19F-magnetic resonance spectroscopy and chemical shift imaging for schizophrenic patients using haloperidol decanoate

Haloperidol decanoate is widely used in the maintenance treatment of schizophrenia and other psychotic disorders, but knowledge concerning its pharmacokinetics at the injected region is very limited. Because the chemical structure of haloperidol contains fluorine, in vivo 19F-magnetic resonance (MR) spectroscopy (repetition time (TR) = 1 s) and chemical shift imaging (CSI; TR = 1 s, pixel size = 15 x 15 mm) were performed in schizophrenic patients who were treated with haloperidol decanoate (three men and one woman) to measure its diachronic change at the injection point and visualize its local distribution after intramuscular injection. 19F signals (T1 time = 365 ms) were obtained at the haloperidol decanoate-injected region. The decrease rate of the signal-to-noise ratio (SNR) by 19F-MR spectroscopy seemed large in comparison with that of the plasma haloperidol concentration. The distribution was clearly visualized by 19F-CSI for a few days after the injection, but after 1 week could no longer be seen. Although the slow-release characteristics of depot neuroleptics have been explained by the slow diffusion of esterified neuroleptics from the oil vehicle, this result may suggest that there are other mechanisms involved in maintaining the plasma haloperidol concentration. In vivo 19F-MR spectroscopy and CSI are potentially applicable for the pharmacokinetic analysis of haloperidol and other drugs containing fluorine in their structure.

Detection of experimental autoimmune myocarditis in rats by 111In monoclonal antibody specific for tenascin-C

BACKGROUND

Although the identification of inflammatory infiltrates in endomyocardial biopsy specimens is necessary for the definite diagnosis of myocarditis, the biopsy test is invasive and is not sensitive. Therefore, a new diagnostic technique for the early and noninvasive evaluation of myocarditis has been awaited. Expression of tenascin-C (TNC), one of the oligometric extracellular glycoproteins, is induced in various pathological states, including inflammation, suggesting that TNC can be a molecular marker of myocarditis.

METHODS AND RESULTS

An 111In anti-TNC monoclonal antibody Fab' fragment was injected intravenously into rats with experimental autoimmune myocarditis (EAM), and the biodistribution of this radiotracer was measured. Rapid clearance of radioactivity from the blood was observed in both EAM and control rats (<1% at 6 hours after injection). Myocardial uptake of the tracer was much higher in EAM rats than in control rats (7.54-, 4.39-, and 3.51-fold at 6, 24, and 48 hours after injection, respectively). By autoradiography, high radioactivities were clearly observed in the regions indicative of inflammation in EAM rats. Single-photon emission CT imaging demonstrated the focal myocardial uptake of 111In anti-TNC Fab' in vivo.

CONCLUSIONS

Radiolabeled anti-TNC Fab' may be useful for the noninvasive diagnosis of myocarditis.

Distinctly abnormal brain metabolism in late-onset ornithine transcarbamylase deficiency

OBJECTIVE

To assess alterations in brain metabolites in patients with late-onset ornithine transcarbamylase deficiency (OTCD).

METHODS

Six unrelated, asymptomatic Japanese late-onset OTCD patients were analyzed by proton MRS ((1)HMRS) using a point-resolved spectroscopy technique (repetition and echo times, 5000 and 30 ms). Localized spectra for the centrum semiovale were acquired and absolute metabolite concentrations were calculated using an LCModel.

RESULTS

Compared with age-matched controls, N-acetylaspartate and creatine concentrations were normal in all patients. The glutamine (Gln) plus glutamate concentration was increased in four patients, which progressed in proportion to the clinical stage. myo-inositol (mI) could not be detected in five symptomatic patients. A decreased choline (Cho) concentration was detected in two clinically severe patients. (1)HMRS after liver transplantation in one patient revealed the normalization of all metabolites.

CONCLUSION

These findings suggest progression of neurochemical events in OTCD, i.e., mI depletion and Gln accumulation followed by Cho depletion, which is reverse of that in hepatic encephalopathy, i.e., Cho depletion followed by mI depletion and Gln accumulation.

Age-related decline of serotonin transporters in living human brain of healthy males

There is growing interest in serotonin transporter (5-HTT) function in the human brain, since alteration in 5-HTT has been suggested in a variety of neurophychiatric disorders. Age-related decline in postsynaptic 5-HT receptors has been demonstrated in postmortem human studies and in vivo imaging studies, and has been assumed to be related to changes in mental function in the normal aging process. However, few studies have investigated the aging effect on 5-HTT in human brain in vivo, since the availability of suitable ligands has been limited. To investigate the aging effect on 5-HTT in living human brain, we performed positron emission tomography (PET) scans with a selective ligand for 5-HTT, [11C](+)McN5652. We examined 28 healthy male volunteers aged between 20 and 79 years. The uptake was quantified in the thalamus and midbrain by graphical analysis with the cerebellum as a reference tissue, and binding potential (BP) was used for the index of 5-HTT binding. There was a significant age-related decline in BP in the thalamus and midbrain. The decline in [11C](+)McN5652 binding was 9.6% per decade in the thalamus and 10.5% per decade in the midbrain.

Positron emission tomography: quantitative measurement of brain acetylcholinesterase activity using radiolabeled substrates

A new method for quantitative measurement of brain acetylcholinesterase (AChE) activity in living human brain using positron emission tomography (PET) is described. We tested several radiolabeled lipophilic acetylcholine analogs, e.g., N-methylpiperidyl esters, which readily entered the brain via the blood-brain barrier, were hydrolyzed selectively by AChE, and were then trapped in the brain. Among them, and tested and N-[11C]methylpiperidin-4-yl acetate ([11C]MP4A) was chosen as the tracer for PET. Quantitative measurement of cortical AChE was accomplished by fitting the time course of cerebral radioactivity concentration measured by PET and the metabolite-corrected arterial plasma input function using a nonlinear least-squares fitting method. Normal control studies of subjects with a wide range in age (24-89 years) showed no decrease in AChE activity in the cerebral cortex with age. Studies on patients with Alzheimer's disease demonstrated a widespread reduction of AChE activity in the cerebral cortex (more profound in early-onset than in late-onset Alzheimer's disease). Parkinson's disease and progressive supranuclear palsy, clinically similar disorders, could be differentiated with [11C]MP4A/PET studies. Simple methods without using an arterial input function are also proposed. The method provides a quantitative measure of the cholinergic aspect of brain function and proved to be useful in diagnosis of neurodegenerative disorders including Alzheimer's disease.

Oncological diagnosis using positron coincidence gamma camera with fluorodeoxyglucose in comparison with dedicated PET

The purpose of this study was to compare the utility of a dual-head positron coincidence detection gamma camera (PCD) with that of dedicated positron emission tomography (PET) in the imaging of various malignancies using (18)F-fluorodeoxyglucose (FDG). 25 patients with known or suspected malignancies at various sites underwent imaging with both methods, and diagnostic performance on a lesion basis was compared. Tumour lesions were analyzed visually and semi-quantitatively using the ratio of tumour-to-background counts (T/B ratio). FDG PCD and FDG PET visually detected 34 (72.3%) lesions and 37 (78.7%) lesions, respectively. The mean T/B ratio and standard deviation (SD) of FDG PCD was 3.5+/-3.3, significantly lower than that of FDG PET (8.4+/-7.1, p<0.001). When tumour lesions were less than 2.0 cm in diameter, the sensitivity of FDG PCD was 37.5%, significantly inferior to that of FDG PET (50.0%, p<0.01). Sensitivity between FDG PCD and FDG PET in lesions of more than 2.0 cm diameter showed no statistically significant difference. This study indicates that FDG imaging with a dual-head coincidence detection gamma camera can provide suitable diagnostic performance for lesions greater than 2.0 cm diameter, but performed significantly worse than dedicated PET for lesions smaller than this.

Brain N-acetylaspartate is elevated in Pelizaeus-Merzbacher disease with PLP1 duplication

OBJECTIVE

To assess alterations in brain metabolites of patients with Pelizaeus-Merzbacher disease (PMD) with the proteolipid protein gene 1 (PLP1) duplications using quantitative proton MRS.

METHODS

Five unrelated male Japanese patients with PMD with PLP1 duplications were analyzed using automated proton brain examination with the point resolved spectroscopy technique (repetition and echo time of 5,000 and 30 msec). Localized spectra in the posterior portion of the centrum semiovale were acquired, and absolute metabolite concentrations were calculated using the LCModel.

RESULTS

Absolute concentrations of N-acetylaspartate (NAA), creatine (Cr), and myoinositol (MI) were increased by 16% (p < 0.01), 43% (p < 0.001), and 31% (p < 0.01) in patients with PMD as compared with age-matched controls. There was no statistical difference in choline concentration.

CONCLUSION

The increased concentration of NAA, which could not be detected by previous relative quantitation methods, suggests two possibilities: axonal involvement secondary to dysmyelination, or increased cell population of oligodendrocyte progenitors. Elevated Cr and MI concentrations may reflect the reactive astrocytic gliosis. Our study thus emphasizes the importance of absolute quantitation of metabolites to investigate the disease mechanism of the dysmyelinating disorders of the CNS.

Measurement of the electrical properties of human skin and the variation among subjects with certain skin conditions

In this study the dielectric properties are reported for human skin tissues over the frequency range 1-450 MHz at 36 degrees C. Healthy volunteers, collagen disease patients and dialysis patients are studied in order to investigate, primarily, the variability among (1) different regions of one individual, (2) the same region among different individuals and (3) skin conditions due to diseases. Considerable differences exist among the skin dielectric properties obtained from different regions of one individual body. Although region dependence is observed, larger variability is found even in the same skin region among individuals.

Decreased dopamine D2 receptor binding in the anterior cingulate cortex in schizophrenia

BACKGROUND

The clinical efficacy of dopamine D2 receptor antagonism on the psychotic symptoms of schizophrenia has been widely demonstrated. However, most in vivo imaging studies have not been able to detect significant changes in striatal D2 receptors in schizophrenia. On the other hand, a number of studies have reported abnormalities in the cerebral cortex of schizophrenia. The aim of this study was to examine the extrastriatal D2 receptors of patients with schizophrenia.

METHODS

Eleven drug-naive male patients with schizophrenia were examined with positron emission tomography using carbon 11-labeled FLB 457. Symptoms were assessed using the Brief Psychiatric Rating Scale. Eighteen healthy controls were used for comparison. Region-of-interest analysis was performed using the reference tissue method, and binding potential (BP) was used for the index of dopamine D2 receptor binding.

RESULTS

The BP value was significantly lower, by about 12.5%, in the anterior cingulate cortex in drug-naive patients with schizophrenia than in healthy controls. A significant negative correlation was observed between BP in the anterior cingulate cortex and the positive symptom score on Brief Psychiatric Rating Scale.

CONCLUSIONS

The lower BP values indicate fewer D2 receptors in the anterior cingulate cortex in patients with schizophrenia. Alterations in D2 receptor function in the extrastriatal region may underlie the positive symptoms of schizophrenia.

Epidemiological study on improving the QOL and oral conditions of the aged--Part 2: Relationship between tooth loss and lifestyle factors for adults men

Oral health in early- and mid-adulthood is essential for the improvement of one's QOL, this study was investigated to include an epidemiological analysis of the relationship between tooth loss and life style, such as smoking, regular exercise, and the food habits of approximately 2,000 employees. Compared with the group with mild or no periodontal disease (CPI of 0, 1, or 2), the frequency of tooth loss in the group with advanced periodontal disease (CPI of 4) was 2.00 times (odds ratio, 2.00; 95% confidence limit, 1.37 to 2.93). The probability of tooth loss showed statistical significance in relation to smoking, alcohol drinking, and frequency of meals. Compared with non-smokers, the probability that current smokers will lose teeth is 1.53 times greater (odds ratio, 1.53; 95% confidence limit, 1.20 to 1.96). It was concluded that periodontal disease and smoking must be averted for preventing tooth loss.

Epidemiological study on improving the QOL and oral conditions of the aged--Part 1: The relationship between the status of tooth preservation and QOL

In part 1 of this epidemiological study, a survey was conducted for all senior citizens aged 70 and over who resided in a mountainous village in the mid-section of Hyogo Prefecture. It focused on the relationship among the number of existing teeth, life environment, health status, and activities of daily living; and the correlation between oral status and QOL was analyzed. The daily activities of individuals were compared between those having one or more teeth and others who were totally edentulous. Subsequently, it was found that for both males and females, the odds ratio was significantly high for the dentulous individuals, in comparison with edentulous individuals, to exhibit a behavior indicative of a better QOL (such as "opportunity for conversation with family members or others)", "regular physical activities", and "attend meetings or group outings"). The result of this survey indicates that the presence of teeth is very closely related to one's daily activities. It was concluded that preventing tooth loss is vital for maintaining the masticatory function; so to prevent tooth loss, periodontal disease must be averted.

Kinetic analysis of [(11)C]MP4A using a high-radioactivity brain region that represents an integrated input function for measurement of cerebral acetylcholinesterase activity without arterial blood sampling

N -[(11)C]methylpiperidin-4-yl acetate ([(11)C]MP4A) is an acetylcholine analog. It has been used successfully for the quantitative measurement of acetylcholinesterase (AChE) activity in the human brain with positron emission tomography (PET). [(11)C]MP4A is specifically hydrolyzed by AChE in the brain to a hydrophilic metabolite, which is irreversibly trapped locally in the brain. The authors propose a new method of kinetic analysis of brain AChE activity by PET without arterial blood sampling, that is, reference tissue-based linear least squares (RLS) analysis. In this method, cerebellum or striatum is used as a reference tissue. These regions, because of their high AChE activity, act as a biologic integrator of plasma input function during PET scanning, when regional metabolic rates of [(11)C]MP4A through AChE (k(3); an AChE index) are calculated by using Blomqvist's linear least squares analysis. Computer simulation studies showed that RLS analysis yielded k(3) with almost the same accuracy as the standard nonlinear least squares (NLS) analysis in brain regions with low (such as neocortex and hippocampus) and moderately high (thalamus) k(3) values. The authors then applied these methods to [(11) C]MP4A PET data in 12 healthy subjects and 26 patients with Alzheimer disease (AD) using the cerebellum as the reference region. There was a highly significant linear correlation in regional k(3) estimates between RLS and NLS analyses (456 cerebral regions, [RLS k(3) ] = 0.98 x [NLS k(3) ], r = 0.92, P < 0.001). Significant reductions were observed in k(3) estimates of frontal, temporal, parietal, occipital, and sensorimotor cerebral neocortices (P < 0.001, single-tailed t-test), and hippocampus (P = 0.012) in patients with AD as compared with controls when using RLS analysis. Mean reductions (19.6%) in these 6 regions by RLS were almost the same as those by NLS analysis (20.5%). The sensitivity of RLS analysis for detecting cortical regions with abnormally low k 3 in the 26 patients with AD (138 of 312 regions, 44%) was somewhat less than NLS analysis (52%), but was greater than shape analysis (33%), another method of [(11)C]MP4A kinetic analysis without blood sampling. The authors conclude that RLS analysis is practical and useful for routine analysis of clinical [(11)C]MP4A studies.

Long-term assessment of posttransplant renal prognosis with 31 P magnetic resonance spectroscopy

BACKGROUND

31P-magnetic resonance spectroscopy (MRS) has been widely used to study pretransplantation renal viability, and although some had discussed posttransplant renal viability, no one has examined long-term posttransplant renal prognosis. We discuss the use of 31P-MRS to assess the long-term prognosis from the time when MRS was performed.

METHODS

We studied 20 patients with renal allografts. 1.5 Tesla clinical magnetic resonance imaging (MRI) and 15 cm surface coil was used for 31P-MRS. Localized 31P-MRS was done using image selected in vivo spectroscopy (ISIS) method. Individual peaks were fitted by Lorenzian line-shapes with a least square method and peak area ratios were calculated.

RESULTS

A beta-adenosine triphosphate/inorganic phosphate (beta-ATP/Pi) ratio >1.2 had sensitivity of 92.8%, specificity of 100%, and accuracy of 95% for predicting 3-year renal survival; a beta-ATP/Pi ratio >1.2 had sensitivity of 90.9%, specificity of 66.7%, and accuracy of 76.9% for predicting 5-year renal survival. We compared 31P-MRS spectra data between the survived group and failed group. The survived group had significantly higher beta-ATP/Pi, alpha-ATP/Pi, and phosphodiester (PDE)/Pi ratios than the failed group.

CONCLUSIONS

We discussed the beta-ATP/Pi value as a parameter for predicting long-term survival of a transplanted kidney from the time when MRS was performed. A value above 1.2 suggests a high probability of 3-year renal survival, whereas a value over 2.5 indicates that the transplanted kidney could survive over 5 years. 31P-MRS may be useful for predicting long-term survival of transplanted kidneys, but additional studies are needed.

Age-related reduction of extrastriatal dopamine D2 receptor measured by PET

Although the aging effect of dopamine D2 receptor in the striatum is well-documented, the effect of age on the extrastriatal dopamine D2 receptor has not been fully examined. Since the density of extrastriatal dopamine D2 receptor is very low, suitable ligands are limited. In this study, we used [11C]FLB 457 to quantify the extrastriatal dopamine D2 receptor in the living human brain. Twenty-seven healthy male subjects aged from 21 to 82 years participated in the positron emission tomography study. Extrastriatal [11C]FLB 457 binding was quantified with a reference tissue model using cerebellum as a reference region. Binding potentials corresponding to Bmax/Kd were used to evaluate age-related change. We found age-related decreases of D2 receptor binding in all measured extrastriatal regions. The decrease of D2 receptor binding was 13.8% per decade in frontal cortex, 12.0% in temporal cortex, 13.4% in parietal cortex, 12.4% in occipital cortex, 12.2% in hippocampus, and 4.8% in thalamus. These findings suggest that the amounts of D2 receptor declines in all brain regions as part of the normal aging process.

Positron emission tomographic measurement of brain acetylcholinesterase activity using N-[(11)C]methylpiperidin-4-yl acetate without arterial blood sampling: methodology of shape analysis and its diagnostic power for Alzheimer's disease

N-[11C]methylpiperidin-4-yl acetate ([11C]MP4A) is a radiotracer that has been used successfully for the quantitative measurement of acetylcholinesterase (AChE) activity in the human brain with positron emission tomography (PET) using a standard compartment model analysis and a metabolite-corrected arterial input function. In the current study, the authors evaluated the applicability of a simple kinetic analysis without blood sampling, namely shape analysis. First, the authors used computer simulations to analyze factors that affect the precision and bias of shape analysis, then optimized the shape analysis procedure for [11C]MP4A. Before shape analysis execution, the later part of dynamic PET data except for the initial 3 minutes were smoothed by fitting to a bi-exponential function followed by linear interpolation of 8 data points between each of adjacent scan frames. Simulations showed that shape analysis yielded estimates of regional metabolic rates of [11C]MP4A by AChE (k3) with acceptable precision and bias in brain regions with low k3 values such as neocortex. Estimates in regions with higher k3 values became progressively more inaccurate. The authors then applied the method to [11C]MP4A PET data in 10 healthy subjects and 20 patients with Alzheimer's disease (AD). There was a highly significant linear correlation in regional k3 estimates between shape and compartment analyses (300 neocortical regions, [shape k3] = 0.93 x [NLS k3], r = 0.89, P < 0.001). Significant reductions in k3 estimates of frontal, temporal, parietal, occipital, and sensorimotor cerebral cortices in patients with AD as compared with controls were observed when using shape analysis (P < 0.013, two-tailed t-test), although these reductions (17% to 20%) were somewhat less than those obtained by compartment analysis (22% to 27%). The sensitivity of shape analysis for detecting neocortical regions with abnormally low k3 in the 20 patients with AD (92 out of 200 regions, 46%) also was somewhat less than compartment analysis (136 out of 200 regions, 68%). However, taking its simplicity and noninvasiveness into account, the authors conclude that quantitative measurement of neocortical AChE activity with shape analysis and [11C]MP4A PET is practical and useful for clinical diagnosis of AD.

Effect of donepezil on brain acetylcholinesterase activity in patients with AD measured by PET

Acetylcholinesterase (AChE) activities in the brain of three patients with AD were measured once before and once during donepezil treatment (5 mg/d in two patients, 3 mg/d in one patient) using PET and N-[11C]methylpiperidin-4-yl acetate. Donepezil reduced k(3) values, an index of AChE activity, in the cerebral cortex by 39 +/- 5%. All patients showed some degree of symptomatic improvement, and it was concluded that this improvement was likely caused by improved cholinergic activity by inhibition of AChE in the brain.

Dose relationship of limbic-cortical D2-dopamine receptor occupancy with risperidone

RATIONALE

It has been suggested that the antipsychotic effect of antipsychotics is mediated by the antagonism of the dopamine D2 receptor in the limbic-cortical regions. Risperidone has an atypical property, but its effect on limbic-cortical regions has not been evaluated.

OBJECTIVES

In this study, we examined the relationship among doses of risperidone and limbic-cortical dopamine D2 receptor occupancy using positron emission tomography.

METHODS

Seven patients with schizophrenia were scanned during the steady state with risperidone. Their occupancies in limbic-cortical regions were determined using positron emission tomography with [11C]FLB 457.

RESULTS

The average occupancy ranged from 38% to 80% on doses of 1-6 mg/day. The saturation curve plotted against the drug level fit the data well.

CONCLUSIONS

Our results demonstrate that the D2 receptor occupancy with risperidone in the limbic-cortical regions seems to be similar to that of previous reports regarding the striatum, and it would be comparable to that of typical antipsychotics.

Trihalomethane removal by activated carbon fiber

For the safety of drinking water, trihalomethanes are removed by adsorption onto activated carbon fiber from single-component solutions. The amounts adsorbed onto adsorbents with large surface area and/or pore volume were small. Stronger surface hydrophobicity of adsorbent was correlated with a larger amount of trihalomethanes adsorbed. A trihalomethane with bromine was adsorbed to a greater extent than that with chlorine. The differences in the amounts adsorbed among trihalomethanes can be explained by the polarity of trihalomethane molecules. The amount of trihalomethanes adsorbed was mainly dominated by the strength of hydrophobicity of activated carbon fibers.

Adenosine-induced coronary flow reserve in Watanabe heritable hyperlipidemic rabbits

The Watanabe heritable hyperlipidemic (WHHL) rabbit develops coronary atherosclerosis and hypercholesterolemia because of a genetic deficiency of low-density lipoprotein receptors and is therefore a good animal model for studying the relationships of coronary atherosclerosis, hypercholesterolemia and coronary flow reserve. The aim of the present study was to assess myocardial perfusion at baseline and during adenosine infusion (0.2 mg x kg(-1) x min(-1)) in 8 WHHL rabbits (13.8+/-0.5 months) with 13N-ammonia, small-animal positron emission tomography (PET) and colored microspheres. Results were compared with those from 6 age-matched Japanese white rabbits. Plaque distribution was also examined in the extramural coronary arteries. All 8 WHHL rabbits had coronary plaques, with 6 showing multiple plaques. Mean global myocardial blood flow (ml x min(-1) x g(-1)) did not differ significantly between control and WHHL groups both at baseline (3.67+/-0.72 vs 4.26+/-1.12 ml x min(-1) x g(-1), p=NS) and with adenosine (7.92+/-2.00 vs 9.27+/-2.91 ml x min(-1) x g(-1), p=NS), nor did coronary flow reserve (2.16+/-0.37 vs 2.18+/-0.41, p=NS). None showed evidence of regional perfusion abnormalities by visual and semiquantitative analyses of PET images. It was concluded that WHHL rabbits preserve adenosine-induced coronary flow reserve despite coronary atherosclerosis and hypercholesterolemia, suggesting that a compensatory mechanism develops in this animal model.

Tumor uptake of radioiodinated anti-human pulmonary surfactant-associated protein monoclonal antibody PE10 in nude mice bearing human pulmonary adenocarcinoma in combination with an unlabeled preload

This study assessed the potential use of radioimmunoscintigraphy of pulmonary alveolar Type II cells tumor with the radiolabeled anti-human surfactant-associated protein (SP) monoclonal antibody (MAb) PE 10 in combination with preloads of unlabeled MAb. The in vitro binding of iodine-125 ((125)I)-labeled MAb PE 10 (1 microg), which had a specific radioactivity of 400 MBq/mg, on human pulmonary papillary adenocarcinoma NCI-H441 cells that produced SP was investigated. In NCI-H441 tumor-bearing nude mice, the tumor uptake of (125)I-MAb PE 10 (5 microg) was examined in combination with preloads of unlabeled MAb PE 10 (0, 5, 10, and 50 microg). An isotype-matched unassociated murine MAb was used as a control both in vitro and in vivo. (125)I-MAb PE 10 showed specific cell binding compared with (125)I-control MAb. Tumor uptake of (125)I-MAb PE 10 in vivo reached a peak of 4.97+/-0.33% injected dose per gram (%ID/g) at 48 h postinjection. Preloads of 5 and 10 microg unlabeled MAb PE 10 significantly enhanced tumor uptake at 48 h postinjection ( 5.94+/-0.29% ID/g and 5.72+/-0.29% ID/g, respectively), whereas preload of 50 microg unlabeled MAb PE 10 significantly decreased tumor uptake ( 2.75+/-0.32% ID/g) at 48 h. Preload of 5 microg unlabeled MAb PE 10 significantly increased the tumor-to-blood radioactivity ratio at 48 h ( 2.39+/-0.16). Preloads of unlabeled control MAb did not cause any significant change in tumor uptake. Immunohistochemistry showed the intracellular and pericellular patterns of SP expression in tumor cells. In conclusion, radioimmunoscintigraphy with MAb PE 10 labeled with a gamma-emitting radioiodine such as (123)I might be a useful means of targeting pulmonary alveolar Type II tumor cells in combination with preloading with an optimal dose of the unlabeled MAb.

Brain acetylcholinesterase activity in Alzheimer disease measured by positron emission tomography

Brain acetylcholinesterase activity was measured in 14 patients with Alzheimer disease and 14 age-matched control subjects by positron emission tomography with a radioactive acetylcholine analogue. Kinetic analysis was performed to calculate k3, an index of acetylcholinesterase activity. The k3 values were significantly reduced in the neocortex, hippocampus, and amygdala of all patients with Alzheimer disease, suggesting a loss of cholinergic innervation from the basal forebrain. Most profound reductions of k3 values were observed in the temporal (-30%) and parietal cortices (-31%), although reductions of k3 values were relatively uniform in the cerebral neocortex. This technique may be a powerful tool for early diagnosis of Alzheimer disease and also for therapeutic monitoring of acetylcholinesterase inhibitors in Alzheimer disease.