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Biomedical subjects

S C Jones

Publications and source records attributed to S C Jones.

At least 91 records · Page 5Linked to original sources
PubMed1985

Selecting measures of emotional and behavioral disorders of childhood for use in general populations.

This paper puts forward suggestions for assessing the suitability of existing measures of emotional and behavioral disorders of childhood for use in general populations. Specific attention is focused on the definition of emotional and behavioral disorder, measurement approaches and guidelines for choosing which disorders to study. The measurement criteria under review include acceptability, applicability, procedural adequacy, reliability and validity. These criteria are applied to seven instruments previously described as suitable for epidemiological and clinical research. Among these instruments, the ones developed by Rutter, Achenbach and Quay best meet the criteria and show the most promise of being useful in general populations. Among research priorities for the future, the foremost should include the specification of rules of evidence for establishing the validity of new measures of emotional and behavioral disorder.

Adolescent↗
PubMed1984

Tandem Van de Graaff accelerator production of positron labeled radiopharmaceuticals for routine clinical use.

This paper describes a facility to produce positron labeled radiopharmaceuticals with a tandem Van de Graaff accelerator. 11C labeled carbon monoxide (11CO), 15O labeled H2O (H2 15O) and 18F labeled 2-deoxy-2-fluoro-D-glucose ([18F]2FDG), were chosen so that physiological measurements of cerebral blood volume, cerebral blood flow, and the cerebral metabolic rate for glucose could be made routinely in our PET center. This facility uses a tandem Van de Graaff accelerator which is relatively remote from the clinical area. Measurements of radionuclide yield and beam penetration showed that it was feasible to deliver sufficient amounts of radioactivity for the measurements. Both 11CO and H2 15O presented significant delivery problems due to their shorter half-lives. For H2 15O a continuous delivery system for water vapour and an infusion system for the administration of H2 15O in saline were designed and constructed. 11CO and [18F]2FDG were hand carried. This facility has demonstrated that a tandem Van de Graaff accelerator can routinely supply a PET center with adequate quantities of these three radiopharmaceuticals.

Carbon Monoxide↗
PubMed1983

Brain uptake and organ distribution of 11C from 11C-labeled glucose.

The time course of the distribution of carbon-11 (11C, t1/2 = 20.4 min) in brain after the i.v. administration of 11C-labeled glucose [( 11C]glucose) was studied in an effort to understand and explore its behavior in relation to the known factors concerning the catabolic fate of glucose carbon in the brain. The biodistribution of 11C from [11C]glucose was studied in rats using organ dissection. Human radiation doses were estimated from rat biodistribution data. All the rat organs except the brain cleared with a half time of 30-60 min. The brain showed delayed uptake that plateaued from 20 to 60 min. The 11C distribution in normal, non-ischemic, brain 30 min after intravenously administered [11C]glucose is due to labeled carbon incorporation into amino acids associated with tricarboxylic acid cycle intermediates. External imaging with the Massachusetts General Hospital positron camera, PC I, was performed in dogs and humans and the time course of 11C incorporation was similar to the rat brain results. Regional uptake paralleled known metabolic differences between grey and white matter in normal human volunteers. A patient with progressive dementia had less uptake in an area of decreased perfusion as demonstrated angiographically, suggesting that the image obtained 20 min after tracer administration could be used to detect abnormalities in cerebral metabolism due to pathology.

Adult↗
PubMed1982

Use of 2-deoxy-D[1-11C]glucose for the determination of local cerebral glucose metabolism in humans: variation within and between subjects.

The deoxyglucose technique for the measurement of local cerebral glucose metabolism (LCMRgl) has been widely applied in animals utilizing 14C-deoxyglucose and in humans employing 18F-fluorodeoxyglucose. Repeat studies in humans over a relatively brief period of time have not been possible because of the 110-min half-life of fluorine-18. With the synthesis of 11C-deoxyglucose it has now become possible to utilize this short-lived (20 min) tracer for the measurement of LCMRgl and to determine its variability within subjects over a 2-h period. The kinetic rate constants for 11C-deoxyglucose were determined for gray and white matter and found to be very similar to those for 18F-fluorodeoxyglucose, suggesting that these two analogues of glucose have similar affinities for the facilitated transport system and are similar substrates for hexokinase in the brain. The coefficient of variation of repeated measurements of LCMRgl in a series of six normal subjects was 5.5% to 8.7% for various gray matter structures and 9.7% and 14.0% for white matter structures. The pattern of cerebral metabolic rates is relatively constant in a given individual when the conditions of the study are unchanged. The ability to make repeat measurements in the same subject reduces the variance due to between-subject differences, allowing smaller changes in LCMRgl to be detected with confidence.

Brain↗
PubMed1982

Error analysis for the determination of cerebral blood flow with the continuous inhalation of 15O-labeled carbon dioxide and positron emission tomography.

The inhalation of C15O2 can be used for determining local cerebral blood flow (LCBF) using a quantitative model. The determination of LCBF in three dimensions using positron emission tomography (PET) involves errors due to counting statistics, data manipulation, and the estimation of parameters in the mathematical model. This work examines error propagation and its relation to the radiation dose to the subject's lungs. An expression has been derived for the root mean square uncertainty in LCBF as a function of LCBF, the spatial resolution and the sensitivity of PET instrument, the normal variability in the brain-blood partition coefficient for water, and absorbed radiation dose to the subject's lungs. The error in LCBF increases as CBF increases. At a normal cortical LCBF of 80 ml/100 g-m and a PET instrument with a 1.65 cm FWHM resolution, and a 46,000 cps per microCi/g sensitivity per slice, an error (coefficient of variation) of 5% results from an inhaled activity of 250 mCi, resulting in a lung dose of 5 rads, the maximum permissible dose allowed. For a more acceptable dose of 1.2 rads, the error is 7%. At a higher resolution (0.8 cm FWHM) and lower sensitivity (15,000 cps per microCi/g per slice), errors become on the order of 28% for a lung dose of 1.2 rads. Errors due to other factors such as blood sample counting, and instrument cross calibration can be virtually eliminated by proper technical strategies. This consideration of error and its relation to radiation dose is important for the application of this inhalation technique for the quantification of LCBF.

Administration, Intranasal↗
PubMed1982

The radiation dosimetry of 2 [F-18]fluoro-2-deoxy-D-glucose in man.

Bladder and brain time-activity measurements in humans were performed after the intravenous administration of 2-[F-18]fluoro-2-deoxy-D-glucose. Radiation doses were calculated using the MIRD schema. The bladder wall received an average of 440 mrad/mCi (s.e. 76) in ten subjects who voided at 2 hr after administration of tracer. If these subjects had voided at 1 hr, the bladder-wall dose would have been reduced to 220 mrad/mCi. The brain received an average of 81 mrad/mCi in eight subjects. The doses to other organs, calculated from published dog biodistribution data, are between 50 and 85 mrad/mCi except for spleen and heart, which both received 160 mrad/mCi. These time-activity measurements for the critical organ in the human avoid the assumptions made in using animal biodistribution data for human dosimetry calculations.

Adult↗
PubMed1980

Evaluation of a hemolysis-in-gel test for detection and quantitation of antibodies to bluetongue virus.

A hemolysis-in-gel (HIG) test was developed to detect and quantitate antibody to bluetongue virus (BTV). The HIG test was sensitive and accurate when applied to sera from sheep and cattle infected with BTV. Sensitized sheep RBC were prepared by adsorption of partly purified BTV to the cells. Regression analysis of data showed a linear relationship between the diameter of the hemolytic zone and the log of the antibody concentration. The HIG test did not differentiate among antiodies to four serotypes of BTV, but did differentiate between antibody of BTV and antibody to epizootic hemorrhagic disease virus.

Animals↗
PubMed1976

Plaque neutralization of bluetongue virus and epizootic hemorrhagic disease virus in BHK21 cells.

Plaque assay and plaque neutralization of blue-tongue virus and epizootic hemorrhagic disease virus were studied in baby hamster kidney (BHK21) cells grown under an overlay containing gum tragacanth. Tests were done in plastic panels, each with 24 wells, and variables were established for achieving reproducible results. Four serotypes of bluetongue virus were compared, and their antigenic differences were confirmed with this new plaque-neutralization test.

Bluetongue virus↗