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Biomedical subjects

J Prescott

Publications and source records attributed to J Prescott.

52 records · Page 3Linked to original sources
PubMed1990

Kava use in Australia.

The use of the traditional South Pacific beverage kava by Australian Aboriginal communities is discussed. There are few systematic data on the effects of kava, although there has been recent concern regarding its health consequences. The role of the traditional context in minimizing any adverse effects of kava is discussed. It is suggested that government intervention in prohibiting kava use is probably inappropriate particularly with our current state of knowledge.

Journal Article↗
PubMed1989

Coordinate increase in collagenase mRNA and enzyme levels in human fibroblasts treated with the tumor cell factor, TCSF.

Cocultures of human fibroblasts and LX-1 human lung carcinoma cells expressed 8-10 fold higher levels of collagenase mRNA than the sum of the individual cells, in parallel with similar increases in collagenase activity. Addition of the tumor cell collagenase stimulatory factor, TCSF, purified from LX-1 cells, to these fibroblasts also gave a 3-4 times increase in collagenase mRNA level. However, various fibroblast cell lines differed in their response to TCSF stimulation. Thus one cell line, GM 1391, did not respond to TCSF but responded to another potent collagenase stimulator, tetradecanoyl phorbol ester. Another cell line 5383 did not respond significantly to either agent. In each case collagenase activity and mRNA levels responded in a parallel fashion.

Cell Line↗
PubMed1988

Event-related potential indices of speech motor programming in stutterers and non-stutterers.

CNVs were recorded from stutterers and non-stutterers prior to spoken words which varied according to the number of syllables, whether the words were the same or different on each trial, and the degree of repetition within the word. The effects of these response parameters on slow potential activity recorded over the speech motor area were evident both prior to, and also during, the response, suggesting that the slow potentials were reflecting both speech pre-programming and ongoing programmed control. Differences between groups were only evident prior to the response, particularly when words were familiar and therefore likely to be entirely pre-programmed. This suggests that stutterers have difficulty in setting up the parameters of the response, rather than in ongoing programmed control.

Adult↗
PubMed1986

The effects of response parameters on CNV amplitude.

The contingent negative variation (CNV) was recorded using an inter-stimulus interval of 4 sec in the context of variations in the parameters of button press responses to be performed following S2. The response parameters manipulated were response duration, the number of fingers used, the number of discrete movements and the complexity of response sequences. The CNVs were averaged with reference to both the stimuli and the response. Variations in response parameters were apparent only in measures of response averaged CNVs. Negativity following response onset was also related to response parameters, again only for response-locked averages. These results support the contention that the CNV, like the Bereitschaftspotential (BP), is primarily related to response factors, and hence that the CNV and the BP are essentially the same phenomenon. It is suggested that the results indicate that negativity prior to, and possibly following, response onset represents the formulation of response-specific motor programs.

Adult↗
PubMed1984

Early and late components of the contingent negative variation prior to manual and speech responses in stutterers and non-stutterers.

The early and late components of the CNV were measured in 18 stutterers and 18 non-stutterers, all dextral, prior to a manual and 3 speech tasks. It was hypothesized that, due to a proposed deficit in articulatory timing, prior to the more complex speech tasks, stutterers would show reduced late CNV amplitudes over Broca's area when compared to the non-stutterers. This hypothesis was not confirmed. In both groups, there was a finding of greater late CNV activity over the right hemisphere prior to speech responses. Explanations for this finding in terms of (a) CNV polarity, and (b) right hemisphere involvement in the speech responses used, are proposed. It is suggested that attention be paid to the nature of the response when attempting to record slow brain potentials prior to speech.

Adult↗
PubMed1984

The augmenting/reducing phenomenon in the auditory evoked potential.

Auditory evoked potentials (AEPs) were recorded to 4 intensities of tones (70, 80, 90, 100 dB) in 22 normal subjects. Augmenting (generally increasing amplitude with increasing stimulus intensity) and reducing (a levelling off or decrease in amplitude with increasing stimulus intensity) were found to occur at both central (Cz, C3, C4) and temporal (T3, T4) placements, regardless of which peak or peak-through measure was examined. There were generally low levels of agreement between central amplitude/intensity response patterns and those at temporal placements. An individual was seldom classified the same way (i.e. augmenter or reducer) when the augmenting or reducing was assessed using different AEP measures. These results suggest that in the AEP the suitability of the conventional definition and the validity of certain interpretations of augmenting/reducing are questionable.

Adult↗