PubMed Health⌕ Search

Biomedical subjects

G N Martin

Publications and source records attributed to G N Martin.

18 recordsLinked to original sources
PubMed1998

Human electroencephalographic (EEG) response to olfactory stimulation: two experiments using the aroma of food.

The present studies sought to examine the effect of olfactory stimulation on human Central Nervous System activity. In the first experiment (n = 21), EEG response to the 'synthetic' odours of chocolate, spearmint, almond, strawberry, vegetable, garlic and onion, and cumin or no odour was recorded from 19 electrodes (F3, F4, F7, F8, Fz, T3, T4, T5, T6, P3, P4, Pz, O1, O2, C3, C4, Cz) in all EEG frequencies (delta, theta, alpha, beta1 and beta2). Exposure to the odour of chocolate was associated with significant reductions in theta activity when compared with the odours of almond and cumin, with a trend towards significance when compared with no-odour control. Exposure to the odour of spearmint was associated with a significant reduction in EEG theta when compared with the no-odour control. No significant effects were observed in other frequencies. In a second experiment (n = 15), EEG response to the odours of real foods (chocolate, baked beans, rotting pork) and two controls (no odour and hot water) was recorded as in Experiment 1. The odour of chocolate was associated with significantly less theta activity than was any other stimulus. It is hypothesised that the alterations in theta reflect shifts in attention or cognitive load during olfactory perception, with a reduction in theta indicating a reduced level of attention.

Adolescent↗
PubMed1996

Olfactory remediation: current evidence and possible applications.

A number of recent psychological investigations has suggested a significant role for olfactory stimulation in the alteration of cognition, mood and social behaviour. These orthodox investigations have a common, if uneasy, relationship with the holistic practice of so-called aromatherapy. This paper reviews the therapeutic effects of dour on health-related behaviour. It distinguishes two types of research activity, one which is quantitative and science- and medicine-based, the other which is qualitative and anecdote- and experience-based. Both of these endeavours are critically assessed and suggestions are made for improvement in methodology and experimental design.

Aromatherapy↗
PubMed1996

The effects of audience laughter on men's and women's responses to humor.

Forty participants (20 men and 20 women) listened individually to a recording of a radio comedy show under one of two conditions: an experimental condition, with audience laughter present, or a control condition, with laughter absent. While the participants were listening to the tape, their spontaneous responses were covertly videotaped so that the frequency of laughter and smiling could be measured. After listening to the program, the participants rated the material for funniness and enjoyment. Those participants who listened with laughter present gave significantly higher ratings of the funniness and enjoyability of the recording. Moreover, they laughed and smiled more in the experimental condition, although the score for the difference in smiling failed to reach significance. In contrast with some published studies, no differences between men and women were found--a result that is attributed to the greater ecological validity of the context and to the stimuli used in the present study.

Adult↗
PubMed1991

The effects of adenosine triphosphate (ATP) and related purines on human isolated subcutaneous and omental resistance arteries.

1. Human resistance arteries were obtained from specimens of omentum and subcutaneous fat removed at surgery. They were studied in vitro by use of a myograph technique to determine the effects of purines on the arteries. 2. In preparations where tone had been raised with noradrenaline, low concentrations (1 nM-1 microM) of adenosine triphosphate (ATP) and 2-methylthioATP, but not alpha,beta-methyleneATP, produced concentration-dependent relaxation. There was a lack of relationship between the relaxation response to acetylcholine and that to ATP. 3. In preparations under basal tone, high concentrations (1 microM-1 mM) of ATP, 2-methylthioATP and alpha,beta-methyleneATP produced concentration-dependent contractions. 4. The rank order of potency of the purine nucleotide analogues for the relaxation response was 2-methylthioATP > ATP > alpha,beta-methyleneATP and for the contractile response it was alpha,beta-methyleneATP > ATP = 2-methylthioATP. 5. Adenosine produced concentration-dependent relaxation in preparations under raised tone and was less potent than ATP but did not produce contraction in preparations at basal tone. Relaxation responses to adenosine, but not to ATP, were antagonized by 8-phenyltheophylline. 6. These results indicate the presence of vasodilator P2y- and P1-purinoceptors and vasoconstrictor P2x-purinoceptors on human resistance arteries isolated from omental and subcutaneous sites.

Adenosine Triphosphate↗
PubMed1989

Postjunctional alpha 2-adrenoceptors mediate vasoconstriction in human subcutaneous resistance vessels.

1. In vitro studies have been performed on human medium-sized muscular arteries (internal diameter 1-4 mm) in a classical organ bath and with human subcutaneous resistance arteries (internal diameter 103-626 microns) in a microvascular myograph. 2. Although the medium-sized muscular arteries showed no response to either of the alpha 2-agonists B-HT 933 or UK 14304 in concentrations up to 10 microM, the subcutaneous resistance arteries from all regions examined showed well-pronounced and concentration-dependent responses to B-HT 933, the pD2 (-log EC50) being 5.11 +/- 0.09. 3. In the resistance arteries the alpha 2-antagonist yohimbine caused a parallel shift to the right of the B-HT 933 concentration-response curve; the yohimbine pA2 for the B-HT 933 receptor was 7.86 +/- 0.12. 4. There was an inverse relationship between the maximum response to B-HT 933 and the calibre of the resistance vessels. 5. These results indicate the presence of a postjunctional alpha 2-adrenoceptor in human subcutaneous resistance arteries and not in medium sized muscular arteries.

Adult↗
PubMed1989

Human vascular responses to endothelin-1: observations in vivo and in vitro.

These studies have investigated the effect of endothelin-1 (ET-1) on human resistance vasculature in vivo and in vitro. ET-1 was infused via the brachial artery and forearm blood flow (FBF) measured by venous occlusion plethysmography. Isolated resistance vessels were studied in a myograph. ET-1 (10 pmol-10 nmol/min, i.a.) reduced forearm blood flow. Endothelin-1-induced forearm vasoconstriction was slow to recover following washout. ET-1 (10 pM-10 nM) contracted isolated human subcutaneous and omental resistance vessels. Contractile responses to ET-1 were sustained and washout recovery was slow. Responses to ET-1 displayed marked tachyphylaxis. Calcium channel blockers and removal of extracellular calcium failed to completely abolish responses to ET-1 in vitro.

Adult↗
PubMed1988

Size and site-dependent heterogeneity of human vascular responses in vitro.

Ring segments of splanchnic, peripheral, coronary, pulmonary and uterine conduit arteries obtained during surgery were studied in tissue baths. Resistance arteries dissected from various sites were studied in a myograph. Both conduit and resistance vessels contracted in response to the alpha 1-agonist phenylephrine (10(-7) to 10(-4) mol/l), an effect that was antagonized by the alpha 1-antagonist doxazosin (10(-8) to 10(-6) mol/l). However, the alpha 2-agonists BHT 933 (10(-7) to 10(-4) mol/l) and UK 14304 (10(-7) to 10(-4) mol/l) only contracted the resistance vessels and not the conduit arteries. The response to BHT 933 was competitively antagonized by the alpha 2-antagonist yohimbine (3.10(-8) to 3.10(-7) mol/l) and the magnitude of the contractile response was inversely related to vessel size. Similarly, neuropeptide Y (10(-9) to 10(-6) mol/l) contracted only the resistance vessels, and induced marked tachyphylaxis. Atrial natriuretic peptide (ANP; 10(-8) to 10(-6) mol/l) produced concentration-dependent relaxation in all conduit arteries studied, being ineffective in resistance arteries from subcutaneous or omental sites, but relaxed those from renal tissue and skeletal muscle. Calcitonin gene-related peptide (10(-8) to 10(-6) mol/l) and vasoactive intestinal peptide (10(-9) to 10(-6) mol/l) relaxed both conduit and resistance arteries. This response was dependent on the integrity of the endothelium in the systemic conduit but not the resistance vessels. These results indicate that the receptors for adrenergic agonists and vasoactive peptides are varyingly distributed throughout the human vasculature.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗
PubMed1985

The release of the endothelium derived relaxing factor from isolated human arteries.

Isolated human arterial segments have been used to demonstrate the presence and release of the endothelium derived relaxing factor (EDRF) in human vasculature. This has been shown in peripheral, splanchnic and coronary arteries. Agents which have been shown to promote the release of the human EDRF in these studies include acetylcholine (by a muscarinic mechanism), the calcium ionophore A23187, histamine and vasoactive intestinal peptide (VIP). Nordihydroguaretic acid (NDGA), methylene blue and haemoglobin reverse the effect of the EDRF. The EDRF effect is calcium-dependent and is not inhibited by indomethacin. Atheromatous disease in coronary arteries impairs the response to agents which release EDRF; its relative absence in this circumstance may play a role in the phenomenon of coronary artery spasm. The possibility of a specific alpha 2-adrenoceptor mechanism for the release of EDRF was investigated. This does not appear to be present in the human vasculature.

Adolescent↗
PubMed1975

Saliva stimulation in dogs with permanent duct fistulae.

Saliva fluids were collected from catheters inserted in the duct openings of permanent paratid and sublingual duct fistulae prepared in dogs. In anesthetized dogs stimulants applied to the tongue had no effect on saliva output. In awake dogs topically applied sucrose (1.25%-20%) had no significant stimulating effect on salivary secertion when compared to water control responses. Citric acid (1.25%-20%), applied topically, resulted in dose-related fluid increases, with parotid volumes consistently higher than sublingual volumes. Pilocarpine (0.125 mg/kg, IV), elicited similar saliva volumes in awake and anesthetized animals; sublingual secretions were higher than parotid volumes. For comparing drug secretion or saliva composition in awake and anesthetized animals, use of the same, preferable an IV, stimulant administered on a milligram perper-kilogram basis is suggested.

Administration, Topical↗