The effect of carbon dioxide level and temperature on the in vitro metabolism of testis tissue

• 1.1. Normal testis tissue from sixty mature rabbits was studied to determine the effect of 0, 2, 5 and 10% CO₂ levels, temperature (33 and 37°C) and length of incubation time, at hourly intervals from 1 to 4, on glucose and O₂ uptake and lactate and CO₂ production.
• 2.2. There was generally a significant effect of the time of incubation due to a high activity during the first hour and no evident effect thereafter. This was possibly due to either tissue damage or substrate depletion during preparation.
• 3.3. Increased temperature caused increased metabolic activity as shown by other workers in vivo.
• 4.4. At 0 and 10% CO₂ there was marked decrease in metabolic activity, indicating a need for some CO₂ by the testis tissue and an inhibitory effect by CO₂ at higher levels. At these two levels there was a shift in metabolism from respiration to glycolysis.
• 5.5. The maximum metabolic activity occurred at 2 and 5% Co₂ which is near the levels previously reported in vivo.

     

The effect of active substances on nerve fiber regeneration in nerve tissue cultures

Explants of the ganglion trigeminale from chick embryos and hippocampi from embryonal rats were incubated in maximowchambers with semisynthetic media. The different parts of nervous tissue were influenced experimentally by addition of biological extracts and by substances with known composition. The regeneration of nerve fibers was investigated by the index of growth. The growth index was calculated from the ratio of nerve fibre index of the test cultures to that of the influenced cultures. Under these conditions biological extracts enhanced the growth of nerve fibres. In the same way the growth of nerve fibres was statistically significantly stimulated by substances with known composition of aminoacids, orotic acid, sodium orotate and cyclic monophosphates. A stimulating effect of cyclic guanosinmonophosphate seems to exist only in CNS explants and only in young fetal rats and consists in an increased migration and proliferation of cells as well as in the formation of fibres from neuroblasts. The investigations gave strong evidence for the in vitro testing to be very useful in studies of nerve fibre regeneration. However the choice of suitable reference systems, suitable quantitative parameters, optimal concentration and periods of application of effective substances and the age of the animals are of fundamental importance for the evaluation of the results. Experiments regarding the stimulation of the differentiation of neurons and the growth of nerve fibres are of practical clinical and therapeutical interest.     

Influence of opioid peptides on nerve tissue in vitro

The influence of opioid peptides (gamma- and beta-endorphins, leu- and met-enkephalins, as well as certain synthetic analogs of enkephalin) was investigated on organotypic cultures of rat spinal and sympathetic ganglia. The cellular composition and size of the zone of growth were evaluated on the basis of intravital observations and an analysis of the specimen obtained using the method of impregnation, according to Holmes and the detection of catecholamines with glyoxylic acid. It was established that under the action of all the investigated substances that possess high affinity for opiate receptors, growth of the neurites from an explant was enhanced, and the number of glial and fibroblastoid cells in the growth zone was increased. The effect was observed most distinctly on a model of sympathetic ganglia. The tested compounds exhibited a significant growth-stimulating effect in the range of concentrations 10^–8–10^–14 M. The maximum size of the growth zone of the explants of the sympathetic ganglia in the case of a mean effective concentration of the peptides 10^–10 M by the third to fifth day of culturing was approximately 2–2.5 times this value in the control. The reaction was similar to the response of the nerve cells to nerve growth factor, used as a standard. Thus, the opioid peptides exhibit a pronounced growth effect on the structures of the nerve tissue under conditions of culture. It is suggested that this group of compounds, together with its currently well-known functions, may play a definite role in processes of the development and regenera-of nerve tissue.Institute of Experimental Cardiology, All-Union Cardiologic Science Center, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 17, No. 4, pp. 550–557, July–August, 1985.     

The regulatory effect of phosphates on bone metabolism in vitro

Summary One of the most important indicators in vitro of the bone-cell phenotype is the synthesis of mineralized bone-like tissue. This has been achieved by supplementing isolated bone-cell and tissue cultures with organic phosphates, in particular, -glycerophosphate. To analyze the effects of -glycerophosphate on bone-cell metabolism and osteogenesis in vitro, both biochemical analyses and computer-assisted morphometry were used. Simultaneous autoradiographic and histochemical analyses of proliferating and alkaline phosphatase-positive cells were used to measure osteogenic events at the cellular level. Morphometric data showed that -glycerophosphate-treated cultures mineralized, but exhibited significantly less bone matrix (P < 0.05) than non-mineralizing controls. Cultures treated with inorganic phosphate failed to mineralize. Cellular proliferation was unaffected by -glycerophosphate; however, there was a decrease in the amount of ³H-thymidine incorporation into the DNA of -glycerophosphate-treated cells as detected by autoradiography. The percentage of alkaline phosphatase-positive cells was identical in -glycerophosphate-treated or control cultures. In agreement with previous biochemical results, there was a decrease in the amount of alkaline phosphatase enzyme activity per cell. The kinetics of alkaline phosphatase enzymes were measured on individual cells by microdensitometry. -Glycerophosphate-treated cultures exhibited more rapid reaction rates than control cultures (p < 0.05). Taken together, the results suggest that -glycerophosphate has global effects on bone-cell metabolism in vitro including its importance in mineralization.     

The effect of methionine-sulphoximine on nerve and glia cells in vitro

Summary The effect of methionine-sulphoximine (MSI) on the behaviour of the nerve and glia elements from brain and cerebellum of rat and chick in tissue culture was studied. It was observed that a concentration of MSI^–3 M inhibits the growth of early brain expiants. Concentrations of 10^–4 and 10^–5 M did not show this effect. Time lapse cinematographic recordings evaluating continually the behaviour of living glial and neuronal elements in tissue culture showed that MSI in a concentration of 10^–3 caused, very shortly after administration, a conspicuous oedema of cellular elements. The highest degree of swelling occurred in the perikarya and processes of astrocytes. Cell bodies of the oligodendroglia swelled only in the beginning and later shrank again considerably. This shrinkage was accompanied by a retraction of the glial processes, their fragmentation, and destruction. The perikaryon of the oligodendroglia contracted discontinually. Similarly the volumetric increase of astrocytes was accompanied by rhythmic contractions. In neuronal as well as oligodendroglial perikarya movements of mitochondria and other cytoplasmic particles first accelerated, later slowed down. Synchronously with cytoplasmic swelling of neurons the formation of many vacuoles is observed. From a comparison of these changes, their time course, and the degree of damage in various cell types it may be concluded that MSI attacks in the first place glial elements, among them most intensely the oligodendroglia.     

The effect of ADP on platelet metabolism in vitro.-III-

ADP induces an apparent platelets protrusion by rat's megakaryocytes in vitro.     

The effect of x-radiation on the glutathione metabolism of intact erythrocytes in vitro

The x-irradiation of intact washed erythrocytes results in an inhibition of the glyoxalase activity of the cells chiefly as a result of a decrease in the reduced glutathione level. The percentage inhibition is markedly increased by an increase in the dilution of the cells in physiological saline suggesting that the effect of radiation is indirect, via the production in the aqueous medium of free radicals, H₂O₂, etc. This is supported by the decrease in the inhibition produced by lowering the oxygen tension or by the addition of catalase. The inhibition of glyoxalase activity is also decreased by the addition of methylglyoxal, plasma, adenosine, inosine, glucose, and a number of other sugars to the erythrocyte suspension prior to radiation. Furthermore, some reactivation of the glyoxalase system results from the addition of plasma, glucose, adenosine, and inosine following radiation. These results are discussed in relation to the role of SH compounds, particularly glutathione, in the toxicity of ionizing radiations.     

Effect of orotic acid on the in vitro cultured nerve tissue]

Cell- and explantcultures of the hippocampus of 18 days old fetal rats and explantcultures of the ganglion trigeminal of 9 days old chick embryos were cultivated in Maximow-chambers. Orotic acid, Sodiumorotate and methylglucaminorotate by concentrations of 10(-3)...10(-7) g/ml medium were added to the cultures. By concentrations of 10(-7) g/ml medium in the CNS-cultures and 10(-6) g/ml medium in the PNS-cultures is stimulated the nerve fiber growth and is increased the nerve fiber index. After three weeks in vitro is a higher number of neurons in the cultures compared to the controls.