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Biomedical subjects

M D Craggs

Publications and source records attributed to M D Craggs.

15 recordsLinked to original sources
PubMed1992

The effects of AMPA receptor antagonists on kindled seizures and on reflex epilepsy in rodents and primates.

Two potent glutamate antagonists, NBQX and GYKI 52466, that act selectively on non-NMDA receptors, have been tested for anticonvulsant activity in 3 models of reflex epilepsy (sound-induced seizures in DBA/2 mice and in genetically epilepsy-prone rats and photically-induced myoclonus in Papio papio) and in amygdala kindled rats. Both compounds potently but transiently suppress reflexly-induced epileptic responses. GYKI 52466 also reduces behavioral seizures and afterdischarge duration in amygdala kindled rats, but with a lower potency than it suppresses reflex epilepsy. These data are similar to earlier results with antagonists acting selectively on NMDA receptors; they do not support a specific involvement of enhanced AMPA receptor sensitivity as a major factor in the expression of kindled seizures.

Acoustic Stimulation↗
PubMed1976

The stability of the electrical stimulation map of the motor cortex of the anesthetized baboon.

We have made repeated maps of the movements obtained by threshold electrical stimulation, with surface cathodal trains of pulses, of the motor cortex of 4 baboons, using chronically implanted arrays of electrodes. The electrode arrays were judged to remain in a constant relationship with the cortex because they did not move relative to the skull, and the arm/leg border obtained remained stable. There was evidence of a stability of response over a period of weeks. In 3 of the 4 animals, there was stability of the responding digit(s) regardless of the movement made by the digit(s), and of the digital movements performed (regardless of the digits involved). The stability of the map from minute was almost complete. Those variations that occur do so mainly by confusion within the motor homunculus, rather than by its movement as a whole across the cortex. Reasons for the imperfect long-term stability of the map are discussed in terms of variations in the physiological 'set' of the presumed polysynaptic pathways that are stimulated.

Animals↗
PubMed1976

The real bladder electromyogram.

The nature of bladder electrical activity was investigated in anaesthetised cats and 1 baboon. A time-locked muscle response to sacral ventral root stimulation was most clearly detected within a 10-40 Hz frequency band, the response preceding the rise in intravesical pressure. During reflex voiding only activity in the 10-40 Hz band was consistently related to reflex voiding and to the small contractions leading up to voiding. It is concluded that only a very limited part of the wide band electrical activity recorded from the bladder can be considered genuine electromyogram and that the 10-40 Hz frequency band probably excludes the worst of the artefact. Possible sources of artefact and their relation to changes in intravesical pressure are presented in Table I.

Animals↗
PubMedDate not supplied

A preliminary report on a new hydraulic sphincter for controlling urinary incontinence.

A new pressure-regulated artificial urinary sphincter (AUS) has been developed which overcomes many of the deficiencies of earlier devices. This implantable AUS comprises a circular occluder cuff and the means to inflate and deflate through a pressure-regulated valve. The device is made from medical-grade silicone rubber and filled with radio-opaque isotonic fluid. A few days before surgery the implant is coated on the outside with an antibiotic-loaded silicone rubber solution. Tests have shown that the regulated pressure was very easily adjusted in situ by injecting or withdrawing the hydraulic fluid through a hypodermic needle penetrating a self-sealing filling port. When set, the regulated pressure remained very stable. The mechanism by which cuff pressure was increased to overcome stress incontinence worked well. Of the five earlier devices (AUS Mk I) implanted, none has survived without mechanical failure. The two latest implants (Mk II), which were rigorously tested for defects before implantation, have been more successful.

Adolescent↗