PubMed Health⌕ Search

Biomedical subjects

W V Weber

Publications and source records attributed to W V Weber.

18 recordsLinked to original sources
PubMed1981

Protein rotation, enzyme activity and photooxidation of SH groups in sarcoplasmic reticulum Ca2+-ATPase.

The binding of probe molecules such as fluorescein isothiocyanate, eosin isothiocyanate and erythrosin isothiocyanate to the Ca2+-ATPase of sarcoplasmic reticulum followed by illumination of the labelled protein causes substantial reductions of ATPase activity over a 1-h period. The degree of light-sensitivity induced by these probes is related to the triplet yield of these probe molecules. Consistent with this, the greatest effect is seen with erythrosin isothiocyanate and the least effect with fluorescein isothiocyanate. These reductions of ATPase activity associated with illumination are also associated with an aggregation of the protein molecules. This is indicated by laser flash photolysis measurements and also by polyacrylamide gel electrophoresis. A reduction in the number of thiol groups present on the ATPase molecule parallels the reduction of enzyme activity and changes in the protein mobility. The results are discussed in relation to the use of these probe molecules to study biological systems and also in terms of oxidative processes which may affect protein function in vivo.

Animals↗
PubMed1969

Reflex discharges into thoracic white rami elicited by somatic and visceral afferent excitation.

1. Reflex discharges in white rami (WR) were elicited by single-shock stimulation of dorsal roots (DR), splanchnic (SPL) and intercostal nerves (IC).2. The reflexes have been compared in anaesthetized cats with intact neuraxis, after mid-brain transection and after high cord transection. The brain stem can maintain moderate inhibition of the WR responses, but strong inhibition of IC responses. After cord transection all reflexes are released again.3. Stimulation of ventromedial medullary reticular substance could completely, and independently, inhibit maximal SPL-to-WR and IC-to-WR reflexes.4. Carotid sinus distension did not reduce WR responses, indicating that the major part of the volley is not in vasoconstrictor fibres.5. Central delay of DR-to-WR responses is longer than delay of DR-to-IC responses and is unchanged by transections of the neuraxis at mid-brain or high spinal levels.6. There was no facilitation of WR responses by a prior conditioning volley in the visceral or somatic afferent pathway in contrast to early facilitation of the IC responses.

Animals↗
PubMed1968

Cord cells responding to fine myelinated afferents from viscera, muscle and skin.

1. Micro-electrode recordings were made in the thoracic cord of acute spinal cats. Cells, which were located in the histologically defined lamina 5, responded both to the fine myelinated afferents from the splanchnic nerve and to afferents from the skin. Splanchnic afferents inhibit the effect of converging cutaneous inputs for periods up to 150 msec. Skin stimuli may also inhibit the effect of afferent nerve impulses from viscera. Some cells respond monosynaptically to the splanchnic afferents, others indirectly.2. Fine myelinated afferents from gastrocnemius (group 3) stimulate lamina 5 cells which also have cutaneous receptive fields. Cutaneous and group 3 muscle afferents interact by mutual inhibition in their effect on the cells.3. Fine myelinated afferents from skin excite lamina 5 cells. The cutaneous responses of lamina 5 cells contrast with those of lamina 4 cells in the following respects: (a) the receptive fields are larger, (b) they respond with an increased latency to Abeta afferents, (c) there is a low pressure threshold at the edge, (d) they respond to a wide range of pressure stimuli from light brush to heavy pinch applied to the centre of the receptive fields and (e) they respond to ADelta afferents.4. Lamina 5 cells receive fine myelinated afferents either from viscera or from muscle or from skin. Lamina 4 receives large myelinated afferents from skin and lamina 6 receives large myelinated afferents from muscle. The results suggest the hypothesis that some fine myelinated afferents form a class of afferents which signal the state of tissue, and end on lamina 5 cells.

Animals↗