Thomas E. Boothe

Positron emission tomographic studies during serial word-reading by normal and dyslexic adults.

Positron-emission tomography (PET) was used to study regional cerebral metabolic activity during oral reading in right-handed adult males with, and without a childhood and family history of developmental dyslexia. Significant group differences in normalized regional metabolic values were revealed in prefrontal cortex and in the lingual (inferior) region of the occipital lobe. Lingual values were bilaterally higher for dyslexic than normal readers. In contrast to the asymmetry observed in prefrontal and lingual regions in nondyslexic subjects during reading, the dyslexic pattern was more symmetric. These results demonstrate that individuals who suffered from familial developmental dyslexia as children, activate different brain regions during reading as adults, as compared to individuals without such childhood history.

Behavioral Activation and the Variability of Cerebral Glucose Metabolic Measurements

Variability in cerebral glucose metabolism was examined between and within subjects when paired studies were performed in the resting state or in a behaviorally activated state. Both normal and demented subjects were studied twice each, from 1 to 6 weeks apart, under near-identical conditions, using positron emission tomography (PET) and [18F]fluorodeoxyglucose. Resting state studies were repeated in nine normal and four demented subjects. A picture-viewing test, used for activation during PET, was used repeatedly in seven normal and five demented subjects. Within-subject variability, as assessed by the percent difference in metabolic rates in paired studies, was reduced by 60–70% for activation state compared to resting state studies in normals. It is concluded that PET studies of brain metabolism, which are designed to study the active brain, should indeed be performed in functionally activated states, as in addition to demonstrating metabolism during a defined functional state, activation studies show reduced variability of cerebral metabolic measures.

EVALUATED CROSS SECTION AND THICK TARGET YIELD DATA BASES OF ZN + P PROCESSES FOR PRACTICAL APPLICATIONS

Abstract On the basis of the present experimental work and available literature results, we have evaluated the cross section/integral thick target physical yield data for 66Zn(p, x)65Zn, natZn(p, x)65Zn, 66Zn(p, n)66Ga, 67Zn(p, 2n)66Ga, 68Zn(p, 3n)66Ga, natZn(p, xn)66Ga, 67Zn(p, n)67Ga, 68Zn(p, 2n)67Ga, natZn(p, xn)67Ga, 68Zn(p, n)68Ga and natZn(p, xn)68Ga nuclear reactions up to 30xa0MeV. The data sets were evaluated via curve fitting to supply recommended values for practical applications such as routine radioisotope production, nuclear wear/corrosion measurements and nuclear analytical applications.

CEREBROCEREBELLAR RELATIONSHIP DURING BEHAVIORAL ACTIVATION : A PET STUDY

The effect of behavioral activation on cerebral and cerebellar glucose metabolism was studied in normal subjects when performing either a verbal memory task or a tactile somatosensory task. Each subject was also studied in a resting state control condition, either 1 h earlier or later than the activation task. Compared to the resting state, both tasks produced asymmetrical metabolic activation, which was opposite in direction within the cerebral and cerebellar hemispheres. In both tasks, the difference of activation of CMRglc in the right and left hemispheres in the cerebellum was negatively correlated with that in the sensory-motor region. This apparently coupled metabolic activation of one cerebellum and areas within the opposite cerebral hemisphere represents the inverse of the crossed cerebellar diaschisis phenomenon commonly observed when a vascular lesion affects one cerebral hemisphere and hypometabolism occurs in the opposite cerebellum. Because these correlations were selective and concordant with known anatomical connections, and were found in two different tasks, they suggest strong functional connections between these specific brain regions.

Compilation of cross sections/thick target yields for 66Ga, 67Ga and 68Ga production using Zn targets up to 30 MeV proton energy

Abstract As a part of our continuing efforts to compile nuclear data relevant to the production of routinely used radioisotopes for nuclear medicine using small or medium size proton accelerators, we have reviewed the excitation functions and production data of 66 Ga, 67 Ga and 68 Ga appearing in the literature up to the end of 1992. We have compiled the cross section data as well as calculated and measured thick target yields of 66 Zn(p, n) 66 Ga, 67 Zn(p, 2n) 66 Ga, 68 Zn(p, 3n) 66 Ga, 67 Zn(p, n) 67 Ga, 68 Zn(p, 2n) 67 Ga and 68 Zn(p, n) 68 Ga nuclear reactions in the energy range up to 30 MeV.

A radioisotopic method for the simultaneous quantitation of regional cerebral blood flow and glucose utilization in small dissected samples: Validation studies and values in the nitrous oxide-anesthetized rat

A method is described for the simultaneous determination of the rates of regional cerebral blood flow (rCBF) and regional cerebral glucose utilization (rCMRgl) in 6-7 mg brain samples dissected from multiple areas of interest. The method utilizes [131I]iodoantipyrine ([131I]IAP) to measure rCBF by indicator fractionation, and [14C]2-deoxyglucose to measure rCMRgl. [131I]IAP was synthesized with specific activity exceeding 350 Ci/mmol and radiochemical purity greater than 99.5% by the radioiodination of antipyrine with Na131I. A triple-counting strategy was developed to quantitate 14C activity of the dissected brain samples in the presence of 131I. The factors contributing to the propagated error of the double-label separation strategy were defined and optimal assay parameters were determined. The separation strategy was validated by measuring rCBF simultaneously with both [131I]IAP (x) and [14C]IAP (y) in a series of rats. The equation of the regression line was y = 1.025 x -0.065 (correlation coefficient 0.985), denoting excellent agreement. In another series of 5 normocapnic rats anesthetized with nitrous oxide, rCBF and rCMRgl were measured simultaneously. In individual animals, the rates of rCBF within 14-16 brain areas were closely coupled to their respective rates of glucose metabolism. For the group data, the linear regression equation relating rCBF (y) to rCMRgl (x) was y = 1.76 x + 0.13 (correlation coefficient 0.93, P less than 0.001). These studies provide direct evidence, based upon data obtained in the same brain, of a close coupling of regional metabolic rate and blood flow.

1-[11C]Butanol: Synthesis and development as a radiopharmaceutical for blood flow measurements☆

Abstract 1-[ 11 C]Butanol was synthesized via two routes: carbonylation of an organoborane and carbonation of a Grignard reagent. The reaction of 11 CO with B- n -propyl-9-borabicyclo[3.3.1]nonane, followed by oxidation in alkaline medium, produced 1-[ 11 C]butanol in 33–71% yield (EOB) in 60 min. The reaction of 11 CO 2 with 1-propylmagnesium bromide, followed by a lithium aluminum hydride reduction, produced 1-[ 11 C]butanol in 55–74% yield (EOB) in 25–27 min. The radiochemical purity was 95–99% in each case.

Syntheses with isotopically labelled carbon. Methyl iodide, formaldehyde and cyanide

Many of the uniquely labelled synthetic precursors currently employed in the design of sophisticated radiolabelled compounds have their origins in the field of hot atom chemistry. Particularly, the development during the past few years of automated, on-line synthetic procedures which combine the nuclear reaction, hot atom and classical chemistry, and rapid purification methods has allowed the incorporation of useful radionuclides into suitable compounds of chemical and biochemical interest. The application of isotopically labelled methyl iodide, formaldehyde, and cyanide anion as synthetic intermediates in research involving human physiology and nuclear medicine, as well as their contributions to other scientific methodology, is reviewed.

Preparation of 11C-Urea from No-carrier-added 11C-Cyanide☆

Abstract Carbon-11 labeled urea was synthetized by thermal transformation of 11 C-labeled ammonium cyanate. The 11 C-cyanate was prepared by oxidation of 11 C-cyanide. The total synthesis was accomplished in 20 min starting from 11 CN − to obtain 11 C-urea in 85±5% radiochemical yield with purity greater than 98%. HPLC was utilized to examine the various reactants and products.

Radioisotopic labelling by surface catalysis—I. Preparation and quality control of 131I-4-iodoantipyrine☆

Abstract A new method of radioiodination, apparently involving halogen exchange by surface catalysis, has been developed for the synthesis of 131I-4-iodoantipyrine (131I-4-IAP) in high specific activity. On a silica gel surface, for instance, radioiodide reacts with antipyrine (AP) in hydrochloric acid at pH 1.0 to form 131I-4-IAP in a radiochemical yield of 82.2 ± 1.8%. Subsequent separation of the 131I-4-IAP from the AP by thin layer chromatography (TLC) has afforded greater than 99.5% radiochemically pure 131I-4-IAP. Quality control procedures utilizing TLC and high performance liquid chromatography have been developed.