was hospital-acquired (HA) MRSA.

SIGNIFICANCE AND IMPACT OF THE STUDY

CA-MRSA clone which possessed ST72-SCCmec type IV-PVL negative-SEG/SEI was spread most commonly among MRSAs that were associated with food-borne diseases. This is the first report of ST903 strain in Korea.

Killer-cell Immunoglobulin-like Receptor (KIR) gene profiles modify HIV disease course, not HIV acquisition in South African women

BACKGROUND

Killer-cell Immunoglobulin-like Receptors (KIR) interact with Human Leukocyte Antigen (HLA) to modify natural killer- and T-cell function. KIR are implicated in HIV acquisition by small studies that have not been widely replicated. A role for KIR in HIV disease progression is more widely replicated and supported by functional studies.

METHODS

To assess the role of KIR and KIR ligands in HIV acquisition and disease course, we studied at-risk women in South Africa between 2004-2010. Logistic regression was used for nested case-control analysis of 154 women who acquired vs. 155 who did not acquire HIV, despite high exposure. Linear mixed-effects models were used for cohort analysis of 139 women followed prospectively for a median of 54 months (IQR 31-69) until 2014.

RESULTS

Neither KIR repertoires nor HLA alleles were associated with HIV acquisition. However, KIR haplotype BB was associated with lower viral loads (-0.44 log10 copies/ml; SE = 0.18; p = 0.03) and higher CD4+ T-cell counts (+80 cells/μl; SE = 42; p = 0.04). This was largely explained by the protective effect of KIR2DL2/KIR2DS2 on the B haplotype and reciprocal detrimental effect of KIR2DL3 on the A haplotype.

CONCLUSIONS

Although neither KIR nor HLA appear to have a role in HIV acquisition, our data are consistent with involvement of KIR2DL2 in HIV control. Additional studies to replicate these findings are indicated.

Cloning and characterisation of JAZ gene family in Hevea brasiliensis

Mechanical wounding or treatment with exogenous jasmonates (JA) induces differentiation of the laticifer in Hevea brasiliensis. JA is a key signal for latex biosynthesis and wounding response in the rubber tree. Identification of JAZ (jasmonate ZIM-domain) family of proteins that repress JA responses has facilitated rapid progress in understanding how this lipid-derived hormone controls gene expression and related physiological processes in plants. In this work, the full-length cDNAs of six JAZ genes were cloned from H. brasiliensis (termed HbJAZ). These HbJAZ have different lengths and sequence diversity, but all of them contain Jas and ZIM domains, and two of them contain an ERF-associated amphiphilic repression (EAR) motif in the N-terminal. Real-time RT-PCR analyses revealed that HbJAZ have different expression patterns and tissue specificity. Four HbJAZ were up-regulated, one was down-regulated, while two were less effected by rubber tapping treatment, suggesting that they might play distinct roles in the wounding response. A yeast two-hybrid assay revealed that HbJAZ proteins interact with each other to form homologous or heterogeneous dimer complexes, indicating that the HbJAZ proteins may expand their function through diverse JAZ-JAZ interactions. This work lays a foundation for identification of the JA signalling pathway and molecular mechanisms of latex biosynthesis in rubber trees.

Nasal endoscopic findings and nasal symptoms in patients with asthma: a clinical study from a rhinological perspective

OBJECTIVE

Allergic rhinitis (AR), non-allergic rhinitis (NAR), chronic rhinosinusitis with nasal polyps (CRSwNP), and chronic rhinosinusitis without nasal polyps (CRSsNP) occur frequently in asthmatic patients. We evaluated nasal symptoms and nasal endoscopic findings in patients with asthma and correlated them to asthma severity.

METHODS

Subjects (n=150) with asthma completed questionnaires designed to provide information related to asthma and nasal disease. Patients were divided into four groups based on asthma severity. Pulmonary function tests, skin-prick tests (SPTs) and nasal endoscopy were performed on every patient. Clinical findings were compared in asthma patients by rhinologists.

RESULTS

The total incidence of AR, NAR, CRSwNP and CRSsNP in these patients with asthma was 76%. By using Fisher's Exact Test, there was no statistical significance between asthma severity and the incidence of AR, NAR, CRSwNP and CRSsNP (P=0.311). There was a significant difference in the total nasal symptoms score among subjects with different grades of asthma (P=0.002). However, there were no significant differences in the total Lund-Kennedy endoscopic score (LKS) (P=0.736). The nasal endoscopic scores were significantly correlated at a high degree with the nasal symptoms score (P=0.000). A significant correlation was found between the nasal endoscopic score and the duration of asthma in the patients with different grades of asthma (P<0.05).

CONCLUSIONS

The relationship between rhinitis and asthma is complex. Nasal airways should become part of standard clinical assessment and follow-up in patients with asthma.

Quality control metrics improve repeatability and reproducibility of single-nucleotide variants derived from whole-genome sequencing

Although many quality control (QC) methods have been developed to improve the quality of single-nucleotide variants (SNVs) in SNV-calling, QC methods for use subsequent to single-nucleotide polymorphism-calling have not been reported. We developed five QC metrics to improve the quality of SNVs using the whole-genome-sequencing data of a monozygotic twin pair from the Korean Personal Genome Project. The QC metrics improved both repeatability between the monozygotic twin pair and reproducibility between SNV-calling pipelines. We demonstrated the QC metrics improve reproducibility of SNVs derived from not only whole-genome-sequencing data but also whole-exome-sequencing data. The QC metrics are calculated based on the reference genome used in the alignment without accessing the raw and intermediate data or knowing the SNV-calling details. Therefore, the QC metrics can be easily adopted in downstream association analysis.

Improved methods for selective cryolipolysis results in subcutaneous fat layer reduction in a porcine model

BACKGROUND/AIMS

Cryolipolysis is a noninvasive method for the selective reduction of localized fat tissues. It has demonstrated efficacy in both clinical and preclinical trials; however, despite its popularity, its mechanisms of action and evaluation methods are not yet fully defined. The purpose of this study was to improved methods for cryolipolysis using a porcine model.

METHODS

The abdomens of female PWG micro-pigs were treated with a cooling device (CRYOLIPO II(™)), and we examined the treatment effects using photography, three-dimensional photography, ultrasound, gross, and microscopic pathology, and serum lipid level analyses in order to determine the mechanism of action, efficacy, and safety of CRYOLIPO II(™).

RESULTS

CRYOLIPO II(™) successfully reduced abdominal fat in our porcine model. Gross and microscopic histological results confirmed the noninvasive cold-induced selective subcutaneous fat destruction, and showed increases in pre-adipocyte differentiation and in the activation of lipid catabolism. In particular, we found that CRYOLIPO II(™) may increase PPARδ (delta) levels in adipose tissue at 30-60 days post-treatment.

CONCLUSION

Fat reduction by cryolipolysis was successfully achieved in our porcine model. Thus, our findings indicate that CRYOLIPO II(™) may be a promising fat reduction device for body contouring and fat reduction in humans, and that cryolipolysis exerts its effects, at least partly, by targeting the PPARδ signaling pathway. These results show that both investigative and diagnostic potentials capacity.

Dynamic layer rearrangement during growth of layered oxide films by molecular beam epitaxy

The A(n+1)B(n)O(3n+1) Ruddlesden-Popper homologous series offers a wide variety of functionalities including dielectric, ferroelectric, magnetic and catalytic properties. Unfortunately, the synthesis of such layered oxides has been a major challenge owing to the occurrence of growth defects that result in poor materials behaviour in the higher-order members. To understand the fundamental physics of layered oxide growth, we have developed an oxide molecular beam epitaxy system with in situ synchrotron X-ray scattering capability. We present results demonstrating that layered oxide films can dynamically rearrange during growth, leading to structures that are highly unexpected on the basis of the intended layer sequencing. Theoretical calculations indicate that rearrangement can occur in many layered oxide systems and suggest a general approach that may be essential for the construction of metastable Ruddlesden-Popper phases. We demonstrate the utility of the new-found growth strategy by performing the first atomically controlled synthesis of single-crystalline La3Ni2O7.

Quantum dot-based nanoprobes for in vivo targeted imaging

Fluorescent semiconductor quantum dots (QDs) have attracted tremendous attention over the last decade. The superior optical properties of QDs over conventional organic dyes make them attractive labels for a wide variety of biomedical applications, whereas their potential toxicity and instability in biological environment have puzzled scientific researchers. Much research effort has been devoted to surface modification and functionalization of QDs to make them versatile probes for biomedical applications, and significant progress has been made over the last several years. This review article aims to describe the current state-of-the-art of the synthesis, modification, bioconjugation, and applications of QDs for in vivo targeted imaging. In addition, QD-based multifunctional nanoprobes are also summarized.