A key assumption of optogenetics is that light only affects opsin-expressing neurons. However, illumination invariably heats tissue, and many physiological processes are temperature-sensitive. Commonly used illumination protocols increased the temperature by 0.2-2 °C and suppressed spiking in multiple brain regions. In the striatum, light delivery activated an inwardly rectifying potassium conductance and biased rotational behavior. Thus, careful consideration of light-delivery parameters is required, as even modest intracranial heating can confound interpretation of optogenetic experiments.

Introduction

Open tibia fractures are some of the most common types of Orthopedics injuries in low- and middle-income countries (LMICs). In Tanzania, open tibia fractures are treated either conservatively by prolonged cast or surgically by external fixation (EF) or intramedullary nail (IMN) when available. The cost of treatment and amount of time patients spend away from work are major economic concerns with prolonged casting and EF. The goal of this study was to determine the cost effectiveness of IMN versus EF in the treatment of open diaphyseal tibia fractures at Muhimbili Orthopaedic Institute (Dar es Salaam, Tanzania).

Methods

This is a prospective randomized control study conducted of patients with a closeable AO/OTA 42 open diaphyseal tibia fracture. The patients underwent surgical fixation with either IMN or EF at Muhimbili Orthopaedic Institute (MOI), and were followed up at 2, 6, and 12 weeks postoperatively. A micro-costing method was used to estimate the fixed and variable costs of IMN and EF of the open diaphyseal tibial fracture.

Results

The mean total cost per patient was lower for the IMN group ($425.8 ± 38.4) compared to the EF group ($559.6 ± 70.5, p < 0.001), with savings of $133.80 per patient for the IMN group. The mean hospital stay was 2.72 ± 1.40 days for the IMN group and 2.44 ± 1.47 days for the EF group (p = 0.5). Quality-adjusted life years (QALYs) were 0.26 per patient for the IMN group and 0.24 in the EF group at 12 weeks (p = 0.8). Ninety-two percent of patients in the IMN group achieved fracture union versus 60% in the EF group at three months postoperatively (p = 0.03).

Conclusion

IM nailing of a closeable open diaphyseal tibial fracture is more cost effective than EF. In addition, IM nailing has better union rates at three months compared to EF.

Background

Open tibial fractures are common injuries in low and middle-income countries, but there is no consensus regarding treatment with intramedullary nailing versus external fixation. The purpose of the present study was to compare the outcomes of initial treatment with intramedullary nailing or external fixation in adults with open tibial fractures.

Methods

We conducted a randomized clinical trial (RCT) at a tertiary orthopaedic center in Tanzania. Adults with acute diaphyseal open tibial fractures were randomly assigned to statically locked, hand-reamed intramedullary nailing or uniplanar external fixation. The primary outcome was death or reoperation for the treatment of deep infection, nonunion, or malalignment. Secondary outcomes included quality of life as measured with the EuroQol-5 Dimensions (EQ-5D) questionnaire, radiographic alignment, and healing as measured with the modified Radiographic Union Scale for Tibial fractures (mRUST).

Results

Of the 240 patients who were enrolled, 221 (92.1%) (including 111 managed with intramedullary nailing and 110 managed with external fixation) completed 1-year follow-up. There were 44 primary outcome events (with rates of 18.0% and 21.9% in the intramedullary nailing and external fixation groups, respectively) (relative risk [RR] = 0.83 [95% confidence interval (CI), 0.49 to 1.41]; p = 0.505). There was no significant difference between the groups in terms of the rate of deep infection. Intramedullary nailing was associated with a lower risk of coronal malalignment (RR = 0.11 [95% CI, 0.01 to 0.85]; p = 0.01) and sagittal malalignment (RR = 0.17 [95% CI, 0.02 to 1.35]; p = 0.065) at 1 year. The EQ-5D index favored intramedullary nailing at 6 weeks (mean difference [MD] = 0.07 [95% CI = 0.03 to 0.11]; p < 0.001), but this difference dissipated by 1 year. Radiographic healing (mRUST) favored intramedullary nailing at 6 weeks (MD = 1.2 [95% CI = 0.4 to 2.0]; p = 0.005), 12 weeks (MD = 1.0 [95% CI = 0.3 to 1.7]; p = 0.005), and 1 year (MD = 0.8 [95% CI = 0.2 to 1.5]; p = 0.013).

Conclusions

To our knowledge, the present study is the first RCT assessing intramedullary nailing versus external fixation for the treatment of open tibial fractures in sub-Saharan Africa. Differences in primary events were not detected, and only coronal alignment significantly favored the use of intramedullary nailing.

Level of evidence

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

The discordance between genome size and the complexity of eukaryotes can partly be attributed to differences in repeat density. The Muller F element (∼5.2 Mb) is the smallest chromosome in Drosophila melanogaster, but it is substantially larger (>18.7 Mb) in D. ananassae To identify the major contributors to the expansion of the F element and to assess their impact, we improved the genome sequence and annotated the genes in a 1.4-Mb region of the D. ananassae F element, and a 1.7-Mb region from the D element for comparison. We find that transposons (particularly LTR and LINE retrotransposons) are major contributors to this expansion (78.6%), while Wolbachia sequences integrated into the D. ananassae genome are minor contributors (0.02%). Both D. melanogaster and D. ananassae F-element genes exhibit distinct characteristics compared to D-element genes (e.g., larger coding spans, larger introns, more coding exons, and lower codon bias), but these differences are exaggerated in D. ananassae Compared to D. melanogaster, the codon bias observed in D. ananassae F-element genes can primarily be attributed to mutational biases instead of selection. The 5' ends of F-element genes in both species are enriched in dimethylation of lysine 4 on histone 3 (H3K4me2), while the coding spans are enriched in H3K9me2. Despite differences in repeat density and gene characteristics, D. ananassae F-element genes show a similar range of expression levels compared to genes in euchromatic domains. This study improves our understanding of how transposons can affect genome size and how genes can function within highly repetitive domains.

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25-50%) than euchromatic reference regions (3-11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11-27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4-3.6 vs. 8.4-8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.