Search PubMed⌕ Search

Biomedical subjects

M D Craggs

Publications and source records attributed to M D Craggs.

At least 19 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↗
PubMed1989

The validation of a new ambulatory spike and wave monitor.

The reliability of a new pocket-size ambulatory monitor designed to automatically detect, indicate, measure and store spike and wave episodes in the EEG was determined. Eleven teenage children with epilepsy were studied. All had spike and wave episodes that were around 3/sec in frequency. A double-blind trial was carried out in which 2 experienced encephalographers scored independently the simultaneous records of the monitor and EEG. Correlation coefficients were calculated and, taking into account any inconsistencies between the 2 scorers' sets of data, a validation based on unity was determined for the monitor's record for each child. Of the 11 children studied only one had a validity measure that was less than 0.9, suggesting that when correctly adjusted for each child the monitor gave a reliable automatic indication of the duration and number of spike and wave events.

Adolescent↗
PubMed1986

A putative non-cholinergic mechanism in urinary bladders of New but not Old World primates.

The effects of atropine on bladder contractions evoked by sacral ventral root stimulation were investigated in two species of New World monkey (marmoset and cebus) and in paraplegic man. The findings were then compared to those previously obtained for the cat and two species of Old World monkey (rhesus and baboon). The results show the marmoset and cebus to represent a transitional stage between the complete sensitivity of the bladders of Old World monkeys to atropine and the relative insensitivity of the cat bladder. The bladder response is shown to comprise two components, an atropine sensitive component which is slow in onset and an atropine resistant component which is easily fatigued. The experiments in paraplegic people confirm that the parasympathetic innervation of the bladder of man is, like that of Old World monkeys, exclusively cholinergic. A behavioural interpretation is tentatively offered to explain the two types of innervation.

Animals↗
PubMed1985

Bladder electromyograms and function in monkeys after atropine.

Voiding induced in conscious monkeys by infusion of sterile saline into the bladder via a chronically implanted bladder catheter was stable over many months. Artefact-free recordings of electrical activity were obtained from the bladder neck and dome of these animals during bladder filling and voiding. Characteristic voiding electromyograms were recorded from both sites but were seen first in the record from the neck. Small doses of methyl-atropine abolished both voiding and the electromyograms; evoked responses to sacral ventral root stimulation were similarly prevented. Therefore the bladders of both man and monkey are very sensitive to atropine, unlike the bladders of most other animals.

Anesthesia↗
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↗