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Notes: —(1) Rats received single intraperitoneal injections of various neuroactive chemicals in order to compare the changes of gross behaviour and the level of pyridoxal phosphate as well as the activity of the decarboxylase of aromatic amino acids, of glutamate decarboxylase and of tyrosine transaminase in the brain.(2) The majority of excitatory agents tested (i.e. convulsives like amino-oxyacetate, thiosemicarbazide, pentylenetetrazol and oxotremorine; stimulants such as amphetamine, theophylline and methylphenidate; the amphetamine-like monoamine oxidase inhibitor tranylcypromine as well as the classical monoamine oxidase inhibitor iproniazid when combined with the monoamine releaser Ro 4-1284) caused a decrease in aromatic decarboxylase activity which was coexistent with maximal changes of gross behaviour and partly preceded the latter. The level of pyridoxal phosphate was only partially parallel. As an exception, depression of aromatic decarboxylase was lacking after cocaine (which reduced pyridoxal phosphate only), atropine, the hallucinogens lysergic acid diethylamide and mescaline as well as the combination of the dopamine precursor l-DOPA and the aromatic decarboxylase inhibitor Ro 4-4602.(3) Depression of obvious central nervous functions was almost regularly accompanied and in part preceded by increase of DCA activity (i.e. with the anaesthetics pentobarbitone, diethyl ether and chloroform, the neuroleptics chlorpromazine, haloperidol, reserpine and the benzoquinolizine Ro 4-1284 as well as the tranquillizers diazepam and chlordiazepoxide). Pyridoxal phosphate was increased during or after maximal behavioural changes by pentobarbitone and chlorpromazine only. As an exception, activation of aromatic decarboxylase was absent after morphine.(4) The activity of glutamate decarboxylase was significantly reduced by thiosemicarbazide only, whereas a distinct increase in enzyme activity was exclusively observed after atropine.(5) Tyrosine transaminase activity was significantly diminished by amino-oxyacetate only and showed a late increase after tranylcypromine.(6) It is concluded that there is an inverse relationship, in the majority of neuroactive chemicals tested, between changes of gross behaviour and cerebral aromatic decarboxylase activity. Thereby, the latter is neither regularly related to corresponding variations of the total cerebral pyridoxal phosphate nor to hitherto described alterations of the monoamine turnover nor to effects on other vitamin B6-dependent enzymes.

Notes: Abstract: The glutamate transporters in the plasma membranes of neural cells secure termination of the glutamatergic synaptic transmission and keep the glutamate levels below toxic concentrations. Astrocytes express two types of glutamate transporters, GLAST (EAAT1) and GLT1 (EAAT2). GLT1 predominates quantitatively and is responsible for most of the glutamate uptake activity in the juvenile and adult brain. However, GLT1 is severely down-regulated in amyotrophic lateral sclerosis, a progressive neurodegenerative disease. Furthermore, selective loss of this transporter occurs in cultured astroglia. Expression of GLAST, but not of GLT1, seems to be regulated via the glutamate receptor signalling. The present study was undertaken to examine whether neuronal factors, other than glutamate, influence the expression of astroglial glutamate transporters. The expression of GLT1 and GLAST was examined in primary cultures of cerebellar granule neurons, cortical neurons, and astrocytes under different experimental conditions, including those that mimic neuron-astrocyte interactions. Pure astroglial cultures expressed only GLAST, whereas astrocytes grown in the presence of neurons expressed both GLAST (at increased levels) and GLT1. The induction of GLT1 protein and its mRNA was reproduced in pure cortical astroglial cultures supplemented with conditioned media from cortical neuronal cultures or from mixed neuron-glia cultures. This treatment did not change the levels of GLAST. These results suggest that soluble neuronal factors differentially regulate the expression of GLT1 and GLAST in cultured astroglia. Further elucidation of the molecular nature of the secreted neuronal factors and corresponding signalling pathways regulating the expression of the astroglial glutamate transporters in vitro may reveal mechanisms important for the understanding and treatment of neurological diseases.

Notes: Abstract. After the radical political changes of 1989, new possibilities for the development of political science appeared in Bulgaria. The discipline went through its own transitional periods. The first was the legitimisation of political science and its institutionalisation in the major academic institutions. The second, which remains at an early stage, is the establishment of a community of scholars and university staff with the necessary theoretical knowledge and resources for assuring its development. Of the major challenges which political science is facing today, one is the need to ensure the expansion of the community of scholars who are sufficiently familiar with recent developments in the discipline. Another is the need to overcome the politicisation of the discipline which was typical of many social scientists (and especially political scientists) at the beginning of the period of change. To an increasing extent, political science is not merely a product of democracy but also one of the major scientific resources for achieving its consolidation.

Notes: Theory presents two channels through which profit sharing can cause workers to increase their coworkers' productivity: greater cooperation and increased peer pressure. This paper argues that these generate opposite influences on coworker relations, and that which dominates varies according to circumstances and type of worker. Using German data, we show that, for non-supervisory men, profit sharing increases cooperation, but that for those who highly value success on the job, it has no influence on cooperation, and for supervisors it reduces cooperation. Moreover, the findings show striking gender differences in the effect of profit sharing. We contend these patterns fit with underlying theoretical expectations.

Notes: Kidney tissue from the freshwater chondrostean fish, Polyodon spathula, was examined by light microscopy. P. spathula has a glomerular excretory kidney. The tubule leading from the glomerulus, based on a variety of stain reactions, is composed of two major cell types. Also based on stain reactions, it appears that ion reabsorption, hence conservation, occurs in distal portions of the tubules. Also observed were stain reactions of arteriole walls, similar to renin producing cells in other vertebrates.

Notes: The exchange of ions between plant tissues and the external solution in vitro exhibits prominent biphasic kinetics. This is generally ascribed to the different contribution of the two compartments – apoplast and symplast – involved in the process. In this regard, an electro-diffusion model of the leakage is proposed in the paper. On the basis of the balance of fluxes through the plasmalemma and the cell wall, a system of differential equations describing the ion concentration in the outer solution is found. For a wide range of the system's coefficients, its behaviour is well approximated by a previously obtained analytical function. The values of the function's parameters, derived from the fit with experimental data, correlate adequately with the water deficit conditions of the samples. Hence, these parameters may be used to characterize the physiological status of the investigated plants.