Restoring implant fixation strength in osteoporotic bone with a hydrogel locally delivering zoledronic acid and bone morphogenetic protein 2. A longitudinal in vivo microCT study in rats

Osteoporosis poses a major public health challenge, and it is characterized by low bone mass, deterioration of the microarchitecture of bone tissue, causing a consequent increase in bone fragility and susceptibility to fractures and complicating bone fixation, particularly screw implantation. In the present study, our aim was to improve implant stability in osteoporotic bone using a thermoresponsive hyaluronan hydrogel (HA-pNIPAM) to locally deliver the bisphosphonate zoledronic acid (ZOL) to prevent bone resorption and bone morphogenetic protein 2 (BMP2) to induce bone formation. Adult female Wistar rats (n = 36) were divided into 2 treatment groups: one group of SHAM-operated animals and another group that received an ovariectomy (OVX) to induce an osteoporotic state. All animals received a polyetheretherketone (PEEK) screw in the proximal tibia. In addition, subgroups of SHAM or OVX animals received either the HA-pNIPAM hydrogel without or with ZOL/BMP2, placed into the defect site prior to screw implantation. Periprosthetic bone and implant fixation were monitored using longitudinal in vivo microCT scanning post-operatively and at 3, 6, 9, 14, 20 and 28 days. Histological assessment was performed post-mortem. Our data showed that pure hydrogel has no impact of implant fixation The ZOL/BMP2-hydrogel significantly increased bone-implant contact and peri-implant bone fraction, primarily through reduced resorption. STATEMENT OF CLINICAL SIGNIFICANCE: Local delivery of ZOL and BMP2 using a biocompatible hydrogel improved implant stability in osteoporotic bone. This approach could constitute a potent alternative to systemic drug administration and may be useful in avoiding implant loosening in clinical settings.

Titanium Wear Particles Exacerbate S. epidermidis-Induced Implant-Related Osteolysis and Decrease Efficacy of Antibiotic Therapy

Total joint arthroplasty (TJA) surgeries are common orthopedic procedures, but bacterial infection remains a concern. The aim of this study was to assess interactions between wear particles (WPs) and immune cells in vitro and to investigate if WPs affect the severity, or response to antibiotic therapy, of a Staphylococcus epidermidis orthopedic device-related infection (ODRI) in a rodent model. Biofilms grown on WPs were challenged with rifampin and cefazolin (100 µg/mL) to determine antibiotic efficacy. Neutrophils or peripheral blood mononuclear cells (PBMCs) were incubated with or without S. epidermidis and WPs, and myeloperoxidase (MPO) and cytokine release were analyzed, respectively. In the ODRI rodent model, rats (n = 36) had a sterile or S. epidermidis-inoculated screw implanted in the presence or absence of WPs, and a subgroup was treated with antibiotics. Bone changes were monitored using microCT scanning. The presence of WPs decreased antibiotic efficacy against biofilm-resident bacteria and promoted MPO and pro-inflammatory cytokine production in vitro. WPs exacerbated osteolytic responses to S. epidermidis infection and markedly reduced antibiotic efficacy in vivo. Overall, this work shows that the presence of titanium WPs reduces antibiotic efficacy in vitro and in vivo, induces proinflammatory cytokine release, and exacerbates S. epidermidis-induced osteolysis.

Growth modulation of angular deformities with a novel constant force implant concept-preclinical results

PURPOSE

Varus-valgus deformities in children and adolescents are often corrected by temporary hemi-epiphysiodesis, in which the physis is bridged by an implant to inhibit growth. With standard implant solutions, the acting forces cannot be regulated, rendering the correction difficult to control. Furthermore, the implant load steadily increases with ongoing growth potentially leading to implant-related failures. A novel implant concept was developed applying a controlled constant force to the physis, which carries the potential to avoid these complications. The study aim was to proof the concept in vivo by analyzing the effect of three distinct force levels on the creation of varus deformities.

METHODS

The proposed implant is made of a conventional cerclage wire and features a twisted coil that unwinds with growth resulting in an implant-specific constant force level. The proximal medial tibial physes of 18 lambs were treated with the implant and assigned to three groups distinct by the force level of the implant (200 N, 120 N, 60 N).

RESULTS

The treatment appeared safe without implant-related failures. Deformity creation was statistically different between the groups and yielded on average 10.6° (200 N), 4.8° (120 N) and 0.4° (60 N) over the treatment period. Modulation rates were 0.51°/mm (200 N), 0.23°/mm (120 N) and 0.05°/mm (60 N) and were constant throughout the treatment.

CONCLUSION

By means of the constant force concept, controlled growth modulation appeared feasible in this preclinical experiment. However, clinical trials are necessary to confirm whether the results are translatable to the human pathological situation.

Impact of low bone mass and antiresorptive therapy on antibiotic efficacy in a rat model of orthopedic device-related infection

A significant proportion of orthopedic devices are implanted in osteoporotic patients, but it is currently unclear how estrogen deficiency and/or exposure to antiresorptive bisphosphonates (BPs) influence orthopedic device-related infection (ODRI), or response to therapy. The aim of this study is to characterize the bone changes resulting from Staphylococcus epidermidis infection in a rodent ODRI model and to determine if ovariectomy (OVX) or BP treatment influences the infection or the success of antibiotic therapy. A sterile or S. epidermidis-contaminated screw was implanted into the proximal tibia of skeletally mature female Wistar rats (n = 6-9 per group). Bone changes were monitored over 28 days using in vivo micro-computed tomography scanning. OVX was performed 12 weeks before screw implantation. The BP zoledronic acid (ZOL) was administered 4 days before screw insertion. A combination antibiotic regimen (rifampin plus cefazolin) was administered from Days 7-21. In skeletally healthy animals, S. epidermidis induced marked changes in bone, with peak osteolysis occurring at Day 9 and woven bone deposition and periosteal mineralization from Day 14 onwards. Antibiotic therapy cleared the infection in the majority of animals (2/9 infected) but did not affect bone responses. OVX did not affect the pattern of infection-induced changes in bone, nor bacterial load, but reduced antibiotic efficacy (5/9 infected). ZOL treatment did not protect from osteolysis in OVX animals, or further affect antibiotic efficacy (5/9 infected) but did significantly increase the bacterial load. This study suggests that both BPs and OVX can influence host responses to bone infections involving S. epidermidis.

Relative effects of age on implant integration in a rat model: A longitudinal in vivo microct study

The effect of age on implant fixation in bone is not always considered during the design of preclinical models. The decision on animal's age is often related to practical or historical reasons, which ultimately may affect the reproducibility of results. This study aimed to quantify the effect of age by monitoring the fixation of contrast-enhanced PEEK screws in rats, hypothesizing that the kinetics of fixation is impaired in older animals but that age effects are less severe than osteoporotic effects. The time course of implant fixation was investigated in healthy rats at 24, 40, and 60 weeks of age; and in ovariectomized rats. Implant fixation was monitored using in-vivo microCT and dynamic histomorphometry during 1 month. The rats were euthanized 28 days post screw insertion. The data was analyzed both in absolute value and after normalization to baseline bone mass. In absolute terms, greater age had a detrimental effect on bone implant contact, bone fraction, implant stiffness, and bone remodeling but less than ovariectomy. Interestingly, once data was normalized to baseline bone mass this effect disappeared, suggesting that the physiologic response to implant placement was not affected by age. In conclusion, implant fixation kinetics is less affected by age than by baseline bone mass in this rat model. Animals of different ages can therefore be compared but data must be construed relatively to baseline bone mass and not in absolute terms. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-12, 2018.

Structure and dynamics of the radical cation of ethane arising from the Jahn-Teller and pseudo-Jahn-Teller effects

The pulsed-field-ionization zero-kinetic-energy photoelectron spectrum of C₂H₆ has been recorded in the region of the adiabatic ionization threshold. The partially rotationally resolved spectrum indicates the existence of several vibronic states of C₂H₆⁺ with less than 600 cm^-1 of internal excitation. The analysis of the rotational structures assisted by ab initio calculations enabled the determination of the adiabatic ionization energy of C₂H₆ and the investigation of the structure and dynamics of C₂H₆⁺ at low energies. The ground state of C₂H₆⁺ is found to be a ²A_g state of diborane-like structure with strongly mixed (a_1g)^-1 and (e_g)^-1 configurations. The vibrational structure reveals the importance of large-amplitude nuclear motions involving the diborane distortion modes, the C-C stretching motion, and the internal rotation at elongated C-C distances. The spectrum is analyzed in the light of the information obtained in earlier studies of C₂H₆⁺ by ab initio quantum chemistry, EPR spectroscopy and photoelectron spectroscopy.

Efficient utilization of EBUS-TBNA samples for both diagnosis and molecular analyses

BACKGROUND

The assessment of an increasing number of molecular markers is becoming a standard requirement from endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) specimens. However, it is unclear how many needle passes should be performed and the amount of lung cancer cells that should be sent for molecular analyses. The objective of this study was to determine if it is feasible to divide the material obtained by EBUS-TBNA to allow for molecular analysis without compromising the accuracy of mediastinal staging.

OBJECTIVE

We aimed to determine if dividing EBUS-TBNA specimens has a negative impact on either histopathological diagnosis or molecular analysis.

METHODS

EBUS-TBNA was performed in 249 enlarged lymph nodes. Negative or ambiguous histopathological results were confirmed by surgical means and clinical follow-up over 6 months. The tissue obtained by EBUS-TBNA was placed onto a glass slide and divided for histopathological workup and molecular analysis. The number of passes was recorded. Both the accuracy of the mediastinal lymph node staging and the applicability of the sample division for molecular analysis were assessed.

RESULTS

Each lymph node was punctured an average of 3.18 times and division of the obtained material for diagnosis and molecular analysis was feasible in all cases. The sensitivity and accuracy of the mediastinal lymph node staging were 96.6% and 97.6%, respectively. A cytokeratin (CK)-19-mRNA concentration-based molecular test was feasible in 74.1% of cases.

CONCLUSION

Dividing EBUS-TBNA samples for both histopathological diagnosis and molecular testing is feasible and does not compromise the accuracy of mediastinal staging. This method may be an alternative to taking additional needle passes for molecular analyses.

[Role of pretherapeutic biomarkers in lung cancer with special regards to bronchoscopic procedures]

Molecular biomarkers are becoming increasingly significant in the workup of lung carcinoma patients. They assist in diagnosis, selecting the most adequate therapy and determining prognosis. Obtaining blood based biomarkers or volatile markers in exhaled breath may provide a less invasive method in the future. For the time being, bronchoscopy is still the method of choice to obtain specimen and assess tissue based biomarkers. The techniques how specimen are collected and processed for analysis are of paramount importance.

Assessment of SHOX2 methylation in EBUS-TBNA specimen improves accuracy in lung cancer staging

BACKGROUND

Endobronchial ultrasound with transbronchial needle aspiration (EBUS-TBNA) is a well-established method to assess mediastinal lymph nodes for lung cancer. However, a proportion of patients require further investigation, due to the low negative predictive value (NPV). The objective of this study was to determine whether the assessment of short stature homeobox 2 (SHOX2) DNA methylation level in lymph node tissue obtained by EBUS-TBNA improves the accuracy of mediastinal staging.

PATIENTS AND METHODS

EBUS-TBNA was carried out for suspicious lymph nodes of 154 patients. Negative or ambiguous histological results were confirmed by surgical means and clinical follow-up over 6 months. EBUS-TBNA was assessed on 80 positive and 85 negative classified lymph nodes and compared with the result of the SHOX2 DNA methylation real-time PCR analysis. Relative methylation measured by delta-delta cycle threshold (ΔΔCt) was used to classify the samples. Clinical performance of the EBUS-TBNA procedure with and without the additional SHOX2 assessment was calculated against the final classification according to the gold standard.

RESULTS

Based on data from 105 patients, an average 80-fold increase in the SHOX2 methylation level was measured for positive compared with negative lymph nodes. SHOX2 results with a ΔΔCt value of <6.5 indicate positive lymph nodes. Applying this molecular analysis to EBUS-TBNA cases, not diagnosed by pathologic assessment, the sensitivity of staging was improved by 17%-99%. The NPV increased from 80% to 99%.

CONCLUSIONS

The combination of EBUS-TBNA and SHOX2 methylation level strongly improves the assessment of the nodal status by identifying additional malignant lesions and confirming benign nodes and therefore avoiding invasive follow-up procedures.

2-diethylaminoethyl-dextran methyl methacrylate copolymer nonviral vector: still a long way toward the safety of aerosol gene therapy

Revealing the lung tumor genome has directed the current treatment strategies toward targeted therapy. First line treatments targeting the genome of lung tumor cells have been approved and are on the market. However, they are limited by the small number of patients with the current investigated genetic mutations. Novel treatment administration modalities have been also investigated in an effort to increase the local drug deposition and disease control. In the current study, we investigated the safety of the new nonviral vector 2-diethylaminoethyl-dextran methyl methacrylate copolymer (DDMC; Ryujyu Science), which belongs to the 2-diethylaminoethyl-dextran family by aerosol administration. Thirty male BALBC mice, 2 month old, were included and divided into three groups. However, pathological findings indicated severe emphysema within three aerosol sessions. In addition, the CytoViva technique was applied for the first time to display the nonviral particles within the pulmonary tissue and emphysema lesions, and a spectral library of the nonviral vector was also established. Although our results in BALBC mice prevented us from further investigation of the DDMC nonviral vector as a vehicle for gene therapy, further investigation in animals with larger airways is warranted to properly evaluate the safety of the vector.

[Hemoptysis--targets in diagnostic and therapy]

Hemoptysis (coughing up blood) is an extremely alarming situation for the patient, caused by various different underlying diseases. First of all, a peripheral venous catheter should be placed and oxygen should be supplied as patients are threatened by impaired gas exchange caused by the bleeding. Bronchoscopy should be performed immediately, although computed tomography of the thorax may give valuable diagnostic information and should be performed if permitted by the clinical situation. Rigid bronchoscopy should be performed as it allows a broader spectrum of therapeutic options.

Cryobiopsy increases the diagnostic yield of endobronchial biopsy: a multicentre trial

Forceps, brushes or needles are currently the standard tools used during flexible bronchoscopy when diagnosing endobronchial malignancies. The new biopsy technique of cryobiopsy appears to provide better diagnostic samples. The aim of this study was to evaluate cryobiopsy over conventional endobronchial sampling. A total of 600 patients in eight centres with suspected endobronchial tumours were included in a prospective, randomised, single-blinded multicentre study. Patients were randomised to either sampling using forceps or the cryoprobe. After obtaining biopsy samples, a blinded histological evaluation was performed. According to the definitive clinical diagnosis, the diagnostic yield for malignancy was evaluated by a Chi-squared test. A total of 593 patients were randomised, of whom 563 had a final diagnosis of cancer. 281 patients were randomised to receive endobronchial biopsies using forceps and 282 had biopsies performed using a flexible cryoprobe. A definitive diagnosis was achieved in 85.1% of patients randomised to conventional forceps biopsy and 95.0% of patients who underwent cryobiopsy (p<0.001). Importantly, there was no difference in the incidence of significant bleeding. Endobronchial cryobiopsy is a safe technique with superior diagnostic yield in comparison with conventional forceps biopsy.

[Tracheoesophageal fistula]

Congenital deformities, various forms of trauma, foreign bodies, granulomatous infection and tumors are the most common causes of tracheoesophageal fistulas. This is a rare but life-threatening complication with mortality rates up to 60% due to chronic aspiration and innominate artery arrosion and bleeding. Bronchoscopy should be done promptly if a fistula is suspected, followed by esophagoscopy. Radiologic examinations are only helpful for operational planning. Surgical treatment is mandatory for benign fistulas with excellent short-term and long-term results. However, for malignant fistulas the survival time is often only weeks to months and are best treated by palliative stenting, which offers a short-term improvement in the quality of life.