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S J Friedman

Publications and source records attributed to S J Friedman.

At least 55 records · Page 3Linked to original sources
PubMed1986

Cell cycle control during the contact mediated growth inhibition of rat C6 glioma cells.

Two separate control processes govern the cell cycle of rat C6 glioma cells. In subconfluent cultures growth inhibition is caused by cell contact interactions and the cell cycle is regulated primarily by changes in the duration of S phase. During advanced multilayering, medium depletion becomes the primary mechanism of growth inhibition and causes a pronounced G1 accumulation. Contact modulation acts by altering the velocity with which cells progress through the cell cycle, while depletion causes cycle arrest.

Animals↗
PubMed1986

Cytolocalization artifacts with immunofluorescent probes.

Formaldehyde fixation, nonionic detergent extraction, and ligand binding are commonly used in conjunction with immunofluorescence microscopy to visualize antigens and lectin-reactive molecules in cytoskeletal preparations. These procedures have the potential to produce serious artifacts in cytolocalization studies, as is shown in the present investigation of wheat-germ agglutinin (WGA) binding and localization in BeWo choriocarcinoma cells. Formaldehyde fixation of intact cells reduced the binding of 125I-labeled WGA by 30% and altered the pattern of staining with fluorescein isothyocyanate (FITC)-WGA. Except for perinuclear sites which were brightly stained, the binding of FITC-WGA to other cell surface regions was significantly decreased. Nonionic detergent extractions had two different effects on lectin binding activity depending on whether or not the cells had been pretreated with lectin. In lectin-pretreated cells, 50% of bound lectin was solubilized by detergent but all of the surface binding sites appeared to be retained in active form in the detergent-insoluble residue. Nuclear-cytoskeletal monolayers prepared from cells that were not lectin pretreated lost considerable binding activity, however. These results suggest that a number of erroneous conclusions can be drawn from studies on cytoskeletal associations with membrane components using immunofluorescence microscopy on fixed and detergent-extracted cells.

Binding Sites↗
PubMed1986

Clarinettist's cheilitis.

A 15-year-old clarinettist with a median lower lip cheilitis corresponding to the distribution of a cane reed is reported. Thorough patch testing was unsuccessful in demonstrating an allergic contact hypersensitivity. The cheilitis was probably due to irritant contact factors.

Adolescent↗
PubMed1985

Telangiectasia.

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Adolescent↗
PubMed1985

A rapid naphthol yellow S method for measuring the cellular protein content of anchorage cultures.

A rapid method has been developed for measuring the cellular protein content of mono- and multilayered anchorage cultures. Fixed or air dried cultures are stained for 30 min with 0.2% Naphthol Yellow S (NYS) dissolved in 1% acetic acid. Unbound dye is removed by a series of four 2.5 min washes in 1% acetic acid, and protein-bound dye extracted with 10 mM unbuffered Tris base for spectrophotometric optical density determination at 433 nm. The NYS method exhibited a least-squares correlation coefficient of 0.99997 with the Oyama-Eagle Lowry method.

Animals↗
PubMed1985

Sclerodermoid changes of porphyria cutanea tarda: possible relationship to urinary uroporphyrin levels.

From 1950 to 1982, fifteen patients were seen at the Mayo Clinic with a diagnosis of sclerodermoid changes of porphyria cutanea tarda. Fourteen patients had changes similar to scleroderma limited to the skin, and one patient had scleroderma-like skin changes accompanied by visceral abnormalities. Both light-exposed and unexposed areas of the body were affected. Areas of involvement included the chest, the V-shaped area of the neck, and the back, face, and shoulders. In six patients, morpheaform changes represented the presenting cutaneous sign of porphyria cutanea tarda. Follow-up examination, after treatment that included abstinence from alcohol and phlebotomy, revealed that the sclerodermoid skin changes had disappeared in six patients and improved in four. Generally, the degree of improvement of the sclerodermoid changes was proportional to the reduction of the urinary uroporphyrin levels toward normal (p = 0.02).

Adult↗
PubMed1985

Erythema multiforme associated with contact dermatitis.

A garment worker developed erythema multiforme concurrently with allergic contact dermatitis of the hands. Patch testing revealed sensitivity to nickel (which was present in her scissors) and to paraphenylenediamine (a commercial dye). During the course of the patch-test evaluation, both the hand dermatitis and the erythema multiforme became exacerbated. Later, patch testing to only nickel sulfate resulted in the development of erythema multiforme on the face and hands. The allergic pathogenesis, involving the absorption of an allergen through the skin and resulting in a type III allergic reaction from nickel, is discussed.

Allergens↗
PubMed1985

Mechanisms of cholesterol synthesis inhibition by D-glucosamine.

The amino sugar D-glucosamine possesses antitumor activity which is thought to depend in part upon its ability to impair cholesterol biosynthesis and damage cellular membranes. The present study examined the effect of glucosamine on acetate utilization for lipid and sterol synthesis in rat C6 glial tumor cells. At cytotoxic concentrations, the amino sugar inhibited [14C]acetate incorporation into nonesterified sterols and lipids but increased the flow of label into cholesteryl esters. A comparison of the rates of acetate utilization for glucosamine metabolism (N-acetylation) and sterol and lipid synthesis suggested that glucosamine might act by competing for a common cytosolic pool of acetyl CoA. The inhibition of lipid and sterol synthesis, however, remained constant over a wide range of extracellular acetate concentrations. These results suggest that, if glucosamine acts by restricting the supply of acetate for these biosynthetic processes, it probably inhibits a step prior to the formation of acetyl CoA. Alternative mechanisms are discussed.

Acetates↗
PubMed1985

IgE antibodies to Staphylococcus aureus. Prevalence in patients with atopic dermatitis.

We determined the prevalence of IgE antibodies to Staphylococcus aureus by optimized immunoradiometric assay methods in serum specimens from 69 patients with atopic dermatitis. All patients had positive aerobic cultures for S aureus from skin. Significant binding attributable to IgE antibodies was noted in three of 25 patients with atopic dermatitis and superimposed impetiginization or pustules, but antibodies were not detected in the remaining 44 patients whose lesions were colonized with S aureus. By comparison, IgE antibodies to S aureus were uniformly present in high titer in serum samples from patients with the hyperimmunoglobulin E syndrome. We conclude that most patients with atopic dermatitis do not have detectable levels of IgE antibodies to S aureus.

Antibodies, Bacterial↗
PubMed1984

Whole organisms and purified cell walls compared as immunosorbents for the detection of IgE antibodies to Staphylococcus aureus.

We have developed an immunoradiometric assay for IgE antibodies to Staphylococcus aureus (Staph IgE-Ab) which uses purified cell walls (PCW) from the Wood 46 strain of S. aureus as an immunosorbent. We compared Wood 46 PCW and whole organisms (WO) as immunosorbents for Staph IgE-Ab by performing tests on sera from patients with atopic dermatitis (AD) or the hyperimmunoglobulin E syndrome (hyper IgE syndrome). Sera with Staph IgE-Ab demonstrated dose-dependent binding to PCW and WO, but the ratio of specific to non-specific binding was much greater with PCW. Mean non-specific binding to WO was greater than to PCW, 5% versus 2%; and non-specific binding to WO varied directly with the serum concentration of IgE. Results of tests on patients' sera indicated that PCW are required in screening assays for Staph IgE-Ab to avoid false positive results caused by high levels of non-specific binding to WO.

Antibodies, Bacterial↗
PubMed1984

Nonrandom spatial distribution by mammalian cells in culture.

Quadrat analysis was used to investigate the spatial distribution of seven mammalian cell lines in culture. The number of cells in replicate unit areas of the culture was determined, and the variance to mean ratio used as an index of random and nonrandom spatial distribution. Only mouse SV3T3 cells distributed themselves randomly throughout the entire culture growth cycle. The remaining six lines all assumed a nonrandom distribution at some point in their growth cycles. Mouse L929 cells displayed avoidance behavior, and spaced themselves at regular intervals in a uniform spatial distribution. The five remaining lines (mouse S180, rat C6, hamster CHO, canine MDCK, and human BeWo) formed multicellular clusters, and were distributed aggregatively rather than randomly. Random walk migration can account for the random distribution of SV3T3 cells. Random walk combined with contact inhibition of movement provides a satisfactory explanation for the uniform distribution of L929 cells. Random walk and contact inhibition are incompatible with cell clustering, however. Thus other mechanisms of motility or adhesiveness must contribute to cell clustering. It is possible that random walk and contact inhibition may be less common components of cell movement than generally assumed.

Animals↗
PubMed1984

Changes in cell-substratum adhesion and nuclear-cytoskeletal anchorage during cytodifferentiation of BeWo choriocarcinoma cells.

Changes in the substratum anchorage of cells and nuclei were examined during methotrexate (MTX)-induced cytodifferentiation of BeWo human choriocarcinoma cells. During this process cytotrophoblast-like cells (CTLs) transform into giant mono- and multinucleated syncytiotrophoblast-like cells (STLs). Cells treated with MTX for 24 h exhibited significantly faster rates of substratum detachment by EDTA, trypsin-EDTA, EDTA-glycine, and DMSO than did uninduced controls. The decrease in cell-substratum adhesiveness occurred prior to the onset of morphological transformation. By 48 h, when morphological transformation was first observed, there had occurred a marked change in nuclear-cytoskeletal anchorage to the substratum, as evidenced by a difference in sensitivity of Triton-extracted STL and CTL monolayers to detachment by KI. STL monolayers were completely detached within 5 min of exposure to 0.3 M KI, while CTL monolayers remained firmly attached to the substratum for at least 3 h. KI-extracted residues were examined by electron microscopy and found to consist of nuclear shells attached to intermediate filaments. When cytoskeletal residues and KI-extracted proteins of STL and CTL cells were compared by two-dimensional polyacrylamide gel electrophoresis (PAGE), qualitative and quantitative differences were seen in a number of minor components. Thus the sensitivity of STL nuclear-cytoskeletal monolayers to removal by KI, an effective actin depolymerizing agent, may involve changes in the organization, stability, or interactions of actin with other components of the cytoskeletal framework.

Cell Adhesion↗