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Biomedical subjects

S B Klein

Publications and source records attributed to S B Klein.

At least 19 recordsLinked to original sources
PubMed1996

Treatment of a human breast cancer xenograft with an adenovirus vector containing an interferon gene results in rapid regression due to viral oncolysis and gene therapy.

Treatment of a human breast cancer cell line (MDA-MB-435) in nude mice with a recombinant adenovirus containing the human interferon (IFN) consensus gene, IFN-con1 (ad5/IFN), resulted in tumor regression in 100% of the animals. Tumor regression occurred when virus was injected either within 24 hr of tumor cell implantation or with established tumors. However, regression of the tumor was also observed in controls in which either the wild-type virus or a recombinant virus containing the luciferase gene was used, although tumor growth was not completely suppressed. Tumor regression was accompanied by a decrease in p53 expression. Two other tumors, the human myelogenous leukemic cell line K562 and the hamster melanoma tumor RPMI 1846, also responded to treatment but only with ad5/IFN. In the case of K562 tumors, there was complete regression of the tumor, and tumors derived from RPMI 1846 showed partial regression. We propose that the complete regression of the breast cancer with the recombinant virus ad5/IFN was the result of two events: viral oncolysis in which tumor cells are being selectively lysed by the replication-competent virus and the enhanced effect of expression of the IFN-con1 gene. K562 and RPMI 1846 tumors regressed only as a result of IFN gene therapy. This was confirmed by in vitro analysis. Our results indicate that a combination of viral oncolysis with a virus of low pathogenicity, itself resistant to the effects of IFN and IFN gene therapy, might be a fruitful approach to the treatment of a variety of different tumors, in particular breast cancers.

Adenoviruses, Human↗
PubMed1996

Cell surface binding characteristics correlate with consensus type I interferon enhanced activity.

The binding characteristics of a genetically engineered consensus interferon with unusually high biologic activity were compared to the characteristics of recombinant interferon-alpha 2. Both interferon-alpha 2 and the consensus interferon produced typical biphasic Scatchard plots, indicating multiple independent binding sites. The consensus interferon, which exhibited a biologic potency more than 10-fold greater than all other type I interferons, also exhibited binding site affinities greater than those for IFN-alpha 2b. In addition, a larger number of high, and low-affinity cell surface sites were recognized by the consensus interferon, resulting in equivalent numbers of sites at reduced molar concentrations compared to IFN-a2b. Thus, at any given biologic activity, similar numbers of sites were bound by the consensus interferon and IFN-alpha 2, despite differences in their molar concentrations. No differences in internalization kinetics were identified between the two interferons, indicating that the differences in cell surface binding may be sufficient to produce the differences in biologic activity.

Cell Line↗
PubMed1996

The biologic activity and molecular characterization of a novel synthetic interferon-alpha species, consensus interferon.

Consensus interferon (Infergen) is a wholly synthetic type I interferon (IFN), developed by scanning several interferon-alpha nonallelic subtypes and assigning the most frequently observed amino acid in each position, resulting in a consensus sequence. The antiviral, antiproliferative, NK cell activation activity, cytokine induction, and interferon-stimulated gene-induction activity of consensus interferon has been compared with naturally occurring type I interferons. In all of these comparisons, consensus interferon had a higher activity when compared, on a mass basis, with IFN-alpha 2a and IFN-alpha 2b, although the activity was the same for all of these parameters on an antiviral unit basis. That a synthetic type I interferon could have higher activities than naturally occurring molecules is surprising and may be a result of the higher affinity for the array of type I interferon receptors demonstrated for consensus interferon when compared with IFN-alpha. In contrast, consensus interferon was shown to be an inferior inducer of IL-1 beta when compared with IFN-alpha. These results may reflect differential binding to multiple accessory proteins interacting with a type I interferon receptor. These unique biologic properties may lead to a favorable clinical benefit for consensus interferon when compared with the naturally occurring recombinant molecules. Ongoing clinical trials will ascertain whether consensus interferon can be used in a wide array of disease situations, such as chronic viral infections and certain malignancies.

Amino Acid Sequence↗
PubMed1996

Oleic acid and linoleic acid are the major determinants of changes in keratinocyte plasma membrane viscosity.

Keratinocytes were grown in medium with no essential fatty acids as well as in media with specially selected fatty acid augmentations. Gas chromatographic determinations of 21 fatty acids in the phospholipids were correlated with plasma membrane viscosity obtained by electron paramagnetic resonance studies (n = 24). Using standard procedures from multivariate analysis, we derived an expression that modeled the viscosity data as a function of four key fatty acid levels: [formula see text] where the fatty acids are given in mole percent of total lipids and are identified as two number sequences: number of carbons followed by number of double bonds. No other fatty acid made a significant contribution to the regression equation. The range of viscosity was very large, varying from 60 to 120 cP over the sample population. The results are interpreted to indicate that polyunsaturated fatty acids are replaced with monounsaturated fatty acids by the keratinocytes and that dihomogamma-linolenic acid (20:3, n-6) plays an important role in membrane viscosity when essential fatty acids are available in the growth medium of these adult human cultured keratinocytes.

Cell Division↗
PubMed1995

Comparison of the in vitro host range of recombinant met-interferon-con1, interferon-alpha 2b, and interferon-beta [corrected].

The antiviral activity of human r-metIFN-con1 was compared with that of IFN-alpha 2b and IFN-beta on a number of human, other primate, rodent, feline, and canine cell lines. Although the specific activities of r-metIFN-con1 and IFN-alpha 2b differed 10-fold, the host range was very similar. The host range of IFN-beta differed from that of r-metIFN-con1 and IFN-alpha 2b in that Vero cells were 100-fold better protected by IFN-beta and MDBK protected at a 100-fold less efficiency. In general, there were only minor differences between the host ranges of the three interferons, human and primate cells being better protected than those of other species. However, the tissue of origin of the cell appears to be more important than the species of origin in defining host range [corrected].

Animals↗
PubMed1994

IDO mutants cross resistant to type I interferon retain p91-dependent gene induction.

Genetic analyses of mutants have yielded valuable information about p91-associated interferon signal transduction. It was thus discovered that p91 is an essential protein for the induction of both type I and type II interferons. We previously reported the development of ME180 mutants resistant to interferon-gamma because of a signaling defect resulting in the loss of IDO induction. IDO does not respond to type I interferon despite an ISRE-like sequence upstream of the coding region. However, the IDO mutants were found to be cross-resistant to the growth-inhibitory effects of type I interferon. We therefore examined the effects of both types of interferon on interferon-stimulated gene mRNA accumulation and examined alterations in cellular protein introduced by the mutation. The induction of the p91-responsive gene 6-16 was not altered in either of the mutants, and the early-induced gene IRF1 exhibited differences only in the kinetics of mRNA accumulation. The later induced gene, p68, also exhibited different kinetics, possibly reflecting the changes in IRF1. Immunoprecipitated p91 exhibited normal, interferon-induced phosphorylation in both mutants. Two-dimensional gel electrophoresis revealed that the mutant cells contained 20 peptides with altered biochemistry. These results suggest that IDO induction is controlled by a distinct set of proteins not directly correlated with p91 activation.

Cell Division↗
PubMed1993

An interferon resistant variant of the hairy-cell leukemic cell line, Eskol: biochemical and immunological characterization.

The B-lymphoblastoid cell line Eskol, which is composed of differentiated cells resembling hairy-cell leukemia, has been used to study the effects of type I interferon in vitro. In order to study the mechanism of delayed interferon therapy resistance, a hairy-cell leukemia-like clonal cell line (IREs-4) was isolated from Eskol after 4 months of exposure to r-metIFN-con1. When compared to Eskol cells, the IREs-4 cells were resistant to the antiproliferative effect of type I interferons as well as interferon induced protection against LAK cells. Treatment of IREs-4 with type I interferon did not induce MHC antigens, although both MHC class I and II antigens were induced in Eskol. Binding studies indicated the presence of equal numbers of high affinity binding sites with similar affinities on both cell lines. The resistant phenotype appears to result from an intracellular event which is essential to interferon signal transduction. It is hypothesized that this variant may reflect heterogeneity in the normal population of hairy-cell leukemia cells, and may explain the partial resistance of HCL patients to IFN therapy.

Blotting, Northern↗
PubMed1993

Consensus interferon induces peak mRNA accumulation at lower concentrations than interferon-alpha 2a.

The biological activity of a novel recombinant interferon, r-metIFN-con1, which represents a consensus sequence of the most commonly appearing amino acids at each locus of 14 naturally occurring IFN-alpha s, was assessed and compared to that of IFN-alpha 2a. The increase in cellular mRNA levels for three IFN-inducible genes served as a quantitative measure of the effectiveness of the stimulation by each of the IFNs. Three cell lines were treated with equimolar amounts of two IFNs encompassing a 5 log range and mRNA was extracted at five different times after treatment. In all cases, r-metIFN-con1 produced mRNA increases at lower concentrations than IFN-alpha 2a. HLA-DR alpha mRNA, which is not affected by IFN-alpha in ME180 or Daudi cells, was also not affected by r-metIFN-con1. However, in Eskol cells, both IFNs effected an increase in HLA-DR alpha mRNA to similar levels. The r-metIFN-con1 was effective at approximately 10-fold lower molar concentrations. At effective concentrations (10-fold lower molar dose of r-metIFN-con1), both IFNs produced similar kinetics of accumulation of all three mRNAs tested. r-metIFN-con1 is therefore more effective than IFN-alpha 2a at the level of mRNA regulation as well as the antiviral and antiproliferative activities that have been reported previously.

Amino Acid Sequence↗
PubMed1992

Regulation of TGF-alpha expression in human keratinocytes: PKC-dependent and -independent pathways.

Transforming growth factor-alpha (TGF-alpha) is an autocrine growth factor for epidermal keratinocytes that can induce its own expression (autoinduction). Because the regulation of this process may be important for the control of epidermal growth, we examined the roles of EGF receptor tyrosine kinase and protein kinase C (PKC) in TGF-alpha autoinduction in cultured human keratinocytes. Antiphosphotyrosine immunoblot analysis demonstrated that EGF and TGF-alpha rapidly and markedly stimulated tyrosine phosphorylation of a 170 kDa protein in growth factor-deprived keratinocytes. This protein was identified as the EGF receptor by immuno-precipitation using anti-EGF receptor mAbs. Tyrosine phosphorylation and TGF-alpha mRNA accumulation in response to EGF and TGF-alpha were both inhibited by a monoclonal antibody against the EGF receptor and by the EGF receptor tyrosine kinase inhibitor RG50864, demonstrating the involvement of the tyrosine kinase activity of the receptor in TGF-alpha autoinduction. The monoclonal antibody inhibited keratinocyte growth and TGF-alpha autoinduction with similar potency (IC50 approximately 0.1 microgram/ml). TGF-alpha and the PKC activator tetradecanoyl phorbol 12-myristyl, 13-acetate (TPA) had similar effects on TGF-alpha steady-state mRNA levels, suggesting that PKC activation might be a downstream mediator of TGF-alpha autoinduction. However, down-regulation of more than 90% of keratinocyte PKC activity by bryostatin pretreatment abrogated the induction of TGF-alpha mRNA in response to TPA without affecting the autoinductive response or EGF-stimulated tyrosine phosphorylation. These results indicate that EGF receptor and PKC stimulate TGF-alpha gene expression by different pathways, and suggest that PKC is not required for TGF-alpha autoinduction in this system. Moreover, the fact that EGF-stimulated tyrosine phosphorylation and TGF-alpha autoinduction were not potentiated after PKC down-regulation suggests that PKC does not exert a tonic inhibitory influence on EGF receptor tyrosine kinase activity in normal human keratinocytes.

Antibodies, Monoclonal↗
PubMed1990

Protooncogene expression in normal and psoriatic skin.

The expression of the c-myc, c-fos, c-jun, c-erbB, and c-Ha-ras protooncogenes was compared by Northern blot analysis of total RNA extracted from keratome biopsies of normal skin and psoriatic plaques. Isolation of intact RNA from frozen tissue required careful attention to technique during the early stages of extraction. Densitometric analysis revealed 1.5- to 2.5-fold elevations of c-myc transcript levels in lesional psoriatic relative to normal epidermis. Similar increases in cyclophilin and lipocortin II transcripts were also observed and may reflect characteristic differences in RNA preparations from normal and psoriatic epidermis. C-myc, c-jun, c-erbB, c-fos, and c-Ha-ras transcript levels were not significantly increased in lesional psoriatic epidermis when protooncogene mRNA levels were normalized to those of the cyclophilin or lipocortin genes. In contrast, transforming growth factor-alpha (TGF-alpha) transcripts were significantly increased (10- to 20-fold) with or without prior normalization. C-myc, c-fos, and c-jun transcripts were significantly induced over in vivo levels 2-4 h after organ culture of normal or psoriatic keratome biopsies, demonstrating that these genes can be highly expressed in the context of tissue injury. Our results suggest that overexpression of these protooncogenes per se is not central to the pathogenesis of psoriatic epidermal hyperplasia.

Epidermis↗
PubMed1989

Effects of item-specific and relational information on hypermnesic recall.

The role of encoding conditions in producing hypermnesia (increased recall over successive trials) was examined by manipulating the availability of item-specific and relational information at encoding. Our findings demonstrate that encodings providing item-specific information (e.g., elaborative encodings) produce hypermnesia by facilitating the recovery of new items over trials, whereas encodings providing relational information (e.g., organizational encodings) produce hypermnesia by protecting against the loss of previously recalled items. Thus, the effects of encodings on hypermnesia may be understood by considering the type of trace information they make available.

Adult↗
PubMed1986

Elaboration, organization, and the self-reference effect in memory.

Relating information to the self (self-referent encoding) has been shown to produce better recall than purely semantic encoding. This finding has been interpreted as demonstrating that self-reference produces a more elaborate memory trace than semantic encoding, and it has been cited frequently as evidence that the self is one of the most highly elaborated structures in memory. The experiments reported in this article challenge this interpretation of the self-reference effect by demonstrating that self-referent and semantic encodings produce virtually identical free recall levels if they are first equated for the amount of organization they encourage. On the basis of our findings we conclude the following: Organization, not elaboration, is responsible for the superior recall performance obtained when information is encoded self-referentially, and organization is not a necessary component of self-referent encoding and can be orthogonally varied within self-referent and semantic encoding tasks. Finally, we discuss how a single-factor theory based on organization can account for many of the self-referent recall findings reported in the literature.

Cues↗
PubMed1984

Polydipsia's contribution to temporal discrimination of rats on a fixed interval schedule.

This experiment concerned the contribution of polydipsia on the temporal discrimination of rats during a fixed-interval 60-sec. schedule. In this study, the timing accuracy of 12 rats which had access to water during training was compared to that of 12 rats which had no water during training. The rats were trained for 25 sessions on an FI 60-sec. schedule. In early sessions before polydipsia was fully developed, no differences existed between the timing accuracy of the water group and no-water group. As the amount of water drunk by the water group increased as the number of sessions increased, a parallel increase was noted in the timing accuracy of the water group. In the final sessions, a significant difference was found between the timing accuracy of rats in the water group and that of those in the no-water group. It was concluded that polydipsia facilitated the development of the temporal discrimination which is characteristic of a fixed-interval 60-sec. schedule.

Animals↗
PubMed1977

Illness-alone exposure as a source of interference with the acquisition and retention of a taste aversion.

Four studies were conducted to explore the effects of unpaired lithium chloride (LiCl) injections, the unconditioned stimulus (US), on the acquisition and retention of a taste aversion. In Experiment 1, subjects were preexposed to a US; for one group the US was paired with a distinctive taste, whereas for a second group it was not. Following this preparation, both groups received the US paired with a novel taste. Only the US-alone group showed a retardation of subsequent taste-aversion conditioning. Experiment 2 indicated that an exposure to LiCl without a specific gustatory cue will interfere with the avoidance of a specific taste, regardless of whether the US experience occurs before or after a single taste-LiCl pairing. Following sucrose-LiCl pairings in Experiment 3A, LiCl-alone exposures retroactively interfered with the retention of the prior aversion to sucrose, with the level of post-US interference becoming an increasing function of the number of US-alone experiences. In Experiment 3B, the association of sucrose with LiCl did not interfere with the development of an almond aversion, whereas LiCl-alone exposures following the acquisition of a sucrose aversion proactively interfered with the development of a second taste aversion (almond). It is suggested that a physiological explanation will not adequately account for the present results of these experiments. The results are discussed within the framework of alternative associative models.

Animals↗