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Biomedical subjects

M A Lieberman

Publications and source records attributed to M A Lieberman.

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

Growth inhibitory protein(s) in the 3T3 cell plasma membrane. Partial purification and dissociation of growth inhibitory events from inhibition of amino acid transport.

It has been reported previously that a plasma membrane-enriched fraction from 3T3 cells arrests the growth of sparse 3T3 cells early in the G1 phase of growth (Whittenberger et al., '78, '79). Addition of membranes to sparse 3T3 cells also results in a decrease of the rate of transport of alpha-aminoisobutyric acid (Lieberman et al., '79). We have partially purified the growth-inhibitory proteins from plasma membrane of 3T3 cells. These growth-inhibitory proteins behave as intrinsic membrane proteins and do not require membrane lipids for activity. The partially purified proteins arrest cell growth without affecting the rate of alpha-aminoisobutyric transport; thus, inhibition of both transport and cell growth are not obligatorily coupled events.

Aminoisobutyric Acids↗
PubMed1981

Density-dependent regulation of cell growth: an example of a cell-cell recognition phenomenon.

Cell-to-cell contact can result in a variety of changes in the cell's physiology. For different cell types, this may include both the initiation as well as the cessation of cell growth and changes in the state of differentiation. This review examines in detail one such phenomenon, density-dependent inhibition of growth, which is observed with many fibroblasts in culture. Data are summarized which demonstrate that the cessation of growth at high cell density is in part a consequence of cell-to-cell contact. An approach to the study of the molecular basis of this phenomenon is presented based on the demonstration that plasma membranes, when bound to sparse growing cells, mimic contact inhibition of growth. The present status of attempts to purify plasma membrane proteins responsible for this effect are summarized, and the properties of these membrane proteins are compared to those of previously described "soluble" proteins that inhibit cellular growth.

Animals↗
PubMed1981

The stress process.

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Adaptation, Psychological↗
PubMed1979

Effect of plasma membranes on solute transport in 3T3 cells.

Sparse cultures of Swiss 3T3 cells are arrested early in the G1 phase of growth by the addition of a plasma membrane fraction obtained from confluent 3T3 cells. We have examined whether the changes in solute transport which are usually associated with cessation of growth at confluency also take place when cell growth is arrested by the addition of plasma membranes. We find that the rate of uptake of alpha-aminoisobutyric acid and uridine is decreased after the addition of plasma membranes to 3T3 cells, but the rate of uptake of 2-deoxyglucose and phosphate is not. We conclude from these observations that uptake of uridine and alpha-aminoisobutyric acid are related to contact inhibition of growth, while the decline in the rate of uptake of 2-deoxyglucose and phosphate observed at high cell density must be due to changes other than cell to cell contact.

Aminoisobutyric Acids↗
PubMed1979

The psychotherapeutic impact of women's consciousness-raising groups.

The psychotherapeutic impact of women's consciousness-raising (CR) groups was assessed for 32 women entering groups formed in suburban, middle-class communities. Changes occurring over a six-month period were examined through pre-CR group and follow-up questionnaires and intensive interviews. Women increased in self-esteem and identification with the Women's Movement, but symptom distress was not alleviated, nor were marital relationships affected. While women expressed more positive self attitudes with greater feelings of autonomy and assertiveness, few participants manifested life-style or behavioral changes. The CR groups in this study thus served a limited psychotherapeutic function. In addition, CR and professional psychotherapy were seen as complementary and not as antagonistic help-giving systems.

Adult↗
PubMed1979

Requirements of acetyl phosphate for the binding protein-dependent transport systems in Escherichia coli.

In Escherichia coli, acetyl phosphate can be formed from acetyl-CoA via the phosphotransacetylase (phosphate acetyltransferase; acetyl-CoA:orthophosphate acetyltransferase, EC 2.3.1.8) reaction and from acetate (plus ATP) via the acetate kinase (ATP:acetate phosphotransferase, EC 2.7.2.1) reaction. By restricting acetyl phosphate formation to the phosphotransacetylase reaction alone, through the use of metabolic inhibitors, we were able to show that, with pyruvate as a source of energy, mutants defective in phosphotransacetylase are unable to transport glutamine, histidine, and methionine. However, with the same energy source, mutants defective in acetate kinase are normal in the transport of these amino acids. The inability of the phosphotransacetylase mutants to transport is due to their presumed inability to form acetyl phosphate, because pyruvate is found to be metabolized to acetyl-CoA in these mutants. Thus acetyl phosphate has been implicated in active transport. Evidence is also presented that neither the protonmotive force nor the ecf gene product is required for the shock-sensitive transport systems.

Acetates↗
PubMed1978

Does help help? The adaptive consequences of obtaining help from professionals and social networks.

This study reports on a longitudinal analysis of changes in adaptation associated with seeking help on a representative sample of Chicago area adults who had experienced one of three transitions or four crises during the interval between 1972 and follow-up 1976--77 interviews. For each event, respondents are classified into three groups according to their help-seeking behavior: those who went to professionals, those who went only to their social networks, and those who had the event but sought no help. Nine measures of adaptation are used: symptoms of anxiety and depression and strains and stresses in four role areas. Statistical controls equate the groups on demographic characteristics, perceived stress, personal resources, access to help, and elapsed time since the event. There are no consistent statistical significant differences among the groups. No evidence is found that help-seeking has positive adaptive consequences. The findings are not likely to result from an inadequate sample, outcome measures, or statistical controls, but could result from insufficient information on the kind, quality, and duration of the help provided.

Adaptation, Psychological↗
PubMed1978

Inhibition of growth of 3T3 cells by extract of surface membranes.

The growth of Swiss 3T3 cells can be inhibited by the addition of a plasma membrane enriched fraction from 3T3 cells [Whittenberger, B & Glaser, L. (1977) Proc. Natl. Acad. Sci. USA 74, 2251--2255]. We report conditions for the extraction of the inhibitory components from the membranes with octylglucoside. The solubilized components reversibly inhibit the rate of cell division of 3T3 but not of simian virus 40-transformed 3T3 cells. The inhibitory activity is heat labile and nondialyzable. The inhibition observed with the soluble extract can be reversed by mitogenic factors present in serum.

Cell Division↗
PubMed1977

Energy coupling factor as target of colicin K: characterization of a colicin K-insensitive ecf mutant of Escherichia coli.

We isolated a colicin K-insensitive energy uncoupled mutant of Escherichia coli. This mutant was presumed to be an ecf mutant as evidenced by its similarity to a known ecf mutant (M. A. Lieberman and J.-S. Hong, 1974) with respect to the mutational site, reversion pattern, and defects in transport and growth. The mutation conferring the colicin K-insensitivity resided in the ecf gene as the majority of the secondary mutations overcoming the ecf phenotype reverted the colicin K-insensitive phenotype to colicin K-sensitive. The insensitivity of the mutant to colicin K was not due to either a defect in adsorption or to a lack of the energized membrane state. The defect was most probably due to the inability of colicin K molecules to interact with their target. Our previous studies concerning the role of the ecf gene product in energy coupling to active transport and oxidative phosphorylation support the contention that the ECF protein is itself the direct target of colicin K.

Bacterial Proteins↗
PubMed1976

Institutional alternatives to psychotherapy. A study of growth center users.

Are growth centers used as alternative institutions to traditional mental health facilities? Survey methods compared growth centers (N=426) and National Training Laboratories (N=108) participants with clinic patients (N=89). Symptoms, life stress, motivations for participation, process expectations, and various attitudes toward authority, time, and help were assessed prior to participation. Comparisons on degree of psychological distress and avowed motivation indicated that most who attend such activities do so for "psychotherapeutic purposes." Growth centers were found not to be an alternative to traditional psychotherapy, but rather an addition. Eighty percent of the growth center sample had previous or current psychotherapeutic experience. Of the people studied, most go to both rather than to one or the other, and from the perspective of the participants, the institutions do not differ greatly in what they offer, how long the process will take, or what goals will be met.

Adolescent↗