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Biomedical subjects

S E Grossberg

Publications and source records attributed to S E Grossberg.

At least 73 records · Page 4Linked to original sources
PubMed1981

Interferon stabilization and enhancement by rare earth salts.

The addition of salts of the rare earth elements (lanthanides) enhances by a factor of two or more the initial activity of human fibroblast, leukocyte and immune interferons as well as mouse L-cell interferon. Furthermore, the salts of the lanthanides (0.01 to 0.002 M) preserve the activity of human fibroblast interferon not only after 4 days of heating at 37 degrees C but also after exposure to severe shearing forces; human leukocyte interferon was stabilized to a lesser degree, albeit significantly.

Animals↗
PubMed1980

The reactivation of human interferons by guanidine thiocyanate.

The addition of 1.5 M guanidine thiocyanate (GuSCN) reactivates inactive human leukocyte interferon. The biological activity of inactivated human fibroblast interferon can be only partially recovered with GuSCN if additional (thermal) energy is supplied.

Fibroblasts↗
PubMed1980

Interferon inhibits the conversion of 3T3-L1 mouse fibroblasts into adipocytes.

Confluent Swiss mouse 3T3-L1 fibroblasts slowly differentiate functionally and morphologically into adipocytes, a conversion hastened by insulin. The cells are sensitive (although less than L929 cells) to the antiviral action of mouse fibroblast interferons but not to interferons from heterologous species (human and chicken). Cultures stimulated with insulin in the presence of partially purified or electrophoretically pure mouse interferons have a much lower percentage of cells accumulating lipid than do insulin-treated control cultures. Interferon-treated cell cultures also contain much less triglyceride, cholesterol, and cholesterol esters than do replicate control cultures stimulated by insulin to differentiate. Increased de novo lipid biosynthesis that occurs during differentiation is inhibited, as determined by incorporation of [14C]acetate into lipids extractable by the Folch method. This incorporation is a sensitive bioassay of the antidifferentiation effect of interferon; less than 1 antiviral unit is inhibitory. Variously inactivated or mock interferon preparations as well as interferons from several heterologous species fail to inhibit 3T3-L1 adipocyte conversion. Interferon is inhibitory even when applied as long as 3 days after insulin stimulation. The effect of interferon does not appear to depend upon its competition with insulin for cell surface receptors. Because interferon can alter the program of events involved in conversion of 3T3-L1 fibroblasts into adipose cells, it may be able to affect the regulation of eukaryotic cell differentiation.

Adipose Tissue↗
PubMed1980

Protection against Japanese encephalitis virus in mice and hamsters by treatment with carboxymethylacridanone, a potent interferon inducer.

A low-molecular-weight chemical inducer of interferon, 10-carboxymethyl-9-acridanone (CMA), effectively prevented death caused by Japanese encephalitis virus (JEV) injected peripherally into weanling mice and baby hamsters. Marked reductions in mortality were seen in mice when a single dose of CMA was administered intraperitoneally, subcutaneously, or intramuscularly to animals challenged intraperitoneally with JEV. The degree of protection was dependent on dose and time of administration of CMA in relation to virus challenge: all hamsters given CMA on the same day as JEV survived, with lesser although still significant protection when CMA was given one or two days after JEV. Viremia, an important characteristic of the pathogenesis of natural JEV infection, was reduced nearly 10,000-fold in hamsters treated with CMA. Thus, in the experimental animal models developed for these studies, CMA provided marked therapeutic and prophylactic effect against JEV.

Acridines↗
PubMed1980

The effects of interferon on 3T3-L1 cell differentiation.

Mouse 3T3-L1 fibroblasts, after attaining confluence, slowly differentiate functionally and morphologically into adipose cells. This conversion, characterized by a great accumulation of lipids, mostly triglycerides, is hastened by added insulin. The cells are relatively sensitive to the antiviral action of mouse fibroblast interferon (IF). Most cells treated with insulin in the presence of partially or highly purified interferon fail to differentiate. IF-treated cell cultures have far fewer adipose cells and much less lipid that replicate control cultures likewise stimulated to differentiate. The greatest differences are noted in the intracellular levels of triglycerides, cholesterol, and cholesterol esters, as well as in the incorporation of [14C]acetates into Folch-extractable lipids. Variously inactivated or mock IF preparations as well as several heterologous species interferons fail to inhibit 3T3-L1 differentiation. Thus, interferon appears to alter the program of events involved in the conversion of 3T3-L1 fibroblasts into adipose cells.

Adipose Tissue↗
PubMed1980

High-yield interferon induction by 10-carboxymethyl-9-acridanone in mice and hamsters.

10-Carboxymethyl-9-acridanone (CMA) was shown to be a very potent interferon inducer in young and old Swiss albino as well as congenitally asplenic mice. This compound (molecular weight, 275) induced titers of interferon in plasma comparable to those obtained with the best viral inducers, attaining > 400,000 U/ml in mice in 2 to 3 h. CMA concentrations were highest in mouse plasma 1 h after intraperitoneal or oral delivery. Induction was dose dependent over a wide range. Intraperitoneal, subcutaneous, or intramuscular injections of CMA gave comparable ranges of interferon titers. Oral delivery by gavage gave lower titers (65,000 U/ml), but higher than those reported with other low-molecular-weight interferon inducers in mice. CMA injected into week-old hamsters (which usually produce iterferon poorly) induced levels of interferon as high as 6,400 U per ml of plasma in a dose-dependent fashion, but kinetics of interferon induction was less rapid than in mice. The mouse and hamster interferons induced by CMA had physical characteristics similar to those of virus-induced interferons of the homologous species. The unusually high yields of interferon obtainable with this chemical inducer suggest its use for further experimental antiviral or antitumor therapy.

Acridines↗
PubMed1980

Enzymatic modifications of human fibroblast and leukocyte interferons.

The sensitivity of highly purified human fibroblast interferon and partially purified human leukocyte interferon to several proteolytic and glycolytic enzymes was determined with respect to antiviral activity, isoelectric point, molecular weight, and thermal stability. Leucine aminopeptidase altered the distribution of isoelectric points for both interferons but produced little change in molecular weights; this enzyme somewhat reduced the activity of only leukocyte interferon. Treatment of fibroblast interferon with carboxypeptidases A and B did not greatly decrease antiviral activity, but it did slightly reduce the molecular weight of the interferon and substantially altered the distribution of isoelectric point values; similar treatment of leukocyte interferon caused some loss in activity, especially of the 17,000-molecular-weight species. Both interferons were inactivated rapidly by treatment with the endoproteases trypsin, pepsin, bromelain, and subtilisin. Chymotrypsin shifted the isoelectric points of both interferons, but only leukocyte interferon was significantly inactivated. Treatment with neuraminidase and beta-galactosidase changed the isoelectric point distribution but did not affect the activity or thermal stability of either interferon; such a treatment reduced the molecular weight of fibroblast interferon and the size heterogeneity of leukocyte interferon. Treatment with neuraminidase and then leucine aminopeptidase greatly reduced the activity of both interferons, especially leukocyte interferon. The data indicate that biologically active forms of fibroblast and leukocyte interferons can be distinguished by their relative sensitivity to certain proteases.

Carboxypeptidases↗
PubMed1979

Production of interferon by human tumor cell lines.

Fourteen continuous human cell lines, including nine derived from tumors and five from non-neoplastic tissues, produced interferon in response to induction with bluetongue virus (BTV), Newcastle disease virus (NDV), and poly(I) . poly(C) complexed with DEAE-dextran. The seven best interferon-producing cell lines (one from a melanoma, five derived from carcinomas, and one SV40-virus-transformed kidney cell line) responded to at least one of the viral inducers with yields of interferon over 1000 units/ml. Because the HT-1376 bladder carcinoma cell line produced high yields of interferon in this survey, and is easily propagated, the optimal conditions for interferon production were investigated, using BTV as the inducer. Interferon yields in 59 inductions over a period of about two years consistently fell within a 6-fold range, and had a geometric mean titer of about 2700 reference units (RU)/ml, representing the production of about 3 RU/10(3) cells. This yield is comparable to mean titers of 1 to 10 RU/10(3) cells obtained by others with human leukocytes, foreskin cell strains, or the Namalva lymphoblastoid cell line. UV-inactivated BTV at a multiplicity corresponding to 10 PFU/cell was as effective an inducer in the HT-1376 cell line as the fully infectious virus at a multiplicity of 1 PFU/cell. The interferon produced by the HT-1376 epithelial cell line has characteristics similar to the interferon induced by poly(I) . poly(C) in human diploid fibroblasts. These studies clearly demonstrate that many different types of tumor-derived cells have the capacity to produce interferon, and that some equal or surpass the efficiency of diploid cells.

Bluetongue virus↗
PubMed1978

Thermal and vortical stability of purified human fibroblast interferon.

The loss of biological activity upon heating or agitation of human interferons is markedly altered by changing their aqueous environment. Low pH significantly stabilizes liquid fibroblast interferon at 68 degrees C and 37 degrees C whereas chaotropic salts stabilize at 68 degrees C but not at 37 degrees C; this anomalous result may be due to reactivation of biological activity at the higher temperature. The concentration of extraneous proteins influences the apparent thermal stability at any temperature and pH; thus, interferon was not stable even at low pH at protein concentrations less than 5 microgram/ml. Solutions of partially purified fibroblast interferon can be inactivated by mechanical stress; the addition of proteins or nonionic detergents prevents such inactivation. Freeze-dried preparations show the greatest thermal stability. The use of high-temperature, accelerated storage tests makes it possible to predict the shelf-life of freeze-dried interferon.

Drug Stability↗
PubMed1978

Production of interferon in human cell cultures by a new, potent viral inducer.

A new discovered double-stranded RNA inducer of interferon, bluetongue virus (BTV), stimulates the production of large amounts of interferon in animals as well as in many types of mammalian cell cultures, including human leukocytes, and continuous cell lines. The exceptional pH lability of BTV and its lack of pathogenicity for man further recommend its use as an interferon inducer. Among several human cell lines tested, the most efficient producer of interferon was a continuous cell line designated HT-1376, derived from a bladder carcinoma. With infectious BTV as the inducer, the HT-1376 line produced more interferon per cell than did leukocytes; interferon yields ranged from 10,000 to 60,000 units per ml of crude, unconcentrated supernatant fluid. Noninfectious BTV, inactivated by ultraviolet irradiation, was as effective as infectious virions. The interferon produced in HT-1376 cells has physicochemical and antigenic properties resembling those of fibroblast interferon produced in diploid cells.

Bluetongue virus↗
PubMed1977

Effect of chaotropic salts and protein denaturants on the thermal stability of mouse fibroblast interferon.

Altering the aqueous environment, especially with agents that affect hydrogen bonds, markedly affects the stability of mouse L cell interferon. Low pH stabilizes interferon whereas high pH labilizes it; heavy water further enhances interferon thermostability at pH 2 but not at pH 9. Exposure to the protein denaturants, 4 M-guanidine hydrochloride and 6 M-urea, significantly decreases the activity of interferon at pH 2 and pH9; however, the residual interferon activity is relatively thermostable. Certain chaotropic salts protect interferon against thermal destruction, and in terms of effectiveness, their sequence is in the order SCN- greater than 1- larger than or equal to Cl- = CiO4- - Br- greater than NO3-. Interferon becomes more stable to heat as the NaSCN concentration is increased from 0-25 M to 2-0 M. Molecular sieve chromatography of interferon in the presence of 1-5 M-NaSCN at pH 7 shows a shift in its apparent mol. wt. from 25000 to 42000. Unlike most proteins, the unfolded conformation of interferon appears to be more stable to heat than the molecule with a smaller Stokes' radius.

Deuterium↗
PubMed1977

Stabilization of interferons.

It is now obvious that there are a number of factors which can influence the stability of interferons. Since human fibroblast interferon is especially unstable both to heat and mechanical stress, the use of stabilizing conditions such as low pH or thioctic acid should facilitate purification and concentration of this interferon. Leukocyte interferon, on the other hand, seems to be more stable even when highly purified; however, losses in activity can occur in very dilute solutions containing low concentrations of protein. Inactivation during storage of interferons may be avoided by using freeze-dried preparations. In order to generate large quantities of purified, stable interferons for clinical use, there is a need to establish an armamentarium of different nontoxic techniques and approaches that will enable investigators to stabilize human interferons at each step in preparation, processing, concentration, purification, shipment and storage.

Fibroblasts↗