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  • Author: G. C. Chung x
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Abstract

Quercus acutissima is a large deciduous tree of hillsides ranging from South Korea to Japan. It occurs in many plant communities, often as a pioneer species in monospecific stands which colonized gaps after gap formation. This study used multilocus allozyme genotypes mapped from two disturbed populations near farm houses in southern Korea to compare our results with previous studies conducted on undisturbed populations of trees in southern Korea. Coancestry measures (fij), RIPLEY’s L-statistics, and WRIGHT’s F-statistics were then calculated to examine the distribution of individuals and spatial genetic structure both within and between populations. RIPLEY’s Lstatistics indicated significant aggregation of individuals at interplant distances. A weak but significant positive fine-scale genetic structure at 10 m distance was detected in the two disturbed populations, which is consistent with the structure found in an inland, disturbed population in southern Korea. Estimates of near-distance fij in the two populations (0.020 and 0.036) were considerably lower than that expected for half-sibs (0.125) under random mating, suggesting secondary seed dispersal and substantial overlap of seed shadows. The levels of genetic diversity within the two disturbed populations of Q. acutissima were found to be comparable to the within-mean for populations of other oak species. Significant deficits of heterozygosity were detected in both populations, probably due to several parent-offspring and sib matings. Finally, a significant but low differentiation between the two disturbed populations of Q. acutissima was found, which is likely to be attributable to long-distance pollen movement by wind, which should enhance homogeneity of allele frequencies between adjacent local oak populations.

Abstract

Background and aims

There has been no comprehensive evaluation of the efficacy of transcutaneous electric nerve stimulation (TENS) for acute low back pain (LBP). The aim of this systematic review was to investigate the efficacy and safety of TENS for acute LBP.

Methods

We searched MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, CENTRAL, CINAHL and PsycINFO (inception to May 2018) for randomised placebo controlled trials. The primary outcome measure was pain relief in the immediate term (within 2-weeks of administration) assessed using the 100 mm visual analogue scale. A mean difference of at least 10 points on the 100-point pain scale was considered clinically significant. Methodological quality of the eligible studies was assessed using the PEDro scale and overall quality assessment rating was assessed using GRADE.

Results

Three placebo controlled studies (n = 192) were included. One low quality trial (n = 63) provides low quality evidence that ~30 min treatment with TENS in an emergency-care setting provides clinically worthwhile pain relief for moderate to severe acute LBP in the immediate term compared with sham TENS [Mean Difference (MD) – 28.0 (95% CI – 32.7, −23.3)]. Two other studies which administered a course of TENS over 4–5 weeks, in more usual settings provide inconclusive evidence; MD −2.75 (95% CI −11.63, 6.13). There was limited data on adverse events or long term follow-up.

Conclusions

The current evidence is insufficient to support or dismiss the use of TENS for acute LBP.

Implications

There is insufficient evidence to guide the use of TENS for acute LBP. There is low quality evidence of moderate improvements in pain with a short course of TENS (~30 min) during emergency transport of patients to the hospital. Future research should evaluate whether TENS has an opioid sparing role in the management of acute LBP.