Morphology and proliferation kinetics of early tumor stages induced by dimethylnitrosamine in rat kidneys

A total of 49 dimethylnitrosamine (DMN)induced rat renal cell tumors were analyzed and classified cytomorphologically at an early stage of development. Of these, 17 were basophilictubular tumors, two of which showed a direct transition to proximal tubules of the P₃segment; 21 lesions were vacuolated and contained glycogen; these were defined cytomorphologically as a separate tumor type the histogenetic derivation of which from the collecting duct system was established by documentation of a direct transition. Morphological similarities point to the lipidstoring variant of the basophilic tumor, but a carcinoma of the ducts of Bellini is another possible human equivalent of this tumor type. Another seven lesions were clear and granular cell tumors. In two of these a direct transition from the collecting duct system was found, thus confirming that this only recently established origin of experimentally induced rat renal clear cell tumors also applies to lesions induced by DMN. The proliferation kinetics of DMNinduced lesions were studied in autoradiograms after pulselabeling with tritiated thymidine. The basal proliferation of these early tumor stages displayed a marked proliferative advantage over the normal parenchyma. The lesions were still subject to physiological growth stimulation as determined by³HTdRcontinuouslabeling with osmotic minipumps following unilateral nephrectomy. However, compared with normal kidney parenchyma, the³HTdRlabeling index of the lesions was even higher indicating a response modification during early neoplasia.     

Applied microfacies analysis: Provenance studies of Roman mosaic stones

Summary Provenance analysis of archaeological materials is an essential tool of archaeometry but has been rarely applied to antique mosaics. Many mosaics are made of carbonate mosaic stones (tesserae). Hence, microfacies analysis offers a great potential in differentiating these limestone tesserae and provenancing their local, regional, imported or recycled origins. The methods of microfacies analysis and their prospects for studying mosaics are demonstrated by case studies of Roman mosaics from southern Germany (Kraiburg, Bavaria). Austria (Hemmaberg near Globasnitz, southern Carinthia), Italy (Asolo north of Padova) and late Punic and Roman mosaics from Tunisia (Carthage and Hergla). Microfacies-based provenance analysis comprises six stages: 1) Macroscopic assessment and definition of rock colour groups of tesserae, 2) Sampling based on rock-colour categories, 3) Definition of microfacies types and attribution to standard microfacies types based on thin-section criteria, 4) Evaluation of the mosaic site with respect to geological and paleontological data followed by comparisons of the microfacies inventory of the region with microfacies types of the tesserae, 5) Assessment of carbonate tesserae to specific geological rock/time units followed by suggestions of provenance sites. 6) Critical evaluation of provenance assessment within the archaeological context. Principal limestone colours do not necessarily coincide with specific limestone types. Uniformly coloured tesserae can represent different limestone types from different sources (cf. Kraiburg, Hemmaberg). On the other hand, a specific limestone type may be characterized by different rock colours (cf. Carthage). Provenance assessment of mosaic stones results in relatively narrow (Hemmaberg, Asolo) or only broad (Carthage, Hergla) indications of sites characterized by exposures of carbonate rocks whose microfacies criteria, geological age and rock colour correspond to those of the carbonate tesserae. The case studies argue for local and/or imported (Kraiburg) as well as regional provenances of the mosaic material (Hemmaberg, Asolo; source area within a distance between 10 and about 40 km) and indicate that off-cuts of building stones exploited within a regional frame might possibly have been used (Carthage). Differences in the composition and diversity of carbonate rocks used for the fabrication of mosaics reflect time-dependent changes in major quarrying and potential source areas (Carthage). Further provenance research of mosaics should be based on statistically representative tesserae samples, supplemented by microfacies studies of the building material used at the mosaic sites as well as investigation of nonlithic tesserae and the mortar bedding of the mosaics. The isotopic composition of limestone and dolomite tesserae also assists in the critical evaluation of microfacies categorization.     

The development of the MCH system

Although a great deal is published on the MCH neurons, very few works were devoted to the study of their development. However, existing literature points out two important traits: first, these neurons differentiate a MCH phenotype very early in all species studied so far, which might suggest a role for the MCH peptide during development; second, in the rat, birth date greatly influence the phenotype of MCH neurons. At least two sub-populations were described on the basis of their chemical phenotype, projection pattern and birth date. The understanding of processes involved in the differentiation of these sub-populations may help understand the medio-lateral differentiation of the tuberal hypothalamus.     

Effect of colchicine on vasopressin and melanin-concentrating hormone neurons of rat hypothalamus: hybridocytochemistry and immunocytochemistry studies]

48 hrs. after an intra-cerebroventricular injection of colchicine (100 micrograms), antisera to three putative peptides included in the rat melanin-concentrating hormone (MCH) precursor, strongly stained the secretory granules accumulated in perikarya. In control rats, these antisera stained endoplasmic reticulum, Golgi apparatus, or neurosecretory granules respectively. Colchicine also induced a dramatic decrease in hybridization signal obtained with a probe complementary to the prepro-MCH-mRNA. Similarly, colchicine induced a strong increase in vasopressin immunoreactivity in neurons of the paraventricular and supraoptic nuclei, and a strong decrease of the vasopressin precursor mRNA. These results demonstrated that, in two peptidergic neuron populations of the rat hypothalamus, colchicine lowers mRNAs and impairs neuropeptide protein synthesis, consecutively to the accumulation of neurosecretory granules in perikarya.     

Biofuels – challenges & chances: How biofuel development can benefit from advanced process technology

The presented article highlights the process of biofuel production with a special focus on bioethanol. After a short introduction to the “problems” of biofuels – the “first generation” biofuels (in regards to their competition to feed and food production) and the “second generation” biofuels (in regards to the required more complex process technology) − the different steps in the process from natural resources towards the final product are presented and the underlying biotechnological challenges discussed: the pre-treatment of the natural resources followed by the biotechnological processes of hydrolysis and fermentation. Topics such as enzyme screening for efficient or even multi-step hydrolysis as well as microbial strain selection under process conditions and the optimization of the anaerobic fermentative conversion of the saccharides to bioethanol are discussed. Optimizing the production of bioethanol to be competitive with petrochemical fuels is the main challenge for the underlying process development.     

Influence of Age on the Rhythm in Basal and Forskolin-Stimulated Adenylate Cyclase Activity of the Rat Heart

-In male rats of three different ages (Group 1:7 weeks, Group II: 4 months, Group III: ≥ 10 months) basal and forskolin-stimulated adenylate cyclase (AC) activity were investigated in rat heart ventricles of animals sacrificed at 8 time points within 24 hours of a day. Maximum (Emax) and half-maximum (EC50) stimulation by a water-soluble forskolin (FOR; 0.1-100 μmol/l) were determined from dose-response curves. In young rats (Group I) significant rhythmicity was found in basal and FOR-stimulated AC activity, which was successively reduced or abolished with age by a reduction in amplitude. Mean basal AC activity increased about 2-fold from Group I to Group II/III. Mean maximum in for stimulation was about 12-fold in Group I and about 7-fold in Group II and ID. EC50-values displayed neither a significant rhythmicity in either group nor an age-dependency. It is concluded that the stimulatory potency of the catalytic subunit of the AC is reduced with age.     

Numerical flow simulation of pool-type fishways: new ways with well-known tools

Fish passage structures are built to restore the connectivity of rivers and allow the migration of aquatic fauna. In order to assess the functioning of a pool-type fishway, it is necessary, inter alia, to possess detailed knowledge of its flow structure, since observations of fishways, and in particular of the visible water surface, can only provide a rough idea of the actual conditions inside the pools. Numerical simulation has been used for many years to support engineering sciences. Especially, the modeling of flow processes in hydraulic machines can, on the one hand, help avoid major problems during the design stage of fish passage structures and, on the other, improve the structure’s hydraulic performance. To this end, two diploma theses within the framework of a research project of the local energy supplier Energie Baden-Württemberg AG (EnBW) employed modeling tools for 3D flow simulation, primarily for pool-slot fishways (PSF), and for traditional vertical slot fishways (VSF). Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries