Studies in dopamine-depleted rats indicate that the external globus pallidus (GPe) contains two main types of GABAergic projection cell; so-called "prototypic" and "arkypallidal" neurons. Here, we used correlative anatomical and electrophysiological approaches in rats to determine whether and how this dichotomous organization applies to the dopamine-intact GPe. Prototypic neurons coexpressed the transcription factors Nkx2-1 and Lhx6, comprised approximately two-thirds of all GPe neurons, and were the major GPe cell type innervating the subthalamic nucleus (STN). In contrast, arkypallidal neurons expressed the transcription factor FoxP2, constituted just over one-fourth of GPe neurons, and innervated the striatum but not STN. In anesthetized dopamine-intact rats, molecularly identified prototypic neurons fired at relatively high rates and with high regularity, regardless of brain state (slow-wave activity or spontaneous activation). On average, arkypallidal neurons fired at lower rates and regularities than prototypic neurons, and the two cell types could be further distinguished by the temporal coupling of their firing to ongoing cortical oscillations. Complementing the activity differences observed in vivo, the autonomous firing of identified arkypallidal neurons in vitro was slower and more variable than that of prototypic neurons, which tallied with arkypallidal neurons displaying lower amplitudes of a "persistent" sodium current important for such pacemaking. Arkypallidal neurons also exhibited weaker driven and rebound firing compared with prototypic neurons. In conclusion, our data support the concept that a dichotomous functional organization, as actioned by arkypallidal and prototypic neurons with specialized molecular, structural, and physiological properties, is fundamental to the operations of the dopamine-intact GPe.

Background Non-union in non-operatively managed humeral shaft fractures are associated with significant morbidity. Hence, developing a robust system that could help with early diagnosis is important. We aimed to evaluate the validity of the Radiographic Union Score for HUmeral fractures (RUSHU) at 6 weeks (RUSHU-6) and test whether a RUSHU at 12 weeks (RUSHU-12) would be a better predictor of non-union. Methods We retrospectively reviewed all non-operatively managed humeral diaphyseal fractures from 2012 to 2018. Statistical analysis was used to determine the cut-off RUSHU-12 and evaluate the effect of RUSHU-6 and RUSHU-12 on non-union prediction. Results In sum, 32 patients had radiographs at 6 weeks post-injury, 27 of which also had radiographs at 12 weeks. A RUSHU cut-off of 9 was the best predictor of non-union at 12 weeks. Only RUSHU-12 had a statistically significant influence predicting non-union (P = 0.011) and there was a significant correlation (P = 0.003) between score progression from RUSHU-6 to RUSHU-12 and the development of non-union. Discussion A RUSHU-12 of <9 and a low score progression between 6 and 12 weeks suggest superior predictive value in determining the likelihood of non-union. Further validation in the form of a large multicentred study is however required.

The hip fractures in the elderly are on the rise. In 1998, the total number of hip fractures worldwide was about 1.26 million and is estimated to be about 2.6 million by the year 2025 and 4.5 million by the year 2050. 1 The majority of the patients with fragility hip fractures are frail and have multiple comorbidities. The aim of service delivery in this high-risk group is to minimize hospitalization, morbidity, and mortality. Perioperative hemoglobin levels are an important marker of patient recovery, hospital stay, readmissions, and mortality. Low perioperative hemoglobin is said to be one of the most important factors that delay patient mobility in early postoperative period 2 and therefore potentially increase the risk of medical complications and increase hospital stay. The perioperative hemoglobin levels can predict the mortality in elderly patients with hip fractures. Hemoglobin level below 10 g/ dL is associated with increased mortality in elderly hip fractures. 3 The higher postoperative hemoglobin reduces the length of hospital stay and readmissions within 2 months of surgery. 4 There is a higher in-patient stay, increased morbidity, and mortality in elderly

The use of digital templating for Total Hip Arthroplasty (THA) is now the standard approach for pre-operative planning. Digital templating holds potential to reduce operative time and post-op complications however, this often relies on imprecise assumptions. The relationship between the X-ray source, subject and detector alters the perceived magnification. We therefore determine if Body Mass Index (BMI) is positively correlated with true magnification and if a predictive model based these parameters exists. A single surgeon series (n=107) was included in this study. Two independent observers assessed both pre- and post-operative AP pelvis radiographs using TraumaCad™. Post-operative radiographs were assessed to calculate the true magnification by calibrating from a known femoral head prosthesis size. Finally, a scatter plot with regression was used to determine if a predictive model of magnification existed using the Body Mass Index. The mean pre-operative magnification using a scaling marker was 124.2 ± 8.90%. The mean post-operative magnification using a known femoral head prosthesis size (true magnification) was 123.7 ± 3.98%. Significant variability exists in pre-operative marker data. Regression modelling showed no significant correlation between BMI and true magnification (post-op magnification). This study’s suggests that the precision and reliability of the radiographic marker in daily practice is poor. Regression modelling showed no significant correlation between BMI and the true magnification factor. Therefore, a pre-op predictive model cannot be reliably used. The data from this study suggest that a fixed magnification factor of 124% remains the most reliable and accurate method.

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