Uptake and cellular effects of PE, PP, PET and PVC microplastic particles.

Humans are exposed to small plastic particles through contaminated food. Such contaminations usually comprise different particulate plastic materials differing in size, shape and surface. Up to now, data on intestinal uptake and adverse effects resulting from plastic particles other than polystyrene are scarce. In order to fill these knowledge gaps, this study aims to elucidate the gastrointestinal uptake and effects of microplastic particles of the materials polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) using human in vitro systems. The human intestinal epithelial cell line Caco-2 was used to study particle uptake in vitro, including an inverse culture system for buoyant particle species like PE and PP. Cytotoxicity was investigated using the human cell lines Caco-2, HepG2 and HepaRG in order to detect a possible impact on the first organs which come into contact with ingested particles: the intestine and the liver. The results of the study demonstrate that especially 1-4 µm PE microparticles were transported to a small but significant extent through the intestinal epithelium in vitro, to a substantially higher amount than PS particles of the same size. The present results suggest that intestinal exposure to plastic microparticles is material- and size-dependent. Only excessively high concentrations far beyond realistic dietary exposure of consumers induce cytotoxic effects.

Analytical and preparative separation and isolation of functionalized fullerenes by conventional HPLC stationary phases: method development and column screening.

Isolation and purification of functionalized fullerenes from often complex reaction mixtures is challenging due to the hydrophobic nature and low solubility in regular organic solvents. We have developed an HPLC method that efficiently, employing regular reversed phase stationary phases, separates not only C60 from C70 in a model mixture, but also C60 monoadducts from polyadducts and unreacted C60 from fulleropyrrolidine and hydroarylation example reaction mixtures. Six HPLC columns with regular reversed phase stationary phases were evaluated using varying proportions of acetonitrile in toluene as eluent; with C18 and C12 stationary phases with high surface area (450-400 m2 g-1) being the most efficient regarding separation efficiency and analysis time for all mixtures. The analytical method is effectively transferrable to a preparative scale to isolate the monoaddition products from complex fullerene reaction mixtures.

Impact of artificial digestion on the sizes and shapes of microplastic particles.

Current analyses show a widespread occurrence of microplastic particles in food products and raise the question of potential risks to human health. Plastic particles are widely considered to be inert due to their low chemical reactivity and therefore supposed to pose, if at all only minor hazards. However, variable physicochemical conditions during the passage of the gastrointestinal tract gain strong importance, as they may affect particle characteristics. This study aims to analyze the impact of the gastrointestinal passage on the physicochemical particle characteristics of the five most produced and thus environmentally relevant plastic materials polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate and polystyrene. Scanning electron microscopy (SEM) and subsequent image analysis were employed to characterize microplastic particles. Our results demonstrate a high resistance of all plastic particles to the artificial digestive juices. The present results underline that the main stages of the human gastrointestinal tract do not decompose the particles. This allows a direct correlation between the physicochemical particle characteristics before and after digestion. Special attention must be paid to the adsorption of organic compounds like proteins, mucins and lipids on plastic particles since it could lead to misinterpretations of particle sizes and shapes.

An inverse cell culture model for floating plastic particles.

Plastic waste has become a major environmental problem. An increasing number of studies investigate microplastic particles with regard to their uptake and effects in cell culture systems. Individual plastic materials vary in their molecular structure, composition, size distribution, material density, and may also differ with respect to their toxicological effects. Plastic particles with lower densities than the cell culture medium, for example polyethylene (PE), pose a particular problem for in vitro assays as they float up during the incubation and thus do not contact the cells located on the bottom of the culture dish. We thus developed a practical and easy-to-use in vitro inverse cell culture model for investigating cellular effects of floating plastic particles. Cytotoxicity tests with floating PE particles were performed to demonstrate the utility of the inverted cell model. PE particles incubated in overhead culture were cytotoxic to HepG2 cells, while under the same cultivation conditions, except for inversion, no cytotoxicity occurred. These positive results demonstrate that inverted cell culture was required to detect the effects of PE particles and underlines the necessity to adapt cell culture conditions to the physicochemical properties of particles in order to obtain a more accurate estimate of the effects of floating particles on cells.

Ultrasonographic Appearances of Cervical Lymph Nodes in Healthy Turkish Adults Subpopulation: Preliminary Study.

OBJECTIVES: The aim of the study was to assess whether there was any relation between age, gender and body mass index (BMI) and nodal forms and vascular type in healthy Turkish adults. STUDY DESIGN: Three neck areas in 25 wholesome patients who were aged from 21 to 58 years, were assessed by gray-scale and color doppler ultrasonography. Ultrasonographic examinations were performed using an ALOKA Prosound Alpha 6 (Hitachi Aloka Medical Systems, Tokyo, Japan) and the images were obtained with a 7.2 MHz linear array transducer. Hajek's categorization of cervical lymph nodes for sonographic analysis was used. The ultrasonographic characteristics like size, shape, short axis/long axis ratio (S/L), hilum were evaluated. Ultrasonographic examinations of upper cervical, submandibular and submental lymph nodes were carried out and recorded. RESULTS: The mean age of patients was 31.84±12.80 years. The ratios of lymph nodes with avascular pattern were 96% for the upper cervical lymph area, 92% for the submandibular area and 96% for the submental area. The lowest and highest ratios of short to long axis diameter (S/L) were calculated as 0.18 and 0.66 in all areas. Most normal nodes in the study were oval with an S/L ratio of less than 0.5. CONCLUSION: Normal cervical lymph nodes are oval, with an unsharp border and an echogenic hilum but no relation between the age, gender and BMI. Also ultrasonography is an applicable imaging modality for the examination of cervical lymph nodes. However, the deficiency in the number of patients might not allow to generalise our findings to the general populations.

Cone beam computed tomographic evaluation of styloid process: A retrospective study of 1000 patients.

OBJECTIVE: The styloid process (SP) is a bony projection, located just anterior to the stylomastoid foramen, the normal length of which is approximately 20-30 mm. The length of SP when exceeds 30 mm it is said to "elongated." The purpose of this retrospective study was to assess the prevalence of elongated SP (ESP) by cone beam computed tomography (CBCT) examination in Turkish subpopulation and its relation to gender and age. MATERIALS AND METHODS: This study analyzed CBCT of 1000 patients who were randomly selected to participate and were aged from 14 to 78 years. Any radiograph with questionable SP was excluded from the study. The apparent length and thickness of the SP were measured by two dental and maxillofacial radiologists. The ESP was classified with radiographic appearance-based morphology of elongation. The data were analyzed with the IBM SPSS Statistics 20.0. RESULTS: The mean age of patients was 42.49 ± 14.83 years. The length of SP was measured over 30 mm in 151 patients (15.1%). A total of 151 CBCT showed ESP, of which 87 (57.6%) were noticed in males and 64 (42.4%) in female patients. The length of right-sided SP ranged from 30.05 to 85.49 mm and left-sided SP from 30.14 to 83.72 mm. CONCLUSION: CBCT is a valuable diagnostic imaging tool which makes accurate length measurements. It is important for the clinicians to be aware of natural variations of the SP whose clinical importance is not well understood.