An estimate of the number of cells arising by division in mouse cerebral hemispheres from age one to 12 months: an autoradiographic study of DNA synthesis.

Male CBA strain mice aged 1, 2, 4, 6, 8 and 12 months were injected with 5 muCi of 6-H3-thymidine per gm body weight and killed two hours after the injection. Incorporation of the isotope, as a measure of DNA synthesis and cell division, was studied in the cerebral cortex and corpus callosum by light-microscope autoradiography. DNA synthesis was found in a small number of nuclei of non-neuronal cells, both of ecto- and mesodermal origin. The percentage of labeled cells (Labeling Index, or LI) decreased in both regions exponentially with age. On the base of measured LI values, the total number of cells arising from age one to 12 months was calculated. As the reference value the number of cells in one month-old animals was taken. The calculated cell increment in the ectodermal population in the cortex amounted to 19.7-20.6% (average 20.2%) and to 196.0-425.0% (average 247.0%) in the corpus callosum (pairs of figures correspond to values calcualted from LI values measured in sagittal and frontal sections). When all labeled cells (LC) were taken into consideration (of both ecto- and mesodermal origin) the corresponding cell increment ranged from 25.0-30.5% (average 26.8%) in the cortex and from 205.0-454.8% (average 263.0%) in the corpus callosum. The number of all newly arising cells in the whole hemisphere (including both cerebral cortex and corpus calosum) calculated from mean LI values of all LC in sagittal and frontal sections amounted to 52.0%. It is suggested that the observed DNA synthesis and cell division, particularly in the corpus callosum and mesodermal cell groups of both regions studied, correspond mainly to renewal of cell populations. In the cerebral cortex accumulation of some newly arising cells in situ cannot be excluded.

Failure to detect the presence of pluripotential haemopoietic stem cells in the mouse brain.

Single cell suspensions prepared from adult mouse brains were tested for the presence of pluripotential haemopoietic stem cells (colony-forming units, CFU) by transfer into an irradiated recipient and enumeration of the CFU in the recipient's spleen. In contrast to the findings of others (Bartlett, 1982), we did not detect CFU after injection of brain cell suspensions, although they were detectable after inoculation with bone marrow cells. The number of CFU in recipients after transfer of increasing numbers of brain cells was the same as that detected in the irradiated controls which had not received any transferred cells. Finally, cells from the brain, in contrast to bone marrow cells, were not able to protect recipient animals from the effects of lethal irradiation.

Morphological maturation and survival of chicken and rat embryonic neurons on different culture substrata.

Neuronal cells from chicken and rat embryonic cerebral hemispheres were plated at a low cell concentration and cultured either on collagen or on a supporting continuous glial layer for periods of up to 21 days. The glial layer was either homologous or heterologous with regard to the animal species; the survival and maturation of the neuronal cells in these different conditions were investigated by light and electron microscopy. Neuronal cells cultured on collagen formed aggregates similar to those formed by neuronal cells plated at high cell density as described in a previous paper; a few aggregated neurons formed processes after 24 h and, only after 48 h of culture, more fibres had developed; the majority of the cells progressively degenerated between days 7 and 21 of culture. In contrast to this, neuronal cells cultured on a supporting glial layer, whether homologous or heterologous, progressively differentiated: neuronal perikarya remained well separated from each other and many processes were already formed after 24 h; later on, networks of fibres developed. At the electron microscopic level, microtubules and neurofilaments were present at a high density in the cells and fibres; immature synapses could be found, but infrequently. Differentiated cells were represented mostly by neurons; oligodendroglial cells were absent, and myelinated fibres could not be detected. The highest positive effect on the maturation and survival of neuronal cells was observed in the presence of a layer of glial cells from the same species. These results emphasize the essential role of glial cells for the neuronal maturation in the absence of contact between neuroblasts.

The metabolism of glucose of nerve cells cultivated under different conditions.

1. The consumption of glucose and formation of lactate was studied in medium of long-term cultivated nerve tissue. Fragments of chicken brain embryo dissociated and reaggregated brain cells were cultivated in Rose chambers, Falcon plastic dishes and Erlenmayer flasks. 2. Dissociated cells were cultivated in Petri dishes in media containing 100 mg/100 ml glucose. Consumption of glucose and formation of lactate increases until the 9th day. Glucose is completely exhausted in the medium up to the 2nd week of cultivation. 3. The time curve of both glucose consumption and lactate production is similar in cultures cultivated in Rose chambers, Petri dishes and Falcon plastic dishes. Cultures in Rose chambers utilize glucose at later stages anaerobically, whereas in Petri dishes and Falcon plastic dishes approximately 25% is utilized by aerobic glycolysis. 4. Cells dissociated by trypsinization and sieving are metabolically more active than cells separated mechanically (sieving only). During later stages of cultivation of enzymatically dissociated cells in 100 mg/100 ml glucose, lactate is utilized like a substrate, because of concentration of glucose in the medium is not being sufficient. 5. The concentration of glucose is essential for utilization by the aerobic pathway. In dissociated cells, cultivated in media enriched by 400 mg/100 ml of glucose in Falcon plastic dishes 75% of aerobic glycolysis is found during first 10 days and 50% in later stages. In the same system, cultivated in 100 mg/100 ml of glucose, glucose is exhausted up to the 12th day and lactate is utilized as a substrate. 6. In the close system of cultivation, i.e. in Rose chambers, 50% of glucose is utilized by the aerobic pathway if the medium contains 400 mg/100 ml of glucose. Early cultivation period of dissociated cells in Falcon plastic dishes is slowed, because cells adhere slowly to the plastic ground. 7. Structural development of cultures and differentiation of cells was studied during the cultivation period. Cells cultivated in elevated glucose concentration exhibit signs of better differentiation.

Nuclear pore complexes in cells of the developing mouse cerebral cortex.

The nuclear pore complexes of cells of the superficial layers of the cerebral cortex of mice were studied by freeze-etch technique. The nuclear membrane was found to be randomly penetrated by typical octagonal pore complexes in all age groups studied. The density of pores (per micron2) amounted to 7.8, 14.0, 17.0, 18.1 and 14.1 on the 18th to 20th embryonic and the 8th, 15th, 50th and 180th postnatal day respectively. The total number of pores per nucleus increases 5.2 times from the 18th to 20th prenatal to the 15th postnatal day and then decreases toward the 180th postnatal day (1257, 6582 and 3385 pores per nucleus respectively). The density of pores in cells of brain cortex, found in young adult mice is relatively high, if compared with other cell types.

Structure and ultrastructure of cultivated glial cells from Corpus callosum.

1. Explants and dissociated cells from Corpus callosum (c. c.) of rats and rabbits were cultivated in Petri dishes and Rose chambers. 2. Different types of glial cells were found in the cultivated Corpus callosum (c. c.) explanted from 12 days old rats: a) adendritic glial cells, typical for migrating oligodendroglial cells, b)-migrating large, nondifferentiated astrocytes with pronounced phagocytosing activity, c) macro- and microglial cells which differentiated during cultivation. 3. The population of differentiated glial cells is mostly composed of oligodendroglia, less of astrocytes and microglial cells are rare. 4. Differentiation of dissociated cells from c. c. in homogenous and mixed population was studied. The appearance of first processes of macroglial cells is postponed to 6 to 10 days of cultivation. No substantial difference was observed between homogenous and mixed population. A higher incidence of macrophages was observed in the later. 5. Glial cells differentiate surrounded by degenerated nerve fibers and myelin, exhibiting phagocytoses and cleaning reaction.

Differentiation of corpus callosum glial cells and factors influencing their maturation in vitro.

1. Explants of Corpus callosum (c. c.) from 12-day-old rats were cultivated under different experimental conditions. 2. Migration and differentiation is activated by the presence of neighbouring explants, toward which glial cells predominantly migrate. Glial cells migrate if closely adhering to the supporting collagen and the process of differentiation is enhanced by presence of underlying cell layers. 3. Migratory activity of glial cells decreases and is delayed with age of donors. Migrating cells have a similar appearance as in cultures from 12 days old donors. The presence of immature types of glial cells in c. c. of adult animals was proved. 4. Glucose was found to be an adequate metabolical substrate, utilisation of glucose being lower than in cultivated neurons. In the absence of glucose or serum in the medium, neither migration nor differentiation of glial cells was observed. 5. The addition of embryonal extract and embryonic brain extract enhanced only initial stages of cell migration and differentiation.

Plasma beta-endorphin immunoreactivity (PL-beta-ED-ir) in patients with ulcer disease and its management by acute and chronic administration of gastrozepin.

The initial level of PL-beta-ED-ir was significantly lowered in a group of 14 patients with gastroduodenal ulcer disease as compared with healthy volunteers (P less than 0.05). Immediately after i.m. administration of 20 mg gastrozepin (G) the PL-beta-ED-ir level increased but not significantly. Given orally over two weeks, G (50 mg/day) led to a more than doubling of the initial level (P less than 0.05). Controls showed no significant changes. A further meaningful change represented the time relationship of PL-beta-ED-ir during 5-hour observation to i.m. administration of 20 mg G before the start and after the end of the 2-week oral therapy. The placebo character of the above findings rules out the absence of any deviations of PL-beta-ED-ir in the diseased and healthy group after i.m. injection of saline. The study deals with the findings in relation to the pathophysiology of ulcer disease, and with a potential interference of G in the interrelation of the cholinergic and endogenous opiate systems.

Suppression of experimental allergic encephalomyelitis in rats by suppressor factor from a permanent T cell line.

An antigen non-specific suppressor factor (SF4) produced by a permanent mouse T cell line inhibits the mitogen- and antigen-induced proliferation of cells in vitro. The suppression of immune response is not restricted by interspecies barrier. Administration of the SF4 factor in vivo had a significant suppressive effect on the induction and manifestation of experimental allergic encephalomyelitis (EAE) in rats. Rats treated with SF4 factor, the first dose being injected on the day of EAE induction, had no clinical manifestations or developed only mild clinical signs of EAE. Administration of the SF4 starting on day 4 after EAE induction, when the immune system had been activated, depressed the course of EAE. The results obtained in this model autoimmune disease indicate that the described suppressor factor is active in vivo and that it may be used to depress the autoaggressive immune reactions.

Inflammatory and autoimmune diseases of the nervous system; possibilities of laboratory diagnostic methods in cerebrospinal fluid.

Contemporary aspects of cerebrospinal fluid analysis are discussed, including the relationship to neuro-infective, autoimmune and other neurological diseases. The actual state of cerebrospinal fluid microbiological and cytological investigation and analysis of cerebrospinal fluid protein fractions are described in detail.

[Determination of chlorine levels in Presept, a modern disinfectant]. / Stanovení obsahu chloru v moderním dezinfekcním prostredku Presept.

Presept (containing sodium dichloroisocyanurate as active component) was shown to be an excellent analytical reagent superior to classical Chloramine T and Chloramine B. Potentiometric titration of potassium ferrocyanide was found to be most suitable for estimation of chlorine content in Presept solutions. The presence of serum albumin can block or reverse the oxidation of ferrocyanide completely, whereas that of a detergent is of little importance. The content of available chlorine in various Presept tablets was found to be as a rule slightly higher than that guaranteed by the dilution rules of Johnson & Johnson. Presept solutions are remarkably stable, paradoxically the concentration of available chlorine in open vessels remains higher than in perfectly closed vessels.