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Biomedical subjects

I J Frew

Publications and source records attributed to I J Frew.

5 recordsLinked to original sources
PubMed1999

Nitric oxide donors selectively potentiate thrombin-stimulated p70(S6k) activity and morphological changes in Swiss 3T3 cells.

Thrombin stimulates both DNA synthesis and cell morphological changes in Swiss 3T3 cells, although the mechanism of signal coordination leading to these responses is unknown. We report here that nitric oxide (NO) donors selectively enhance thrombin-stimulated p70(S6k) activity by 40-60%, an effect that was sustained for 24 h. Potentiation of p70(S6k) also was observed with cGMP analogues indicating that this effect is mediated by cGMP-activated protein kinase. NO donors also induced morphological changes characterized by spindle-shaped cells in confluent, nondividing cells or by extended protrusions from the trailing edge in subconfluent, polarized cells. NO donors had no significant effects on intracellular Ca(2+) mobilization, DNA synthesis, proliferation, or ERKs 1 and 2 and p90RSK activities, indicating that mitogenic responses and cell division are not altered by NO donors. We conclude that NO donors modulate the morphological changes associated with cellular motility in response to thrombin stimulation through selective enhancement of p70(S6k) activity.

3T3 Cells↗
PubMed1997

Competition by second messenger systems for receptor interaction and activation: implications for tissue-specific responses and disease therapy.

1. At any one instant, most receptors are now recognized to be able to stimulate multiple signal transduction pathways in a cell when activated by an appropriate hormone. These different signalling pathways appear to allow for distinct cellular responses, such as cell proliferation, differentiation, and shape change. 2. In addition, many different types of cell will possess the same type of receptor. Therefore, for a hormone to be able to transmit differential signals to the various cell types able to respond to it, cells must discriminate the stimulus at some point. Such discrimination would seem to be an absolute requirement to allow a tissue-specific response to an identical initial stimulus. In theory, this specificity could occur at many points in the receptor signal transduction cascade, including cytosolic receptor coupling systems and tissue/cell-specific responsive genes. 3. The present paper summarizes our work and that of others which has determined some of the coupling systems of G-protein-coupled receptors and tyrosine kinase receptors and how these systems may be interacting. 4. In addition to these theoretical considerations, a potential therapeutic strategy underlies the ability of receptors to couple to more than one signal transduction system. If a response to a hormone were, for example, either cell proliferation or cell morphological change or differentiation and separate receptor-coupled signalling systems were responsible for these effects, pharmacological intervention may allow the transfer from one signalling system to another. If such a change allowed a permanent change to the differentiated phenotype, this could potentially form the basis of a signal-based cancer therapy.

Animals↗
PubMed1976

Betahistine hydrochloride in Méniére's disease.

A double-blind, placebo-controlled, cross-over clinical trial was performed to assess the effect of betahistine hydrochloride (Serc) in Ménière's disease. The diagnosis was based on paroxysmal attacks of rotational vertigo, with tinnitus, and a fluctuating sensori-neural deafness, together with the results of auditory and vestigular tests. Twenty-eight patients were admitted to the trial over 3 years. Twenty-two patients completed the trial. In total, they received betahistine 32 mg daily, for a period of 16 weeks, and placebo also for the same length of time, preceded in every case by a 4-week pre-treatment period. Daily symptom score cards were kept. There was a statistically significant improvement in favour of the drug with regard to vertigo, tinnitus and deafness. Vertigo was the most responsive symptom. No adverse reactions were observed.

Adult↗