Exploring the genome and transcriptome of the cave nectar bat Eonycteris spelaea with PacBio long-read sequencing

Background

In the past two decades, bats have emerged as an important model system to study host-pathogen interactions. More recently, it has been shown that bats may also serve as a new and excellent model to study aging, inflammation, and cancer, among other important biological processes. The cave nectar bat or lesser dawn bat (Eonycteris spelaea) is known to be a reservoir for several viruses and intracellular bacteria. It is widely distributed throughout the tropics and subtropics from India to Southeast Asia and pollinates several plant species, including the culturally and economically important durian in the region. Here, we report the whole-genome and transcriptome sequencing, followed by subsequent de novo assembly, of the E. spelaea genome solely using the Pacific Biosciences (PacBio) long-read sequencing platform.

Findings

The newly assembled E. spelaea genome is 1.97 Gb in length and consists of 4,470 sequences with a contig N50 of 8.0 Mb. Identified repeat elements covered 34.65% of the genome, and 20,640 unique protein-coding genes with 39,526 transcripts were annotated.

Conclusions

We demonstrated that the PacBio long-read sequencing platform alone is sufficient to generate a comprehensive de novo assembled genome and transcriptome of an important bat species. These results will provide useful insights and act as a resource to expand our understanding of bat evolution, ecology, physiology, immunology, viral infection, and transmission dynamics.

Patellar resection during total knee arthroplasty: effect on bone strain and fracture risk

Patellae in small knees, or after severe patellar erosion, may be vulnerable to fracture after resection during arthroplasty. The patellar remnant may be thin, while the polyethylene component has a standard thickness. Anterior patellar bone strain was measured in cadaver knees loaded via the quadriceps, from 0 to 90 degrees flexion, with the patella intact, and after resections to 16, 13 and 11 mm thick and replacement by an 8-mm-thick polyethylene component. Strain increased significantly with knee flexion with constant 500 N quadriceps tension. Resection caused significant changes from intact values in knee flexion and extension and no significant effect at 30 degrees flexion. In flexion, bending caused the anterior surface to become more convex, with high tensile bone strains. In extension, resection caused negative anterior strains, representing bending in the opposite direction, with large tensile strains on the cut posterior surface. For normal activities, such as rising from a chair (1.8 kN quadriceps tension) the patella appears safe against fracture with a minimal resection to 16 mm thick. An eroded patella resected to 11 mm thickness may be at risk of fracture with that loading.

Prospective trial of resurfaced patellaversus non-resurfaced patella in simultaneous bilateral total knee replacement

INTRODUCTION

A prospective trial was carried out in simultaneous bilateral total knee replacement to compare the outcome of resurfaced versus non-surfaced patella.

METHODS

Thirty-five patients between 1997 and 2002 had simultaneous bilateral total knee replacement with resurfaced patella on the left and non-resurfaced patella on the right knee using the same implant in both.

RESULTS

There were 29 females and six males with a mean age of 65.3 years. Mean follow-up was 3.18 years. There was no significant difference between the resurfaced and non-resurfaced knees with respect to the overall Knee Society clinical score (p = 0.093 preoperative, 0.310 postoperative) or the pain (p = 0.715 preoperative, 0.395 postoperative) or function subscores (p = 0.126 preoperative, 0.317 postoperative). The postoperative range of motion was 109 and 110 degrees for the resurfaced patella and non-resurfaced patella respectively (p = 0.894). The post-operative knee scores between patients with or without pre-operative anterior knee pain (p = 0.238) and between those who were obese and non-obese (p = 0.387) were not significantly different. 82.9% of patients felt that the resurfaced knee and 80% felt that the non-resurfaced knee were much better than before. There was no major preference for either knee for climbing stairs and getting out of chair.

CONCLUSION

The functional and symptomatic outcome of total knee replacement with or without patella resurfacing is the same in the local population. Also, the present study demonstrated no evidence that the weight of the patient or the presence of preoperative anterior knee pain should be considered as factors in the decision to resurface the patella.

Influence of patellar thickness on results of total knee arthroplasty: does a residual bony patellar thickness of <or=12 mm lead to poorer clinical outcome and increased complication rates?

With patellar thickness averaging 24.0 mm and 21.9 mm in Singapore men and women undergoing total knee arthroplasty, achievement of precut thickness is difficult if the recommended residual bony thickness of 15 mm is maintained. We retrospectively compared the clinical outcome of 56 patellae resurfaced <or=12 mm (mean residual thickness, 10.4 mm) with 56 patellae resurfaced >12 mm (mean residual thickness, 13.7 mm). Both groups were comparable in terms of demographic characteristics, presentation, precut patellar thickness, and operative details (P> .05). Knee scores (P= .627), extensor mechanism function (P= .625), and postoperative range of motion (P= .344) were comparable. Differences in the overall (P= .167) and patellar (P= .061) complication rates as determined by chi-square test on the SPSS 10.0 program were not significant, although there were 4 patella-related complications in group 2. Increased patella-related complications may be associated with an excessive patellar composite of the patellofemoral articulation. A residual patellar thickness of <12 mm did not appear to affect the clinical outcome in this series.