Paternal phylogeography and genetic diversity of East Asian goats.

This study was a first analysis of paternal genetic diversity for extensive Asian domestic goats using SRY gene sequences. Sequencing comparison of the SRY 3'-untranslated region among 210 Asian goats revealed four haplotypes (Y1A, Y1B, Y2A and Y2B) derived from four variable sites including a novel substitution detected in this study. In Asian goats, the predominant haplotype was Y1A (62%) and second most common was Y2B (30%). Interestingly, the Y2B was a unique East Asian Y chromosomal variant, which differentiates eastern and western Eurasian goats. The SRY geographic distribution in Myanmar and Cambodia indicated predominant the haplotype Y1A in plains areas and a high frequency of Y2B in mountain areas. The results suggest recent genetic infiltration of modern breeds into South-East Asian goats and an ancestral SRY Y2B haplotype in Asian native goats.

Copper-62 ATSM as a hypoxic tissue tracer in myocardial ischemia.

Copper-62 labeled diacetyl-bis(N4-methylthiosemicarbazone) (62Cu-ATSM) has been proposed as a generator produced positron-emitting tracer for hypoxic tissue imaging. To clarify the usefulness of 62Cu-ATSM for myocardial ischemia, 62Cu-ATSM PET was performed in 7 patients with coronary artery disease. Increased myocardial uptake of 62Cu-ATSM was observed (myocardium/blood ratio: 3.09) in one patient with unstable angina, who had increased 18F-fluorodeoxyglucose (18F-FDG) uptake under the fasting condition. The other 6 patients, who were clinically stable, did not have increased 62Cu-ATSM uptake, although abnormal 18F-FDG uptake was seen in 4 patients. This preliminary study suggests that 62Cu-ATSM is a promising PET tracer for hypoxic imaging in acute ischemia.

Acute effects of stereotactic radiosurgery on the kinetics of glucose metabolism in metastatic brain tumors: FDG PET study.

UNLABELLED: Hyperacute changes in the expression of glycolysis-associate gene products as well as FDG uptake in tumor cells after high-dose irradiation reflect response of the cells to noxious intervention and may be a potential indicator of the outcome of treatment. To understand acute effects on the kinetics of glucose metabolism of tumors in vivo after high-dose irradiation, we analyzed dynamic FDG PET data in patients with metastatic brain tumors receiving stereotactic radiosurgery. MATERIALS AND METHODS: We studied 5 patients with metastatic brain tumors by means of dynamic FDG PET before and 4 hours after stereotactic radiosurgery. Rate constants of glucose metabolism (K1*- k3*) were determined in a total of 13 tumors by a non-linear least squares fitting method for dynamic PET and arterial blood sampling data. Rate constants after radiosurgery were compared with those before radiosurgery. Changes in the rate constants induced by the therapy were also correlated with changes in tumor size evaluated by CT and/or MRI 6 months later. RESULTS: Four hours after radiosurgery, the phosphorylation rate indicated by k3* was significantly higher (0.080 +/- 0.058) than that before radiosurgery (0.049 +/- 0.023) (p < 0.05, paired t test), but there was no significant change in the membrane transport rates indicated by K1* and k2*. Although increases in the net influx rate constant K* (= K1*k3*/(k2* + k3*)) were correlated with increases in k3*, K* after radiosurgery (0.027 +/- 0.011) was not significantly different from that before the therapy (0.024 +/- 0.012). The reduction in the tumor size was correlated with k3* after radiosurgery. CONCLUSION: Acceleration of the phosphorylation process was demonstrated in vivo in metastatic brain tumors as early as 4 hours after stereotactic radiosurgery, as shown experimentally in vitro in a previous report. The phenomenon may be a sensitive indicator of cell damage.

Characterization of acetate metabolism in tumor cells in relation to cell proliferation: acetate metabolism in tumor cells.

To reveal the metabolic fate of acetate in neoplasms that may characterize the accumulation patterns of [1-(11)C]acetate in tumors depicted by positron emission tomography. Four tumor cell lines (LS174T, RPMI2650, A2780, and A375) and fibroblasts in growing and resting states were used. In uptake experiments, cells were incubated with[1-(14)C]acetate for 40 min. [(14)C]CO(2) was measured in the tight-air chamber, and the metabolites in cells were identified by thin layer chromatography and paper chromatography. The glucose metabolic rate of each cell line was measured with [2,6-(3)H]2-deoxy-glucose (DG), and the growth activity of each cell line was estimated by measuring the incorporation of [(3)H]methyl thymidine into DNA. Compared with resting fibroblasts, all four tumor cell lines showed higher accumulation of (14)C activity from [1-(14)C]acetate. These tumor-to-normal ratios of [1-(14)C]acetate were larger than those of DG. Tumor cells incorporated (14)C activity into the lipid-soluble fraction, mostly of phosphatidylcholine and neutral lipids, more prominently than did fibroblasts. The lipid-soluble fraction of (14)C accumulation in cells showed a positive correlation with growth activity, whereas the water-soluble and CO(2) fractions did not. These findings suggest that the high tumor-to-normal ratio of [1-(14)C]acetate is mainly due to the enhanced lipid synthesis, which reflects the high growth activity of neoplasms. This in vitro study suggests that [1-(11)C]acetate is appropriate for estimating the growth activity of tumor cells.

Ultrasound activates the auditory cortex of profoundly deaf subjects.

Using three-dimensional PET, the cortical areas activated by bone-conducted ultrasound were measured from five profoundly deaf subjects and compared with the cortical areas of normal-hearing subjects activated by stimuli through bone-conducted ultrasonic, air-conducted, bone-conducted, and vibro-tactile hearing aids. All of the hearing aids, including the ultrasonic hearing aid, consistently activated the medial portion of the primary auditory cortex of the normal volunteers. The same cortical area was also significantly activated in the profoundly deaf subjects although the percentage increase in regional cerebral blood flow (rCBF) was smaller than in normal subjects. These results suggest that extra-cochlear routes convey information to the primary auditory cortex and can therefore produce detectable sound sensation even in the profoundly deaf subjects, who reported a sensation themselves.

Dynamic changes in glucose metabolism accompanying the expression of the neural phenotype after differentiation in PC12 cells.

To assess what properties of glucose metabolism are most closely related to expression of the neural phenotype, some parameters of glucose metabolism in PC12 cells before (tumor-type) and after differentiation (neuron-type) were investigated. Neuron-type cells exhibited a 2.7-fold higher level of [3H]DG retention than tumor-type cells, accompanied by a higher glucose transport rate and higher levels of hexokinase activity. [14C]CO2 production from [U-14C]glucose in neuron-type was also more than four-times greater than that in tumor-type cells. The levels of [14C]carbon in macromolecules from [14C]glucose in neuron-type cells were also much higher (10.6-fold) than those in tumor-type cells, and the levels of incorporation of [14C]carbon were almost as high as those of [14C]CO2. From the metabolite analysis, amino acids appeared to be the major compounds converted from glucose. On the other hand, the uptakes of [35S]methionine-[35S]cysteine and [3H]uridine in neuron-type cells were lower than those in tumor-type cells. Following depolarization with 50 mM potassium, [14C]CO2 production increased, but the retention of [14C]carbon was not changed in neuron-type cells. The largest change accompanied by acquisition of the neural phenotype was carbon incorporation into the macromolecules derived from glucose. This property may be important for the expression of the neural phenotype as well as the higher levels of both glucose uptake and oxygen consumption.

Age-related changes in energy production in fresh senescence-accelerated mouse brain slices as revealed by positron autoradiography.

To investigate age-related changes in cerebral energy production, we compared senescence-accelerated prone mice (SAMP8) as an animal model of accelerated aging and senescence-accelerated resistant mice (SAMR1) as a control. Considering that the cerebral glucose metabolic rate (CMRglc) at the time of O(2) deprivation and 2,4-dinitrophenol (DNP) loading would reflect anaerobic glycolytic capacity and mitochondrial function, respectively, we investigated dynamic changes in CMRglc before and after loading with these perturbations. Fresh brain slices were incubated with [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, and serial two-dimensional time-resolved images of [(18)F]FDG uptake in these slices were obtained on the imaging plates. The fractional rate constant (=k(3)*) of [(18)F]FDG proportional to the CMRglc was evaluated by applying the Gjedde-Patlak graphical method to the image data. The k(3)* value before the hypoxic perturbation in all of the brain sites analyzed was higher in SAMP8 than SAMR1 in both the 2- and 10-month-old groups. With O(2) deprivation, k(3)* values were higher without site specificity in the 2-month-old SAMP8 than in 2-month-old SAMR1, whereas in 10-month-old mice, there was no significant difference between the two groups. In contrast, with DNP loading, while no significant difference was noted between 2-month-old SAMP8 and 2-month-old SAMR1, in 10-month-old mice, the SAMP8 group showed lower values in certain regions than SAMR1 mice. These results suggest that in the brain tissue of SAMP8, a marked transient enhancement of anaerobic glycolytic capacity in the 2-month-olds and a decrease in mitochondrial function in the subsequent period occur, as a result of which glucose metabolism appears to be enhanced in both the 2- and 10-month-old groups compared to SAMR1 mice.

Myocardial FDG-PET examination during fasting and glucose loading states by means of a one-day protocol.

We propose a new method to measure the myocardial FDG uptake during fasting and glucose loading in one day, a myocardial FDG-PET one-day protocol, with both 2- and 3-dimensional data acquisition (2D and 3D) without background activity subtraction. To confirm it, we evaluated the effect of scatter correction in the 2D and 3D modes of a PET scanner both in phantom and patient studies. In the phantom study, we used a cardiac phantom with six divided chambers and two cylindrical phantoms placed as the activity outside the field of view. Each chamber was filled with a different concentration of F- 18 solution. Regions of interest (ROI) were placed on a polar map generated from reconstructed images and were compared to the concentration of the solution in each chamber in both 2D and 3D. In the patient study, 10 non-diabetic patients with coronary artery disease were studied. Each patient received a myocardial FDG study during fasting (F) and glucose loading (L). L images with background subtraction (Lsub(+)) and without background subtraction (Lsub(-)) were compared by polar map analysis. The ROI counts for the true activity in 2D and 3D demonstrated a linear relationship, and quite similar slopes were observed (0.72 in 2D, 0.69 in 3D). The background fraction in Lsub(-) was 3.59+/-1.83%. There were significant differences between Lsub(-) or Lsub(+) and F in both normal and ischemic myocardium. Scatter correction was successfully performed in both 2D and 3D modes. Background activity is thought to be negligible and this proposed method is simple touse in measuring the myocardial FDG uptake in one day.

Retention mechanism of hypoxia selective nuclear imaging/radiotherapeutic agent cu-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) in tumor cells.

The retention mechanism of the novel imaging/radiotherapeutic agent, Cu-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) in tumor cells was clarified in comparison with that in normal tissue in vitro. With Cu-ATSM and reversed phase HPLC analysis, the reductive metabolism of Cu-ATSM in subcellular fractions obtained from Ehrlich ascites tumor cells was examined. As a reference, mouse brain was used. To determine the contribution of enzymes in the retention mechanisms, and specific inhibitor studies were performed. In subcellular fractions of tumor cells, Cu-ATSM was reduced mainly in the microsome/cytosol fraction rather than in the mitochondria. This finding was completely different from that found in normal brain cells. The reduction process in the microsome/cytosol was heat-sensitive and enhanced by adding exogenous NAD(P)H, an indication of enzymatic reduction of Cu-ATSM in tumor cells. Among the known bioreductive enzymes, NADH-cytochrome b5 reductase and NADPH-cytochrome P450 reductase in microsome played a major role in the reductive retention of Cu-ATSM in tumors. This enzymatic reduction was enhanced by the induction of hypoxia. Radiocopper labeled Cu-ATSM provides useful information for the detection of hypoxia as well as the microsomal bioreductive enzyme expression in tumor.

Greater resistance and lower contribution of free radicals to hypoxic neurotoxicity in immature rat brain compared to adult brain as revealed by dynamic changes in glucose metabolism.

Seven-day-old rat brain slices were incubated at 36C in oxygenated Krebs-Ringer solution containing [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG), and serial two-dimensional time-resolved images of [(18)F]FDG uptake by the slices were obtained. The Gjedde-Patlak graphical method was applied to the image data, and the duration limit of hypoxia loading that allowed recovery of the fractional rate constant (k3*) of [(18)F]FDG (proportional to the cerebral glucose metabolic rate) after hypoxia loading to the unloaded control level was 50 min, and MK-801 as an N-methyl-D-aspartate antagonist had neuroprotective effects, but PBN as a free radical scavenger was ineffective. In our previous study in adult (7-week-old) rat brains [Murata et al., Exp Neurol 2000, 164:269-279], the limit of the hypoxia loading time was 20 min, and both MK-801 and PBN were effective. In the immature rat brains, the ratio of aerobic glucose metabolism to the total glucose metabolism was low compared with the adult rat brains, suggesting only a slight involvement of free radicals in hypoxic neurotoxicity. These data suggest that the higher resistance of immature brains to hypoxia compared to that of adult brains is attributable to a lower involvement of free radicals due to a lower aerobic glucose metabolic rate.

Evaluation of 62Cu labeled diacetyl-bis(N4-methylthiosemicarbazone) as a hypoxic tissue tracer in patients with lung cancer.

62Cu labeled diacetyl-bis(N4-methylthiosemicarbazone) (62Cu-ATSM) has been proposed as a generator-produced, positron-emitting tracer for hypoxic tissue imaging. From basic studies, the retention mechanism of 62Cu-ATSM is considered to be closely related to cytosolic/microsomal bioreduction, a possible system for hypoxic bioreductive drug activation. In order to evaluate the characteristics of 62Cu-ATSM, PET studies were performed in 4 normal subjects and 6 patients with lung cancer. 62Cu-ATSM cleared rapidly from the blood with little lung uptake (0.43+/-0.09, uptake ratio; divided by the arterial input function) in normal subjects. Intense tumor uptake of 62Cu-ATSM was observed in all patients with lung cancer (3.00+/-1.50). A negative correlation was observed between blood flow and flow-normalized 62Cu-ATSM uptake in three of four patients. In contrast, 62Cu-ATSM uptake was not related to that of 18F-fluorodeoxyglucose. The negative correlation between blood flow and flow normalized 62Cu-ATSM uptake suggests an enhancement of retention of 62Cu-ATSM by low flow. 62Cu-ATSM is a promising PET tracer for tumor imaging, which might bring new information for chemotherapeutic treatment as well as radiotherapy of hypoxic tumors.

Posthypoxic reoxygenation-induced neurotoxicity prevented by free radical scavenger and NMDA/non-NMDA antagonist in tandem as revealed by dynamic changes in glucose metabolism with positron autoradiography.

Using a positron autoradiography technique, dynamic changes in the cerebral glucose metabolic rate (CMRglc) induced by hypoxia/reoxygenation were investigated in living brain slices. After incubating fresh rat brain slices (300 microm thick) with [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, serial two-dimensional time-resolved images of [(18)F]FDG uptake in the slices were obtained on imaging plates. As compared to the unloaded control values, with hypoxia-loading [(18)F]FDG uptake increased markedly, suggesting enhanced glycolysis. The net influx constant (K) of [(18)F]FDG at pre-hypoxia-loading and after reoxygenation with loading hypoxia for various periods of time was quantitatively evaluated by applying the Patlak graphical method to the image data. Regardless of the brain region, with hypoxia of /=20 min duration only partial or no recovery was seen, indicating irreversible neuronal damage. The 30-min administration of either N-methyl-D-aspartate (NMDA)/non-NMDA antagonist or a free radical scavenger at the same time as reoxygenation after 20 min hypoxia showed a neuroprotective effect inhibiting the decrease in the post-hypoxia-loading K value. In contrast, no such neuroprotective effect was evident with administration of either of these agents only during hypoxia loading, possibly indicating that immediately after reoxygenation neuronal damage was induced mediated by excitatory amino acids and free radicals in tandem. These results demonstrate that serial quantitative evaluation of CMRglc using this technique may be of use in investigating the brain tissue injury associated with hypoxia/reoxygenation as well as clarifying the underlying mechanisms and protective effect of various drugs against such injury.

Neurotoxicity after hypoxia/during ischemia due to glutamate with/without free radicals as revealed by dynamic changes in glucose metabolism.

Fresh rat brain slices were incubated with [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, and serial two-dimensional time-resolved images of [18F]FDG uptake in the slices were obtained on imaging plates. The fractional rate constant of [18F]FDG (proportional to the cerebral glucose metabolic rate) from pre-loading of ischemia (O(2) and glucose deprivation)/hypoxia (O(2) deprivation) to the reperfused/reoxygenated post-loading phase was quantitatively evaluated by applying the Gjedde-Patlak graphical method to the image data. Against ischemia an N-methyl-D-aspartate antagonist and hypothermia, but not a free radical scavenger, showed a protective effect when administered during ischemia, whereas no such effect was achieved with any of the above agents when administered after reperfusion. Against hypoxia, there was no protective effect with any of the above agents when administered during hypoxia, although an effect was noted with each when administered after reoxygenation. Excitatory amino acids during ischemia loading were found to be the main factor in the neuronal damage associated with ischemia, while in hypoxia, excitatory amino acids working in tandem with free radicals immediately after reoxygenation were implicated.

Hypoxic but not ischemic neurotoxicity of free radicals revealed by dynamic changes in glucose metabolism of fresh rat brain slices on positron autoradiography.

Dynamic changes in the regional cerebral glucose metabolic rate induced by hypoxia/reoxygenation or ischemia/reperfusion were investigated with a positron autoradiography technique. Fresh rat brain slices were incubated with [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, and serial two-dimensional time-resolved images of [18F]FDG uptake in the slices were obtained. In the case of loading hypoxia (oxygen deprivation)/pseudoischemia (oxygen and glucose deprivation) for various periods of time, the net influx constant (K) of [18F]FDG at preloading and after reoxygenation/pseudoreperfusion (post-loading) was quantitatively evaluated by applying the Patlak graphical method to the image data. Regardless of the brain region, with hypoxia lasting > or =20 minutes, the postloading K value was decreased compared with the unloaded control, whereas with pseudoischemia of < or =40 minutes, approximately the same level as the unloaded control was maintained. Next, the neuroprotective effect against hypoxia/pseudoischemia loading induced by the addition of a free radical scavenger or an N-methyl-D-aspartate (NMDA) antagonist was assessed by determining whether a decrease in the postloading K value was prevented. Whereas with 20-minute hypoxia, both agents exhibited a neuroprotective effect, in the case of 50-minute pseudoischemia, only the NMDA antagonist did so, with the free radical scavenger being ineffective. These results demonstrate that hypoxia causes irreversible neuronal damage within a shorter period than ischemia, with both free radicals and glutamate suggested to be involved in tandem in the neurotoxicity induced by hypoxia, whereas glutamate alone is involved in ischemic neurotoxicity.

Noninvasive measurement of cerebral metabolic rate of glucose using standardized input function.

UNLABELLED: The purpose of this study was to propose and validate a method for the noninvasive measurement of cerebral metabolic rate of glucose (CMRGlc) by fluorodeoxyglucose (FDG) PET with a standardized input function (SIF) and an autoradiographic method. METHODS: Plasma input functions, measured by intermittent arterial blood samplings after the intravenous injection of FDG, in 44 patients who had fasted for at least 6 h, were used to generate the SIF. The input function of each patient was normalized with the net injected dose (nID) of FDG and body mass as indicated by body surface area (BSA) or body weight (BW). The SIF was generated as an average of 44 normalized input functions. The estimation of the input function and CMRGlc with SIF was validated in 10 additional patients, who underwent FDG PET after fasting for at least 6 h. CMRGlc was estimated with a simulated input function (IFsim) generated with the following equation: IFsim = SIF x (nID/body mass). The estimated CMRGlc was compared with the measured CMRGlc. RESULTS: Based on BSA, the percentage error of the area under the curve of IFsim was 3.5%+/-2.2%. The percentage error of CMRGlc was 2.9%+/-1.9% in gray matter and 3.4%+/-2.2% in white matter. A similar percentage error was obtained based on BW. CONCLUSION: The proposed method is noninvasive and accurate, and therefore is clinically acceptable for measuring CMRGlc in patients in fasting states.

Hyperacute changes in glucose metabolism of brain tumors after stereotactic radiosurgery: a PET study.

UNLABELLED: Cultured tumor cells show a marked increase in deoxyglucose uptake as early as 3 h after single high-dose irradiation, reflecting hyperacute response of the cells to noxious intervention. To evaluate the hyperacute effect of high-dose irradiation on tumor glucose metabolism in vivo, we measured 2-[18F]fluoro-2-deoxy-D-glucose (FDG) tumor uptake before and immediately after stereotactic radiosurgery. METHODS: A total of 19 brain tumors (17 metastatic and 2 primary, a meningioma and a central neurocytoma) in eight patients were treated with stereotactic radiosurgery. The received dose was between 24 and 32 Gy delivered to the central target point in the tumor. FDG PET was performed within 1 wk before radiosurgery and again 4 h after treatment. The net influx constant (Ki) was calculated on a pixel-by-pixel basis using graphical analysis, and the Ki ratio of tumor to ipsilateral cerebellum was used as an index of FDG uptake of the tumor. RESULTS: Eighteen of 19 irradiated tumors, all metastatic tumors and the meningioma, showed a 29.7% +/- 14.0% increase in the Ki ratio, which was significantly higher than that of nonirradiated tumors (4.1% +/- 3.6%, n = 8, P < 0.0001, analysis of variance). In metastatic tumors, an increase in the Ki ratio was significantly correlated with a decrease in the size of the irradiated tumors, as revealed by follow-up with CT or MRI (r = 0.61, P = 0.012, simple regression). The meningioma did not show a significant decrease in size, probably due to the short follow-up period. The central neurocytoma did not show any change in the Ki ratio or in tumor size. CONCLUSION: Serial FDG PET could be a potential tool for predicting the outcome of radiosurgery for brain tumors by detecting hyperacute changes in tumor glucose metabolism.

Dynamic changes in glucose metabolism induced by thiamine deficiency and its replenishment as revealed by a positron autoradiography technique using rat living brain slices.

Dynamic changes in the cerebral glucose metabolic rate (CMRglc) before and after thiamine replenishment were investigated in living brain slices obtained from pyrithiamine-treated (PT) and pair-fed control rats by use of a positron autoradiography technique. Fresh rat brain slices (300 microm thick) were incubated with [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, during which serial two-dimensional images of [18F]FDG uptake in the slices were constructed on the imaging plates. The net influx constant (=K) of [18F]FDG was determined by a Patlak graphical method of the image data. Prior to thiamine pyrophosphate (TPP)-loading, the K value in the neurologically symptomatic PT was higher in all brain regions except the thalamus and mammillary body than the control, suggesting compensatory enhanced glycolysis. The rapid decrease in this heightened net influx constant immediately after TPP-loading was surmised to be due to activation of pyruvate oxidation with lactate as the substrate, with this inhibiting the glycolysis. From > or = 150 min after TPP-loading, the K value continued to show low values in the thalamus and mammillary body, which are regarded as the responsible sites for Korsakoff syndrome, whereas in all other sites recovery to control values was observed. These findings suggest that using this technique the quantitative evaluation of serial local changes in CMRglc from thiamine deficiency to after its replenishment may be useful in elucidating the pathophysiology and prognosis of Wernicke's encephalopathy.

A trial for the quantification of regional myocardial blood flow with continuous infusion of Tc-99m MIBI and dynamic SPECT.

UNLABELLED: We propose a new method to quantify regional myocardial blood flow (rMBF) by continuous infusion of Tc-99m MIBI and dynamic SPECT. METHODS: Five patients with old myocardial infarction were studied. During continuous infusion of MIBI (approximately 740 MBq) with a syringe pump in 10 min, dynamic SPECT scan was performed every minute and lasted 20 min after the start of infusion to identify myocardial uptake of MIBI. Input function was obtained from the radioactivity in the left ventricle (LV) in dynamic SPECT images. Spillover fraction between LV and myocardium (M) was corrected with phantom data. The influx constant (Ku) was calculated by Patlak plot graphical analysis, and compared with rMBF measured by PET (F) with N-13 ammonia based on Patlak plot analysis with correction for the extraction fraction. To correct the limited first-pass extraction of MIBI, linearization correction by means of the permeability-surface area (PS) product value was also applied. RESULTS: Spillover fractions of MIBI were 0.169+/-0.056 from LV to M, and 0.042+/-0.021 from M to LV. Ku was well correlated with F (Ku = 0.057 + 0.220F, r = 0.83, p < 0.01) and the slope and correlation were improved after linearizaiton (F(MIBI) = -0.131+0.858F, r = 0.94, p < 0.01). CONCLUSION: The proposed method has the potential to be a clinically feasible tool for quantitative measurement of rMBF.

A novel 111In-labeled antisense DNA probe with multi-chelating sites (MCS-probe) showing high specific radioactivity and labeling efficiency.

A multi-aminolinked oligodeoxynucleotide (ODN) was synthesized by substitution of dT with aminolinked dU in the sequence, following conjugation with isothiocyanobenzyl-EDTA (IBE) for 111In labeling. As a model target gene, the c-erbB-2 protooncogene was used. The probability of the number of aminolinked dU in the 20mer ODN was 5, but there were actually 3 and 4 in the selected antisense and sense ODNs, respectively. The IBE/ODN conjugation levels of probes with multi-chelating sites (MCS-probe) were 1.6 (antisense) and 2.4 (sense), more than 50 times higher than those of our previous studies using 5'-end aminolinked ODNs (IBE/ODN = 0.03). Labeling studies using the MCS-probe and 111In indicated that specific radioactivity as high as 48 MBq/nmol could be obtained with a labeling efficiency of over 90%. The 111In-antisense-MCS-probe could bound to sense ODN under physiological conditions, but the 111In-sense-MCA-probe could not. Thus, side-chain modification of ODN for metal labeling is considered to be useful for antisense techniques.

Dynamic changes in glucose metabolism of living rat brain slices induced by hypoxia and neurotoxic chemical-loading revealed by positron autoradiography.

Fresh rat brain slices were incubated with 2-deoxy-2-[18F]-fluoro-D-glucose ([18F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, and serial two-dimensional time-resolved images of [18F]FDG uptake were obtained from these specimens on imaging plates. The fractional rate constant (= k3*) of [18F]FDG proportional to the cerebral glucose metabolic rate (CMRglc) was evaluated by applying the Gjedde-Patlak graphical method to the image data. With hypoxia loading (oxygen deprivation) or glucose metabolism inhibitors acting on oxidative phosphorylation, the k3* value increased dramatically suggesting enhanced glycolysis. After relieving hypoxia < or = 10-min, the k3* value returned to the pre-loading level. In contrast, with > or = 20-min hypoxia only partial or no recovery was observed, indicating that irreversible neuronal damage had been induced. However, after loading with tetrodotoxin (TTX), the k3* value also decreased but returned to the pre-loading level even after 70-min TTX-loading, reflecting a transient inhibition of neuronal activity. This technique provides a new means of quantifying dynamic changes in the regional CMRglc in living brain slices in response to various interventions such as hypoxia and neurotoxic chemical-loading as well as determining the viability and prognosis of brain tissues.