GABA and GAD-like immunoreactivity in the primate retina

GABA immunoreactivity was studied and compared with GAD immunoreactivity in the retinae of baboon, cynomolgus monkey and man. The central and peripheral parts of the retinae were investigated separately in cynomolgus monkey and in man. The same kinds of structures were stained with both antisera. Cells with a position corresponding to amacrine cells were stained, as well as processes in the inner plexiform layer and some cells in the ganglion cell layer. The outer plexiform layer and some cells with the position and configuration of horizontal cells also appeared immunoreactive. Staining was also observed in bipolar-like cells, in man most clearly when using the GABA antiserum in sections from the central parts of the retina. It is possible that horizontal cells, as well as bipolar-like cells, may play a previously unsuspected role in GABAergic transmission in the primate retina.     

Large scale production of recombinant mouse and rat growth hormone by fed-batch GS-NSO cell cultures

Investigations of biological effects of prolonged elevation of growth hormone in animals such as mice and rats require large amounts of mouse and rat growth hormone (GH) materials. As an alternative to scarce and expensive pituitary derived materials, both mouse and rat GH were expressed in NSO murine myeloma cells transfected with a vector containing the glutamine synthetase (GS) gene and two copies of mouse or rat GH cDNA. For optimal expression, the mouse GH vector also contained sequences for targeting integration by homologous recombination. Fed-batch culture processes for such clones were developed using a serum-free, glutamine-free medium and scaled up to 250 L production scale reactors. Concentrated solutions of proteins, amino acids and glucose were fed periodically to extend cell growth and culture lifetime, which led to an increase in the maximum viable cell concentration to 3.5×10⁹ cells/L and an up to 10 fold increase in final mouse and rat rGH titers in comparison with batch cultures. For successful scale up, similar culture environmental conditions were maintained at different scales, and specific issues in large scale reactors such as balancing oxygen supply and carbon dioxide removal, were addressed. Very similar cell growth and protein productivity were obtained in the fed-batch cultures at different scales and in different production runs. The final mouse and rat rGH titers were approximately 580 and 240 mg/L, respectively. During fed-batch cultures, the cell growth stage transition was accompanied by a change in cellular metabolism. The specific glucose consumption rate decreased significantly after the transition from the growth to stationary stage, while lactate was produced in the exponential growth stage and became consumed in the stationary stage. This was roughly coincident with the beginning of ammonia and glutamate accumulation at the entry of cells into the stationary stage as the result of a reduced glutamine consumption and periodic nutrient additions.     

Autoradiography of nucleoside uptake into the retina

A selective uptake mechanism for some nucleosides and related substances was found in retinae of light adapted rabbits and fish. After the intravitreal injection in vivo of [³H]adenosine, [³H]inosine, [³H]guanosine and certain related compounds, the distribution of radioactivity was studied by autoradiography. Retinae were also incubated in [³H]adenosine and [³H]inosine and then were similarly processed.In rabbits, the accumulation of radioactivity from [³H]adenosine and [³H]guanosine was predominantly into glial cells, but also into neurons. [³H]Inosine labelled glia almost exclusively. However, the adenosine analog, [³H]methylphenylethyl-adenosine, resulted in well-defined neuronal labelling in this species. In fish, a few photoreceptor cell bodies exhibited strong radioactivity with the nucleosides, presumably representing incorporation into nucleic acids of replicating cells. Labelling was also seen in horizontal cells, amacrine cells and ganglion cells after the injection of either [³H]adenosine, [³H]guanosine or [³H]inosine.To some extent, the selective accumulation of radioactivity is likely to be due to cell replication, but in most neurons, other factors must be responsible. Judging from what is known about the actions of adenosine in central nervous tissue, signal transmission in the retina could be such a factor.     

The uptake of the GABA agonist, [H]isoguvacine, by the isolated retina of the rabbit

Previous autoradiographic studies aimed at showing neurones using GABA as their neurotransmitter have been hampered by the fact that the substance is a ubiquitous metabolite and therefore accumulated by a large variety of cells, including glia. Consequently, GABA uptake markers without this widespread uptake are desirable, and one, [³H]isoguvacine, has shown promising results in autoradiographic experiments. Its uptake has now been further studied with quantitative radiochemical techniques.

The uptake of the drug was slow compared to GABA uptake and reached a tissue/medium ratio of about 3 after 120 min. The uptake could be inhibited by GABA, beta-alanine or ouabain, and by incubating the retinas at 0°C. The uptake kinetics were complex but suggested a high affinity uptake system (K_m about 10⁻⁸ M) and perhaps one or several systems with lower affinities.

The results indicate that [³H]isoguvacine and [³H]GABA are accumulated and retained by the same neurones, which most likely use GABA as their neurotransmitter.     

Effect of pH and butyrate concentration on the production of acetone and butanol by Clostridium acetobutylicum grown in continuous culture

Summary When Clostridium acetobutylicum was grown in continuous culture under glucose limitation at neutral pH and varying dilution rates the only fermentation products formed were acetate, butyrate, carbon dioxide and molecular hydrogen. The Y _glucose ^max and (Y _ATP ^max ) _gluc ^exp values were 48.3 and 23.8 dry weight/mol, respectively. Acetone and butanol were produced when the pH was decreased below 5.0 (optimum at pH 4.3). The addition of butyric acid (20 to 80 mM) to the medium with a pH of 4.3 resulted in a shift of the fermentation from acid, to solvent formation.A preliminary report of part of this work was presented at a symposium Trends in the Biology of Fermentations for Fuels and Chemicals held December 7–11, 1980, at Brookhaven National Laboratory, Upton, New York; Gottschalk and Bahl 1981     

Somatostatin and VIP neurons in the retina of different species

Summary Neurons displaying somatostatin or vasoactive intestinal polypeptide (VIP) immunoreactivity were detected among the amacrine cells in the retina of baboon, cynomolgus monkey, squirrel monkey, cow, pig, cat, rabbit, guinea-pig, rat, mouse, frog and goldfish. Generally, immunoreactive cell bodies were located in the inner nuclear layer with processes ramifying in three more or less well-defined sublayers in the inner plexiform layer. The density of the sublayers and their location varied with the peptide and species investigated. In most cases there was a sublayer in the outermost part (Ramon y Cajal's sublamina 1) of the inner plexiform layer and this sublayer was usually the best developed. In some species a few somatostatin fibres were also detected in the outer plexiform layer, suggesting that some interplexiform cells contain somatostatin. In the baboon VIP was found exclusively in interstitial amacrine cells which have their cell bodies and processes entirely within the inner plexiform layer.     

Monoaminergic neurons of the mudpuppy retina

Summary The mudpuppy retina was investigated with the histofluorescence method of Falck and Hillarp in normal animals and in animals injected intraocularly with -methylnoradrenaline, 5,6-dihydroxytryptamine, or a combination of the two drugs. Catecholaminergic amacrine cells were found to form a thin layer of terminals at the border between the inner nuclear and the inner plexiform layers. Catecholaminergic interplexiform cells were not found. Indoleamine-accumulating amacrine cells were also observed. They are fifteen to twenty times more numerous than the catecholaminergic cells, and their terminals occur diffusely throughout the inner plexiform layer. In a number of eyes the majority of the indoleamine-accumulating terminals were eliminated with intraocular injections of the neurotoxin, 5,7-dihydroxytryptamine, but the reproducibility of this effect was not consistent. Intravitreal injections of 5,6-dihydroxytryptamine were used to label both types of neurons for electron microscopy. They were found to make conventional type synapses on amacrine cells and, less frequently, on bipolar cells.     

Über die rationelle Milchpasteurisierung

Ohne ZusammenfassungDie Arbeit wurde dem R. Istituto Lombardo Scienze e Lettere am 5. Juni 1934 vorgelegt (Rend. 67, 671, 1934).