When a new wastewater treatment plant is being designed by computer simulation, detailed data about organic fractions of influent wastewater (measured as chemical oxygen demand) are usually not available, but knowledge of the typical ranges of these fractions is indispensable. The influent chemical oxygen demand fractions can substantially influence the results of simulation-based design such as reactor volumes, solids residence time, effluent quality, oxygen demand, sludge production, etc. This article attempts to give an overview of wastewater organic fractions as modeling parameters and presents new chemical oxygen demand fractionation results from Hungary. According to the data from literature, the ratio of chemical oxygen demand components in raw wastewater is very different and the average composition is as follows: Inert particulate = 17.1 %, slowly biodegradable = 57.9 %, inert soluble = 7.8 % and readily biodegradable = 17.5 %. The Hungarian wastewater samples were analyzed according to STOWA (Dutch foundation for applied water research) protocol and the obtained results were not much different from those of literature ( inert particulate = 23.7 %, slowly biodegradable = 49.8 %, inert soluble = 4.6 % and readily biodegradable = 21.9 %), but some typical characteristics were observed.

The nitrergic system of the ileal myenteric plexus of four mammalian species was studied by means of NADPH diaphorase histochemistry which in aldehyde-fixed tissue stains only those cells that contain the constitutive, calcium-dependent nitrogen monoxide synthase isoenzyme. Since previous studies assumed minor species-specific anatomical variations, we sought similarities and differences in the nitrergic innervation pattern of the ileal musculature. In rat and guinea-pig, the ratio of nitrergic cells slightly exceeds 20%, in rabbit it is close to this number (16%), and it is lowest in cat (about 10%). The nitrergic neurons target the circular muscle layer in all investigated species where they participate in inhibitory motoric transmission. Apart from this, some elements of the sensory innervation of the circular musculature may derive from nitrergic neurons in rat and rabbit. The tertiary plexus (longitudinal muscles) is strongly supplied by NADPH diaphorase positive fibres in rat, moderately in guinea-pig and cat and not at all in rabbit. The rest of the nitrergic neurons may serve as inhibitory interneurons and control other (probably excitatory motor) neurons in the myenteric plexus. We conclude that the diverse physiological and pharmacological properties of the nitrergic system described in the small intestine in different species can be connected with the anatomical heterogeneity of its elements.

Enteric neurons have distinct neurochemical codings in each species. The basal tone of the gastrointestinal tract of the rabbit is low and produces neurally evoked pendular movements. Therefore, it might have an innervation pattern different from that of other laboratory animals. We have characterised myenteric neuron populations in rabbit ileum with neurochemical markers that are known to be associated with distinct cell types and/or fibre systems in the myenteric plexus. The density of nerve cells estimated with the NADH-diaphorase technique was about 2500 cells/cm2 and most, if not all, neurons contained microtubule-associated protein 2. NADPH-diaphorase-positive cells were numerous. One cell type was large and emitted long straight processes, whereas small cells bore thin filamentous dendrites. Neurons immunoreactive for 28-kDa calcium-binding protein were rare. Over 70% of them had very strongly labelled lamellar dendrites. Their axons were beaded and formed pericellular baskets around unstained somata. We found very few small tyrosine-hydroxylase-positive cells. The fibre network in the plexus was very strong; the axons formed many pericellular baskets. In double labelling studies, no co-localisation was revealed between the 28-kDa calcium-binding protein and NADPH-diaphorase. Some fibres containing 28-kDa calcium-binding protein formed only a few contacts on somata of NADPH-diaphorase-positive cells. None of the NADPH-diaphorase-labelled cells were found to be stained for tyrosine hydroxylase. Tyrosine-hydroxylase-positive fibres rarely made pericellular baskets on the surface of NADPH-diaphorase-positive somata. Strongly immunolabelled pericellular baskets were never observed around NADPH-diaphorase-positive cell somata. The results suggest that myenteric neurons in rabbit comprise distinct and characteristic neurochemical properties that are different from the rodent pattern. Therefore, the explanation of the motility pattern of rabbit intestine can be approached on a chemical neuroanatomical basis.

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Postmortem examination of the carcass of an approximately 10-year-old male Red-eared slider ( Trachemys scripta elegans ) was performed. The thyroid gland was enlarged, showed follicular structure, and shifted the base of the heart caudally. Histology revealed differently shaped and sized follicles in the thyroid gland. Based on the macroscopic appearance and histopathological changes of the thyroid gland, the pathological process was established as a papillary-cystic carcinoma. Neoplasia of the endocrine organs, especially of the thyroid gland, is rare in reptiles. The current case seems to be the first report of thyroid carcinoma in a Red-eared slider.