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Neurons from fetal rat brain in a new cell culture system: a multidisciplinary analysis.

A new culture system for cells from the mammalian brain was developed by a modification of a previously established technique. This modification involved the use of fluorodeoxyuridine and adult horse serum. The cultures contained large, easily visualized neurons both isolated from other neurons and in networks of varying complexity. These cells were large enough to permit reliable intracellular electrophysiologic recording and were often sufficiently dispersed to allow examination of membrane responses to iontophoretically applied neurotransmitter candidates. Many responses characteristic of central neurons in situ were seen, including evoked and spontaneous action potentials, complex patterns of inhibitory and excitatory post-synaptic potentials, and neurotransmitter-induced membrane responses. These preparations were examined by phase contrast microscopy, by light microscopy after silver impregnation and by Nomarski interference optics. Total choline acetyltransferase (CAT) activity was little changed and specific activity was increased in the new culture system as compared with the earilier system. Conditions which gave the highest specific activity of CAT also provided the best cultures from the standpoint of electrophysiologic and morphologic analysis. This new approach will allow, in culture, detailed multidisciplinary analyses of individual neurons and small networks of neurons from the mammalian brain.

Acetylcholine↗

Non-neuronal cell proliferation in tissue culture: implications for axonal regeneration in the central nervous system.

A tissue culture model has been developed to examine the hypothesis that proliferating non-neuronal cells may constitute a physical and/or chemical barrier to regenerating neurons in the central nervous system. Explants from the sensorimotor cortex of 20-day-old fetal rats were cultured in serum medium (control) or serum medium containing 10(-5) M cytosine arabinoside (AraC), a mitotic inhibitor, for varying periods: 2-10, 4-12, 4-10, 4-8 and 4-7 days in vitro (DIV). The center and outgrowth zone of the explants were examined by phase-contrast microscopy at varying intervals between 3 and 18 DIV. The extent of central degeneration was greatest in explants treated with AraC from 2 DIV, and was least in the 4-7 day treated group in which only minimal degeneration was evident at 13 and 18 DIV. In the outgrowth zone at 18 DIV non-neuronal cell proliferation was controlled in the 4-10 day treated explants, although this was accompanied by extensive degeneration of neurites. Further examination of neurite viability, using a neurite viability ratio, revealed that degeneration was first evident at 6 DIV in the 2-10 day treated explants, but not until 9 or 13 DIV in any of the explants exposed to AraC from 4 days onwards. There was minimal degeneration in the 4-7 day treated explants. Electron microscopic examination revealed the presence of atypical inclusions in non-neuronal cells of 4-8 day treated explants, suggesting that the cytotoxic effect of AraC may be due to a disturbance in lipid and/or ganglioside metabolism. Quantitative electron microscopic analysis of the outgrowth zone at 18 DIV revealed a significant increase in the summated area of neuronal tissue (from 7 to 18 microns2/100 microns2) and a decline in the summated area of non-neuronal cells (from 83 to 61 microns2/100 microns2) for explants treated with AraC from 4 to 7 DIV compared to control. Diminishing the potential of non-neuronal cells to act as a barrier by controlling their proliferation may, therefore, be of importance in enhancing the regenerative response of central neurons.

Animals↗

Interaction of water with egg lecithin in benzene solution.

Benzene solutions of purified egg lecithin, with small amounts of water added, have been examined by 60 MGz and 100 MHz NMR spectroscopy, infrared spectrophotometry and phase contrast microscopy. The transverse relaxation times of the water, N-methyl and O--H protons are dependent on water concentration. This dependence changes sharply for the water proton at a level of one water molecule per lecithin monohydrate molecule. These results do not fully agree with those reported by other workers. Four mathematical models are examined which could account for the behaviour of the water protons. Models which assume a constant transverse relaxation time for water protons above a level of one water molecule per lecithin molecule cannot predict the behaviour observed. It is sufficient to assume that water protons above this concentration have a single relaxation time which is a linear function of water concentration. The added water associates primarily with the phosphate in the lecithin head group. Above nine water molecules per lecithin monohydrate molecule free water is present in the system.

Benzene↗

Ice crystal patterns in artificial gels of extracellular matrix macromolecules after quick-freezing and freeze-substitution.

Artificial gels, composed of collagen with or without hyaluronate (HA), a glycosaminoglycan (GAG), and chondroitin sulfate (CS), were prepared and quick-frozen for the purpose of studying the influence of composition and concentration on ice patterns. Dilute gels were spread on coverslips, plunged into a slush of 30% isopentane/70% propane (-185 degrees C), freeze-substituted, and examined by phase-contrast microscopy. Ice patterns were revealed as "ice cavities" in the gel after freeze-substitution. Ice morphology in the gels was gel-type-specific, suggesting that composition in dilute gels can influence ice pattern formation. Crystallization patterns reflecting high, intermediate, and low rates of freezing were observed in all gel types. Intermediate freezing in differentiating gel-type-specific ice patterns. Gels which included hyaluronate (HA) and chondroitin sulfate (CS) altered the ice crystal pattern commonly observed in collagen gels. Ice structure in collagen gels consisted predominantly of long, parallel crystals in the herringbone pattern. Ice crystals separated gel into thin, unbranched fibers with a primary spacing of approximately 2 microns. Ice morphology in HA gels formed a mosaic consisting of packets of ice crystals. Contiguous packets were often oriented at right angles to each other. Periodic crossbridges interconnect primary gel fibers of HA gels and interrupt the lengthwise growth of ice crystals. Smooth beads were visible on primary strands in HA gels frozen at intermediate velocities. The addition of CS to collagen gels resulted in formation of randomly oriented ice crystals in gels frozen at intermediate rates. CS has little influence on ice morphology at low freezing velocities. Primary strands in CS gels were decorated with rough-surfaced, osmiophilic aggregates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Morphological differentiation of embryonic rat sympathetic neurons in tissue culture. II. Serum promotes dendritic growth.

In the preceding paper, we reported that embryonic rat sympathetic neurons formed axons, but not dendrites, when they were maintained in the absence of serum and nonneuronal cells. To assess the effects of serum-derived factors on cellular morphology, cultures were initially maintained in serum-free medium while nonneuronal cells were eliminated. Subsequently some cultures were chronically exposed either to fetal calf serum (10%) or to a high-molecular-weight ammonium sulfate fraction of serum (P40 material, 500 micrograms/ml). Phase-contrast microscopy revealed that serum and P40 material did not alter neuronal survival, but did cause flattening of the somata and fasciculation of processes. When neurons exposed to serum or P40 material were injected with Lucifer Yellow, it was found that the majority (greater than or equal to 90%) had local, tapered processes that could be identified as dendrites by light microscopic criteria. These local processes also exhibited other dendritic characteristics in that (1) they reacted with monoclonal antibodies to nonphosphorylated forms of the M and H neurofilament subunits and to microtubule-associated protein 2; and (2) they had substantial amounts of RNA as determined by [3H]uridine autoradiography. Quantitative measurements of the effects of serum and P40 material on dendritic morphology revealed that (1) an 8-day exposure caused most neurons (greater than 80%) to form dendrites; (2) neurons typically had more than one dendrite (mean of 4.1 +/- 0.2 dendrites/cell after a 28-day exposure); and (3) the dendrites were relatively short with the maximum extent of the dendritic arbor being 110 +/- 13 micron after 4 weeks. Serum and P40 material did not routinely cause the formation of supernumerary axons, did not alter radial axonal outgrowth from ganglion explants, and did not significantly increase [3H]leucine incorporation. Thus, serum contains a factor (or factors) which selectively stimulates the extension of dendrites, but not axons. If such a factor were operative in situ, it could play an important role in determining the morphology of sympathetic neurons. In examining the mechanism of serum-induced dendritic growth, we found that even high concentrations (5 micrograms/ml) of nerve growth factor failed to promote dendritic growth in the absence of serum; thus, nerve growth factor by itself is not a sufficient condition for the extension of dendrites.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Purification of meiotic spindles and cytoplasmic asters from mouse oocytes.

The unfertilized mouse oocyte is arrested at second metaphase of meiosis with microtubules existing exclusively in the meiotic spindle. Multiple inactive cytoplasmic microtubule organizing centers (MTOCs) are also present. These MTOCs can be identified immunocytochemically with an autoimmune serum (No. 5051) directed against pericentriolar material (PCM) and also by their nucleating capacity in the presence of taxol which effectively lowers the critical concentration for tubulin polymerization. Taxol induces the formation of cytoplasmic microtubule asters around the PCM foci, a process which also occurs in untreated eggs after fertilization. The molecular characterization of these structures has not been undertaken previously, probably due to the very small amount of material available. We have developed a single-step purification procedure by which very clean preparations of meiotic spindles and cytoplasmic asters can be obtained, as judged by phase-contrast microscopy and transmission electron microscopy. The purified structures were shown to correspond to those observed in vivo: positive staining of the spindles was observed with anti-tubulin and anti-phosphoprotein (MPM2) antibodies, and positive staining of the MTOCs was observed with MPM2, No. 5051, and anti-calmodulin antibodies. As expected, tubulin was the major protein present in the preparations. Silver staining of SDS-PAGE also revealed the presence of a small number of other polypeptides (Mr of around 47, 35, and 25K). Amongst newly synthesized polypeptides associated with the preparation, two prominent high molecular weight proteins (greater than 200K) were enriched in addition to tubulin and polypeptides with Mr of around 52, 41, and 35K.

Animals↗

Memantine is highly potent in protecting cortical cultures against excitotoxic cell death evoked by glutamate and N-methyl-D-aspartate.

The capacity of memantine to protect cultured cerebrocortical cells against N-methyl-D-aspartate (NMDA)- and glutamate-induced cell death was examined. Excitotoxic cell death was evaluated by phase contrast microscopy and quantified by estimating the release of lactic dehydrogenase from damaged cells. Memantine showed a strong, long-lasting and concentration-dependent protective effect against the excitotoxic damage induced by glutamate and NMDA, with almost complete protection being attained at a memantine concentration of 0.1 mM. The present findings indicate that memantine has potential value as a drug against excitotoxic brain damage.

Animals↗

Differential inhibition of human basal keratinocyte growth to silver sulfadiazine and mafenide acetate.

The impact of topical antimicrobial agents on improving the survival of patients with major thermal injuries is significant. However, the effects of these agents on cells responsible for wound healing has only recently received attention. Fresh human basal keratinocytes were grown in serum-free modified MCDB 153 medium under standard tissue culture conditions. Cells were subsequently exposed to concentrations of silver sulfadiazine and mafenide acetate as low as 1/100 of that used clinically over a period of 5-7 days. Cellular responses documented with hemocytometer cells counts, cellular protein assays, phase-contrast microscopy, and transmission electron microscopy show only severe toxicity to mafenide acetate. Such data imply that inhibition of wound epithelialization is greater with the use of mafenide acetate than with the use of silver sulfadiazine.

Cell Count↗

Measuring platelet function with platelet shape change, an early event in aggregation.

Platelet shape change precedes aggregation and is sensitive to significantly less stimulant. In this study, differences in percent light transmission (%T) through stirred suspensions of spheroid or discoid platelets are exploited for studying the response of platelets to Platelet Activating Factor (PAF). Changes in %T between stirred and non-stirred suspensions of unstimulated platelets in Platelet Rich Plasma (PRP) varied with the starting concentration. Aggregation was blocked by the presence of citrate while activation by ADP was minimized by apyrase. However, phosphatidic acid formation, ATP release and minimal serotonin release occurred. A shape change parameter (SCP) was defined which varied with the concentration of PAF. Its dependence on PAF was shifted to lower concentration with washed platelets. The dose-response curves for the SCP were found to be virtually identical for both sheep and human platelets. Human platelets were then used to correlate morphology, as determined by phase contrast microscopy, with spectrophotometric data in the form of the SCP. A linear regression analysis of SCP and percent activation revealed a virtual 1:1 correspondence with a slope of 1.066 and an intercept of 0.009 with the standard error of the estimate equal to 0.053. The correlation coefficient was 0.990, making it significant at p less than 0.001. This method provides an alternative to platelet aggregation assays as a convenient, sensitive and reliable measure of platelet activation.

Adenosine Triphosphate↗

Prostaglandin E2 and atriopeptin III oppose the contractile effect of angiotensin II in rat kidney mesangial cell cultures.

Effects of vasoconstrictory and of dilatory hormones were studied on the contractile activity of cultured rat kidney mesangial cells. By phase contrast microscopy, a rapid contraction was seen of most cells treated with angiotensin II (10(-6) - 10(-10) mol/L), which was sometimes followed by autonomous relaxation after 10 to 20 min. Prostaglandin E2 and atriopeptin III prevented the contractile effect of angiotensin II in a dose-dependent manner. Angiotensin II, but not atriopeptin III, stimulated prostaglandin E2 synthesis in mesangial cell cultures.

Angiotensin II↗

Localization of endoplasmic reticulum in living and glutaraldehyde-fixed cells with fluorescent dyes.

Certain fluorescent dyes, previously reported to localize mitochondria, when used at higher concentrations also localize a continuous net-like structure in both living and glutaraldehyde-fixed cells. A similar reticular structure can be detected by phase-contrast microscopy and whole-mount electron microscopy in potassium permanganate-fixed cells as well. This structure is mostly tubular, with some patch-like areas, and is likely to be the endoplasmic reticulum (ER). The organization of the reticular structure is sensitive to colchicine and rotenone but not to cytochalasin B, taxol, monensin, the calcium ionophore A23187, 12-O-tetradecanoylphorbol 13-acetate, or hydrocortisone.

Animals↗

Interface analysis of titanium and zirconium bone implants.

A thin layer of titanium or zirconium was evaporated onto the surface of a plastic implant which was then inserted in the rabbit tibial metaphysis for six months. The implants and surrounding bone were cut out en bloc and sectioned for phase contrast microscopy, scanning- and transmission-electron microscopy. The intact bone-to-metal interface in the case of titanium revealed a fibrous tissue-free boundary zone with a 200-400 A thick proteoglycan coat immediately adjacent to the titanium oxide. Thereafter collagen filaments were seen and, at approximately 1000 A from the interface, collagen bundles. The tissues surrounding the zirconium-coated implant consisted of a 300-500 A thick proteoglycan layer, followed by a zone with collagen filaments and collagen bundles, not closer to the zirconium oxide than a few thousand A.

Animals↗

Organotypic monolayer cultures of nervous tissue.

Cultivation of nervous tissue by means of the roller-tube technique yields thin organotypic cultures. Explants or slices prepared from 1- to 20-day-old rats are embedded in a plasma clot on flying coverslips and cultivated for weeks in roller-tubes. Due to the flattening of the tissue, individual nerve cells are often arranged in monolayer thickness and can, therefore, be viewed with phase-contrast microscopy. This technique is utilized to culture and co-culture nervous tissue derived from various brain regions. The degree of organotypic organization depends on the age of the animals used for culturing. Stable intracellular recordings arae obtained from nerve cells which are impaled under visual control. In view of the accessibility of individual living cells, this approach seems to be particularly well-suited for physiological and pharmacological studies on morphologically identified nerve cells.

Animals↗

Quantitation and morphological characterization of rapid axon and dendritic growth from single cerebral hemispheric neurons in hydrated collagen lattice culture.

Quantitative and qualitative data are reported for single cerebral hemispheric neurons in a 3-dimensional hydrated collagen lattice (HCL) culture system. Individual neurons not in contact with other cells or cell processes, including synapses, rapidly displayed two morphologically distinct classes of processes that could be traced from origin to termination: long thin processes interpreted as being axons, and shorter tapering and sometimes branched processes interpreted as being dendrites. Axons and dendrites of single neurons that had at least one process longer than the cell body were measured on each of 3 days after plating using an image analysis system coupled to a phase-contrast microscope and a microcomputer. Mean lengths of axons and dendrites alone or combined as total new growth per neuron, increased 3- to 5-fold and were as high as 745, 694 and 1226 microns respectively after 3 days in HCL, although some individual axons measured over 1500 microns. Other indices of neuron growth and differentiation increased 1- to 5-fold including the number of primary processes, branch points, segments and growth cones. Phase-contrast microscopy, staining with Nissl and silver, and scanning and transmission electron microscopy demonstrated many single multipolar and other neurons with axons, dendrites and well-differentiated properties. The data show that individual central nervous system neurons have an inherent capacity to quickly express characteristic differentiated features and also to grow rapidly in HCL.

Animals↗

Mineralized nodule formation in rat bone marrow stromal cell culture without beta-glycerophosphate.

Rat bone marrow stromal cells were cultured in the presence of 10 nM dexamethasone and various concentrations of beta-glycerophosphate. At day 12-15, some nodules consisting of polygonal cells were formed in all culture conditions, and these nodules were mineralized 2-3 days later. beta-Glycerophosphate significantly enhanced nodule formation at concentrations of not less than 5 mM. The mineralized nodules formed in the absence of beta-glycerophosphate were examined using phase-contrast microscopy, undemineralized and demineralized tissue histology, histochemistry for alkaline phosphatase, immunohistochemistry for type I, II, and III collagen, energy dispersive X-ray microanalysis, electron diffraction, and Fourier transform infrared spectroscopy (FT-IR). Mineralized nodules had histological characteristic similar to bone. Cells associated with nodules exhibited high alkaline phosphatase activity, and extracellular matrix of the nodules predominantly consisted of type I collagen. X-Ray microanalysis showed the presence of Ca and P in the mineralized area, and electron diffraction pattern showed the mineral to have apatite crystal structure. Moreover FT-IR indicated that the mineral was a mixture of hydroxyapatite and carbonateapatite. From these observations, it is concluded that the mineralized nodules formed in our culture system are truly bone-like.

Alkaline Phosphatase↗

Chemically unrelated tumor promoters induce identical morphological changes in cultured rat oral epithelium.

By use of phase contrast microscopy, transmission and scanning electron microscopy the cytomorphological effects of different known tumor promoters (TPA, teleocidin, mezerein and anthralin) were studied and compared to the cytomorphological effects of a variety of non- or weak promoting irritants (ethylphenylpropiolate (EPP), phorbol, acetone, ethanol and dimethyl sulfoxide (DMSO]. The studies were conducted in cultures of stratifying rat tongue epithelial cells. It was demonstrated that the tumor promoters induce characteristic cytomorphological alterations, the most striking changes being elongation of the cells and formation of long cytoplasmic extensions together with induction of so-called "dark cells". The non-promoting irritants exerted well-known cytotoxic reactions like cell rounding and cell sloughing. It is suggested that the characteristic tumor promotor induced cytomorphological effects partly reflects a block of the intercellular communication and thus should be paid more attention as an important characteristic event among the pleiotropic effects exerted by tumor promoters.

Animals↗

Effects on induction of tyrosine aminotransferase in fetal mouse liver in vitro of prednisolone, insulin and thyroxine.

The hormonal requirements for formation of tyrosine aminotransferase (EC 2.6.1.5) in fetal mouse liver were investigated in organ culture using chemically defined medium. The hormones tested were insulin, thyroxine and prednisolone. Prednisolone alone resulted in a two-fold increase in tyrosine amino-transferase activity in explanted liver in hormone-free medium on day 6, and its effect was dose dependent, but neither insulin nor thyroxine alone induced the enzyme. Addition of prednisolone plus thyroxine and prednisolone plus insulin increased the enzyme activity 1.4- and 1.3-fold, respectively, over that of explants with prednisolone alone. These three hormones together had the greatest effect, causing induction of 1.5-fold more activity than that with prednisolone plus insulin or plus thyroxine. The three hormones were not all needed continuously during the culture period: prednisolone and insulin were required during the early part of cultivation and thyroxine during the later part. The effects of these hormones were blocked by actinomycin D or puromycin, suggesting that these hormones increase de novo synthesis of tyrosine aminotransferase. Phase-contrast microscopy showed that prednisolone stimulated liver epithelial cell outgrowth, probably acting with insulin.

Animals↗