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Biomedical subjects

G Cullen

Publications and source records attributed to G Cullen.

10 recordsLinked to original sources
PubMed1998

Test rig and software for recording force and muscle activity.

OBJECTIVE: To design a test rig for measuring isometric quadriceps' force which is easily adjustable, dismountable, transportable, relatively lightweight and inexpensive. Also to produce a data-acquisition software program that enables real-time feedback of the force signal, automatic analysis of maximal voluntary contraction (MVC) force, and submaximal target levels to be displayed on a computer screen, as well as acquisition of other signals such as electromyographic (EMG) activity. METHODOLOGY: A test rig was constructed using an aluminium tubing system which was fully adjustable and could be flat-packed for transportation. The data acquisition software program was written in Borland C++ and is suitable for use with an IBM-compatible PC. The interface is user friendly, and the entire testing system is relatively inexpensive compared to commercially available systems. CONCLUSIONS: The equipment is suitable for various applications in rehabilitation research and clinical testing, and is suitable for examining different muscles. Further technical details are freely available from the authors.

Electromyography↗
PubMed1993

Pertussis toxin treatment increases glutamate release and dihydropyridine binding sites in cultured rat cerebellar granule neurons.

This study was designed to examine the ability of pertussis toxin to block various responses due to (-)-baclofen in cultured cerebellar granule neurons of the rat. Treatment with pertussis toxin for 3 h markedly reduced the ability of (-)-baclofen to stimulate GTPase in membranes, and its ability to inhibit forskolin-stimulated adenylyl cyclase in intact cells, whereas the ability of (-)-baclofen to inhibit glutamate release was not affected at 3 h, but was abolished after 16 and 48 h treatment with pertussis toxin. The amount of ADP-ribosylation of Gi/Go due to pertussis toxin in intact cells correlated well with the former two effects, but not with the prevention of the ability of baclofen to inhibit glutamate release. Pertussis toxin treatment for up to 48 h did not significantly affect the levels of Gs, Gi and Go in membranes from granule neurons determined by immunoblotting. Pertussis toxin treatment for 16 or 48 h but not 3 h increased the total amount of stimulated release of glutamate by about 40% under normal conditions, and by 84% under depolarizing conditions. In parallel experiments it was observed that pertussis toxin treatment for 16 h increased the number of dihydropyridine binding sites by about 90% on intact granule neurons. Whole-cell calcium channel currents, recorded under several conditions in the cells, were not increased in amplitude by pertussis toxin treatment for up to 48 h, although the ability of baclofen to inhibit calcium channel currents was blocked by pertussis toxin. These results indicate that the pertussis toxin-induced increase in glutamate release may be due to an increase in dihydropyridine binding sites, possibly localized to the presynaptic terminals.

Adenosine Diphosphate Ribose↗
PubMed1991

Quality assurance for cyclosporin assays in body fluids.

The United Kingdom Cyclosporin Quality Assessment Scheme has now over 6.5 years experience of the measurement of cyclosporin. The scheme has more than 154 member laboratories in 30 countries. Each laboratory is sent three samples a month for analysis and the returned results allow the laboratories to measure their performance relative to their peers. The data generated by the centres makes it possible to assess independently the performance of the methods available for the measurement of cyclosporin. The data for the 12 month period June 1989 to May 1990 were analysed. Over that period, the proportion of laboratories using plasma rather than whole blood fell from 9% to 7%. Eight different methods were available for the measurement of the drug but three techniques accounted for over three quarters of the results returned; the specific radioimmunoassays Cyclo Trac-SP (48%), and Sandimmun-SP (21%), and high performance liquid chromatography (8%). The specific immunoassays showed a positive bias, approximately 10%, relative to HPLC when measuring the drug in patient samples. However, there are no data to suggest these differences are of clinical significance and the specific immunoassays can be recommended in preference to HPLC because of their better precision and ease of use. The poor performance of some laboratories and the increasing number of methods available for the measurement of cyclosporin suggest that there is a continuing need for the external quality assessment of this measurement.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Lead poisoning.

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Acute Disease↗
PubMedDate not supplied

A new look.

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Body Image↗