Search PubMed⌕ Search

Biomedical subjects

S Goldstein

Publications and source records attributed to S Goldstein.

At least 523 records · Page 29Linked to original sources
PubMed1982

Is transformation associated with an increased error frequency in mammalian cells?

Acute starvation of mammalian cells for amino acids results in translational errors that may be detected by two-dimensional polyacrylamide gel electrophoresis. Using this as an assay for error frequency in mammalian cells, we investigated the hypothesis that neoplastic transformation was associated with an increased error frequency which in turn leads to an increased mutation rate and a decreased efficiency of regulatory controls (phenomena of tumor progression). Although we found that transformation was not always associated with an increased level of mistranslation we showed that SV40 transformation increased the level of translational errors in all cell types tested.

Amino Acids↗
PubMed1982

Energy metabolism in cultured human fibroblasts during aging in vitro.

To explore the relationship between energy metabolism and the limited replicative life span of cultured human fibroblasts, we studied several bioenergetic parameters in normal fibroblasts at early passage (young cells) and at late passage (old cells) and early passage cells from a subject with the Hutchinson-Gilford (progeria) syndrome. Old cells consumed more glucose and produced more lactate during growth, but O2 consumption, both basal and following maximum uncoupling of oxidative phosphorylation by SF-6847, was the same as in young cells. Progeria cells produced the most lactate but did not consume more glucose, while their basal and uncoupled O2 consumption was similar to that of young and old cells during both log and confluent states. Consumption of glutamine, a source of both oxidative energy and lactate, was approximately the same in all three cell types as was 14CO2 production from 2- 14C-pyruvate and 5- 14C-glutamate. ATP and ADP concentrations were similar in all cell types with a rise in the ATP/ADP ratio during growth from log to confluent state. Thus, old and progeria cells, in contrast to young cells, produce more lactate during growth consistent with a rise in energy demand and/or inefficiency of oxidative phosphorylation. Although limitations in total energy output do not appear to be causal to the loss of replicative capacity in normal cells after serial passage, they could play a role in the curtailed replicative capacity of progeria cells.

Adenosine Diphosphate↗
PubMed1982

Human fibroblast strains showing increased sensitivity or resistance to ethidium bromide.

The sensitivity of a number of human fibroblast cell strains towards the DNA intercalating and mutagenic agent ethidium bromide has been examined. Among the cell strains investigated, 3 were of fetal origin, 6 from clinically normal adult persons, 2 from Lesch-Nyhan individuals and 1 each from persons with 3 genetic disorders, xeroderma pigmentosum, Fanconi anemia and Bloom syndrome, which are known to predispose to cancer. Results of our studies show that cells derived from 2 otherwise normal individuals exhibits a marked sensitivity towards ethidium bromide as compared to the rest of the group. At the same time all 3 cell strains of fetal origin were found to be highly resistant to killing by this agent. These results are discussed in relation to the toxic/mutagenic effects of ethidium bromide.

Adolescent↗
PubMed1982

Variability of DNA methylation patterns during serial passage of human diploid fibroblasts.

We have examined DNA methylation in diploid human fibroblasts, early and late in their replicative life-span. The extent of methylation of -C-C-G-G- was measured by comparison of fragment sizes after digestion with methylation-specific restriction enzyme Hpa II or Msp I, or both. Methylation of -C-C-G-G- sites in total DNA, occurring predominantly at internal (3') cytosines, increased from 59% to 64% of sites in one cell strain at late passage, remained constant in another, and decreased in four other strains (54% to 48%, 58.5% to 48%, 55% to 51.5%, and 52% to 44.5%). Base composition analysis confirmed a substantial loss of total DNA 5-methylcytosine (mC) in one strain. Seven clonal isolates, examined at middle to late passage, ranged from 33% to 51% methylation of 3' cytosines in -C-C-G-G- sites. Three discrete classes of highly repetitive DNA were found which contained Msp I sites at intervals of 45, 110, and 175 base pairs. These repeat families consistently had 70-80% of sites methylated at 3' cytosines, in all clones and in all strains examined both at early and at late passage. Thus, altered methylation of repetitive sequences is unlikely to account for the variable -C-C-G-G- methylation observed in total DNA. When DNA from one fibroblast strain and from eight pure clones isolated from that parental culture was digested with Msp I or Hpa II followed by EcoRI and probed for gamma-globin gene sequences, considerable interclonal and intraclonal heterogeneity was observed for methylation at four -C-C-G-G- sites in the gamma-globin coding region of DNA. Therefore, the pattern of methylation in endogenous gene regions appears to undergo random drift during replication of diploid fibroblasts.

Adult↗
PubMed1982

Clonal selection in cultured human fibroblasts: role of protein synthetic errors.

Protein synthetic error frequency, determined in cell-free extracts as delta leu/delta phe incorporation following poly(U) stimulation, has been found to decrease progressively in several strains of human diploid fibroblasts during their limited replicative lifespan. To explore the basis of this phenomenon, we followed a mass (uncloned) culture of one normal strain at 13 stages of its replicative lifespan. We found a progressive tenfold decline in error frequency that was inversely correlated with passage level (r = -.93, p less than .001). This could not be ascribed to the slow rates of replication associated with fibroblast senescence because slowing of growth by serum deprivation did not change error frequency. Additionally, terminal mass cultures maintained for 16 wk at saturation density to minimize cell selection did not change error frequency over this time. Error frequencies in 12 individual clones purified from the parental culture did not decline on repeated passage, either remaining constant or, in two clones, rising abruptly three- to five-fold after initial assays. Error frequencies of clones showed a weak inverse correlation with growth vigor but not with the maximum doubling number. We conclude that selective pressures favor more vigorously dividing clones with low protein synthetic error frequencies leading to their predominance in mass cultures.

Blood↗
PubMed1981

Role of the carbohydrate moiety in the antigenic site(s) of human serum low-density lipoprotein.

Radioimmunoassay techniques have been used to evaluate the contribution of the carbohydrate moiety to the immunological reactivity of human serum low-density lipoprotein (LDL). Low-density lipoprotein (d = 1.024--1.045 g/mL) was isolated from normolipidemic serum by ultracentrifugal flotation. Radioimmunoassay was performed with 125I-labeled LDL and several homologous antisera, each corresponding to different periods (1--18 weeks) of immunization and thus containing various antibody populations. Unlabeled LDL and different monosaccharides characteristic to this particle, i.e., mannose, sialic acid, glucose, N-acetylglucosamine, galactose, N-acetylgalactosamine, and fucose, were used as competitors in the binding of the labeled antigen with antibody. In the reaction with antisera corresponding to the highest antibody titer, unlabeled LDL, sialic acid, and mannose inhibited the binding of labeled LDL up to 62%, 25%, and 16%, respectively; a low degree of inhibition (some 13%) was occasionally obtained with glucose. Galactose, galactosamine, glucosamine, and fucose failed to compete with labeled LDL. Studies with antisera corresponding to different periods of immunization (2, 4, and 8 weeks) indicated that antibodies reacting with mannose appeared early (maximum 31% inhibition at 2 weeks), disappearing at 6--8 weeks; in contrast, antibodies reacting with sialic acid augmented progressively (10% inhibition at 2 weeks, 20% at 4 weeks, and 35% at the end of the immunization). These data are consistent with the conclusion that sialic acid and mannose, the terminal residues of LDL glycopeptides I and II [Swaminathan, N., & Aladjem, F. (1976) Biochemistry 15, 1516--1621], are implicated in the antigenic site(s) of LDL.

Animals↗
PubMed1981

Local intranasal immunotherapy for ragweed allergic rhinitis. I. Clinical response.

Local nasal immunotherapy (LNIT) of ragweed allergic rhinitis was studied in a double-blind controlled trial. Sixty-seven subjects were divided into three groups. Twenty-one received unmodified ragweed extract (RW), 24 received a glutaraldehyde polymer of ragweed extract (PRW), and 22 received placebo. Mean symptom/medication scores during the season were 2.12, 2.76, and 3.93 for the RW, PRW, and placebo groups, respectively. Both RW- and the PRW-treated group scores were significantly lower than those of the placebo group (p less than 0.01, and p less than 0.025, respectively). The results of the patients' self-evaluations indicated that therapy was effective in 71%, 59%, and 41% for the RW-, PRW-, and placebo-treated groups, respectively. Adverse reactions to treatment were limited to the upper respiratory tract and were noted by all patients. They were significantly more severe in the RW-treated patients than those in the PRW- or placebo-treated groups. We conclude that LNIT is an effective therapy for ragweed allergic rhinitis. The use of a PRW decreased adverse reactions significantly while slightly decreasing the therapeutic benefit.

Administration, Intranasal↗