Controls on the release of dissolved organic carbon and nitrogen from a deciduous forest floor investigated by manipulations of aboveground litter inputs and water flux

Although dissolved organic matter (DOM) released from the forest floor plays a crucial role in transporting carbon and major nutrients through the soil profile, its formation and responses to changing litter inputs are only partially understood. To gain insights into the controlling mechanisms of DOM release from the forest floor, we investigated responses of the concentrations and fluxes of dissolved organic carbon (DOC) and nitrogen (DON) in forest floor leachates to manipulations of throughfall (TF) flow and aboveground litter inputs (litter removal, litter addition, and glucose addition) at a hardwood stand in Bavaria, Germany. Over the two-year study period, litter manipulations resulted in significant changes in C and N stocks of the uppermost organic horizon (Oi). DOC and DON losses via forest floor leaching represented 8 and 11% of annual litterfall C and N inputs at the control, respectively. The exclusion of aboveground litter inputs caused a slight decrease in DOC release from the Oi horizon but no change in the overall leaching losses of DOC and DON in forest floor leachates. In contrast, the addition of litter or glucose increased the release of DOC and DON either from the Oi or from the lower horizons (Oe + Oa). Net releases of DOC from the Oe + Oa horizons over the entire manipulation period were not related to changes in microbial activity (measured as rates of basal and substrate-induced respiration) but to the original forest floor depths prior to manipulation, pointing to the flux control by the size of source pools rather than a straightforward relationship between microbial activity and DOM production. In response to doubled TF fluxes, net increases in DOM fluxes occurred in the lower forest floor, indicating the presence of substantial pools of potentially soluble organic matter in the Oe + Oa horizons. In contrast to the general assumption of DOM as a leaching product from recent litter, our results suggest that DOM in forest floor leachates is derived from both newly added litter and older organic horizons through complex interactions between microbial production and consumption and hydrologic transport.     

盆底肌肉康复训练联合盆底重建术对女性盆底功能障碍性疾病患者炎症反应及应激反应的影响

目的:观察盆底肌肉康复训练联合盆底重建术治疗女性盆底功能障碍性疾病(PFD)的疗效及对炎症反应及应激反应的影响。方法:选择2019年1月~2021年1月期间我院收治的PFD患者200例,按乱数表法分为对照组(100例)和研究组(100例)。对照组患者接受盆底重建术治疗,研究组患者接受盆底肌肉康复训练联合盆底重建术治疗。观察两组治疗后的疗效及术后并发症发生情况,对比两组相关量表评分、炎症反应及应激反应指标。结果:研究组治疗后盆底功能影响问卷简表(PFIQ-7)、盆底不适调查表简表(PFDI-20)评分低于对照组(P<0.05)。研究组治疗后盆底Ⅰ类肌纤维肌电压、盆底Ⅱ类肌纤维肌电压高于对照组(P<0.05)。研究组治疗后白介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、超敏C反应蛋白(hs-CRP)低于对照组(P<0.05)。研究组治疗后皮质醇(COR)、去甲肾上腺素(NE)、前列腺素E2(PGE2)低于对照组(P<0.05)。研究组术后并发症发生率低于对照组(P<0.05)。结论:盆底肌肉康复训练联合盆底重建术治疗PFD,可促进盆底功能恢复,减轻机体炎症反应及应激反应,降低术后并发症发生率。     

Directed Dopaminergic Neuron Differentiation from Human Pluripotent Stem Cells

Dopaminergic (DA) neurons in the substantia nigra pars compacta (also known as A9 DA neurons) are the specific cell type that is lost in Parkinson’s disease (PD). There is great interest in deriving A9 DA neurons from human pluripotent stem cells (hPSCs) for regenerative cell replacement therapy for PD. During neural development, A9 DA neurons originate from the floor plate (FP) precursors located at the ventral midline of the central nervous system. Here, we optimized the culture conditions for the stepwise differentiation of hPSCs to A9 DA neurons, which mimics embryonic DA neuron development. In our protocol, we first describe the efficient generation of FP precursor cells from hPSCs using a small molecule method, and then convert the FP cells to A9 DA neurons, which could be maintained in vitro for several months. This efficient, repeatable and controllable protocol works well in human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) from normal persons and PD patients, in which one could derive A9 DA neurons to perform in vitro disease modeling and drug screening and in vivo cell transplantation therapy for PD.     

三维超声技术对于评估压力性尿失禁女性患者盆底肌肉收缩及膀胱颈活动度的价值研究

摘要 目的：探讨三维超声技术对于评估压力性尿失禁（SUI）女性患者盆底肌肉收缩及膀胱颈活动度的价值。方法：选取2020年1月至2021年8月本院的收治的因产后SUI的女性患者60例作为观察组,另选择同期产后正常的女性受试者60例作为对照组,所有受试者均行经会阴三维超声检查。比较两组之间盆底肌肉收缩及膀胱颈活动度等相关指标的差异。结果：在静息状态和最大Valsalva状态下,观察组中盆膈裂孔前后径、左右径、肛提肌裂孔面积以及膀胱颈后角均显著大于对照组（P<0.05）,观察组尿道长度显著低于对照组（P<0.05）;而仅在最大Valsalva状态下,观察组的膀胱颈位置显著低于对照组（P<0.05）;此外观察组膀胱漏斗化所占比例显著高于对照组（P<0.05）。结论：三维超声技术可以清晰直观地显示女性盆底组织结构和功能,对于评估SUI女性患者盆底肌肉收缩及膀胱颈活动度具有一定的诊断价值,并为临床提供真实客观的影像学证据。     

Isolation of keratinophilic fungi from floor dust in Arab elementary and preparatory schools in the West Bank of Jordan

Floor dust collected from classrooms of thirty three elementary schools (16 for girls, and 17 for boys) (children aged 6–11), and twenty four preparatory schools (13 for girls, and 11 for boys) (children aged 12–14) was studied for the occurrence of keratinophilic fungi with respect to human presence and age of children. Tichophyton mentagrophytes was present in 15.4% of the preparatory schools for girls, in 12.5% of elementary schools for girls, and in 11.8% of elementary schools for boys. It was not found in preparatory schools for boys. Microsporum gypseum was found in preparatory schools for girls only (7.7%). Trichophyton terrestre was also only isolated from elementary schools for boys (5.9%). Chrysosporium species were present in 30.3% of all elementary schools (10 schools/33), and in 20.8% of all preparatory schools (5 schools/24). Geotrichum candidum was the most frequent and predominant keratinophilic species in all schools. Pathogenic and potentially pathogenic keratinophilic fungi comprised a large proportion of all fungal isolates recovered from all schools ; they comprised 87.2 %–89.5 % of all fungal isolates in the elementary schools, and 90.4%–93.5% of all fungal isolates in preparatory schools.     

大鼠产后压力性尿失禁模型的建立与探讨

目的 应用在大鼠阴道内放置水囊模拟产伤破坏大鼠盆底组织的方法建立产后压力性尿失禁( postpartum urinary incontinence,PPUI)的动物模型,并对此模型进行初步研究.方法 对40只SD雌性大鼠进行持续8h水囊扩张阴道,随机选取PPUI模型建立成功的大鼠25只并与对照同龄大鼠5只分别于模型建立后1d、1周、2周、4周、8周进行喷嚏实验以及尿动力学测定,张力换能器测定盆底肌肉肌力强度,采用JSCC标准化对应法测定血清生化指标(LDH,CK),应用逆转录-聚合酶链反应检测caspase-3基因表达,胆碱酯酶染色法计数盆底肌肉乙酰胆碱受体数量.结果 建模后喷嚏实验阳性率明显升高,阳性率为72.5％(29/40),尿动力学检测最大膀胱容量及漏尿点压力均降低,盆底肌肉收缩力下降,血清LDH、CK水平上升,盆底耻尾肌乙酰胆碱受体数量减少,与对照组比较均差异有显著性(P＜0.05).耻尾肌组织中caspase-3基因表达在建立模型当日达到最高,与对照组差异有显著性(P＜0.05),之后逐渐下降.结论 大鼠阴道内放置8h水囊的方法可以成功模拟产后压力性尿失禁,引起尿动力以及盆底肌肉的相关损伤指标发生改变.     

Anatomical evidence for glutamatergic transmission in primary sensory neurons and onto postganglionic neurons controlling penile erection in rats: an ultrastructural study with neuronal tracing and immunocytochemistry

In male rats, the dorsal penile nerve (DPN) conveys sensory information from the genitals to the lumbosacral spinal segments of the spinal cord. DPN is the afferent limb of a reflex loop that supports reflexive erections, and that includes a network of spinal interneurons and autonomic and somatic motoneurons to the penis and perineal striated muscles. Autonomic efferent pathways to the penis relay in the major pelvic ganglion (MPG). Glutamate (Glu) is a likely candidate as a neurotransmitter of reflexive erections. Both AMPA and NMDA glutamatergic receptor subunits are present in the lumbosacral spinal cord, and AMPA and NMDA receptor antagonists block reflexive erections. In the present study, we used tract-tracing experiments combined with immunohistochemical and immunocytochemical techniques to ascertain the presence of Glu at two different levels of the network controlling reflexive erections. DPN afferents were localized in the dorsal horn of the lumbosacral cord and displayed the characteristics of either C-fibers or Aδ fibers. DPN terminals (some of them glutamatergic) were mainly distributed in the medial edge of the dorsal horn in the L6 spinal segment. GluR1 subunits were present in some DPN afferents, suggesting that they could be autoreceptors. DPN fibers were also present in the MPG, as were Glu terminals and GluR4 subunits. The results reveal the presence of Glu in DPN fibers and terminals and suggest that both the spinal cord and the MPG use glutamatergic transmission to control reflexive erections. This work was supported by grant no. 5R01MH059811–03 from the NIH and by an institutional grant from the Institut National de la Recherche Agronomique.     

Dynamic Material Flow Analysis for Strategic Construction and Demolition Waste Management in Beijing

Of all materials extracted from the earth's crust, the construction sector uses 50%, producing huge amounts of construction and demolition waste (CDW). In Beijing, presently 35 million metric tons per year (megatonnes/year [Mt/yr]) of CDW are generated. This amount is expected to grow significantly when the first round of mass buildings erected in the 1990s starts to be demolished. In this study, a dynamic material flow analysis (MFA) is conducted for Beijing's urban housing system, with the demand for the stock of housing floor area taken as the driver. The subsequent effects on construction and demolition flows of housing floor area and the concurrent consumption and waste streams of concrete are investigated for Beijing from 1949 and projected through 2050. The per capita floor area (PCFA) is a key factor shaping the material stock of housing. Observations in Beijing, the Netherlands, and Norway indicate that PCFA has a strong correlation with the local gross domestic product (GDP). The lifetime of dwellings is one of the most important variables influencing future CDW generation. Three scenarios, representing the current trend extension, high GDP growth, and lengthening the lifetime of dwellings, are analyzed. The simulation results show that CDW will rise, unavoidably. A higher growth rate of GDP and the consequent PCFA will worsen the situation in the distant future. Prolonging the lifetime of dwellings can postpone the arrival of the peak CDW. From a systematic view, recycling is highly recommended for long‐term sustainable CDW management.     

Increased 5-HT3-mediated signalling in pelvic afferent neurons from mice deficient in P2X2 and/or P2X3 receptor subunits

Extracellular ATP and 5-hydroxytryptamine (5-HT) are both involved in visceral sensory pathways by interacting with P2X and 5-HT₃ receptors, respectively. We have investigated the changes in P2X and 5-HT₃-mediated signalling in pelvic afferent neurons in mice deficient in P2X₂ and/or P2X₃ subunits by whole-cell recording of L₆–S₂ dorsal root ganglion (DRG) neurons and by multi-unit recording of pelvic afferents of the colorectum. In wildtype DRG neurons, ATP evoked transient, sustained or mixed (biphasic) inward currents. Transient currents were absent in P2X₃ ^−/− neurons, whereas sustained currents were absent in P2X₂ ^−/− DRG neurons. Neither transient nor sustained currents were observed following application of ATP or α,β-methylene ATP (α,β-meATP) in P2X₂/P2X₃ ^Dbl−/− DRG neurons. 5-HT was found to induce a fast inward current in 63% of DRG neurons from wildtype mice, which was blocked by tropisetron, a 5-HT₃ receptor antagonist. The percentage of DRG neurons responding to 5-HT was significantly increased in P2X ₂ ^−/−, P2X₃ ^−/− and P2X₂/P2X₃ ^Dbl−/− mice, and the amplitude of 5-HT response was significantly increased in P2X₂/P2X₃ ^Dbl−/− mice. The pelvic afferent response to colorectal distension was attenuated in P2X₂/P2X₃ ^Dbl−/− mice, but the response to serosal application of 5-HT was enhanced. Furthermore, tropisetron resulted in a greater reduction in pelvic afferent responses to colorectal distension in the P2X₂/P2X₃ ^Dbl−/− preparations. These data suggest that P2X receptors containing the P2X₂ and/or P2X₃ subunits mediate purinergic activation of colorectal afferents and that 5-HT signalling in pelvic afferent neurons is up-regulated in mice lacking P2X₂ or P2X₃ receptor genes. This effect is more pronounced when both subunits are absent.     

Fire Severity and Long-term Ecosystem Biomass Dynamics in Coniferous Boreal Forests of Eastern Canada

The objective of this study was to characterize the effects of soil burn severity and initial tree composition on long-term forest floor dynamics and ecosystem biomass partitioning within the Picea mariana [Mill.] BSP-feathermoss bioclimatic domain of northwestern Quebec. Changes in forest floor organic matter and ecosystem biomass partitioning were evaluated along a 2,355-year chronosequence of extant stands. Dendroecological and paleoecological methods were used to determine the time since the last fire, the soil burn severity of the last fire (high vs. low severity), and the post-fire tree composition of each stand (P. mariana vs. Pinus banksiana Lamb). In this paper, soil burn severity refers to the thickness of the organic matter layer accumulated above the mineral soil that was not burned by the last fire. In stands originating from high severity fires, the post-fire dominance by Pinus banksiana or P. mariana had little effect on the change in forest floor thickness and tree biomass. In contrast, stands established after low severity fires accumulated during the first century after fire 73% thicker forest floors and produced 50% less tree biomass than stands established after high severity fires. Standing tree biomass increased until approximately 100 years after high severity fires, and then decreased at a logarithmic rate in the millennial absence of fire. Forest floor thickness also showed a rapid initial accumulation rate, and continued to increase in the millennial absence of fire at a much slower rate. However, because forest floor density increased through time, the overall rate of increase in forest floor biomass (58 g m⁻² y⁻¹) remained constant for numerous centuries after fire (700 years). Although young stands (< 200 years) have more than 60% of ecosystem biomass locked-up in living biomass, older stands (> 200 years) sequester the majority (> 80%) of it in their forest floor. The results from this study illustrate that, under similar edaphic conditions, a single gradient related to time since disturbance is insufficient to account for the full spectrum of ecosystem biomass dynamics occurring in eastern boreal forests and highlights the importance of considering soil burn severity. Although fire severity induces diverging ecosystem biomass dynamics in the short term, the extended absence of fire brings about a convergence in terms of ecosystem biomass accumulation and partitioning.