Einfluß von alimentärem Zn-Mangel auf die Stickstoffelimination und Enzymaktivitäten des Harnstoffzyklus

Influence of alimentary zinc deficiency on nitrogen elimination and activities of urea cycle enzymes
This study was conducted to investigate whether the hyperammonaemia shown in earlier zinc-deficiency experiments was the result of disturbed enzyme activities of the urea cycle. For this study 36 male Sprague-Dawley rats with an average body weight of 85 g were divided into three experimental groups of 12 animals each. Group 1 received the semisynthetic zinc-deficient diet (AIN-93G; 1.2 mg Zn/kg DM) ad libitum over 33 experimental days. Group 2 received the zinc-sulphate-supplemented control diet (60 mg Zn/kg DM) ad libitum and group 3 received the same diet matched to the feed intake of the zinc-deficient rats. Alimentary zinc deficiency reduced the zinc concentration and the activity of the alkaline phosphatase in serum by 75 and 67%, respectively. The activity of the glutamate dehydrogenase and the concentrations of ammonia and urea in the serum of the zinc-deficient rats showed no significant differences compared with pair-fed control rats. On the other hand the hepatic activity of the mitochondrial localized glutamate dehydrogenase of the zinc-deficient rats was significantly increased and the carbamoylphosphate synthetase and ornithine carbamoyltransferase were reduced about half in comparison with both control groups. The activities of the cytosolic liver enzymes such as argininosuccinate synthetase, argininosuccinase and arginase were again significantly increased in zinc-deficient rats compared with both control groups. The increased hepatic activity of the glutamate dehydrogenase possibly led to an enhanced NH₃ elimination in addition to urea synthesis. The typical reduction of feed intake in consequence of zinc deficiency is therefore not the cause of hyperammonaemia due to disturbed urea synthesis, as has been hypothesized in earlier studies.     

A grading system for lymphocytic plasmacytic colitis in dogs

Colonic mucosal samples were obtained every 4 weeks for 13 months from 6 clinically normal dogs and from 47 dogs with a clinical diagnosis of chronic inflammatory bowel disease. All samples were graded on a scale of 0-5, based upon the quantity of lymphocytes and plasma cells in the lamina propria, epithelial changes, and the presence of ulcers and erosions. A grade of less than or equal to 2.0 was considered normal and was assigned to 77 of 78 samples from clinically normal dogs and 28 of 48 samples from dogs with diarrhea. A transient increase in cellularity was noted in 1 sample from 1 control dog. Nineteen dogs with clinical disease had obvious histologic abnormalities. The grading scheme described provides the pathologist with an objective criterion for the microscopic evaluation of colonic mucosal samples obtained by endoscopic techniques and offers clinicians a method of assessing the dog's progress and response to therapy.     

Effect of non-linear adsorption on the transport behaviour of Brilliant Blue in a field soil

The food dye Brilliant Blue FCF (Color Index 42090) is often used as dye tracer in field studies for visualizing the flow pathways of water in soils. Batch studies confirmed findings of other researchers that non‐linear sorption is important for Brilliant Blue, especially at small concentrations (< 10 g l^?1 for our soil), and that retardation increases with decreasing concentrations as well as with increasing ionic strength of solutions. Therefore, it is not obvious if it can be used as an indicator for water flow paths as is often done. In this study, we compared the mobility of Brilliant Blue in a field soil (gleyic Luvisol) with that of bromide. Brilliant Blue and potassium bromide were simultaneously applied as a 6‐mm pulse on a small plot in the field, and the tracers were displaced with 89 mm of tracer‐free water using a constant intensity of 3.9 ± 0.2 mm hour^?1. Both tracer concentrations were determined on 144 soil cores taken from a 1 m × 1 m vertical soil profile. The transport behaviour differed in both (i) mean displacement and (ii) spatial concentration pattern. We found the retardation of Brilliant Blue could not be neglected and, in contrast to the bromide pattern, a pulse splitting was observed at the plough pan. Numerical simulations with a particle tracking code revealed that the one‐dimensional concentration profile of bromide was represented fairly well by the model, but the prediction of the double peak in the Brilliant Blue concentration profile failed. With additional assumptions, there were indications that Brilliant Blue does not follow the same flow paths as bromide. However, the question of Brilliant Blue taking the same flow pathways as bromide cannot be adequately answered by comparing both concentration distributions, because we look at two different transport distances due to the retardation of Brilliant Blue. It became obvious, however, that Brilliant Blue is not a suitable compound for tracing the travel time of water itself.     

Ectopic expression of the serotonin 1c receptor and the triggering of malignant transformation

Neurotransmitter receptors are usually restricted to neuronal cells, but the signaling pathways activated by these receptors are widely distributed in both neural and non-neural cells. The functional consequences of activating a brain-specific neurotransmitter receptor, the serotonin 5HT1c receptor, in the unnatural environment of a fibroblast were examined. Introduction of functional 5HT1c receptors into NIH 3T3 cells results, at high frequency, in the generation of transformed foci. Moreover, the generation and maintenance of transformed foci requires continued activation of the serotonin receptor. In addition, the injection of cells derived from transformed foci into nude mice results in the generation of tumors. The serotonin 5HT1c receptor therefore functions as a protooncogene when expressed in NIH 3T3 fibroblasts.     

Ras p21 as a potential mediator of insulin action in Xenopus oocytes

The oncogene protein product (p21) of the ras gene has been implicated in mediating the effects of a variety of growth factors and hormones. Microinjection of monoclonal antibody 6B7, which is directed against a synthetic peptide corresponding to a highly conserved region of p21 (amino acids 29 to 44) required for p21 function, specifically inhibited Xenopus oocyte maturation induced by incubation with insulin. The inhibition was dose-dependent and specific since (i) the same antibody had no effect on progesterone-induced maturation, (ii) immunoprecipitation and Western blotting indicated that the antibody recognized a single protein of molecular weight 21,000 in oocyte extracts, and (iii) inhibition was not observed with identical concentrations of normal immunoglobulin. Thus, p21 appears to be involved in mediating insulin-induced maturation of Xenopus oocytes. Furthermore, the mechanism may involve phosphorylation of p21, as p21 was found to be a substrate of the insulin receptor kinase.     

( 3 H)lysergic acid diethylamide: cellular autoradiographic localization in rat brain

Intravenous administration of [(3)H]lysergic acid diethylamide(LSD) to rats resulted in accumulation of the drug in the brain within 15 minutes. Autoradiographic methods were used to differentiate free and bound [(3)H]LSD in brain tissue.Free [(3)H]LSD was generally distributed in the pituitary and pineal glands, cerebellum, hippocampus,and choroid plexus.Bound [(3)H]LSD was localized in neurons of the cortex, caudate nucleus, midbrain, and medulla,as well as in choroid plexus epithelium.     

Cryopreservation, culture, and transplantation of human fetal mesencephalic tissue into monkeys

Studies in animals suggest that fetal neural grafts might restore lost neurological function in Parkinson's disease. In monkeys, such grafts survive for many months and reverse signs of parkinsonism, without attendant graft rejection. The successful and reliable application of a similar transplantation procedure to human patients, however, will require neural tissue obtained from human fetal cadavers, with demonstrated cellular identity, viability, and biological safety. In this report, human fetal neural tissue was successfully grafted into the brains of monkeys. Neural tissue was collected from human fetal cadavers after 9 to 12 weeks of gestation and cryopreserved in liquid nitrogen. Viability after up to 2 months of storage was demonstrated by cell culture and by transplantation into monkeys. Cryopreservation and storage of human fetal neural tissue would allow formation of a tissue bank. The stored cells could then be specifically tested to assure their cellular identity, viability, and bacteriological and virological safety before clinical use. The capacity to collect and maintain viable human fetal neural tissue would also facilitate research efforts to understand the development and function of the human brain and provide opportunities to study neurological diseases.