Search PubMed⌕ Search

Biomedical subjects

B Wilson

Publications and source records attributed to B Wilson.

At least 217 records · Page 12Linked to original sources

Success and failure in memory training following a cerebral vascular accident.

This paper describes the treatment offered to a 51 year old man suffering from a severe memory deficit which followed a bilateral stroke. The aims of treatment were: (a) to improve memory generally and (b) to find ways to help him retain new information in 4 specific problem areas namely remembering: (i) his daily timetable, (ii) people's names, (iii) a shopping list, and (iv) short routes. A multiple baseline procedure was used to investigate this. At the end of the treatment period only slight improvement was found in his memory generally, although on a motor memory task he improved steadily throughout. Strategies were found to help him with 3 of the 4 specific problems. The fourth--remembering short routes--was resistant to all the strategies tried. The paper discusses the effectiveness of treatment, the nature of the lesion and how this case contributes towards our understanding of human memory and forgetting.

Amnesia↗

Proton motive force and the physiological basis of delta pH maintenance in thiobacillus acidophilus.

At optimal growth pH (3.0) Thiobacillus acidophilus maintained an internal pH of 5.6 (delta pH of 2.6 units) and a membrane potential (delta psi) of some +73 mV, corresponding to a proton motive force (delta p) of -83 mV. The internal pH remained poised at this value through external pH values of 1 to 5, so that the delta pH increased with decreasing external pH. The positive delta psi increased linearly with delta pH: above a delta pH of 0.6 units, some 60% of the increase in delta pH was compensated for by an opposing increase in delta psi. The highest magnitude of delta pH occurred at an external pH of 1.0, where the cells could not respire. Inhibiting respiration by CN- or azide in cells at optimal pH decreased delta pH by only 0.4 to 0.5 units and caused a corresponding opposite increase in delta psi. Thus, a sizable delta pH could be maintained in the complete absence of respiration. Treatment of cells with thiocyanate to abolish the delta psi resulted in a time-dependent collapse of delta pH, which was augmented by protonophores. We postulate that T. acidophilus possesses unusual resistance to ionic movements. In the presence of a large delta pH (greater than 0.6 pH units), limited diffusion of H+ into the cell is permitted, which generates a positive delta psi because of resistance to compensatory ionic movements. This delta psi, by undergoing fluctuations, regulates the further entry of H+ into the cell in accordance with the metabolic state of the organism. The effect of protonophores was anomalous: the delta p was only partially collapsed, and respiration was strongly inhibited. Possible reasons for this are discussed.

Azides↗

The control of peroxidase-catalysed iodination and de-iodination.

It has been demonstrated that the H2O2/l ratio is a critical factor in the control of iodination and de-iodination of covalently bound tyrosyl residues in proteins and free iodotyrosines by peroxidase enzymes. This has been shown for myeloperoxidase (MPO) isolated from normal human polymorphonuclear lymphocytes in particular, and also for peroxidase of animal origin such as thyroid peroxidase (TPO) and lactoperoxidase (LPO). It has been shown that the H2O2/l ratio exerts a controlling influence on MPO-catalysed reactions of fully iodinated tyrosines, e.g. di-iodotyrosine, and of partially and completely iodinated thyronines such as thyroxine and tri-iodothyronine. Using an in vivo model system it has been shown that MPO catalyses the sequential events of iodination, iodine exchange and de-iodination of tyrosines and, furthermore, that all three reactions are influenced by the rate of H2O2 generation and the iodide concentration of the reaction medium. The action of MPO on iodothyronine substrates only affects de-iodination irrespective of whether the iodothyronine is partially iodinated, as in tri-iodothyronine, or completely iodinated, as in thyroxine. This MPO-catalysed de-iodination of thyroxine and tri-iodothyronine can also be regulated by the H2O2/l ratio. Moreover, the results show that MPO-catalysed iodine exchange can only occur in completely iodinated tyrosines such as di-iodotyrosine (DIT). Iodine exchange in partially iodinated tyrosines such as mono-iodotyrosine (MIT) or in iodothyronines (T3 and T4) cannot be catalysed by MPO irrespective of the H2O2/l ratio. These results introduce a new concept which may be important in understanding the control of thyroid activity in thyroid disease and the control of MPO activity in biological defence mechanisms in man.

Animals↗

Put it in writing.

Explore the source record for details and available documents.

Communication↗