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Biomedical subjects

T Jones

Publications and source records attributed to T Jones.

At least 397 records · Page 22Linked to original sources
PubMed1986

Brain dopamine metabolism in patients with Parkinson's disease measured with positron emission tomography.

L-[18F] fluorodopa was administered in trace amounts intravenously to healthy control subjects and to patients with Parkinson's disease. Striatal uptake of radioactivity was measured using positron emission tomography. The capacity of the striatum to retain tracer was severely impaired in patients compared to controls. This may reflect a reduction of striatal dopamine storage in Parkinson's disease. Patients showing the "on/off" phenomenon had an even greater decrease of striatal storage capacity.

Adult↗
PubMed1986

Increased uptake of 18F-fluorodeoxyglucose in postischemic myocardium of patients with exercise-induced angina.

Regional myocardial perfusion and exogenous glucose uptake were assessed with rubidium-82 (82Rb) and 18F-2-fluoro-2-deoxyglucose (FDG) in 10 normal volunteers and 12 patients with coronary artery disease and stable angina pectoris by means of positron emission tomography. In patients at rest, the myocardial uptake of 82Rb and FDG did not differ significantly from that measured in normal subjects. The exercise test performed within the positron camera in eight patients produced typical chest pain and ischemic electrocardiographic changes in all. In each of the eight patients a region of reduced cation uptake was demonstrated in the 82Rb scan recorded at peak exercise, after which uptake of 82Rb returned to the control value 5 to 14 min after the end of the exercise. In these patients, FDG was injected in the recovery phase when all the variables that were altered during exercise, including regional myocardial 82Rb uptake, had returned to control values. In all but one patient, FDG accumulation in the regions of reduced 82Rb uptake during exercise was significantly higher than that in the nonischemic regions, i.e., the ones with a normal increment of 82Rb uptake on exercise. In the nonischemic areas, FDG uptake was not significantly different from that found in normal subjects after exercise. In conclusion, myocardial glucose transport and phosphorylation seem to be enhanced in the postischemic myocardium of patients with exercise-induced ischemia.

Adult↗
PubMed1986

Comparative study of antigen binding T cells separated by Vicia villosa or streptococcal antigen and the effect of HLA class II antigens.

The antigen binding capacity and function of T cells which adhere to the lectin Vicia villosa (VV) or to streptococcal antigen (SA) have been studied. VV-adherent T8+ cells (T8+ VV+) bind 125I-SA whereas VV non-adherent T8+ cells (T8+ VV-) bind little SA. Similarly, SA-adherent T8+ cells (T8+ SA+) bind 125I-SA specifically, whereas SA-non-adherent T8+ cells (T8+ SA-) show little binding of 125I-SA. The SA binding T8+ VV+ or T8+ SA+ cells can present the antigen to T4+ helper cells which generate helper factors and these enhance anti-DNP-antibodies, when incubated with mouse spleen cells and DNP-SA. Parallel reconstitution studies with either T8+ VV- or T8+ SA- cells have revealed that both subpopulations of cells can suppress T4+ helper cell activity. Further reconstitution experiments between the T8+ VV+ (or T8+ SA+) antigen presenting cells and T8+ VV- (or T8+ SA-) suppressor cells suggest that the former can also prevent the latter cells from inhibiting T4 helper cells, so as to function as contrasuppressor cells. Cross-over, reconstitution studies between the VV and SA separated cells have confirmed that the T8+ VV+ and T8+ SA+ cells have similar functions, in SA binding, presenting and contrasuppressor activities. The dose-response curve of binding 125I-SA to T8+ cells is dependent on the HLA-DR type of cells and the binding of 125I-tetanus toxoid was similar to that of 125I-SA. Whereas DRw6- T cells bind predominantly 1,000 ng SA or tetanus toxoid, DRw6+ T cells bind 1 ng and to a lesser extent 1,000 ng of either antigen. HLA-DRw6+ subjects can be considered as high responders for their T cells bind optimally at low concentrations of antigens which induce helper and contrasuppressor functions. In contrast, HLA-DRw6-subjects can be considered as low responders, as their T cells bind optimally at high concentrations of antigens and only the latter induce helper and contrasuppressor functions.

Antigens, Bacterial↗
PubMed1986

Prolonged metabolic recovery allows late identification of ischemia in the absence of electrocardiographic and perfusion changes in patients with exertional angina.

Regional myocardial perfusion and exogenous glucose uptake were assessed in 10 normal subjects and 10 patients with coronary artery disease and stable angina pectoris using 82Rubiduim and 18F-2-fluoro-2-deoxyglucose with positron emission tomography. At rest regional myocardial perfusion and glucose uptake in patients were comparable with those in normals. In 7 patients and 5 normals a supine bicycle exercise test was performed within the positron camera. In all 7 patients, exercise induced typical chest pain and ischemic electrocardiographic changes accompanied by regional abnormalities of myocardial perfusion which normalized 5 to 14 minutes after the end of exercise. In these patients 18F-2-fluoro-2-deoxyglucose was injected during recovery from exercise when all the parameters that were altered during the test, including myocardial perfusion, were back to control. In all 7, glucose uptake in the regions which showed abnormal perfusion during exercise was significantly higher than in the non ischemic regions (i.e. the ones with a normal increment of 82Rubidium uptake during exercise). In 2 patients the test was repeated on a different day and 18F-2-fluoro-2-deoxyglucose was injected during exercise in the presence of frank ischemia. In contrast to the injection following exercise, in both patients, glucose uptake in the ischemic region was found to be lower than in the non ischemic ones. In conclusion, in patients recovering from exercise-induced ischemia exogenous glucose utilization is enhanced in the previously ischemic myocardium. This occurs in the absence of symptoms and electrocardiographic changes and allows the identification and location of previous myocardial ischemia.

Angina Pectoris↗
PubMed1985

Transient ischemia in angina pectoris: frequent silent events with everyday activities.

To help characterize episodes of transient myocardial ischemia, 80 patients with chronic stable angina and evidence of obstructive coronary disease were studied by ambulatory electrocardiographic (ECG) monitoring outside the hospital to detect both symptomatic and asymptomatic episodes of ST-segment depression. In addition, patients were tested on an outpatient basis by means of positron emission tomography to assess regional coronary blood flow under different conditions. All patients showed ECG evidence of transient ischemia, with or without symptoms, while active outside the hospital. In-hospital testing showed that symptomatic and asymptomatic disturbances in regional coronary blood flow occurred with normal everyday activities and were not caused by physical exertion involving marked increases in heart rate and blood pressure. Most of these provocations were followed by a decrease in coronary blood flow in a poststenotic segment of myocardium and, like the ischemic events monitored out of hospital, the majority were silent. Many of these features characterizing the activity of ischemic heart disease may not be apparent from a patient's anginal history or results of hospital diagnostic testing.

Activities of Daily Living↗
PubMed1985

Clinical problems in coronary disease are caused by wide variety of ischemic episodes that affect patients out of hospital.

Transient ischemia arising from proximal events in epicardial coronary arteries causes important symptoms, such as angina pectoris, and is usually studied in the hospital with provocative tests. However, Holter monitoring of ST-segment disturbances in patients out of the hospital has shown frequent asymptomatic evidence of ischemia that is surprisingly prolonged and that is not associated with the obvious tachycardia of exercise or stress. Positron emission tomography has been developed to measure the regional myocardial uptake of a cation (rubidium-82) in order to assess repeatedly the directional changes in regional coronary blood flow during these events. This method has been used to show that both symptomatic and asymptomatic episodes of ST depression are reliably associated with disturbances in regional myocardial perfusion. The daily activities of patients have been analyzed and reproduced in the hospital to assess the effects of cold stimulation, mental arithmetic, cigarette smoking, and exercise. Physical exercise was associated with angina, ST-segment change, and regional abnormalities of myocardial perfusion, including decreased perfusion in poststenotic segments. The other tests caused the same disturbances in myocardial perfusion; these perfusion disturbances were mostly asymptomatic and surprisingly prolonged, with periods of recovery that were two to five times longer than the ST-segment disturbance and the pain. Current studies using a structured diary indicate that the episodes of transient ischemia occurring out of the hospital are more frequently associated with different levels of mental arousal than with any other activity. Physical exercise is a relatively infrequent cause of transient ischemia. The examination of coronary blood flow using provocative tests derived from the patients' own activities out of the hospital have confirmed that, irrespective of the pattern of angina, patients have frequent episodes of asymptomatic transient ischemia that are surprisingly prolonged and that these episodes occur in response to previously unsuspected ordinary daily activities. The disturbances in coronary blood flow usually include a regional decrease in myocardial perfusion that can only be explained by pathophysiologic events in the proximal epicardial coronary arteries.

Activities of Daily Living↗
PubMed1985

The effects of L-DOPA on regional cerebral blood flow and oxygen metabolism in patients with Parkinson's disease.

Studies performed on 18 patients with Parkinson's disease and 6 control subjects have shown that acute administration of L-DOPA in clinically effective doses gives rise to a diffuse increase in regional cerebral blood flow without accompanying stimulation of regional oxygen utilization. The data suggest that this rise in rCBF is caused by vasodilatation due to a direct action of the drug on the cerebral blood vessels. The effect of L-DOPA on rCBF did not correlate with the degree of clinical improvement seen in each patient after treatment. The therapeutic effect of L-DOPA in the brain was not reflected in any change of regional cerebral oxygen utilization as measured by our technique. We suggest that the pharmacological actions of L-DOPA in the brain take place on at least two different levels.

Adult↗
PubMed1985

HLA typing of Epstein-Barr virus transformed lymphoblastoid cell lines (LCL).

The application of standard tissue typing techniques to cells other than peripheral blood lymphocytes has been accompanied by the problem of extra reactions. This applies as well to Epstein-Barr virus transformed lymphoblastoid cell lines (LCL) as to leukemic cells and human spleen cells. These extra reactions are attributable to additional antibodies in the typing sera which are not apparent under standard conditions with PBLs. Two types are described: Type 1 extras, which becomes apparent after longer incubation times and are attributed to weak antibodies and type 2 extras which are apparent after shorter incubation times and are attributed to subpopulation specific or differentiation antigens. Technical modifications are proposed by which these extras can be circumvented. They include: Only start typing when cells have been cultured for 2 to 3 days. Remove dead cells by spinning over standard ficoll-hypaque or 11% triosil. Use shorter incubation times. Avoid using sera that give too many type 2 extras. In this way phenotypes can be accurately identified on LCL's obtained from kidney transplant donors and recipients. When LCL's were compared with their matching PBL, HLA phenotypes were concordant in 87% of cases for HLA-A, 90% for HLA-B, 81% for HLA-C and 70% for HLA-DR.

Cell Line↗
PubMed1985

A study of cerebral blood flow and metabolism in epileptic psychosis using positron emission tomography and oxygen.

Data are presented on four groups using positron tomography and 15 O inhalation. Compared to age-matched volunteer controls, epileptic patients show regions of low blood flow and hypometabolism as found in previous studies. Epileptic psychotic and non-psychotic patients have been compared, and the main differences noted were lower rOER in the psychotic group, especially in frontal, temporal and basal ganglia regions. When a group of psychotic patients receiving neuroleptic drugs was compared to those free of these medications the rOER was higher in the treated sample, and the rCBF fell, significantly in some areas. These data are discussed in the light of other reports of positron tomography in psychosis.

Antipsychotic Agents↗
PubMed1985

Blood flow and oxygen utilisation in the contralateral cerebral cortex of patients with untreated intracranial tumours as studied by positron emission tomography, with observations on the effect of decompressive surgery.

Using positron emission tomography, regional cerebral blood flow and oxygen utilisation were measured in the contralateral cortex of 14 patients with a variety of intracranial tumours. A comparison was made with cortical values derived from 14 normal controls. Compared with normal subjects, patients with brain tumours had a significant reduction in oxygen utilisation and blood flow in their contralateral cortex. Decompression resulting from craniotomy and biopsy, led to a partial reversal of this cerebral hypofunction.

Adult↗
PubMed1985

Alterations of regional cerebral blood flow and oxygen metabolism in Parkinson's disease.

Regional cerebral blood flow (rCBF) and oxygen metabolism (rCMRO2) were determined in six normals, six unilateral Parkinson's disease (PD) patients, and eight bilateral PD patients. In the unilateral patients, rCBF and rCMRO2 in the basal ganglia contralateral to the symptomatic limbs was 13% higher than on the other side (p less than 0.01); in the frontal cortex it was 8% lower than the other side, suggesting abnormal neuronal function in both regions. The bilateral PD patients had a widespread decrease (20%) in rCBF unaccompanied by comparable changes in rCMRO2, suggesting vasoconstriction due to loss of dopaminergic innervation of blood vessels in more advanced PD patients.

Cerebrovascular Circulation↗
PubMed1985

Regional cerebral oxygen utilization, blood flow, and blood volume in benign intracranial hypertension studied by positron emission tomography.

Using PET, we measured regional cerebral oxygen utilization, oxygen extraction, blood flow, and blood volume in five patients with benign intracranial hypertension. No significant differences in regional cerebral function were found between the patients and 15 age-matched normal controls. Cerebral decompression with a lumboperitoneal shunt produced little change in regional cerebral function in one patient studied serially. The raised CSF pressure of benign intracranial hypertension is therefore not associated with any significant deterioration in cerebral oxygen metabolism or hemodynamics.

Adult↗