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Biomedical subjects

T Jones

Publications and source records attributed to T Jones.

At least 451 records · Page 25Linked to original sources
PubMed1983

In vivo measurements of regional cerebral blood flow and blood volume in patients with brain tumours using positron emission tomography.

In 21 patients with cerebral tumours regional cerebral blood flow (rCBF) and blood volume (rCBV) were measured. In the tumours, blood flow and volume were variable and unrelated even in tumours of the same type and grade. In the contralateral grey and white matter a (linear) relationship was found between rCBF and rCBV. Following operation, rCBF and rCBV in the contralateral hemisphere may increase due to lowering of intracranial pressure. Preliminary data shows that both factors decrease following whole brain irradiation.

Adult↗
PubMed1983

Pharmacological study of the effects of leukotrienes C4, D4, E4 & F4 on guinea pig trachealis: interaction with FPL-55712.

Leukotrienes D4 greater than C4 greater than E4 greater than F4 produced qualitatively similar contractions of guinea-pig trachealis, which were antagonized by the SRS-antagonist FPL-55712. Schild analyses indicated that FPL-55712 when tested in a low concentration range (0.57 - 5.7 X 10(-6) M) was a competitive antagonist of LTC4, LTE4 and LTF4 (slope not significantly different from one). The interaction of FPL-55712 with LTD4 may be noncompetitive (slope less than 1). Comparison of the calculated dissociation constants (-log KB) indicated that FPL-55712 was more effective at blocking LTE4 and LTF4 compared to LTC4 and LTD4. In the presence of higher concentrations of FPL-55712 (1.9 X 10(-5) M) the antagonism of LTC4 became noncompetitive. These findings indicate that important differences exist in the interaction of FPL-55712 with the various peptido leukotrienes in guinea pig trachealis. Discovery of more selective antagonists will be needed to determine if multiple receptor subtypes are present in this tissue.

Animals↗
PubMed1983

The morbidity and utility of periaortic radiotherapy in cervical carcinoma.

From 1971 through 1981, 81 women received 4350 to 5075 rad to the periaortic lymph nodes as part of their primary management for carcinoma of the uterine cervix. While two patients developed chronic small bowel damage, only one required surgical intervention. Five-year disease-free survival was 40%. Approximately one-third of the first recurrences were within the pelvic and periaortic radiation portals, with the remainder in the lungs, liver, bones, abdomen, and supraclavicular lymph nodes. Radiation dose and volume guidelines are presented in order to minimize enteric morbidity.

Adenocarcinoma↗
PubMed1983

Correction for the presence of intravascular oxygen-15 in the steady-state technique for measuring regional oxygen extraction ratio in the brain: 1. Description of the method.

The oxygen-15 steady-state inhalation technique provides quantitative values of regional cerebral blood flow, fractional oxygen extraction, and oxygen utilisation. These last two, however, have been found to be higher than those reported using arteriovenous difference techniques. On theoretical grounds, this overestimation is due to the signal from nonextracted intravascular oxygen-15. In this paper, a method is presented to correct for this intravascular component utilising a measurement of regional cerebral blood volume. The statistical penalty imposed as a result of this correction is defined.

Blood Volume↗
PubMed1983

Correction for the presence of intravascular oxygen-15 in the steady-state technique for measuring regional oxygen extraction ratio in the brain: 2. Results in normal subjects and brain tumour and stroke patients.

Values of regional cerebral oxygen extraction ratio and oxygen utilisation obtained with the oxygen-15 steady-state inhalation technique have been found to be overestimated due to the signal from intravascular oxygen-15. A previously described method to correct for this intravascular component has been applied to a series of studies on normal subjects, and on brain tumour and stroke patients. With this correction the regional cerebral oxygen extraction ratio in normals becomes comparable to the global values previously reported with arteriovenous sampling techniques. Within the lesions of brain tumour and stroke patients, the corrections have been found to be variable and often substantial. It is concluded that failure to apply this correction may result in major errors in the values for regional oxygen extraction ratio and oxygen utilisation. This is especially true when the regional blood flow and oxygen extraction ratio of a tissue is low and regional blood volume is high.

Blood Volume↗
PubMed1983

Serial observations on the pathophysiology of acute stroke. The transition from ischaemia to infarction as reflected in regional oxygen extraction.

Regional cerebral blood flow, fractional oxygen extraction and oxygen metabolism have been measured in 34 patients after acute nonhaemorrhagic cerebral hemispheric infarction. Nine cases showed elevated oxygen extraction in the region of the early infarct, and these were the patients studied earliest after the onset of stroke. The results of serial studies to follow the evolution of the pathophysiology of acute stroke in these 9 patients are presented. The elevated oxygen extraction within the early infarct showed a significant reduction over the week following the onset of stroke. The reason for this fall in the fractional use of available oxygen varied in individual cases, and at the extremes was associated with a marked reduction in oxygen metabolism with a further small fall in residual blood flow, or a return of flow without recovery of oxygen metabolism. The significance of oxygen extraction in terms of potential viability of the tissue is discussed. The finding of a lower oxygen extraction in subcortical grey and white matter compared to cortex within the first hours or days of a major stroke is considered indicative of an earlier change from ischaemia to infarction in the deep tissues, probably related to the anatomy of the microvasculature. The interpretation of the results in the light of knowledge accumulated from studies of ischaemia in animals is presented, and problems imposed on data analysis by current limitations in positron emission tomography are discussed.

Adult↗
PubMed1983

An interictal study of partial epilepsy using positron emission tomography and the oxygen - 15 inhalation technique.

Data from ten patients with complex partial seizures who underwent positron emission tomography using the 15-0 inhalation technique are presented. Decreased flow and metabolism are noted in the hemisphere ipsilateral to the EEG focus, but, in patients with unilateral foci, bilateral changes in temporal cortex are detected. Other areas maximally affected include the basal ganglia, and the cerebellum. The possible role of anticonvulsant drugs in these findings is discussed.

Adult↗
PubMed1982

Measurement of regional cerebral blood flow and oxygen utilisation in patients with cerebral tumours using 15O and positron emission tomography: analytical techniques and preliminary results.

Regional cerebral blood flow and oxygen utilisation have been studied in 8 patients with brain tumours using continuous inhalation of C15O2 and 15O2 and positron emission tomography. The methods used to analyse the regional cerebral pathophysiology are presented. A relative uncoupling between oxygen consumption and blood flow was observed in all tumours as indicated by a decreased regional fractional extraction of oxygen (rOER). This suggest that a major proportion of these tumours had sufficient blood supply to meet oxygen metabolic demand. A decrease of blood flow in grey matter was found both in the affected and contralateral hemispheres of the brain. Matched reductions of flow and oxygen utilisation were observed in oedematous tissue.

Aged↗
PubMed1982

Biological activity of leukotriene sulfones on respiratory tissues.

The biological activity of synthetic leukotriene C4, D4 and E4 sulfone has been determined in respiratory smooth muscle in vitro and in vivo. The sulfones of LTC4, LTD4 and LTE4 were potent contractile agonists on indomethacin-treated guinea pig tracheal chains with respective pD2-values of 8.2, 8.0 and 7.9. Contractions were submaximal (75-85% of the cholinergic maximum), slow in onset, prolonged in duration, slowly reversed by washing (compared to acetylcholine or histamine) and were partially reversed by 2 muM FPL-55712. The sulfones of LTC4, LTD4 and LTE4 also contracted indomethacin-treated guinea pig parenchyma (respective pD2's of 7.9 8.2 and 7.8) and rat parenchyma (respective pD2's of 7.1, 7.2 and 7.2) but were inactive on rat trachea (0.01-2.0 muM). When administered intravenously to anaesthetized guinea pigs, the sulfones of LTD4, LTE4 and to a lesser degree LTC4 (respective ED50's - 0.5; 2.0 and 4.6 microgram/kg) elicited dose-dependent increases in inflation pressure which were antagonized by FPL-55712 and indomethacin. Leukotriene C4, D4 and E4 sulfones display a qualitatively similar profile of biological activity to that of their corresponding sulfides.

Animals↗
PubMed1982

Cerebral oxygen metabolism and blood flow in human cerebral ischemic infarction.

Fifteen patients with acute cerebral hemispheric infarcts have been studied with positron emission tomography and the oxygen-15 steady-state inhalation technique. Thirteen follow-up studies were also performed. The values of cerebral oxygen metabolism (CMRO2), cerebral blood flow (CBF), and oxygen extraction ration (OER) have been calculated for the infarcted regions, their borders, the symmetrical regions in contralateral cerebral hemispheres, and the cerebellar hemispheres. This study demonstrates that in the completed stroke there are thresholds for regional CMRO2 and regional CBF below which the general clinical outcome of the patients is usually poor. The ischaemic lesions invariably produce an uncoupling between the greatly decreased metabolic demand and the less affected blood supply, with very frequent instances of relative hyperperfusion. Remote effects of the hemispheric infarcts have been demonstrated, such as crossed cerebellar diaschisis and contralateral transhemispheric depression. The level of consciousness correlates with oxygen uptake and blood flow both in the posterior fossa and in the contralateral cerebral hemispheres. The follow-up studies of individual patients underline the high variability of metabolism-to-flow balance during the acute phase of the illness, and stress the need for more studies focused on repeated assessments of homogeneous patient populations.

Aged↗
PubMed1982

A statistical study of the steady state technique for measuring regional cerebral blood flow and oxygen utilisation using 15O.

Regional cerebral blood flow and oxygen utilisation can be measured using positron emission tomography and the continuous inhalation of 15O-labelled carbon dioxide and molecular oxygen. However, there is concern about the propagation of errors in this technique. This arises from statistical uncertainties, inherent in the transmission and emission scans, being amplified in the steady state model used for calculating the physiological parameters. The magnitude of this effect has been studied using a series of repeat transmission and emission phantom measurements in which pixel count densities equivalent to those seen in the clinical data were recorded. These measurements have been used to determine the final propagated errors that occur in the calculated values of regional cerebral blood flow, oxygen extraction fraction, and oxygen utilisation rate.

Brain↗