As a consequence of the global ubiquity of plastic pollution, scientists, decision‐makers, and the public often ask whether macroplastics (>5 mm) and microplastics (<5 mm) have a realized ecological threat. In 2016, we conducted a systematic review of the literature and made a call for further research testing hypotheses about ecological effects. In the subsequent years, the amount of relevant research has risen tremendously. Here, we reassess the literature to determine the current weight of evidence about the effects of plastic pollution across all levels of biological organization. Our data spans marine, freshwater, and terrestrial environments. We extracted data from 139 lab and field studies testing 577 independent effects across a variety of taxa and with various types, sizes, and shapes of plastic. Overall, 59% of the tested effects were detected. Of these, 58% were due to microplastics and 42% were due to macroplastics. Of the effects that were not detected, 94% were from microplastics and 6% were from macroplastics. We found evidence that whether or not an effect is detected, as well as the severity and direction of the effect, is driven by dose, particle shape, polymer type, and particle size. Based on our analyses, there is no doubt that macroplastics are causing ecological effects, however, the effects of microplastics are much more complex. We also assessed the environmental relevancy of experimental studies by comparing the doses used in each exposure to the concentrations and sizes of microplastics found in the environment. We determined that only 17% of the concentrations used in experimental studies have been found in nature, and that 80% of particle sizes used in experiments fall below the size range of the majority of environmental sampling. Based on our systematic review and meta‐analysis, we make a call for future work that recognizes the complexity of microplastics and designs tests to better understand how different types, sizes, shapes, doses, and exposure durations affect wildlife. We also call for more ecologically and environmentally relevant studies, particularly in freshwater and terrestrial environments.
The present study investigated the existence of a relationship between Extracellular Enzyme Activity (EEA) of glucosidase and alkaline phosphatase and pollution by carbon and phosphorous at five stations on the Chinchiná River in the water main and the biofilm (epilithon/episammon) during three seasons (rainy, dry and transition). Specific substrates were used as sources: 4-Nitrophenyl-β-D-Glucopyranose as a carbon source and 4-Nitrophenylphosphate as a phosphorus source. The product of catalysis (4-nitrophenol) was detected spectrophotometrically at an emission of 405nm. The ratio of EEA to temperature and pH was also determined. All sampling stations displayed EEA; however, reported results were higher for phosphatase, specifically in the biofilm, in all seasons; this indicates that certain associated microorganisms in this matrix can act as a multi-enzyme system which allows for easy disposal of substrate and the presence of catalysis. A relationship could not be established to describe EEA in dissolved organic carbon (DOC), because EEA was not detected in water samples from all stations during the three sampling seasons (E1, E2 and E4), because the bioavailability of nutrients attributed to the discharge of domestic wastewater from the municipalities of Manizales and Villamaría. Additionally, the complexity of the links between the monosaccharides which comprise polymers affects the degradation rate of the material, since the enzymes produced by microorganisms in the water prefer to hydrolyze specific regions (regiospecific) of the molecule. Enzyme activity can be affected by the structure of the polysaccharide being degraded. Therefore, some trends, such as those which occur at lower DOC concentrations, exhibit greater EEA. During the dry season, a correlation was found between phosphatase and glucosidase EEA in samples of water related to the concentration of orthophosphates and filtered COD, respectively. This indicates that higher concentrations of orthophosphates result in higher EEA of the phosphatase, and that higher concentrations of CODs result in higher EEA of the glucosidase.
1.1. Introduction: Malignant Peripheral Nerve Sheath Tumors (MPNST) are rare and aggressive sarcomata’s tumors with an overall incidence of 0.001% [1] derived from Schwann cells or pluripotent cells of the neural crest [2-8]. MPNSTs are typically seen in patients aged 20-50 years, and usually in the setting of Neuro Fibromatosis Type 1(NF1) and following radiation therapy [8]. The most common sites are the trunk and extremities followed by the head and neck area [7, 8]. 1.2. Presentation of The Case: This case reports a 50-year-old man with a previous diagnosis five years ago of a Plexiform Neuro Fibroma (NF) in the posterior distal third of the right leg and ankle. In this case, we review the most important pathological findings and review the literature by reason of the rarity of this lesion. Actually, the patient is currently on regular follow-up and ongoing disease extension study in another hospital for surgical or oncologic treatment decision. 1.3. Discussion: The majority of MPNSTs are derived from neuro fibroma or they arise de novo in normal peripheral nerves [9, 2]. It is important to focus on the correct diagnosis and especially in the differential diagnosis with other tumors that can mimic MPNST, which include desmoplastic and metastatic melanomas, as well as synovial sarcoma and fibrosarcomatous dermatofibrosarcoma protuberans [10, 11]. In this article, we discuss a case of a patient with a previous diagnosis of plexiform neuro fibroma that some years later presents as an enlarging painful mass that extends to the ankle, a rare location for these tumors as described on the pathological findings and review in the literature. 1.4. Conclusion: MPNSTs are very rare sheath tumors that must be suspected in patients with NF1, especially with a previous diagnosis or another benign lesion, because this is very aggressive and rapidly growing disease.
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