Characterization, in some human breast cancer cell lines, of gastrin-releasing peptide-like receptors which are absent in normal breast epithelial cells

The binding of 125I-Tyr4 bombesin was investigated on plasma membranes of 8 human breast cancer cell lines and 2 long-term cultures of normal human breast epithelial cells. Scatchard plots were compatible with high-affinity, single-site class of receptors in 3 cell lines (KD of 0.75 x 10(-9) and 10(-9) M, Bmax of 0.75 x 10(-13) and 9.7 x 10(-13) M/mg protein in MDA-MB231 and in T47D cells, respectively) while no binding was observed in 5 other cell lines and normal epithelial cells. The neuropeptide and its structural analogues (natural or synthetic) inhibited the binding of 125I-Tyr4 bombesin in the following order of potency: gastrin-releasing peptide (GRP, EC50 = 1.7 x 10(-10) M) greater than BIM 26159 greater than bombesin, Tyr4 bombesin greater than BIM 26147 greater than litorin greater than neuromedin C. In contrast, 125I-Tyr4 bombesin binding was not displaced by neuromedin B, somatostatin, bradykinin and insulin. In agreement with our binding data, SDS-PAGE of the complex 125I-Tyr4 bombesin-receptor covalently linked by ethylene glycol-bis succinimidyl succinate (EGS) identified after autoradiography a single band with a molecular weight of 75,000, which disappeared in the presence of bombesin in excess. No transcription of either GRP or neuromedin B mRNA could be shown in tumor or normal cells. Exogenous gastrin-releasing peptide had no effect on growth of the cell lines when a serum-free medium was used, implicating that in breast cancer cell lines this receptor does not mediate growth but has a functional role.

T-cell activation in Crohn's disease. Increased levels of soluble interleukin-2 receptor in serum and in supernatants of stimulated peripheral blood mononuclear cells

Serum levels of soluble interleukin-2 receptor were determined in 29 patients with active and quiescent Crohn's disease. In addition, the ability of peripheral blood mononuclear cells of 23 of these patients to generate soluble interleukin-2 receptor following mitogenic stimulation was studied in vitro. Serum soluble interleukin-2 receptor concentrations of patients with active Crohn's disease (n = 19) were significantly elevated (757 +/- 438 U/ml) compared with levels in patients with inactive disease (n = 10; 412 +/- 120 U/ml) and healthy control individuals (n = 40; 375 +/- 102 U/ml; p less than 0.003 and p less than 0.0005, respectively). Serial determinations of serum soluble interleukin-2 receptor concentration in a follow-up of 11 hospitalized patients treated for highly active disease showed a decrease from 1252 +/- 494 U/ml to 527 +/- 193 U/ml (p less than 0.004) that corresponded to clinical improvement, as assessed by Crohn's disease activity index and a reduction of inflammatory parameters. In vitro phytohemagglutinin stimulation of peripheral blood mononuclear cells derived from patients with Crohn's disease resulted in elevated soluble interleukin-2 receptor production not only in patients with active disease (3987 +/- 2439 U/ml), but also in patients with inactive disease (3297 +/- 2282 U/ml), compared with the amount of soluble interleukin-2 receptor produced by mononuclear cells of healthy individuals (1523 +/- 1152 U/ml; p less than 0.005 and p less than 0.02, respectively). In addition, cultivation of mononuclear cells without mitogen resulted in higher soluble interleukin-2 receptor production in patients with active disease than in patients with inactive disease (p less than 0.02). However, patients suffering from active ulcerative colitis also had significantly increased serum levels of soluble interleukin-2 receptor (1080 +/- 400 U/ml) compared with the levels in patients with chronic disease (455 +/- 140 U/ml; p less than 0.0025). In addition, peripheral blood mononuclear cells derived from patients with ulcerative colitis produced significantly more soluble interleukin-2 receptor upon mitogenic stimulation with phytohemagglutinin (2314 +/- 936 U/ml), than cells from healthy controls (1523 +/- 1152 U/ml; p less than 0.05). The finding of elevated soluble interleukin-2 receptor serum levels in patients with active Crohn's disease and its increased production by mononuclear cells of patients with both active and inactive disease is a further example of an alteration of the immune system in this condition; however, this alteration can also be found in other inflammatory bowel diseases.

A reversible multi-well chamber for incubation of cultured cells with small volumes: application to screening of hybridoma fusions using immunofluorescence microscopy

Immunofluorescence microscopy is a powerful technique for detecting the location of surface and intracellular antigens in individual cells. However, using standard methods, processing large numbers of samples for immunofluorescence is cumbersome and difficult. To simplify greatly this process, we have developed a chamber that reversibly creates multiple small wells in a large (150 mm) tissue culture dish. This device allows the rapid and convenient processing of hundreds of samples each of 100 microliters volume. Each sample is examined using a short working distance, high numerical aperture immersion objective for maximum sensitivity and resolution. This apparatus makes immunofluorescence a practical method for the primary screening of hybridoma clones.

[The recording of human fibroblast metabolism in vitro by the chromatographic-mass spectrometric determination of the metabolites excreted]

Metabolites excreted into culture medium by human skin fibroblasts have been studied by high resolution gas chromatography and mass spectrometry. Parameters for 29 metabolites have been obtained and 11 of them have been identified. Excreted metabolites reflect activity of certain metabolic processes in fibroblasts. Comparison of chromatographic and mass spectrometric parameters of cellular metabolites with the metabolites excreted with urine revealed that most metabolites excreted from fibroblasts differ from urine metabolites. The possibility for secondary transformation of cell metabolites in organism and specificity of metabolism in different tissues has been discussed.

The effects of thrombin on bovine aortic endothelial and smooth muscle cells

Recent evidence suggests that thrombin interacts with various cell types, stimulating cellular proliferation and protein and prostanoid production. To further delineate its role in vascular healing, we have studied the effects of thrombin on proliferation and matrix production by the cells of the vessel wall. The addition of thrombin (1 unit/ml) to cultures of bovine aortic smooth muscle cells resulted in an increase in cell proliferation (p less than 0.01) and number (p less than 0.03), whereas in cultures of bovine aortic endothelial cells thrombin produced a decrease in cell proliferation (p less than 0.01) and number (p less than 0.02). Thrombin also altered matrix composition in cultures of these cells. In both bovine aortic endothelial cells and bovine aortic smooth muscle cell cultures grown in the presence of thrombin, total protein content was significantly increased when compared to controls (p less than 0.03). In bovine aortic endothelial cell cultures the addition of thrombin resulted in a decrease in collagen content (p less than 0.01) and an increase in sulfated glycosaminoglycan content (p less than 0.02). In contrast, in bovine aortic smooth muscle cell cultures thrombin resulted in an increase in collagen content (p less than 0.03), whereas glycosaminoglycan content was unaffected. These findings suggest that thrombin may significantly influence vascular healing and function by altering cell number and matrix composition.

Enzymatic quantification of sphingosine in the picomole range in cultured cells

An enzymatic method to quantify the mass levels of free sphingosine in cellular lipid extracts was developed. The assay is based upon the observation that ceramide is phosphorylated by Escherichia coli diacylglycerol kinase. Although sphingosine is not recognized by the enzyme, it can be converted to a substrate by acylation with hexanoic anhydride. Using a mixed micellar assay, previously reported for the mass quantification of diacylglycerol, the short-chain ceramide (N-C6-sphingosine), generated by acylation, is quantitatively phosphorylated to N-C6-[32P]sphingosine phosphate. This assay allows quantification of sphingosine over a broad range from 25 to 5000 pmol. When this assay was applied to standard compounds, reverse-phase thin-layer chromatography of the reaction products was adequate to separate the phosphorylated derivatives of long-chain ceramide and N-C6-sphingosine. However, the presence of other lipids in extracts from biological samples (mainly monoalkylglycerols which are also a substrate for the diacylglycerol kinase) interfered and necessitated an additional purification step. The most efficient purification step devised was a combination of anion- and cation-exchange chromatography. The mass levels of free sphingoid bases in different cultured cells were quantified using this assay. Levels varied between 8 to 20 pmol/10(6) cells. When normalized to phospholipids, sphingosine levels varied between 0.01 and 0.04 mol%. The lowest levels were found in L929 cells, while Schwann cells derived from Twitcher mice contained the highest levels. These levels were significantly higher than those of Schwann cells derived from normal mice.

Incorporation of contrast media in cultured cells

Monolayer cultures of human prostatic (PC-3) and cervical (NHIK 3025) carcinoma cells were grown on formvar film and exposed to moderate concentrations of contrast agents for 30 minutes to 4 hours. After the exposure period, the monolayers were quickly frozen, and cryosections were examined by electron microscopy and X-ray microanalysis. Iodine was not detected in control cells, but was found in the cells that had been exposed to iodine-containing contrast media. The amount of intracellular iodine increased with increasing exposure dose and time. Because the cells mostly presented no sign of membrane damage, our findings support the view that contrast media have the ability to enter intact cells.

Desmin distinguishes cultured fat-storing cells from myofibroblasts, smooth muscle cells and fibroblasts in the rat

To differentiate cultured rat liver myofibroblasts, fat-storing cells, aortic smooth muscle cells and skin fibroblasts from each other, desmin and vimentin stainings were undertaken by indirect immunofluorescence using monoclonal antibodies. In myofibroblasts, the reaction with antibodies to vimentin was positive but that with antibodies to desmin was virtually negative. In primary cultures as well as subsequent passage of fat-storing cells, reactions with antibodies to both desmin and vimentin were positive. In primary culture of smooth muscle cells, both reactions were positive, but in the first passage, smooth muscle cells lost the reactivity with antibodies to desmin. Fibroblasts showed a positive reaction with antibodies to vimentin and a negative one with antibodies to desmin. Thus, immunohistochemistry of intermediate filaments allows for the differentiation between fat-storing cells, which are desmin- and vimentin-positive, and myofibroblasts or fibroblasts, which are desmin-negative but vimentin-positive. Smooth muscle cells are also vimentin-positive and become desmin-negative after the first passage.

Double-beam autocompensation for fluorescence polarization measurements in flow cytometry

The degree of depolarization of fluorescent light emitted from an organic dye, which is used as molecular probe, is a powerful tool in probing the microenvironment. By fluorescence depolarization the macromolecular structure can be investigated as well as the the mobility of the marker molecule itself or of the complex formed by the probe. Additional information such as energy transfer rates, donor-acceptor distances, and orientations are also measurable. These data are of particular interest if they can be measured from whole cells. Using flow cytometry, we can analyze a large number of cells with high statistical significance in a short period of time. We describe a newly developed double-beam epi-illumination arrangement for fluorescence polarization measurements that uses an autocompensation technique. This new technique permits the various depolarizing effects within the optical as well as the electronic components of the system to be continually compensated for on a cell by cell basis. Simultaneous measurements of other cell parameters for cell cycle analysis by total fluorescence intensity remains possible. The sensitivity of the system to measure polarization was determined as +/- 0.006 p (0 less than or equal to p less than or equal to 0.5 in isotropic media), which amounts to +/- 1.2% of the maximum p value. Polarization data for latex microspheres plotted in the histogram mode were measured with a standard deviation of 0.006, which proved the high resolution and the high performance of the system.

A semi-automated protein assay for cell cultures

A semi-automated modification of the protein determination procedure of O. H. Lowry, N. J. Rosebrough, A. L. Farr, and R. J. Randall (1951, J. Biol. Chem. 193, 265-275) is described. The assay is well suited to the analysis of the protein of adherent cultured cells. The procedure is carried out in 96-well microtest plates on protein solutions of 50 microliter or less, and can detect less than 0.5 micrograms of protein (equivalent to about 10(3) cultured cells). Optical densities are read and printed by an automatic microplate reader capable of processing 96 samples in less than 2 min.

[Distribution of myosin in a primary culture of human aortic intimal cells]

Using antiserum against smooth muscle myosin of human uterus the distribution of myosin was investigated in primary cell culture of human aortic intima. It was discovered that during the first 5 days of cultivation, 74.5% of cells manifested homogenous distribution of myosin. Single cells contained myosin in the form of continuous fibrils and 25% of cells were not stained by antiserum. In the next days of cultivation the cells experienced modulation and on the 14th day less than 6% of cells were stained homogeneously, while 58.5% of cells were not stained by antiserum. It is assumed that part of human aortic intima cells might be phenotypically modulated.

High pressure liquid chromatographic detection of intracellular retinoid binding proteins from cultured cell and tumor cytosols

We report the first application of high pressure liquid chromatography (HPLC) in the rapid detection of cellular retinoic acid binding protein (CRABP) and cellular retinol binding protein (CRBP). Cytosols from cultured cells (3T6 and MCF-7) or from tumors (melanoma and ovarian) were labeled with [3H]retinoic acid (30 Ci/mmol) and [3H]retinol (43 Ci/mmol) and analyzed via HPLC employing a 60 cm TSK 3000 sw column. In each case CRABP and CRBP were readily detectable at an elution volume of 22.5 ml, consistent with their molecular weights of 14,600. Identity of the binding protein peaks was established by saturability, specificity, and selective inhibition of binding by an organomercurial. Thus, this method, which resolves CRABP and CRBP in crude mixtures from the majority of cytosolic proteins, should be a valuable tool in the evaluation of vitamin A-binding protein interactions and their biological significance.

Monoclonal antibody against microtubule associated protein-1 produces immunofluorescent spots in the nucleus and centrosome of cultured mammalian cells

A monoclonal antibody was raised against the highest molecular weight protein associated with microtubules (MAP-1). Its specific binding to MAP-1 was determined by immunoblotting of the gel electrophoretogram of microtubule proteins prepared from porcine brain. The antibody reacted only with MAP-1, not with MAP-2, tau or tubulin. Indirect immunofluorescent staining by this antibody showed bright intranuclear spots, the centrosome and the faint meshwork of the cytoplasm in several types of cultured mammalian cells; HeLa, PtK2, human skin fibroblasts, mouse melanoma cells, Chinese hamster ovary cells. The nuclear spots in the interphase cells, were replaced by diffuse enhanced fluorescence throughout the cell except for chromosomes during mitosis. They reappeared in late telophase, first in the cytoplasm, late in the nucleus. The punctate pattern of nuclear immunofluorescence was not affected by microtubule-depolymerizing agents. The result that it persisted on residual cell structures after extraction with a high salt concentration buffer containing Triton X-100 followed by digestion with DNase I and RNase A suggests that the antigen is associated with the nuclear skeleton.

Cytokeratin provides a specific marker for human arachnoid cells grown in vitro

Cells from cranial and spinal arachnoid membranes of humans were grown in culture. Their growth characteristics, morphology and details of their cytoskeletal composition are described. Arachnoid membranes, obtained at autopsy, were finely minced and incubated in tissue culture medium. Monolayers of cells of homogeneous morphology grew from these tissue fragments. The cells were flat and polygonal. They divided slowly to form nonoverlapping monolayers of low cell density. Electron microscopic examination of cultured arachnoid cells revealed numerous desmosome-like tight junctions and abundant intermediate filaments (tonofilaments). Both morphological features are characteristic of arachnoid cells in situ, but not of cells in the fibroblast-rich dura mater. Immunofluorescence microscopy with monoclonal antibodies demonstrated cytokeratin in the cytoplasm of primary cultures of arachnoid cells. Thus we demonstrated that these cultured cells retained certain of the specific differentiated properties of arachnoid cells in situ and that they are not fibroblasts (which lack tight junctions and cytokeratins). To our knowledge, there have been no previous reports of in vitro growth of arachnoid cells. This in vitro model should be useful in studying the response of arachnoid cells to a variety of substances thought to be involved in the chronic inflammatory condition of the meninges known as arachnoiditis.

Cytophotometric measurement of the cellular DNA content of [3H]thymidine-labelled spheroids. Demonstration that some non-labelled cells have S and G2 DNA content

Spheroids from the V279-171b and MCa-11 cell lines were incubated continuously for 24 hr in [3H]thymidine for labelling of the outer cells of the viable rim. The spheroids were dispersed into single cells, and the DNA content of photomapped cells was measured by absorption cytophotometry. Autoradiographs were then prepared from which we ascertained cellular labelling. For spheroids of both cell lines, we found a larger proportion of cells with a G0/G1 DNA content among the non-labelled inner spheroid cells than among the labelled outer cells (P less than 0.001). This block of non-labelled spheroid cells in G0/G1 was not a cell cycle perturbation caused by the isotope for the MCa-11 spheroids. Approximately 8% of non labelled MCa-11 spheroid cells had S/G2 DNA content, suggesting that non-cycling cells in spheroids may be blocked in S and G2 as well as in the G0/G1 phase of the cell cycle.

Tumor diagnosis by intermediate filament typing: a novel tool for surgical pathology

In most cell types intermediate or 10-mm filaments (IF) are a major cytoskeletal organization and, thus, directly or indirectly influence the structural appearance of the cytoplasm. In line with the cell type-specific expression patterns of different IF proteins in normal animal and human tissue, IF typing distinguishes the major tumor groups, as documented by results with several hundred human tumors classified by conventional histologic methods. Carcinomas are characterized by cytokeratins, sarcomas of muscle cells by desmin, nonmuscle sarcomas by vimentin, and gliomas by glial fibrillary acidic protein. Furthermore, certain tumors originating from the sympathetic nervous system, e.g., ganglioneuroblastoma, pheochromocytoma, and at least some neuroblastomas, are characterized by the presence of neurofilaments. Carcinomas can often be further subdivided with regard to their possible derivation by examining their cytokeratin profiles. The IF type characteristic of the cell of origin seems to be kept not only in the primary tumor but usually also in solid metastases. In general, tumors do not acquire additional IF types. Therefore, IF typing can provide an unambiguous and rapid characterization in certain cases, that are difficult to diagnose by conventional techniques. Some useful examples are the small cell tumors of childhood and the discrimination between undifferentiated carcinoma and lymphoma. IF typing of a few tumors has already led to a revision or reconsideration of the original light microscopic diagnosis. The combined results indicate that at least certain carcinomas, as well as certain other tumor types, seem to arise by the selective multiplication of a particular and identifiable cell type present in the normal tissue. The procedure is not restricted to tumor material. IF typing of Mallory bodies, Alzheimer's disease tangles, certain myopathies, and the cells of the amniotic fluid offers further interesting applications. Thus, IF typing should become a valuable new tool both in histology and surgical pathology.

Structural defects in DNA from primary hepatocyte cultures

Structural analysis of DNA from primary hepatocytes has been made by chromatography on benzoylated-DEAE-cellulose. DNA was labelled in vivo by incorporation of 3H-TdR after partial hepatectomy 2 weeks prior to animals being used to establish hepatocyte cultures. Structural change in DNA associated with the transition to primary culture was assessed by comparison of data with that obtained when DNA was isolated from the intact organ immediately after death. In terms of this comparison, DNA from primary hepatocytes was bound more extensively to benzoylated-DEAE-cellulose in the presence of 1.0 M NaCl. Thus 32% of primary hepatocyte DNA was recovered in the formamide-eluted fraction after chromatography, a result which regions. This proportion of formamide-eluted DNA in primary hepatocytes could not be further reduced by extensive shearing and could not be affected by manipulation of the isolation procedure. Analysis of DNA isolated from hepatocyte cell lines revealed structural characteristics similar to DNA isolated from intact liver. The data imply that extensive structural damage to DNA is a consequence of the primary status of the hepatocytes examined.

Caution on the use of lymphocytes as standards in the flow cytometric analysis of cultured cells

Flow cytometry was used to compare the fluorescence intensity of the G0/G1 peak of a diploid (WI-38), a hypodiploid (C4I) and a heteroploid (KB) human cell line with that of nonstimulated human lymphocytes. With all three cultured cells the fluorescence intensity was substantially higher than that of lymphocytes. These results, obtained with three different DNA-intercalating fluorochromes, suggest that lymphocytes may not be the standard of choice for flow cytometric studies of the DNA distribution in human cell cultures and that diploid cells such as WI-38 may be more appropriate for this purpose.

Radioimmune, radiobinding and HPLC analysis of 2-5A and related oligonucleotides from intact cells

The enzyme (2-5A synthetase) which synthesizes ppp(A2'p)nA where n=2 to 4 (collectively referred to as 2-5A) is widely distributed in a variety of cells and tissues in amounts which increase response to interferon and vary with growth and hormone status. 2-5A activates a nuclease which inhibits protein synthesis. The non-phosphorylated 'core' of 2-5A ((A2'p)nA, n=2 to 4) can inhibit DNA synthesis and cell growth. Here we describe convenient and sensitive radioimmune (RI) and radiobinding (RB) assays for core and 2-5A. In combination with more satisfactory high performance liquid chromatography (HPCL) methods using reverse-phase C18 columns, these assays have been used to detect core and 2-5A in crude extracts from interferon-treated cells. The novel 2-5A synthetase products NAD2'p5' A2'p5'A and A5'p45'A2'p5'A2'p5'A (ref. 13), which can also be detected using the RB assay, were not found in significant amounts. The natural occurrence of core has not been described previously.

[Isolated liver cells of the rat under the influence of a toxic factor from burnt human and animal skin (author's transl)]

The existence of a burn toxin which could be responsible for the late burn disease has become increasingly accepted. The present study investigates both metabolism and ultrastructure of isolated rat hepatocytes both under the influence of a burn toxin isolated from burnt mouse and human skin and of its native nontoxic precursor. Cells from rats treated with toxin systematically were also investigated. The cells directly incubated with toxin showed no alterations of gluconeogenesis, but a reduced urea--and glycogensynthesis from most precursors used. Cells of pretreated rats were reduced in all functions and showed more distinct ultrastructural damage, while those incubated directly were significantly more altered. The results prove a direct toxic effect of a burn toxin on isolated liver cells.

Solubilization of the low density lipoprotein receptor

The low density lipoprotein (LDL) receptor was solubilized from membranes of bovine adrenal cortex and cultured human cells by incubation with the nonionic detergent octyl-beta-D-glucoside. Receptor activity released into the 100,000 x g supernatant was assayed by a solid-phase procedure: an aliquot of the soluble extract was removed, the detergent was diluted below its critical micellar concentration, causing the receptor to precipitate as a lipid-protein aggregate; the precipitate was collected by centrifugation and incubated with (125)I-labeled LDL ((125)I-LDL); and the receptor-bound (125)I-LDL was separated from free (125)I-LDL by filtration. The (125)I-LDL binding site that was precipitated from the soluble extract of bovine adrenocortical membranes appeared to be the same as the functional LDL receptor of cultured bovine adrenocortical cells and human fibroblasts. It exhibited high affinity and specificity (affinity for LDL more than 200-fold greater than for acetylated LDL, methylated LDL, or high density lipoprotein), dependence on calcium, and susceptibility to destruction by Pronase. The amount of (125)I-LDL binding activity in solubilized membranes from cultured cells was proportional to the number of receptors on the surface of the intact cells. Thus, the number of solubilized receptors was 1/20th of normal in mutant fibroblasts from a subject with homozygous familial hypercholesterolemia and was 1/4th of normal in human epithelioid carcinoma A-431 cells when they were grown in the presence of 25-hydroxycholesterol plus cholesterol. While in the soluble form in the presence of octyl-beta-D-glucoside, the LDL receptor can be carried through several steps of purification.

Biochemical characterization of clonally isolated and continuously cultured type II cells from adult rat lung

Clonally isolated and continuously cultured type II alveolar epithelial cells from adult rat lung (L-2) were compared to clonally cultured rat lung fibroblasts with respect to composition and biochemical function. There was no difference in phospholipid composition betweem those 2 cell types. After incubation with tritiated choline, the specific activity (cpm/nmol of lipid phosphorus) of disaturated phosphatidylcholine (PC) was lower than that of total PC in both cell types. Our findings suggest that, in our cell cultures, disaturated PC is not synthesized as a specific component of pulmonary surfactant, but more likely as a component of cell membranes. The increased DNA content of the L-2 cells indicates transformation and may be associated with the inability to synthesize surfactant. Under the described conditions, we are hesitant to use the clonally derived L-2 cell line as a model system for the study of pulmonary surfactant synthesis and secretion.

Dual-laser flow cytometry of single mammalian cells

An improved dual-laser flow cytometric system for quantitative analysis and sorting of mammalian cells has been developed using a low-power argon and high-power krypton laser as illumination sources, thus permitting the excitation of fluorescent dyes having absorption regions ranging from the ultraviolet to infrared. Cells stained in liquid suspension with fluorescent dyes enter a flow chamber where they intersect two spatially separated laser beams. Separate pairs of quartz beam-shaping optics focus each beam onto the cell stream. Electro-optical sensors measure fluorescence and light scatter signals from cells that are processed electronically and displayed as frequency distribution histograms. Cells also can be electronically separated and microscopically identified. The ease and versatility of operation designed into this system represent a marked technological improvement for dual-laser excited flow systems. Details of this instrument are described along with illustrative examples of cells stained with mithramycin and rhodamine and analyzed for DNA content, total protein, and nuclear and cytoplasmic diameter.

Canine kidney cells. II. Neutral lipids, phospholipids and fatty acids of Madin-Darby canine kidney cells in suspension and monolayer culture

Differences in lipid composition and the effects of monolayer and suspension culture were studied in Madin-Darby canine kidney cells and their plasma membranes isolated by the Warren fluorescein-mercuric acetate technique. Unesterified cholesterol was the major neutral lipid extracted from the whole cells and plasma membranes of cultures except for suspension-grown whole cells which had triglyceride as their major neutral lipid. Triglyceride increased about 7- to 20-fold and glycerol ethers increased about 3- to 20-fold in suspension grown whole cells and their plasma membranes compared to those from monolayer cultures. Total quantities of phospholipids are similar in whole cells of both cultures. Plasma membranes from monolayer cultures have about 1.4-fold more total phospholipids than those from suspension cultures. The distribution of fatty acids in the plasma membranes and whole cells generally follow the composition of calf serum used in the culture medium. However, the phospholipids of plasma membranes from monolayer cultures had substantially higher values for C18 unsaturated fatty acids and somewhat lower values for palmitoleic acid than the values for the fatty acids in calf serum. Also, the phospholipids of suspension-grown whole cells had substantially higher values for lauric acid and lower values for C18 unsaturated fatty acids when compared to calf serum.

Biochemical and histochemical features of human cultured cells (EUE) adapted to hypertonic medium

EUE cells from a human heteroploid line cultured in hypertonic medium (0.274 M NaCl) modify their lipid pattern: sulfolipid concentration reaches 86 to 90 microgram/mg protein whilst it ranges between 19 to 32 microgram/mg in cells cultured in isotonic medium. Ganglioside concentration reaches 2.6 nmoles of sialic acid/mg protein (after 75 days) and 13 (after 85 days) in hypertonic saline medium. Whilst it is 0.5 in isotonic medium. Phospholipid concentration does not show any similar change. Cytoenzymatic analysis reveals that dehydrogenases (lactate, G-6-P dehydrogenases, tetrahydrofolate reductase and NADH diaphorase) appear strongly enhanced in cells grown on hypertonic medium. On the contrary higher acid phosphatase and ATPase activity was demonstrable in cells grown on isotonic medium. These results are similar (except for ATPase activity) to those observed in salt secreting glands involved in strong osmotic work. The results are discussed in relation to the problem of energy supply in cells performing osmotic work.

Proteoglycans synthesized by fetal guinea pig chondrocytes in culture

Short term cultures were carried out with chondrocytes and tissue fragments from fetal guinea pig epiphyseal cartilage. Proteoglycans were isolated from these cultures and their properties were compared with those of proteoglycans from adult hyaline cartilage. It was concluded that the proteoglycans synthesized in culture were essentially similar to those present in cartilage matrix in vivo. The authors therefore suggest that fetal guinea pig chondrocytes cultured in monolayer or as aggregates in suspension constitute a useful system for the study of synthesis and secretion of proteoglycans.

FITC-labelled antibody staining of tropomyosin-containing fibrils in smooth, cardiac and skeletal muscle cells, prefusion myoblasts, fibroblasts, endothelial cells and 3T3 cells in culture

FITC-labelled antibodies to purified chicken gizzard smooth muscle tropomyosin were prepared and used to stain muscle and non-muscle cells in culture. Skeletal muscle myoblasts stained both diffusely throughout the cytoplasm and in fine filamentous structures. Once myotubes developed the staining was localized exclusively in the I-band region of the myofibrils. Similarly, cardiac muscle cells stained in the I-band alone. Primary and subcultured smooth muscle cells, irrespective of their state of differentiation, stained exclusively in long, straight fibrils. The staining of the fibrils was interrupted with stained regions 1-2 micrometer long and unstained spacings 0.5 micrometer. Interrupted fibrils were also observed in fibroblasts and endothelial cells, however their staining reaction was very weak (almost indistinguishable from that with pre-immune serum) and they were few in number. 3T3 cells demonstrated moderate staining in interrupted fibrils. Sheaths of very fine fibrils staining with a similar intensity were also found throught the cytoplasm. Interruptions in these fine fibrils were often aligned to give the whole cell a striated appearance. Sheaths of fibrils were not found in the other cell types studied.

Effect of salt solutions on radiosensitivity of mammalian cells. III. Treatment with hypertonic solutions

V79 Chinese hamster cells were treated with hypertonic solutions of NaCl or KCl and irradiated rat various times before, during, or after exposure to the solution. In solutions of molarities between 0-2 and 0-5 M, the cellular radiosensitivity increases with the molarity of the bathing solution. At these molarities, the hypertonic solution need not be present during irradiation to sensitize cells. Furthermore, radiosensitivity of cells could be increased by exposing cells for longer times to the hypertonic solution before irradiation. At higher salt concentrations (at 1-5 to 1-8 M), significant radioprotection is observed. Survival curve data showed that this protection was characterized by an increase in DO and a decrease in n, while the survival curves of cells sensitized with 0-465 M NaCl or with lower concentrations exhibited mainly changes in DO. The 1-55 M NaCl solution must be present during radiation to give a protective effect. Prolonged exposure to the salt before irradiation reduced the amount of radioprotection afforded by the salt. The results are discussed in terms of the effects of ions on histones, cellular water structure and the cell-aging cycle.

Effect of calcitonin on the phosphorylation of non-histones from cultured bone cells

32P-uptake into non-histones from bone cell cultures was selectively stimulated in the presence of calcitonin. Comparison of the control and experimental radioactivity profiles of non-histones fractionated by SDS gel electrophoresis showed that, in response to calcitonin stimulation, there was a 2- to 3-fold increase in the specific activity associated with non-histone proteins in the molecular weight range of 10,000 to 45,000 daltons while that of bands between 50,000 to 200,000 decreased.

Flow microfluorometric DNA content measurements of tissue culture cells and peripheral lymphocytes

The difference in DNA content of peripheral lymphocytes from normal males, normal females, and an individual with a 48 (xxxy) chromosome constitution was determined by rapid flow microfluorometric techniques. A similar comparison was performed using tissue culture fibroblasts derived from an individual with a 49 (xxxxy) chromosome constitution and WI-38 cells as a normal control. Less than 60 min were required to isolate the lymphocytes, to stain the cells fluorescently, and to measure the increased DNA content. The measured increase in DNA content is consistent with chromosome DNA analyses and chromosome length measurements.

The cornified envelope of terminally differentiated human epidermal keratinocytes consists of cross-linked protein

A small proportion of the protein of stratum corneum of human epidermal callus is insoluble even when boiled in solutions containing sodium dodecylsulfate and a reducing agent. This protein is present in the cornified envelope, a structure located beneath the plasma membrane. When cornified envelopes were dissolved by exhaustive proteolytic digestion and the products analyzed by chromatography, approximately 18% of the total lysine residues were found as the cross-linking dipeptide epsilon-(gamma-glutamyl) lysine. Labeled cornified envelope protein was synthesized by human epidermal keratinocytes allowed to differentiate terminally in culture. The extent of cross-linking, determined from the proportion of radioactive lysine in epsilon-(gamma-glutamyl) lysine after exhaustive proteolysis, was similar to that in stratum corneum. The properties of the cornified envelopes (insolubility in detergent and reducing agents, and solubility following proteolytic digestion) are readily explained by a structure consisting of a cross-linked protein lattice.

Surface exposure of glycosaminoglycans in resting, growing and virus transformed 3T3 cells

Glycosaminoglycans (GAG's) were released by trypsin from the surface of cultured mouse cells (3T3) in two different growing states: during log-growth phase and during resting due to serum starvation. Doubly labelled molecules from resting cells were compared with those from growing as well as from trnsformed cells. Reproducible differences in the elution pattern during ion exchange chromatography and in susceptibility to specific hydrolytic enzymes have been demonstrated: the GAGs pattern of growing normal cells is similar to the pattern of the cells transformed by either Polyoma or SV-40 viruses and very different from the pattern of resting cells. Growing and transformed 3T3 show a relatively low amount of trypsin removable heparan sulphate (HS) and a relatively high amount of hyaluronic acid (HA) while resting cells exhibit an opposite ratio between the two GAG'S. The lowering of HS and the increase of HA in the cell coat is therefore suspected to be more dependent upon growth than upon transformation.