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Positron emission tomography (PET) with fluorodeoxyglucose (FDG), magnetic resonance imaging (MRI), and CT were carried out in a patient with Alzheimer's disease 16 months before he died. At autopsy, the gross appearance of the brain correlated with MRI and CT, which showed some regional atrophy. These were much less revealing than PET, which correlated with microscopic findings of neuronal loss and proliferation of glia. In areas of moderately impaired local cerebral metabolic rate of glucose, as revealed by reduced FDG uptake, there was some gliosis, primarily around the numerous senile plaques. In areas of severe metabolic impairment, there was a profound loss of neurons, extensive gliosis, and a diminished appearance of plaques. PET-FDG is a better measure of the severity of Alzheimer's disease than MRI or CT, because it reflects the degree of neuronal pathology.

We detected croased cerebellar as well as uncrossed basal ganglia and thalamic diaschisis in Alzheimer's disease by positron emission tomography (PET) using 18F-fluorodeoxyglucose. We studied a series of 26 consecutive, clinically diagnosed Alzheimer cases, including 6 proven by later autopsy, and compared them with 9 age-matched controls. We calculated asymmetry indices (AIs) of cerebral metabolic rate for matched left-right regions of interest (ROIs) and determined the extent of diaschisis by correlative analyses. For the Alzheimer pup, we found cerebellar Ah correlated negatively, and thalamic AIs positively, with those of the cerebral hemisphere and fmntal, temporal, parietal, and angular cortices, while basal ganglia AIs correlated positively with frontal cortical AIs. The only significant correlation of AIs for normal subject a was between the thalamus and cerebral hemisphere. These data indicate that PET is a sensitive technique for detecting diaschisis.

PET using 18F-2-fluoro-2-deoxyglucose was carried out on a case of Pick's disease established by necropsy. A sharply decreased cortical metabolic rate for glucose was obtained in specific gyri, especially in the frontal lobes, where there was extensive gliosis and neuronal loss. More moderate decreases were found in areas with numerous Pick bodies and inflated neurons but less gliosis. The PET pattern was sufficiently distinctive to suggest that it might be possible to distinguish Pick's from Alzheimer's disease premortem.

Progress is reported in several areas of design of a positron volume imaging tomograph. As a means of increasing the volume imaged and the detector packing fraction, a lens system of detector light coupling is considered. A prototype layered scintillator detector demonstrates improved spatial resolution due to a unique Compton rejection capability. The conceptual design of a novel mechanism for measuring scattered radiation during emission scans has been tested by Monte Carlo simulation. The problem of how to use effectively the resulting sampled scattered radiation projections is discussed.<>

The correctness of an analytical simulation for single-scattered gamma rays in positron volume imaging was verified by comparing it to Monte Carlo simulation of single scattering. The Monte Carlo simulation was verified using measured tomograph data. The single-scatter analytical simulation was extended to estimate multiple scattering. The multiple-scatter analytical simulation showed good agreement with the Monte Carlo simulation of total object scatter. It is shown using the analytical simulation that the position of a source along the line of response and the shape of the scattering object make a substantial difference in the scatter distribution in the projections. Such projections can be generated in a much shorter time using the analytical simulation than using the Monte Carlo simulation. A scatter correction method which uses the analytical simulation and exploits the inherent smoothness of the scatter distribution to account for three-dimensional effects in scatter distribution and object shape is also proposed.<>

Protective immunity in C57BL/6 mice exposed to optimally irradiated larvae of Schistosoma mansoni operates against challenge parasites in the lungs and is dependent upon T-helper 1 (Th1) lymphocytes which secrete abundant gamma interferon (IFN-gamma). As an initial step in the identification of the molecules which mediate this immunity, antigenic materials released by larvae at various times during in vitro culture were compared for the ability to induce proliferation of lymph node cells recovered from mice 4 to 6 days after exposure to attenuated parasites. Cells from mice vaccinated with cercariae proliferated most strongly to larval antigens released soon after transformation. In contrast, cells from mice immunized with lung-stage schistosomula responded poorly to these early secretions but proliferated vigorously to antigens released by older larvae. In further studies on the cytokine profile of the responding lymphocytes, it was observed that the balance between IFN-gamma and interleukin-4 (IL-4) secretion depended on the source of antigen used for restimulation. Thus, material released between days 6 and 8 by in vitro-cultured larvae, and the soluble extracts of whole lung-stage larvae, induced abundant IFN-gamma but little IL-4. This finding implies that an overwhelming proportion of the lymphocytes responsive to lung-stage antigens had the Th1 phenotype. In contrast, antigens from cercariae and skin-stage larvae induced the lowest levels of IFN-gamma but higher levels of IL-4. It appears that a proportion of the cells with specificities for early antigens had the Th2 or Th0 phenotype. Our results emphasize that antigens from lung-stage larvae are an important source of potentially protective molecules.

We studied 10 patients with early Huntington's disease and 7 normal age-matched controls with positron emission tomography (PET) using fluorodeoxyglucose. Subjects had little or no caudate nucleus atrophy and had not received any medications. The results demonstrated that hypometabolism of glucose preceded tissue loss. Furthermore, patients with minimal neurologic or psychiatric symptoms and no obvious CT changes may be differentiated from normal persons with high accuracy by PET. PET is helpful in the early diagnosis of Huntington's disease irrespective of the mode of presentation. PET may also be useful for preclinical detection and may supplement information from DNA studies.

Regional cerebral glucose metabolism was studied in 16 patients with idiopathic torticollis, using positron emission tomography. Analysis of subcortical regions revealed no consistent focal abnormality of cerebral metabolic rate for glucose, but there was a bilateral breakdown of the normal relationships between the thalamus and basal ganglia. The findings suggest disruption of the pallidothalamic projections in this focal dystonia and may imply a disturbance of GABA.

Protective immunity in C57BL/6 mice exposed to optimally irradiated larvae of Schistosoma mansoni operates against challenge parasites in the lungs and is dependent upon T-helper 1 (Th1) lymphocytes which secrete abundant gamma interferon (IFN-gamma). As an initial step in the identification of the molecules which mediate this immunity, antigenic materials released by larvae at various times during in vitro culture were compared for the ability to induce proliferation of lymph node cells recovered from mice 4 to 6 days after exposure to attenuated parasites. Cells from mice vaccinated with cercariae proliferated most strongly to larval antigens released soon after transformation. In contrast, cells from mice immunized with lung-stage schistosomula responded poorly to these early secretions but proliferated vigorously to antigens released by older larvae. In further studies on the cytokine profile of the responding lymphocytes, it was observed that the balance between IFN-gamma and interleukin-4 (IL-4) secretion depended on the source of antigen used for restimulation. Thus, material released between days 6 and 8 by in vitro-cultured larvae, and the soluble extracts of whole lung-stage larvae, induced abundant IFN-gamma but little IL-4. This finding implies that an overwhelming proportion of the lymphocytes responsive to lung-stage antigens had the Th1 phenotype. In contrast, antigens from cercariae and skin-stage larvae induced the lowest levels of IFN-gamma but higher levels of IL-4. It appears that a proportion of the cells with specificities for early antigens had the Th2 or Th0 phenotype. Our results emphasize that antigens from lung-stage larvae are an important source of potentially protective molecules.

Effective scatter correction techniques are required to account for errors due the high scatter fraction seen in positron volume imaging (PVI). To be effective, the correction techniques must be accurate and practical, but they also must not add excessively to the statistical noise in the image. The authors have investigated the noise added by three correction methods: a convolution/subtraction method; a method that interpolates the scatter from the events outside the object; and a dual energy window method with and without smoothing of the scatter estimate. The methods were applied to data generated by Monte Carlo simulation to determine their effect on the variance of the corrected projections. The convolution and interpolation methods did not add significantly to the variance. The dual energy window subtraction method without smoothing increased the variance by a factor of more than twelve, but this factor was improved to 1.2 by smoothing the scatter estimate.<>

ABSTRACT:Large pyramidal neurons of rat and human neocortex stain immunohistochemically for phosphate-activated glutaminase (PAG). In a limited number of postmortem brains, we find large reductions in cortical PAG activity in Alzheimer's disease (AD). This finding is consistent with histological evidence that pyramidal neurons are affected in AD. The reductions are greater than those found in the same samples in choline acetyltransferase (ChAT) but the possible deleterious effects of coma and similar premortem factors on human PAG activity have yet to be assessed. The activity of (β-glucuronidase, a lysosomal enzyme which occurs in reactive astrocytes, is elevated in the same samples. Positron emission tomography (PET) studies, using 18F-fluorodeoxyglucose (FDG), have demonstrated significant deficiencies in glucose metabolism in the cortex in AD, with the parietal, temporal and some frontal areas being particularly affected. We found in serial scans of 13 AD cases, including one relatively young (44-46 year old) familial case, an exacerbation of the defect over time in most cases. We have found a negative correlation between the regional metabolic rates for glucose (LCMR(s)) measured premortem and the (β-glucuronidase activities measured postmortem on a few AD cases that have come to autopsy. The correlations between LCMR(s) and PAG and ChAT activities tend to be positive. The results are consistent with previous suggestions that decreased LCMR(s) in AD reflect local neuronal loss and gliosis.

Three different computing algorithms for performing positron emission image reconstruction have been compared using Monte Carlo phantom simulations. The work was motivated by the recent announcement of the commercial availability of a positron volume imaging camera, the Siemens-CTI 953 B/31, which has improved axial (slice) resolution and retractable interslice septa. The simulations demonstrate the importance of developing a complete three-dimensional reconstruction algorithm to deal with the increased gamma detection solid angle and the increased scatter fraction that result when the interslice septa are removed from a ring tomograph. The 3-D algorithm has a lower noise level than either the conventional 2-D algorithm (appropriate to tomographs with interslice septa) or the modified 2-D algorithm (proposed to implement positron volume imaging on the new scanner). The new 3-D algorithm is free of a serious artifact that affects the modified 2-D algorithm, caused by spillover of activity from one slice to another.<>

In Chapter X of his book on The structure of appearance, Goodman [1] studies the concept of linear order in finite linear arrays in terms of a two-place symmetrical predicate M, M(x, y)being read as xmatches y. Although arising in the development of a nominalistic philosophical system, many problems relating to the properties of Mare essentially of a mathematical and not of a philosophical nature. Some were considered by Fine in [2]. In the terminology of [1] and [2], the main result of this paper is that there is an effective method for embedding a weakly mapped array (consistently) in a uniform array. This carries with it the result that it is possible to obtain effectively a minimal uniform extension of the original array, that is, a uniform extension with minimum span for such an extension and with the minimum number of elements possible for a uniform extension with this span.

WE have examined by infra-red spectrophotometry the reaction of alkyl trimethyl ammonium bromides of chain-length 4–20 with silica surfaces. For these investigations 10−2M solutions of the ammonium compounds were added to ‘Aerosil’ powder, which had been conditioned by hydration in water at 100° C for 4 h, dried and ignited at 700° C for 72 h, rehydrated as before and finally dried at 120° C. Hockey1has shown that this treatment gives a surface containing 4.6 surface silanol groups per 100 Å2. Since optimum adsorption was found to occur within the pH range 6.6–8.5, the suspension was adjusted to pH. 1 by the addition of 10−2M sodium hydroxide solution. After 2 h the silica plus adsorbate was centrifuged out, dried at 120° C, then pressed into a coherent wafer containing 10–15 mg sample per cm2in a die at 12,000 lb/in.2for 5 min. The wafer was placed in a gas cell, evacuated at a pressure of 10−5mm of mercury for 4 h, and the infra-red spectrum recorded on a Perkin-Elmer 237 double-beam instrument.

Results closely related to those proved in our paper “Common transversal of plane sets” [Journal London Math. Soc.33 (1958), 85–95] have been obtained by N. H. Kuiper and published in his paper “On convex sets and lines in the planes” [Proc. Koninkl. Nederl. Akademie van Wetenschappen Amsterdam(Series A), 60 (1957), 272–283].