Local Translation in Primary Afferent Fibers Regulates Nociception

Recent studies have demonstrated the importance of local protein synthesis for neuronal plasticity. In particular, local mRNA translation through the mammalian target of rapamycin (mTOR) has been shown to play a key role in regulating dendrite excitability and modulating long-term synaptic plasticity associated with learning and memory. There is also increased evidence to suggest that intact adult mammalian axons have a functional requirement for local protein synthesis in vivo. Here we show that the translational machinery is present in some myelinated sensory fibers and that active mTOR-dependent pathways participate in maintaining the sensitivity of a subpopulation of fast-conducting nociceptors in vivo. Phosphorylated mTOR together with other downstream components of the translational machinery were localized to a subset of myelinated sensory fibers in rat cutaneous tissue. We then showed with electromyographic studies that the mTOR inhibitor rapamycin reduced the sensitivity of a population of myelinated nociceptors known to be important for the increased mechanical sensitivity that follows injury. Behavioural studies confirmed that local treatment with rapamycin significantly attenuated persistent pain that follows tissue injury, but not acute pain. Specifically, we found that rapamycin blunted the heightened response to mechanical stimulation that develops around a site of injury and reduced the long-term mechanical hypersensitivity that follows partial peripheral nerve damage - a widely used model of chronic pain. Our results show that the sensitivity of a subset of sensory fibers is maintained by ongoing mTOR-mediated local protein synthesis and uncover a novel target for the control of long-term pain states

Performance evaluation of coconut coir-pith in free water surface constructed wetlands.

A study on wastewater treatment with a submergent wetland system was conducted at the University of Peradeniya, Sri Lanka. The primary objective of this study was to identify the improved potential for wastewater purification due to surplus organic carbon on microbiological activities and adsorption by coconut (Cocos nucifera) coir-pith as an alternative substrate material. Three constructed wetland units (Lysimeters-L1, L2 and L3) were used in the study, each having the dimensions of 5 m, 1 m and 0.6 m in length, width and depth, respectively. The substrate layer of each Lysimeter was amended with coconut coir pith and river sand as 100% river sand (L1), 100% coir-pith (L3) and mixture of then in equal compositions (L2,v/v=1:1). Hydrilla verticillata was planted in each Lysimeter with equal plant density. Influent and effluent water samples were analyzed for pH, conductivity, total suspended solids (TSS), total dissolved solids (TDS), five-day biochemical oxygen demand (BOD5), total nitrogen (TN), ammonia nitrogen (NH4N), and nitrate nitrogen (NO3-N), phosphate phosphorous (PO4-P) and faecal coliform bacteria in weekly interval. A parallel study was conducted at the laboratory in order to examine the best ratio of sand: coir-pith for the growth of H. verticillata. The removal efficiency of NH4-N, PO4-P, BOD5, Total coliform and TSS in L2, were 93%, 74%, 54%, 93% and 62%, respectively, which were higher than the other two Lysimeters (L1 and L3). The results of effluent water quality analysis illustrated that the coir- pith is efficient in removing nutrients from wastewater over sand. The laboratory experiment revealed that the coir and river sand mixture in equal compositions provides the best substrate media for plant growth

Effect of submerged and floating plants on dissolved oxygen dynamics and nitrogen removal in constructed wetlands

Dissolved oxygen (DO) concentration affects the treatment processes in constructed wetlands. This study examined the dissolved oxygen dynamics and total nitrogen removal in constructed wetlands with submerged and floating plants. Four constructed wetland units each with the surface area of 3 x 1 m2 were constructed at University of Peradeniya. Two of those with the depths of 0.3 m (A) and 0.6 m (B) were planted separately with Hydrilla verticillata (submerged) and Lemna minor (floating), respectively. Other two (C and D) were constructed with two sections of 0.3 and 0.6 m depths and planted with H. verticillata and L. minor, respectively in each section. Secondary effluent from student hostel was fed with hydraulic retention time of 6 days. DO was measured at different depths of water, 0.0, 0.1, 0.2, 0.4 and 0.5 m from the water surface and along the longitudinal axis of the wetland at 6 hours interval. The total nitrogen was measured for water samples at inlet and outlets. The average dissolved oxygen concentrations of A and B were 17.7 and 0.4 mg L-1 respectively. Oxic condition was maintained in the submerged plant units. Anoxic condition resulted throughout the day in floating plant system. DO varied significantly with depths in oxic condition. DO dynamics in these wetlands can be explained by photosynthesis,respiration, deaeration and reaeration processes. The highest total nitrogen removal was achieved in unit D where combined anoxic and oxic conditions were maintained together H.verticillata and L. minor could effectively be used to maintain required dissolved oxygen in constructed wetlands for nitrate removal

Groundwater-Based Drinking Water Supply in Sri Lanka: Status and Perspectives

Drinking water is largely from groundwater in Sri Lanka, so quality management is of great concern. In order to achieve the 6th goal of United Nations (UN) Sustainable Development Goals (SDG), more efforts are being undertaken to secure drinking water quality. In this paper, the current status, challenges and opportunities of groundwater quality management and improvement in Sri Lanka were reviewed and discussed, based on previous studies. There are Ca-HCO3 type, Ca–Mg-HCO3 type and Na–SO4–Cl type groundwater dominated in the wet zone, intermediate and the dry zone, respectively. Elevated levels of hardness, fluoride, DOC, and alkalinity, and salinity are reported in the groundwater in the dry zone controlled by geology and arid climate. Although groundwater in some regions contain significant levels of nitrates, arsenic, cadmium and lead, the majority remain at acceptable levels for drinking purposes. As for treatment technologies, existing membrane-based drinking water treatment technologies such as RO (Reverse Osmosis) stations can produce safe and clean drinking water to the community, but this has still a limited coverage. To achieve a safe drinking water supply for all, especially in rural communities of Sri Lanka under the 6th goal of the UN SDG, more efforts in building up the infrastructure and man power are needed to monitor and assess groundwater quality regularly so as to develop management strategies. Research and development can be directed towards more cost-effective water treatment technologies. Protection of groundwater from being polluted, and educational and awareness programs for the stakeholders are also essential tasks in the future

Tropical application of floating treatment wetlands

The treatment efficiencies of floating treatment wetlands (FTWs) containing two types of macrophytes, Typha angustifolia and Canna iridiflora, were investigated in a pilot scale study in the tropical climate of Sri Lanka. In batch experiments, over 80 % of biological oxygen demand (BOD5) and ammonium (NH 4 +-N) removal was observed, while nitrate (NO 3 −-N) removal was over 40 %. Typha angustifolia showed slightly higher BOD5, NH 4 +-N and NO 3 −-N removal than Canna iridiflora. Because of higher and steady root growth, Typha angustifolia resulted in a better performance and has a greater potential to extract nutrients from wastewater and allow water-plant interactions than Canna iridiflora whose root mat is thick and compact. Similar to the batch system, the continuous flow systems performed better at most times with Typha angustifolia. FTWs with Typha angustifolia may be considered a possible solution for lake restoration where there are space and cost constraints

Comparison of the Photochemistry of 3‑Methyl-2-phenyl‑2<i>H</i>‑azirine and 2‑Methyl-3-phenyl‑2<i>H</i>‑azirine

Photolysis of 3-methyl-2-phenyl-2<i>H</i>-azirine (<b>1a</b>) in argon-saturated acetonitrile does not yield any new products, whereas photolysis in oxygen-saturated acetonitrile yields benzaldehyde (<b>2</b>) by interception of vinylnitrene <b>5</b> with oxygen. Similarly, photolysis of <b>1a</b> in the presence of bromoform allows the trapping of vinylnitrene <b>5</b>, leading to the formation of 1-bromo-1-phenylpropan-2-one (<b>4</b>). Laser flash photolysis of <b>1a</b> in argon-saturated acetonitrile (λ = 308 nm) results in a transient absorption with λ_max at ∼440 nm due to the formation of triplet vinylnitrene <b>5.</b> Likewise, irradiation of <b>1a</b> in cryogenic argon matrixes through a Pyrex filter results in the formation of ketene imine <b>11</b>, presumably through vinylnitrene <b>5</b>. In contrast, photolysis of 2-methyl-3-phenyl-2<i>H</i>-azirine (<b>1b</b>) in acetonitrile yields heterocycles <b>6</b> and <b>7</b>. Laser flash photolysis of <b>1b</b> in acetonitrile shows a transient absorption with a maximum at 320 nm due to the formation of ylide <b>8</b>, which has a lifetime on the order of several milliseconds. Similarly, photolysis of <b>1b</b> in cryogenic argon matrixes results in ylide <b>8</b>. Density functional theory calculations were performed to support the proposed mechanism for the photoreactivity of <b>1a</b> and <b>1b</b> and to aid in the characterization of the intermediates formed upon irradiation

Risk Assessment of Trace Element Contamination in Drinking Water and Agricultural Soil: A Study in Selected Chronic Kidney Disease of Unknown Etiology (CKDu) Endemic Areas in Sri Lanka

Unexplained or unclear etiology of chronic kidney disease (CKDu) has been reported in Sri Lanka’s North Central Province (NCP) for more than two decades. Meanwhile, high exposure to heavy metals/metalloids and their accumulation are recognized as the origin of many acute and chronic diseases in certain vulnerable human tissues including kidneys. This study evaluates the contamination status of heavy metals/metalloids of the drinking water and agricultural soil in two CKDu endemic areas compared with a reference area in Sri Lanka based on common indexes and attribute of the commonly used fertilizers evaluated to identify the basic sources of toxic metals in the agricultural soil. Mean concentrations of heavy metals/metalloids such as Mn, Co, As, Cd, Pb, Cu, Zn, and Fe in drinking water of CKDu endemic areas were far below Sri Lankan water quality standards (permissible limits). In addition, all sampling locations dropped below the medium range of the heavy metal pollution index of water (HPI 15–40). Geoaccumulation indexes (Igeo) of soil reveal that paddy soil in CKDu endemic areas is being moderately polluted with toxic metals/metalloids such as As, Pb, Cu, Ni, Cr, Zn, and Cd. On the other hand, the application of fertilizers, which contained a high dose of toxic metals, could be the driving force for agricultural soil pollution, and limitless application of low-quality fertilizer would lead to more soil contamination with heavy metals. Hence, hazardous metals can be incorporated into the food chains via contaminated paddy soil

Spatiotemporal Variation of Groundwater Quality in North Central Province, Sri Lanka

This study focused on fulfilling the demand for a comprehensive investigation of groundwater quality in the North Central Province (NCP) of Sri Lanka to achieve United Nations Sustainable Development Goal 6 (Ensure availability and sustainable management of water and sanitation for all). The NCP was selected as the study area due to its highest prevalence of chronic kidney disease with unknown etiology within Sri Lanka. Here, 334 shallow and deep groundwater samples were collected at the end of wet and dry seasons, respectively. Results revealed that elevated and unexpected levels of salinity, hardness, fluoride, nitrate, sulfate, and dissolved organic carbon and the alkaline nature of groundwater were the main issues, and the Ca-HCO3 type was dominant in the groundwater. Water quality index analyses showed that 8.9% and 13.8% of wells had poor quality undrinkable groundwater in wet and dry seasons, respectively. Only 7% of samples were susceptible to sodium and salinity hazards for irrigational use. Reverse osmosis technology with a softening and activated carbon pretreatment process was identified as the most suitable way to treat groundwater with high salinity for many regions of the NCP. The groundwater quality atlas for the NCP created by this study was very useful for making a master plan of safe drinking water supplies and developing and implementing cost-effective water purification technologies in the NCP