Exploratory activity and spatial learning in 12-month-old APP695SWE/co+PS1/ΔE9 mice with amyloid plaques

APP(695)SWE/co+PS1/DeltaE9 mice with Abeta plaques in neocortex and hippocampus were evaluated in tests of exploratory activity and spatial learning. On the initial testing day, 12-month-old APP(695)SWE/co+PS1/DeltaE9 mice spent more time than non-transgenic controls in the open arms of the elevated plus-maze. The bigenic group also travelled farther in the central region of the open-field without spending more time there. Only the bigenic group alternated above chance in the T-maze. In the Morris water maze, APP(695)SWE/co+PS1/DeltaE9 mice were impaired during acquisition of the hidden platform sub-task and the probe trial but not in the visible platform test. These results indicate a selective spatial deficit and disinhibitory tendencies in a mouse model with amyloid pathology.

Detection of aortic graft infection by fluorodeoxyglucose positron emission tomography: Comparison with computed tomographic findings

OBJECTIVE

Radionuclide imaging with fluorodeoxyglucose (FDG) and positron emission tomography (PET) has been proposed for the identification of vascular graft infection; however, its accuracy has not been determined. We performed this prospective study to compare the usefulness of FDG-PET in the assessment of vascular graft infection relative to computed tomography (CT).

METHODS

FDG-PET was performed for 33 consecutive patients with a suspected arterial prosthetic graft infection. The PET images were then assessed visually in terms of the density of uptake. In cases with positive uptake, the pattern of accumulation was also defined, such as focal or diffuse uptake. We compared the diagnostic efficiency of PET with contemporaneous CT in detection of infection of the arterial prosthetic graft.

RESULTS

On the basis of the surgical, microbiological, and clinical follow-up findings, the aortic grafts were considered infected in 11 patients and not infected in 22 patients. Although the sensitivity of PET (91%) was higher than that of CT (64%), its specificity (64%) was lower than that of CT (86%). When focal uptake was set as the positive criterion in FDG, the specificity and positive predictive value of PET for the diagnosis of aortic graft infection improved significantly to 95% (P < .05 for both).

CONCLUSIONS

Although both techniques are useful in evaluation of patients with suspected aortic graft infection, using the characteristic FDG uptake pattern described previously as a diagnostic criterion made the efficacy of FDG superior to that of CT in the diagnostic assessment of patients with suspected aortic graft infection.

Radionuclide imaging metabolic activity of brown adipose tissue in a patient with pheochromocytoma

We describe a patient with extra-adrenal pheochromocytoma and high plasma norepinephrine levels. Radionuclide images of this patient obtained using (18)F-fluorodeoxyglucose and (123)I-metaiodobenzylguanidine revealed bilateral tracer accumulation in the shoulder and lower neck. The regions of radiotracer uptake corresponded to the location of human brown adipose tissue (BAT). Excessive sympathetic stimulation by high circulating catecholamine concentrations augmented the metabolic activity and tracer uptake in the BAT. This study showed that radionuclide imaging can noninvasively visualize human BAT in terms of metabolic and functional activity.

Evaluation of the use of a standard input function for compartment analysis of [123I]iomazenil data: factors influencing the quantitative results

Adoption of standard input function (SIF) has been proposed for kinetic analysis of receptor binding potential (BP), instead of invasive frequent arterial samplings. The purpose of this study was to assess the SIF method in quantitative analysis of [123I]iomazenil (IMZ), a central benzodiazepine antagonist, for SPECT. SPECT studies were performed on 10 patients with cerebrovascular disease or Alzheimer disease. Intermittent dynamic SPECT scans were performed from 0 to 201 min after IMZ-injection. BPs calculated from SIFs obtained from normal volunteers (BPs) were compared with those of individual arterial samplings (BPo). Good correlations were shown between BP(o)s and BP(s)s in the 9 subjects, but maximum BP(s)s were four times larger than the corresponding BP(o)s in one case. There were no abnormal laboratory data in this patient, but the relative arterial input count in the late period was higher than the SIF. Simulation studies with modified input functions revealed that height in the late period can produce significant errors in estimated BPs. These results suggested that the simplified method with one-point arterial sampling and SIF can not be applied clinically. One additional arterial sampling in the late period may be useful.

Cardiac Tumor as an Initial Manifestation of Acquired Immunodeficiency Syndrome

A cardiac tumor was the first manifestation of acquired immunodeficiency syndrome (AIDS) in a female patient in a state of severe immunodeficiency caused by human immunodeficiency virus (HIV) infection. The extensive cardiac and extracardiac involvement shown by various imaging modalities, including echocardiography and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), suggested that she was in the critical stage of non-Hodgkin's lymphoma (NHL). AIDS was treated by highly active-antiretroviral therapy and the NHL was treated by a combination of rituximab-cyclophosphamide-vincristine-doxorubicine-predonisolone. After 6 cycles of chemotherapy, she was in complete remission. Her cardiac tumor dramatically reduced in size and FDG-PET showed no positive uptake on whole body imaging. Generally, an AIDS-related cardiac tumor tends to be diagnosed at the late stage of the disease because of its nonspecific clinical findings, resulting in an extremely poor prognosis. In the present case, the cardiac tumor was detected by echocardiography and treated with appropriate chemotherapy. Early diagnosis and prompt treatment may improve a patient's prognosis.

Transgenic mice expressing the human C99 terminal fragment of betaAPP: effects on cytochrome oxidase activity in skeletal muscle and brain

In order to furnish a combined model of relevance to human inclusion-body myopathy and Alzheimer's disease, transgenic mice expressing human betaAPP-C99 in skeletal muscle and brain under the control of the cytomegalovirus/beta-actin promoter were produced (Tg13592). These transgenic mice develop Abeta deposits in muscles but not in brain. Cell metabolic activity was analyzed in brain regions and muscle by cytochrome oxidase (CO) histochemistry, the terminal enzyme of the electron transport chain. By comparison to age-matched controls of the C57BL/6 strain, CO activity was selectively increased in dark skeletal muscle fibers of Tg13592 mice. In addition, only increases in CO activity were obtained in those brain regions where a significant difference appeared. The CO activity of Tg13592 mice was elevated in several thalamic nuclei, including laterodorsal, ventromedial, and midline as well as submedial, intralaminar, and reticular. In contrast, the groups did not differ in most cortical regions, except for prefrontal, secondary motor, and auditory cortices, and in most brainstem regions, except for cerebellar (fastigial and interpositus) nuclei and related areas (red and lateral vestibular nuclei). No variation in cell density and surface area appeared in conjunction with these enzymatic alterations. The overproduction of betaAPP-C99 fragments in brain without (amyloidosis did not appear to affect the metabolic activity of structures particularly vulnerable in Alzheimer's disease.

Exploratory activity, anxiety, and motor coordination in bigenic APPswe + PS1/ΔE9 mice

Bigenic APPswe + PS1/DeltaE9 mice with Abeta plaque formation in neocortex and hippocampus were evaluated in three tests measuring exploratory activity. By comparison to a non-transgenic group controlled for age and gender, 7-month-old APPswe + PS1/DeltaE9 mice spent more time in the open arms and had higher open/total entries and duration in the elevated plus-maze, indicative of disinhibitory tendencies. On the contrary, the groups did not differ in T-maze and open-field tests. Moreover, the motor coordination of the bigenic group was equivalent to that of controls in stationary beam, coat-hanger, rotorod, and grip strength tests. No mouse displayed neurological signs, such as pathological reflexes, myoclonus, or convulsions. The results in the elevated plus-maze test are akin to the loss of inhibitory control observed in some patients with Alzheimer's disease.

Superimposed display of coronary artery on gated myocardial perfusion scintigraphy

Fusion of images of vascular anatomy and of myocardial perfusion images might be helpful for understanding the relationship between ischemia and the responsible vessels. The aim of this study was to develop a simple means of superimposing the images obtained from coronary angiography and gated myocardial perfusion SPECT.

METHODS

Right and left oblique views from conventional coronary angiography and left ventriculography (LVG) were stored as 512 x 512 x 8-bit digital datasets and combined. We reconstructed images from routine gated myocardial perfusion imaging (MPI) by using (99m)Tc-tetrofosmin to match the oblique positions between the image from MPI and combined angiographic images. We then generated a 3-dimensional (3D) surface map by using the quantitative gated SPECT (QGS)/quantitative perfusion SPECT (QPS) program. Both the combined angiographic images and the 3D surface map were rescaled and unified by registering the internal landmarks between the 2 images. After subtraction of the LVG image, the coronary angiogram and the 3D surface map were fused into 1 image. All processes were performed with the QGS/QPS program and commercially available graphic software. We applied this method to datasets from a cardiac phantom and from several patients with coronary artery disease.

RESULTS

In the phantom study, our technique could obtain a 3D surface map in which the oblique angle was identified as that of radiography and could realize image registration and superimposition of radiography on scintigraphy. The preliminary results from the patients indicated that the markedly stenotic vessels showed good coincidence with the regional myocardial perfusion abnormalities on the unified images. In addition, these images could show the relationship between the coronary artery and regional wall motion in the gated mode.

CONCLUSION

We developed a simple method of superimposing the image of the coronary artery tree on images from gated MPI. The technique yielded useful information about myocardial perfusion and function as well as the supplying coronary artery.

Transgenic mice overexpressing both amyloid beta-protein and perlecan in pancreatic acinar cells

Heparan sulfate proteoglycans such as perlecan are thought to facilitate amyloid fibril formation. Tg3695 mice overexpress perlecan core protein in many tissues including the brain and pancreas. Tg13592 mice overexpress the signal plus 99-amino acid carboxyl terminal sequences (C99) of amyloid beta-protein precursor in multiple tissues and develop amyloid deposits in the pancreas. To investigate a role of perlecan in beta-amyloidosis, we established doubly transgenic mice by crossing the two lines of transgenic mice. The expression levels of the two transgenes remained unchanged in the brain and pancreas and the doubly transgenic mice did not develop amyloid deposits in the brain up to 19-months of age. Amyloid load detected by thioflavine S in the pancreas of the doubly transgenic mice was not significantly different from that in the transgenic littermates expressing only C99. Amyloid load in the pancreas increased during aging. We found a positive correlation between the Abeta-immunoreactive (non-fibrillar and fibrillar) and thioflavine S-positive (fibrillar) Abeta deposits in the single (C99) but not doubly transgenic mice. Our results suggest that perlecan does not independently influence amyloid formation in the pancreas of the transgenic mice and that there may be other factors that may modulate amyloid formation together with perlecan.

Gated myocardial SPECT to predict response to beta-blocker therapy in patients with idiopathic dilated cardiomyopathy

Because of the difficulty of predicting the response of patients with idiopathic dilated cardiomyopathy (IDC) to beta-blocker therapy, this study was performed to evaluate whether gated myocardial SPECT (gated SPECT) could be useful for predicting that response.

METHODS

We performed gated SPECT with (99m)Tc-sestamibi on 38 patients with IDC before treatment with a beta-blocker and standard medication. Perfusion abnormalities, left ventricular (LV) function, and spheric distortion were assessed by a quantitative software program.

RESULTS

We classified patients into 2 groups according to improvement in LV function after 4 mo of therapy. The groups consisted of 16 poor responders whose LV ejection fraction (LVEF) increased less than 10% and 22 good responders whose LVEF increased by 10% or more. The patient characteristics before therapy, including LV volume and LVEF, did not significantly differ between the 2 groups, but the size of the myocardial perfusion defect and spheric distortion were significantly greater in poor responders than in good responders.

CONCLUSION

Gated SPECT, by allowing simultaneous assessment of perfusion, function and geometry, might be useful for predicting the response of patients with IDC to beta-blocker therapy.

Apoptosis in human oral squamous cell carcinomas is induced by 15-deoxy-delta 12,14-prostaglandin J2 but not by troglitazone

15-deoxy-Delta(12,14)-prostaglandin J(2) (15-d-PGJ(2)) and troglitazone have been shown to induce apoptosis in several carcinoma cell lines. However, apoptotic signaling pathways of these agents are poorly understood. We tested the hypothesis that peroxisome proliferator-activated receptor-gamma ligands such as these two agents will induce caspase-mediated apoptosis in human oral squamous cell carcinomas (SCC). Treatment of these cell lines with 15-d-PGJ(2) or troglitazone decreased cell viability in a time- and dose-dependent manner. 15-d-PGJ(2), but not troglitazone, induced apoptosis, and this effect was time-dependent. Exposure of cells to 20 micro M of 15-d-PGJ(2) initiated early cytochrome c release, followed by late caspase activation. Furthermore, co-treatment with caspase inhibitors such as Z-VAD-FMK or Z-DEVD-FMK of oral SCC cells that had been treated with 20 micro M of 15-d-PGJ(2) blocked apoptosis. Our study demonstrates that treatment with 15-d-PGJ(2), but not troglitazone, induces apoptosis in human SCC cell lines, and 15-d-PGJ(2) appears to work through cytochrome c release and caspase activation.

Visualization of interscapular brown adipose tissue using (99m)Tc-tetrofosmin in pediatric patients

Brown adipose tissue (BAT) is a site of nonshivering thermogenesis in mammals. The mitochondria of BAT operate in an uncoupled mode and increase fatty acid oxidation to produce heat at birth. Thus, the BAT of human infants and children contains more active mitochondria than that of adults. We surmised that because (99m)Tc-tetrofosmin can be absorbed by functional mitochondria in the myocardium and in tumor cells, it could reveal mitochondrial function in BAT.

METHODS

Between January 1999 and December 2002, we retrospectively analyzed 385 consecutive studies of (99m)Tc-tetrofosmin uptake in pediatric patients with cardiac disorders. All patients with symmetric (99m)Tc-tetrofosmin accumulation within the neck and shoulder region according to planar images were selected, and the features of the uptake were analyzed.

RESULTS

Increased symmetric (99m)Tc-tetrofosmin uptake in the interscapular BAT was a typical profile of 65 of the 385 patients (17%). The frequency of (99m)Tc-tetrofosmin uptake was significantly higher in winter than in spring or summer (P < 0.05) and prominent in newborns. The frequency peaked between 0 and 2 y of age and then declined with age.

CONCLUSION

Gamma-camera imaging with (99m)Tc-tetrofosmin can reveal interscapular BAT distribution in infants and children in terms of mitochondrial activity.

Efficacy of screening for primary aldosteronism by adrenocortical scintigraphy without discontinuing antihypertensive medication

BACKGROUND

Recently, it has been proposed that discontinuation of antihypertensive medications is not necessarily essential for the measurement of plasma aldosterone-to-renin ratios. We examined the efficacy of adrenocortical scintigraphy performed without modification of antihypertensive medications.

METHODS

A retrospective study was conducted on 119 patients, in whom functional tests, anatomic studies, and adrenocortical scintigraphy were replete. Interrelationship among these was studied. The patients tested were being treated with antihypertensive medications from several classes including angiotensin-converting enzyme inhibitors, calcium antagonists, beta-blockers, diuretics, and spironolactone.

RESULTS

Significantly higher percentage of scintigraphy positive patients had plasma aldosterone-to-renin ratio of greater than 25:1. Positive rate for adrenal nodules by anatomic studies was significantly higher in the scintigraphy positive patients than in the scintigraphy negative patients. Finally, the percentage of patients who underwent adrenalectomy was higher in the scintigraphy positive patients than in the scintigraphy negative patients.

CONCLUSIONS

We conclude that adrenocortical scintigraphy is a valid evaluation tool for primary aldosteronism and that the discontinuation of antihypertensive medications is not a requirement for this test.

Transgenic mice expressing the betaAPP695SWE mutation: effects on exploratory activity, anxiety, and motor coordination

The functional consequences of the betaAPP transgene with the Swedish mutation in mice were assessed in tests of exploratory activity and motor coordination. The betaAPP(695)SWE (Tg2576) transgenic mice are characterized by Abeta plaque formation in the neocortex and hippocampus. By comparison to non-transgenic mice controlled for age and gender, 17-month-old betaAPP(695)SWE transgenic mice displayed impaired spontaneous alternation, increased activity levels in the peripheral part of the open-field, and reduced anxiety in the elevated plus-maze. These results are similar to the loss of inhibitory control observed in some patients with Alzheimer's disease. These measures may be added to cognitive dysfunctions as testing ground for Abeta vaccination and other attempts at experimental therapies.

Acetazolamide assisted Tc-99m MAG3 renography to assess renal blood flow reserve

OBJECTIVE

The present study examines whether or not baseline and acetazolamide (ACZ) Tc-99m MAG3 renography can assess renal blood flow reserve.

METHODS

Renography proceeded for 50 min after sequential injections of 370 MBq Tc-99m MAG3 for baseline renography and 10 min after a 1,000 mg injection of ACZ for ACZ renography. Effective renal plasma flow of renal cortex (cERPF) in each kidney and the percentage change in cERPF of those parameters (deltaERPF) were obtained before and after the administration of ACZ in 10 subjects without hypertension or diabetes (normal group), in 10 with essential hypertension (hypertensive group) and in 10 who had Type 2 diabetes with hypertension (diabetic group). A placebo test was performed in the 10 without hypertension or diabetes using distilled water instead of ACZ (placebo group).

RESULTS

The placebo test performed in the 10 without hypertension or diabetes using distilled water instead of ACZ indicated that the parameter variance between the two types of renogram was below 3.2%. The cERPF of baseline and ACZ Tc-99m MAG3 renography and deltaERPF in the normal, hypertensive and diabetic groups were 89 +/- 10 and 110 +/- 10 ml/min, 89 +/- 14 and 117 +/- 22 ml/min, 100 +/- 23 and 112 +/- 23 ml/min, respectively, and 24.5 +/- 13.5%, 26.0 +/- 9.7% and 12.3 +/- 11.1%, respectively. The difference in the cERPF value was significant in the normal and hypertensive groups whereas this did not change in the diabetic group before or after ACZ administration.

CONCLUSIONS

We suggested that the deltaERPF determined by baseline and ACZ Tc-99m MAG3 renography is a useful parameter for assessing renal blood flow reserve.

Transgenic mice expressing the human C99 terminal fragment of betaAPP: effects on spatial learning, exploration, anxiety, and motor coordination

The functional consequence of beta-amyloid precursor protein (betaAPP) manipulation on behavior was assessed in Tg13592 mice, characterized by transgene expression of the 99 amino acid C-terminal sequence of human betaAPP in brain and skeletal muscle but with plaque formation only in muscle. By comparison to the C57BL/6 background strain controlled for age and gender, Tg13592 transgenic mice had fewer movements in an automated chamber and fewer enclosed arm entries in the elevated plus-maze. This hypoactivity was probably due to a loss in the motivation to explore novel environmental stimuli rather than motor weakness or anxiety. In addition, the acquisition of place learning in the Morris water maze task was impaired in Tg13592 mice. The transgenic mice were not impaired in a probe trial or while swimming toward a visible platform. These results are concordant with the hypothesis that transgene expression of the C-terminal sequence of human betaAPP in brain is sufficient for causing behavioral abnormalities. The hypoactivity and the spatial learning deficit were associated with higher cytochrome oxidase activity seen in thalamic nuclei, indicating that altered regional brain metabolism caused by betaAPP transgene expression may be responsible for the behavioral changes.

Noninvasive measurement of myocardial activity concentrations and perfusion defect sizes in rats with a new small-animal positron emission tomograph

BACKGROUND

We explored the feasibility of measuring regional tracer activity concentrations and flow defects in myocardium of rats with a high spatial resolution small-animal PET system (microPET).

METHODS AND RESULTS

Myocardial images were obtained after intravenous (18)F-fluorodeoxyglucose (18FDG) in 11 normal rats (group 1) and assembled into polar maps. Regional 18F activity concentrations were measured in 9 regions of interest and compared with tissue activity concentrations measured by well counting. In another 9 rats (group 2), myocardial perfusion images were acquired with 13N-ammonia at baseline and during coronary occlusion. On the polar maps recorded during coronary occlusion, the size of perfusion defects was measured as the myocardium with <50% of maximum activity and expressed as percent total myocardium and was correlated with the area at risk defined by postmortem staining. The diagnostic quality of 18FDG and 13N-ammonia microPET images was good to excellent; the images were easily assembled into polar maps. In group 1, regional (18)F concentrations by microPET and postmortem were correlated linearly (r=0.99; P<0.01 for average and r=0.97; P<0.01 for regional concentrations). In group 2, perfusion defect sizes by microPET and postmortem were correlated linearly (P<0.01; r=0.93).

CONCLUSIONS

The findings indicate the feasibility of noninvasive studies of the myocardium in rats with a dedicated small-animal PET-imaging device.

[Myocardial fatty acid imaging with 123I-BMIPP in patients with chronic right ventricular pressure overload: clinical significance of reduced uptake in interventricular septum]

Regionally reduced 123I-BMIPP uptake in the interventricular septum (SEP) is observed in some patients with chronic right ventricular (RV) pressure overload. We studied the significance of this finding by comparing it with mean pulmonary arterial pressure (mPAP). 123I-BMIPP SPECT imaging was carried out in 21 patients with pulmonary hypertension (PH; 51(+)-14 years; 11 men and 10 women; 7 with primary pulmonary hypertension, 11 with pulmonary thromboembolism, and 3 with atrial septal defect). mPAP ranged from 25 to 81 mmHg (49 +/- 16 mmHg). Using a midventricular horizontal long-axis plane, regional BMIPP distributions in the RV free wall and SEP were estimated by referring to those in the LV free wall. Count ratios of the RV free wall and SEP to the LV free wall (RV/LV, SEP/LV) were determined by ROI analysis. RV/LV showed a linear correlation with mPAP (r = 0.42). However, SEP/LV was inversely correlated with mPAP (r = -0.49). When SEP/RV was compared among three regions of SEP in each patient, basal SEP/RV was most sensitively decreased in response to increased mPAP (r = -0.70). These results suggest that the assessment of septal tracer uptake in 123I-BMIPP SPECT imaging is useful for evaluating the severity of RV pressure overload in patients with PH.

Quantitative analysis of lung perfusion in patients with primary pulmonary hypertension

The aim of this study was to evaluate quantitatively the heterogeneity of lung perfusion scans in patients with primary pulmonary hypertension (PPH) and to compare it with the severity of disease.

METHODS

Lung perfusion scans were obtained on 22 patients with PPH and 12 age-matched control subjects. The perfused area rates (PARs) were calculated by dividing the lung area in each 10% threshold width from 10% to 100% of maximal counts by total lung area. The total absolute difference in the PAR between each patient and the mean control value was assumed as the perfusion index of the lung (P index). The P index was compared with hemodynamic parameters and the right ventricular ejection fraction (RVEF), including 7 patients who received long-term vasodilator therapy.

RESULTS

The P index correlated significantly with mean pulmonary arterial pressure (P < 0.001) and RVEF (P < 0.05). In patients with vasodilator therapy, the P index was improved significantly after therapy (P < 0.05) and was associated with a reduction in pulmonary arterial pressure.

CONCLUSION

Quantitative assessment of lung perfusion irregularity might provide useful information about the severity of disease and the effect of therapy in addition to the routine visual representation.