PubMed Health⌕ Search

Biomedical subjects

F H Marriott

Publications and source records attributed to F H Marriott.

7 recordsLinked to original sources
PubMed1995

Heart rate variation, age, and behavior in subjects with senile dementia of Alzheimer type.

Minute-by-minute heart rate (HR) recordings over a period of 24 h were obtained once for 30 elderly subjects diagnosed as having senile dementia of Alzheimer type (SDAT). Twenty-one of the subjects were studied in a hospital ward setting, and nine were studied in their own homes. Twelve were men and 18 were women. Eleven took some form of sedative medication; 10 took no medication. Thirty-minute mean values were unmasked to take account of the effects of activity and sleep on HR. Results indicate that the masked HR circadian rhythm of SDAT may be more often unimodal than that of normal subjects of similar age, and that phase shift of the endogenous, clock-mediated component of the rhythm (with higher HR at night) is to be expected in a proportion of individuals with SDAT.

Age Factors↗
PubMed1991

Potentiation of neuronal responses to natural visual input paired with postsynaptic activation in the hippocampus of the awake monkey.

Extracellular recordings were made in the hippocampal formation while the monkey performed a simple visual discrimination task in which the stimuli consisted of coloured patterns presented serially. By using this natural visual input to single hippocampal neurones, and experimentally pairing one of the stimuli with postsynaptic excitation induced by iontophoretically applied L-glutamate, we demonstrate that selective synaptic potentiation can result. Seven of 29 neurones tested showed potentiation. The potentiation was selective in that enhanced responses only occurred to the previously paired stimulus, and not to other visual stimuli. The potentiation was observed in CA3 neurones and lasted approximately 15 min. In each case the latency of the potentiated response occurred at 160 ms following the onset time of the stimulus.

Animals↗
PubMedDate not supplied

Evaluation of censored contamination data.

Laboratory measures of low-level contamination are typically strongly skewed, and observations below a specified detection limit are recorded merely as not detectable or less than a specified limit. In these circumstances, a full description of the distribution requires assumptions about the form of the lower tail. If such assumptions are made, the distribution can be described in terms of the usual parameter estimates. The assumptions can be checked if similar samples can be accurately assessed using specialized equipment with a very low detection limit. Methods of fitting suitable distribution to data of this sort are discussed, and evaluated using results from a laboratory with equipment capable of measuring very low contamination levels. Estimates based on the complete data are compared with estimates based on assumed detection limits.

Animals↗