Search PubMed⌕ Search

Biomedical subjects

T Jones

Publications and source records attributed to T Jones.

At least 487 records · Page 27Linked to original sources
PubMed1980

Quantitative measurement of regional cerebral blood flow and oxygen metabolism in man using 15O and positron emission tomography: theory, procedure, and normal values.

A method is described for quantifying regional cerebral blood flow (rCBF), oxygen extraction (rOER), and oxygen utilization (rCMRO2) in man non-invasively, using inhaled 15O-labeled CO2 and O2 and positron emission tomography. The theoretical considerations and practical aspects are described. The results of rCBF, rCMRO2, and rOER for gray and white matter in normal volunteers are presented. The significance and limitations of the results are discussed. The method appears suitable for the study of human cerebral aerobic metabolism and blood flow under differing physiological conditions and in a wide variety of neurological disorders.

Adult↗
PubMed1980

Regional cerebral oxygen utilization and blood flow in normal man using oxygen-15 and positron emission tomography.

Quantitative determination of regional cerebral blood flow (rCBF), regional cerebral oxygen utilization (rCMRO2) and regional oxygen extraction ratio (rOER) was performed in 11 normal volunteers by an oxygen 15 inhalation method and positron emission tomography. Regional values comparable with figures from the literature have been obtained. This non-invasive approach offers the possibility of a simultaneous quantitative evaluation of these physiological parameters in health and disease.

Adult↗
PubMed1979

The neuropsychiatric disorder in systemic lupus erythematosus: evidence for both vascular and immune mechanisms.

As part of a prospective survey of systemic lupus erythematosus (SLE) a detailed collaborative study of the clinical, psychiatric, and laboratory features in 15 patients with nonfocal neuropsychiatric disease has been undertaken. In addition to conventional clinical and psychometric evaluation, electroencephalograph, and cerebrospinal fluid analysis, the study included the assessment of cerebral blood flow with oxygen-15 brain scans and serological testing for the presence of antineuronal and lymphocytotoxic antibodies. Of the 15 patients 12 had psychiatric manifestations, while 13 had various neurological abnormalities. All except 2 episodes of cerebral disease were transient. Striking abnormalities in cerebral blood flow and metabolism were seen in 12 patients, even in the presence of subtle clinical features. Sequential scans showed that improvement in clinical features was accompanied by a reversal of scan abnormalities. All sera contained brain-reactive antibody, either antineuronal IgG antibody (13) or lymphocytotoxic IgM antibody (12) or both (10), though there was an inconsistent association between clinical features and antibody titre. It is suggested that transient disturbances of cerebral vascular function in SLE might allow brain-reactive antibodies from the circulation access to cerebral tissue. In this way the nature of the neuropsychiatric abnormalities would depend on both vascular and immunopathogenic mechanisms.

Adolescent↗
PubMed1979

Regional impairment of cerebral oxidative metabolism in Parkinson's disease.

Twenty-two patients affected by idiopathic Parkinsonism were studied using the oxygen-15 inhalation technique. The production of labelled metabolic water was found to be decreased in the parietal cerebral cortex, indicating an impairment in oxidative metabolism. This metabolic defect was localised mainly to the parietal cortex of the affected hemispheres; in non-affected hemispheres of patients presenting with unilateral Parkinsonism, the uptake was normal. In contrast, regional blood flow was not significantly altered. It is possible that this metabolic impairment is caused by chronic deafferentation.

Aged↗
PubMed1978

Mechanism and kinetics of iron release from ferritin by dihydroflavins and dihydroflavin analogues.

Dihydroflavins reductively release iron rapidly and quantitatively from purified horse spleen or horse heart ferritin. The NAD(P)H:flavin oxidoreductase from Beneckea harveyi is used to generate a constant concentration of dihydroflavin permitting a continuous assay for complete iron release. Sepharose-linked dihydroflavins are not competent to release ferritin iron, demonstrating that the dihydroflavin must pass through the channels of the protein shell prior to iron reduction. Several experiments fail to show any specific flavin binding site, though dihydroflavins do display saturation kinetics with very high apparent Km's. The rates of iron release by a number of dihydroflavin analogues show that the electron transfer is significantly rate determining in iron release by dihydroriboflavin, while diffusion of the dihydroflavin through the protein channel is slow in the release of iron by dihydroFMN. The rate of iron release is also dependent on the initial content of iron, having a maximum at 1200 iron atoms per ferritin.

Animals↗
PubMed1978

Oxygen-15 brain scanning for detection of cerebral involvement in systemic lupus erythematosus.

In 47 patients with systemic lupus erythematosus seen during fifty-one clinical episodes, oxygen-15, a short-lived gamma-emitting isotope, has been employed in a scannng technique to study cerebral oxygen utilisation and blood-flow. Abnormalities in regional distribution of oxygen utilisation and blood-flow were seen in twenty-three out of twenty-four instances of definite central-nervous-system disease, in fourteen out of fifteen instances of suspected C.N.S. lupus, and in ten out of twelve instances in which C.N.S. disease was not clinically apparent. The technique reflected remissions and relapses. It may prove valuable in diagnosis of subclinical cerebral disease, in monitoring of responses to therapy, and in study of the pathophysiology of cerebral lupus.

Adolescent↗
PubMed1978

Study of regional cerebral metabolism and blood flow relationships in man using the method of continuously inhaling oxygen-15 and oxygen-15 labelled carbon dioxide.

A new technique for assessing regional oxygen use and blood flow has been applied to a wide range of neurological patients. The method couples the brain's high metabolic demand for oxygen with a shortlived radioactive form of this metabolite, namely oxygen-15 (half life: 2.1 min). This combination produces during the continuous inhalation of either molecular oxygen-15 or labelled carbon dioxide, steady state functional images of the brain which are relatively free of contribution from extracerebral tissues. These are complementary images in that they relate to regional oxygen uptake and blood flow and hence offer a direct insight to the regional demand-to-supply relationships within the brain in physiological and pathological conditions. In the clinical groups studied, metabolic and circulatory defects were observed and instances of cerebrovascular insufficiency and relative luxury perfusion were defined which hitherto have been deduced from indirect methods. The clinical acceptability of this non-invasive approach allowed us to study those categories of patients which normally do not warrant invasive examination.

Adult↗
PubMed1978

Non-invasive regional study of chronic cerebrovascular disorders using the oxygen-15 inhalation technique.

The regional cerebral metabolism-to-perfusion imbalance has been studied in the three main categories of cerebrovascular disorders in a chronic phase of the disease, using the non-invasive oxygen-15 inhalation technique. In patients presenting with a history of transient ischaemic attacks, regional defects in cerebral perfusion were greater than for the corresponding oxygen uptakes. Areas of relative ischaemia within which there was an enforced increase in the oxygen extraction ratio were highlighted. The reverse pattern was observed frequently in patients with brain infarcts arising from strokes, so indicating areas of relative luxury perfusion as is inferred from the reduction in the oxygen extraction ratio. In the multi-infarct dementia group of patients, there were parallel focal reductions in both flow and metabolism. The oxygen-15 inhalation technique is shown to be a unique tool in investigating cerebrovascular disorders because of its non-invasiveness and its ability to define regional metabolism-to-perfusion imbalance within the brain.

Adult↗
PubMed1978

MMPI criteria for diagnosing schizophrenia.

An attempt was made to find a combination of MMPI scale relationships which were highly discriminating of schizophrenia. Through the use of a standardized structured interview and a diagnostic system for schizophrenia based on the use of discriminant function analysis with nonpathognomonic symptom combinations, a reliable and valid system was used to establish the criterion diagnosis. Approximately 72% of patients reliably diagnosed as schizophrenics were detected on the MMPI via a set of standard criteria (T score on Sc greater than or equal to 80 less than or equal to 100; total raw score on Sc consisted of no more than 35% K items; T score on F greater than or equal to 75 less than or equal to 95; T score on Pt less than or equal to Sc). Only 5.5% of nonschizophrenics obtained all these standard criteria on the MMPI. The assets and liabilities of these MMPI criteria to diagnose schizophrenia are discussed.

Acute Disease↗
PubMed1978

The discriminative validity of the Whitaker Index of Schizophrenic Thinking.

An attempt was made to assess the discriminative validity of the WIST with a sample of psychiatric inpatients. Through the use of a standardized structured interview and a diagnostic system for schizophrenia based on the use of discriminant function analysis with nonpathognomic symptom combinations, a reliable and valid system was used to establish the criterion diagnosis. Approximately 63% of patients reliably diagnosed as schizophrenic were detected via the WIST while only 14% of nonschizophrenic patients scored in the schizophrenic range on the WIST. The assets and liabilities of using the WIST to diagnose schizophrenia are discussed.

Journal Article↗
PubMed1978

Radioactive oxygen 15O studies in cerebral neoplasms.

Methods of diagnosis and anatomical localization of cerebral neoplasms have reached a high level of efficiency. A new method of studying cerebral circulation and metabolism by a simple noninvasive technique of steady-state imaging during the inhalation of radioactive oxygen and radioactive oxygen-labelled CO2 is described. The results of preliminary studies of a group of cerebral neoplasms of various histological types are presented and the implications discussed.

Astrocytoma↗
PubMed1977

The measurement of spleen perfusion in man: a non-invasive method using the ratio between Rubidium-81 and its decay product Krypton-81m.

A non-invasive method has been developed for measuring spleen perfusion in man. This involves recording the gamma-ray energy spectra over the spleen following the localisation of Rubidium-81 within the organ by injecting intravenously labelled heat denatured red cells. The spectra are analysed to provide the ratio of Rubidium-81 to its radioactive decay product Krypton-81 m. This ratio is dependent on the rate of perfusion through the organ. The difficulties encountered in applying this steady state method for monitoring tissue perfusion are illustrated and practical means for their solution presented. The results of applying this method to patients with various splenic disorders are presented and compared with those obtained by other workers using different monitoring techniques.

Humans↗