Matched pair analysis of the effect of longer hypothermic machine perfusion time on kidney transplant outcomes

BACKGROUND Hypothermic machine perfusion(HMP)has demonstrated benefits in terms of early kidney transplant function compared to static cold storage.While longer preservation times have shown detrimental effects,a previous paired study indicated that longer pump times(the second kidney in a pair)might lead to improved outcomes.AIM To revisit the prior paired study's somewhat unexpected results by reviewing our program's experience.METHODS A total of 61 pairs of transplant recipients who received kidneys from the same donor(2012-2021)were analyzed.Patients were divided into two groups depending on whether they were transplanted first(K1)or second(K2).Therefore,the patients in each pair had identical donor characteristics,except for time on the pump.Statistical analyses included Kaplan-Meyer analysis and paired tests,including McNemar's test,student's paired t-test,or Wilcoxon's test,as appropriate.RESULTS The two groups of recipients had similar demographics(age,body mass index,diabetes,time on dialysis,sensit-ization and retransplants).Cold ischemic times for K1 and K2 were 8.9(95%CI:7.9,9.8)and 14.7 hours(13.7,15.8)(P<0.0001),respectively.Overall,K2 had a higher rate of freedom from biopsy-proven acute rejection at 1 year(P=0.015).Delayed graft function was less common in K2,12/61(20%)than in K1,20/61(33%)(P=0.046).Finally,K2 showed a higher graft survival than K1(P=0.023).CONCLUSION Our results agree with a previous study that suggested possible advantages to longer pump times.Both studies should encourage further research into HMP's potential anti-inflammatory effect.

Urban-induced changes in tree leaf litter accelerate decomposition

Introduction:The role of urban areas in the global carbon cycle has so far not been studied conclusively.Locally,urbanization might affect decomposition within urban boundaries.So far,only few studies have examined the effects of the level of urbanization on decomposition.This study addresses the influence of the level of urbanization on decomposition processes.It explores whether potential influences are exerted through leaf litter quality alterations or through direct effects of decomposition site’s level of urbanization.Leaf litter of five different tree species was sampled at urban and periurban sites.Decomposition of this litter was analyzed in three different experiments:a climate chamber incubation,a reciprocal litterbag transplant at urban and periurban sites,and a common garden litterbag transplant.Results:Decomposition site’s level of urbanization did not show a significant effect.However,in all species,when significant differences were observed,leaf litter of urban origin decomposed significantly faster than leaf litter of periurban origin.This effect was observed in all three experiments.In the reciprocal litter transplant experiment,62%±3%mass loss in litter of urban origin compared to 53%±3%in litter of periurban origin was observed.The difference was not as pronounced in the other two experiments,with 94%±1%mass loss of litter originating in urban habitats compared to 92%±1%mass loss of litter originating in periurban habitats in the common garden experiment and 225±13 mg CO2 released from litter originating in urban habitats compared to 200±13 mg CO2 released from litter originating in periurban habitats in the climate chamber incubation.Conclusions:We conclude that the level of urbanization affects decomposition indirectly through alterations in leaf litter quality even over short urban to periurban distances.