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Historically nitric oxide (NO) was viewed as playing a purely paracrine role in the vasculature, acting within the vicinity of its release. Today an endocrine role of NO metabolites is widely accepted, although the species accounting for the vascular regulatory function still remains in contention. The original aim of this thesis was to analyse the two main NO metabolite hypotheses (i.e., SNO-Hb and nitrite hypotheses) to provide a more comprehensive understanding of their potential significance in the human circulation. Initially this involved developing methods capable of measuring baseline levels of NO metabolites in human blood. During this work a major confounding factor was identified influencing the measurement of NO attached to red blood cells/haemoglobin. A means was developed to overcome this via the modification an assay reagent, which was used along with several other methods to analyse NO metabolites in human blood. Ultimately however, levels of SNO-Hb at baseline were on the border of methodological sensitivity, although haemoglobin-bound NO was distinguishable. Consequently my work focused on the potential of nitrite versus haemoglobin-bound NO per se to act as endocrine NO metabolites in the human vasculature. Nitrite metabolism in human whole blood was analysed whilst the vasodilatory properties of nitrite were investigated in relation to the relaxation response observed from native red blood cells under hypoxic conditions. Finally for the first time ever NO metabolites were measured across the coronary and pulmonary vascular beds in the human circulation to address their potential to regulate vascular tone at baseline and under conditions of increased oxygen demand.

Inorganic carbon is fundamental to the physiology of all organisms, however elevated CO2 is generally detrimental. Numerous class III adenylyl cyclases (AC) from both prokaryotic and mammalian organisms have been shown to respond to inorganic carbon in vitro, however, at present there is limited evidence in vivo. This thesis demonstrates in cellulo evidence that hypercapnia CO2 blunts agonist induced cAMP signalling. The eect of CO2 is independent of changes in intracellular and extracellular pH, independent of the mechanism used to activate the cAMP signalling pathway, and is independent of the cell line employed. Through a combination of pharmacological and genetic tools this eect of elevated CO2 on cAMP signalling is demonstrated to require Ca2+ ion release from IP3 receptors in the endoplasmic reticulum. Consistent with these ndings, CO2 caused an increase in cytoplasmic Ca2+ concentrations which require the presence of active IP3 receptors and is absent under comparable acidotic conditions. Physiological relevance for this signalling mechanism is demonstrated through activity of the sodium dependant proton exchanger NHE3. This transporter exhibits well-characterised inhibition by cAMP dependant protein kinase PKA to increase bicarbonaturia in vivo. Overall these results provide conclusive evidence of potentially profound eects of inorganic carbon on intracellular cell signalling, which could lead to signicant insight into the pathophysiology and treatment of numerous disorders including metabolic acidosis, reperfusion injuries, acute lung injury and obesity.

Breath is a mixture of nitrogen, oxygen, carbon dioxide, water vapour, inert gases, and a small fraction of trace volatile organic compounds (VOCs) in the parts per million by volume to parts per trillion by volume range. VOCs can be produced anywhere in the body as a result of physiological and pathophysiological processes, and are transported via the bloodstream to the lungs where they are exhaled in breath. On the basis that VOCs in breath are representative of VOCs in the blood and therefore biochemical processes occurring in the body, the analysis of exhaled breath may become a noninvasive tool for use in clinical practice. This thesis documents the development of the analytical technique of chemical ionisation reaction time-of-flight mass spectrometry (CIR-TOF-MS) for the analysis of VOCs in exhaled breath, exploring the challenges associated with breath sampling to its application in clinical studies. Initial work focused on the design of a suitable breath sampling device that coupled directly to the CIR-TOF-MS instrument to allow the on-line, real-time analysis of breath. The analysis of exhaled breath from healthy individuals allowed a common group of breath VOCs to be identified and quantified. The CIR-TOF-MS system was applied to a number of clinical trials examining the breath of individuals with cystic fibrosis (9 cystic fibrosis children, 4 healthy children), asthma (35 asthmatic subjects, 5 COPD, 28 healthy controls) and cancer (4 female cancer subjects, 10 healthy female controls), for which the latter study required the investigation of off-line breath collection. The analysis of VOCs emitted from bacterial and fungal cultures in vitro was also explored, as a means to support the hypothesis that the measurement of VOCs in exhaled breath could be used to identify infection status in vivo. Within these applications, CIR-TOF-MS was able to demonstrate that the chemical profile of breath has the potential to identify the presence of infection or disease.

In psychiatric illnesses, particularly in the affective disorders, and to a lesser extent in the schizophrenics, there are marked deviations from normal behaviour which have components which may be described, in psychological terms as aberrant, stereotyped, activity and as abnormalities in locomotor and exploratory drives. A hypothesis that a disturbance in one or more of the dopaminergic, noradrenergic or serotonergic neuronal systems in the brain may play a role in psychiatric illness has engendered much research into the functional roles of these systems in animals and man. The published work has been reviewed, particularly that in relation to the behavioural abnormalities which may be induced in lower animals such as the rat and which appear to mimic to some degree the abnormalities in behaviours seen in psychiatric illness in man. The experimental work presented in this thesis is a further contribution to this investigation using an animal model. Previous reports in the literature had, when considered together, indicated that in animals dopaminergic systems played a major role in the mediation of all three types of behaviour monitored - exploratory, locomotor and stereotyped behaviour - with lesser roles being assigned to noradrenergic and serotonergic systems. Individually, the previous studies tended to depend on visual observation of one, or, at most two, of these aspects of behaviour, with exploratory behaviour receiving much less attention than stereotyped or locomotor behaviour. This thesis reports the use of a specially designed automated wholeboard apparatus for the automated recording of exploratory, locomotor and stereotyped behaviour in rats. The automated recordings were backed up by visual observation of behaviour through closed-circuit television monitoring. The behavioural responses to a variety of drugs with varying degrees of selectivity on individual monoamine systems were studied. Amphetamine, which releases all three monoamines from neuronal terminals, at low doses (2 and 4 mg/kg of the DL-sulphate i.p.) led to a stimulation of exploratory and locomotor behaviour as well as sniffing and rearing while a larger dose (8 mg/kg) induced intense stereotyped activity. Baloperidol, a selective dopamine receptor antagonist, virtually abolished both spontaneous and amphetamine-stimulated exloratory, locomotor and stereotyped behaviour in a dose-related manner. Repeated weekly administration of amphetamine led to a potentiation of the response to the drug. Paradoxically, chronic haloperidol pretreatment also led to a potentiation of the response to amphetamine. Phenoxybenzamine (20 mg/kg of the hydrochloride i.p.), and adrenoceptor blocker reduced amphetamine-induced exploratory and locomotor behaviour but not stereotypy. Methysergide, a 5-HT receptor blocker, led to a moderate potentiation of the stimulation of all three behaviours by amphetamine; this was not statistically significant. The "tricyclic" antidepressant drugs desmethylimipramine and chlorimipramine caused a reduction in spontaneous activity which was more marked with the former drug. GPI 654, a selective inhibitor of neuronal 5-HT uptake, induced a moderate stimulation of locomotor and hole-dipping behaviour not statistically significant. Those three drugs, as well as SKF-525A, an inhibitor of the hepaticmicrosomal enzyme systems, all potentiated the behavioural response to amphetamine; this potentiation was in the same rank order as their ability to elevate plasma and brain amphetamine levels. LRCL 5182, a selective inhibitor of neuronal dopamine uptake, and benztropine, an inhibitor of neuronal dopamine uptake which also has potent anticholinergic activity, both induced a marked stimulation of exploratory, locomotor and stereotyped behaviour. Selective bilateral destruction of dopaminergic neuronal terminals in the accumbens nuclei with 6-hydroxydopamine reduced spontaneous and amphetamine-induced locomotor and exploratory behaviour and sniffing activity; amphetamine-induced stereotyped behaviour appeared to be potentiated. Similarly induced bilateral destruction of dopaminergic nerve endings in the caudate-putamen reduced spontaneous activity; amphetamine-induced stereotyped behaviour was abolished. Some animals with severe degrees of neostriatal dopamine depletion were completely unresponsive to amphetamine, apart from intense sniffing activity. Bilateral electrolytic lesions of the accumbens nuclei did not lead to any change in spontaneous or amphetamine-induced activity. Bilateral stereotactically-controlled injections of dopamine (5-50 μg of the hydrochloride salt) into the nucleus accumbens of nialamide-pretreated rats induced a marked stimulation of exploratory and locomotor activity, accompanied by intense sniffing and rearing. Conversely, bilateral injection of dopamine (12.5-50 µg of the hydrochloride salt) into the caudate-putamen induced intense stereotyped activity which was dose-related. The responses were blocked by ip haloperadol. Bilateral injection of noradrenaline (50 μg of the hydrochloride salt) into the accumbens nuclei did not produce any significant behavioural change. The same injection into the caudate-outamen led to a moderate stimulation of stereotyped activity. Bilateral injection of 5-FIT (50 μg of the bimaleinate salt) into the accumbens nuclei induced a moderate locomotor activity with some hole-dipping activity and sniffing; these behaviours were incoordinated and indecisive. The same injection into the caudate-putamen led to a stimulation of locomotor activity and hole-dipping which was predominantly "stereotyped" in character; on visual observation no other striking abnormalities were noted. The experimental results have been critically discussed. It was concluded that dopaminergic inputs into the accumbens nuclei exerted a major mediatory influence on exploratory and locomotor behaviours while dopaminergic inputs into the caudate-putamen were responsible for the mediation of stereotyped activities. The implications of these findings with respect to the behavioural changes in psychotic illness were discussed. On the basis of comparisons between the changes in psychotic illness and the changes in behaviour induced by stereotactic manipulations of the accumbens nuclei and caudate putamen, it was proposed that dopaminergic influences in the accumbens nuclei probably play a major role in the affective disorders, with probable additional involvement of the caudate-putamen in severe illness. Two animal models of mania were proposed based on the stimulation of exploratory locomotor and stereotyped behaviour in animals by amphetamine and the stimulation of locomotor and exploratory activity by application of dopamine into the accumbens nuclei. There were less clear-cut resemblances between the effects of manipulation of the three monoamine systems of behaviour in animals and the behavioural changes seen in the seems irenias. It was suggested that serotonergic influences may be involved in the behavioural changes seen in schizophrenia.

Our knowledge of the endocrine functions of the pituitary gland is comparatively recent. Text-books of physiology published in the late 19th century (e.g. Michael Fost Text-Book of Physiology, 1891 edition) gave a good histological description of the gland, emphasised its ductless nature, but could attribute no definite function to it. The first evidence suggesting any function for the pituitary body was presented by Oliver and Schäfer in 1895. They observed that extracts from the whole pituitary gland had a pressor activity when injected intravenously into the anaesthetised dog. Howell (1898) showed that the substance responsible for this pressor action of pituitary extracts was obtainable only from one part of the organ, and rather surprisingly, only from its posterior, neural lobe. At the time this appeared to be quite an anomalous finding, as the main glandular structures were known to be localised to the anterior lobe of the pituitary.

The change in the pattern of diseases affecting children in industrialised countries during the last century has caused a shift in emphasis from curative to preventive paediatrics. Coronary heart disease (CHD) is one of the major causes of morbidity and mortality in adulthood. Its origins have been shown by epidemiological studies to lie in facets of the Western life style which are biologically disadvantageous. By the time CHD becomes symptomatic, primary prevention is too late; but what is the evidence that by starting these measures in early life benefit would result? The studies described in this thesis were planned to determine whether early deviations from the biological norm occur during childhood for factors known to be associated with CHD in adult life. These factors include blood pressure, personality type, and serum cholesterol. The concentration of cholesterol in serum was chosen because its abnormalities are unequivocally associated with an excess risk of CHD, and because it provides a model for analysis of both genetic and environmental nutritional influences. Although there has been an enormous amount of research into the various influences on serum cholesterol, there is very little data about the subject during the first two years of life when future metabolic homeostatic and nutritional patterns may become established. For that reason a longitudinal study was planned, and the data derived from it was supplemented by cross-sectional studies on older children.

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No description available.