Fixator-assisted nailing of tibial fractures: New surgical technique and presentation of first 30 cases

Background

Intramedullary nailing is considered a “gold standard” for treatment of tibial shaft fractures. However, some types of fractures are typically considered as “difficult for nailing”. This group includes the periarticular fractures, fractures of both bones at the same level, comminuted and segmental fractures of the tibia. Fixator-assisted nailing (FAN) is an effective method treatment of these types of fractures. The main requirements for the ideal reduction device are an ease of its installation and an ability of multiplanar fracture reduction. Fixator-assisted nailing (FAN) with the use of two perpendicular to each other monolateral tubular frames perfectly meets these requirements. In this study we present this new surgical technique and the analysis of first 30 cases.

Decreased in vivo availability of the cannabinoid type 2 receptor in Alzheimer’s disease

Purpose

The cannabinoid type 2 receptor (CB₂R) is expressed by immune cells such as monocytes and macrophages. In the brain, CB₂R is primarily found on microglia. CB₂R upregulation has been reported in animal models of Alzheimer’s disease, with a preferential localization near amyloid beta (Aβ) plaques, and in patients post mortem. We performed in vivo brain imaging and kinetic modelling of the CB₂R tracer [¹¹C]NE40 in healthy controls (HC) and in patients with Alzheimer’s disease (AD) to investigate whether higher CB₂R availability regionally colocalized to Aβ deposits is present in vivo.

Methods

Dynamic 90-min [¹¹C]NE40 PET scans were performed in eight HC and nine AD patients with full kinetic modelling using arterial sampling and metabolite correction and partial volume correction. All AD patients received a static [¹¹C]PIB scan 40 min after injection. In four HC, a retest scan with [¹¹C]NE40 PET was performed within 9 weeks to investigate test–retest characteristics.

Results

[¹¹C]NE40 was metabolized quickly leading to 50 % of intact tracer 20 min after injection and 20 % at 90 min. A two-tissue kinetic model fitted most of the time–activity curves best; both binding potential (BP_ND) and distribution volume (V _T) parameters could be used. Brain uptake was generally low with an average K ₁ value of 0.07 ml/min/ml tissue. V _T and BP_ND were in the range of 0.7 – 1.8 and 0.6 – 1.6, respectively. Test values in HC were about 30 % for V _T and BP_ND. AD patients showed overall significantly lower CB₂R binding. No relationship was found between regional or global amyloid load and CB₂R availability.

Conclusion

Kinetic modelling of [¹¹C]NE40 is possible with a two-tissue reversible model. In contrast to preclinical and post-mortem data, [¹¹C]NE40 PET shows lower CB₂R availability in vivo in AD patients, with no relationship to Aβ plaques. A possible explanation for these findings is that [¹¹C]NE40 binds to CB₂R with lower affinity and/or selectivity than to CB₁R.

     

Latent Subclinical Medullary Thyroid Carcinoma: Diagnosis and Treatment

n = 11), palpable metastatic lymph node ( n = 6), distant metastases ( n = 4). In nine cases the diagnosis was made by both fine-needle aspiration cytology and serum CT measurement. In the four other cases the initial cytology was incorrect, but the diagnosis was revised on the basis of elevated basal CT values. In 11 patients (group 2) presenting with nodular thyroid disease, SMTC was not clinically detectable. SMTC was preoperatively suspected by elevated CT levels: basal CT > 10 pg/ml and pentagastrin-stimulated CT peak > 100 pg/ml. One patient in group 1 with distant metastases was not operated on. All of the other 12 patients underwent total thyroidectomy and extensive lymph node dissection. The mean size of the tumors was 27 mm. Lymph node involvement was found in nine patients. After surgery, CT levels returned to normal in five patients but remained elevated in five others; the two remaining patients died of distant metastases. All 11 patients in group 2 underwent total thyroidectomy and central neck dissection. None of the 11 patients had nodal extension. All 11 patients are biochemically cured. It was concluded that routine measurement of basal serum CT in those with nodular thyroid disease allows early, preoperative diagnosis of subclinical SMTC and improves the results of surgery.     

Optical Properties of Nitrogen-Substituted Strontium Titanate Thin Films Prepared by Pulsed Laser Deposition

Perovskite-type N‑substituted SrTiO₃ thin films with a preferential (001) orientation were grown by pulsed laser deposition on (001)-oriented MgO and LaAlO₃ substrates. Application of N₂ or ammonia using a synchronized reactive gas pulse produces SrTiO_3-x:N_x films with a nitrogen content of up to 4.1 at.% if prepared with the NH₃ gas pulse at a substrate temperature of 720 °C. Incorporating nitrogen in SrTiO₃ results in an optical absorption at 370‑460 nm associated with localized N(2p) orbitals. The estimated energy of these levels is ≈2.7 eV below the conduction band. In addition, the optical absorption increases gradually with increasing nitrogen content.     

Embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma,and medulloepithelioma share molecular similarity and comprise a single clinicopathological entity

Three histological variants are known within the family of embryonal rosette-forming neuroepithelial brain tumors. These include embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma (EBL), and medulloepithelioma (MEPL). In this study, we performed a comprehensive clinical, pathological, and molecular analysis of 97 cases of these rare brain neoplasms, including genome-wide DNA methylation and copy number profiling of 41 tumors. We identified uniform molecular signatures in all tumors irrespective of histological patterns, indicating that ETANTR, EBL, and MEPL comprise a single biological entity. As such, future WHO classification schemes should consider lumping these variants into a single diagnostic category, such as embryonal tumor with multilayered rosettes (ETMR). We recommend combined LIN28A immunohistochemistry and FISH analysis of the 19q13.42 locus for molecular diagnosis of this tumor category. Recognition of this distinct pediatric brain tumor entity based on the fact that the three histological variants are molecularly and clinically uniform will help to distinguish ETMR from other embryonal CNS tumors and to better understand the biology of these highly aggressive and therapy-resistant pediatric CNS malignancies, possibly leading to alternate treatment strategies.     

Cardiovascular autonomic regulation in Non-Obese Diabetic (NOD) mice

Non-Obese Diabetic (NOD) mice show profound pathomorphological changes in sympathetic ganglia during the development of type 1 diabetes mellitus. We tested the hypothesis that NOD mice represent an experimental model to investigate cardiovascular changes seen in humans with diabetic autonomic neuropathy. Blood glucose (BG) levels were measured once a week. Diabetes mellitus was diagnosed as BG levels exceeded 250 mg/dl twice. NOD mice that did not become diabetic served as control group. Blood pressure (BP) and heart rate (HR) were monitored by telemetry and baroreflex sensitivity (BRS) was calculated with the sequence method or with cross spectral analysis. The measurements were obtained before onset of diabetes and during the 4th week of diabetes. The onset of diabetes was accompanied by a continuous decline in HR (615+/-14 vs. 498+/-23 bpm), whereas BP values remained stable (108+/-2 vs. 111+/-2 mm Hg). The circadian HR rhythm increased in diabetic NOD mice. BRS was higher in diabetic NOD mice than in controls. Atropine reduced BRS more profoundly in diabetic mice compared to non-diabetic mice. Despite pathomorphological similarities of the diabetic autonomic neuropathy between patients with diabetes and diabetic NOD mice, the changes in blood pressure regulation are different. In conclusion the use of diabetic NOD mice as a functional model for human diabetes may be questioned.     

Measuring the quality of neuronal identification in ensemble recordings

Technological advances in electrode construction and digital signal processing now allow recording simultaneous extracellular action potential discharges from many single neurons, with the potential to revolutionize understanding of the neural codes for sensory, motor, and cognitive variables. Such studies have revealed the importance of ensemble neural codes, encoding information in the dynamic relationships among the action potential spike trains of multiple single neurons. Although the success of this research depends on the accurate classification of extracellular action potentials to individual neurons, there are no widely used quantitative methods for assessing the quality of the classifications. Here we describe information theoretic measures of action potential waveform isolation applicable to any dataset that have an intuitive, universal interpretation, that are not dependent on the methods or choice of parameters for single-unit isolation, and that have been validated using a dataset of simultaneous intracellular and extracellular neuronal recordings from Sprague Dawley rats.