Biomedical subjects

T Ido

Publications and source records attributed to T Ido.

At least 19 recordsLinked to original sources

PubMed1992

Histamine H1 receptors in human brain visualized in vivo by [11C]doxepin and positron emission tomography.

Histamine H1 receptors in the living human brain were visualized by positron emission tomography (PET) using [N-11C-methyl]-(E)-doxepin ([11C]doxepin). The regional distribution of the carbon-11-labeled compound in the brain corresponded well with that of the histamine H1 receptors measured in vitro using [3H]pyrilamine. The radioactivity in the brain was significantly reduced by intravenous pretreatment with d-chlorpheniramine (5 mg), a histamine H1 antagonist. The regional distribution of [11C]doxepin in the brain 45-90 min after its injection was almost the same as that of [11C]pyrilamine in the brain. These results indicate that [11C]doxepin is useful for measuring histamine H1 receptors in human brain by PET.

Adult↗

PubMed1992

Differences in myocardial fluoro-18 2-deoxyglucose uptake in young versus older patients with hypertrophic cardiomyopathy.

The purpose of this study was to determine whether regional myocardial glucose use in patients diagnosed as having hypertrophic cardiomyopathy (HC) at a younger age differs from that in those diagnosed at middle to old age. Sixteen patients with HC (group 1 aged less than 40 years (n = 8); group 2 aged greater than 40 (n = 8) were studied using positron emission tomography and fluoro-18 2-deoxyglucose (FDG). All patients were diagnosed as having HC within 6 years of the study. Contiguous regions of interest were selected circumferentially on each cross-sectional image of the left ventricular wall. In each region of interest, % FDG fractional uptake was calculated. In each patient, % left ventricular FDG fractional uptake was determined as a mean value of % FDG fractional uptake in each region of interest. Moreover, as a measure of nonhomogeneity, the % interregional coefficient of variation in FDG fractional uptake was calculated in each patient. Whereas % left ventricular FDG fractional uptake did not differ between the 2 groups, the % interregional coefficient of variation in FDG fractional uptake was increased in group 1 compared with that in group 2 (11.5 +/- 3.6 vs 7.4 +/- 1.6%; p less than 0.02). Interventricular septum/left ventricular posterior wall thickness ratio and total counts in cross-sectional image did not differ between the 2 groups. These data suggest that patients diagnosed as having HC at a younger age have more nonhomogeneous myocardial metabolic characteristics than do patients diagnosed at middle or old age, and support the notion that HC in the young may be different from that in the middle-aged or elderly.

Adolescent↗

PubMed1992

On-line [11C]methylation using [11C]methyl iodide for the automated preparation of 11C-radiopharmaceuticals.

A novel method for the efficient preparation of 11C-radiopharmaceuticals by on-line [11C]methylation using [11C]methyl iodide has been developed and applied to a rapid, convenient automated system. [11C]Methyl iodide is first trapped in a short column, containing an adsorber and coated substrate, which is connected to an HPLC injector. DMF is then introduced. Alternatively the substrate is added with the DMF. A whole reaction mixture can be easily injected onto an HPLC column for purification by switching the injector valve immediately after the reaction. Thus, radiochemical yields in the preparation of 11C-labeled doxepin, benztropine, cyproheptadine and N-methylspiperone have been improved remarkably and the synthetic procedure simplified.

Benztropine↗

PubMed1992

Tumor diagnosis by PET: potential of seven tracers examined in five experimental tumors including an artificial metastasis model.

The potential of seven tracers for the metabolic imaging of tumors by positron emission tomography was studied using five experimental tumor models. The tracers examined were 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG), 2-deoxy-2-[18F]fluoro-D-galactose (2-[18F]FdGal) and 2-deoxy-2-[18F]fluoro-L-fucose (2-[18F]FdFuc) for investigating energy metabolism. L-[methyl-11C]Methionine ([11C]Met) and 6-[18F]fluoro-L-fucose (6-[18F]FFuc) were used for assessing protein and glycoprotein synthesis, while [3H]thymidine ([3H]Thd) and 2-deoxy-5'-[18F]fluorouridine ([18F]FdUrd) were used to investigate nucleic acid metabolism. The highest mean uptake by the five different tumors was found for [3H]Thd, followed in order by [18F]FDG, [11C]Met, 2-[18F]FdGal, [18F]FdUrd, 2-[18F]FdFuc and 6-[18F]FFuc. The tumor-to-tissue uptake ratios indicated that the nucleosides, [11C]Met and 6-[18F]FFuc were better tracers in the brain region. All the tracers except for the fucose analogs were suitable for the thoracic region, while [11C]Thd and [18F]FDG were superior in the abdominal region. In comparison with the primary tumor model of Lewis lung carcinoma (3LL), [3H]Thd uptake in the artificial metastatic 3LL model showed the maximum enhancement, followed by [18F]FDG, [11C]Met and the other tracers. The [18F]FDG uptake correlated with the [3H]Thd uptake. [18F]FdUrd, 6-[18F]FFuc and 2-[18F]FdGal could be used for distinguishing different types of tumors. The combined use of these radiotracers can possibly allow the assessment of tumor metabolism, and this indicates the viability of tumors.

Animals↗

PubMed1992

4-Borono-2-[18F]fluoro-D,L-phenylalanine: a possible tracer for melanoma diagnosis with PET.

The potential of 4-borono-2-[18F]fluoro-D,L-phenylalanine ([18F]FBPA), a flurodinated derivative of a target compound for boron neutron capture therapy, for melanoma imaging by positron emission tomography (PET) was studied using animal models. A high uptake of [18F]FBPA was found in murine B16 melanoma or in Greene's melanoma No. 179, a melanotic cell line in hamsters, for the first 6 h after injection. Whole body autoradiography using [18F]FBPA gave a clear image of the B16 tumor. The acid-insoluble 18F in the B16 increased to 27% by 6 h, and most of the free 18F was detected as [18F]FBPA in both B16 and plasma. In the hamster models, No. 179 showed a 1.7 times higher uptake than amelanotic Greene's melanoma No. 178 at 6 h post-injection, although both melanomas indicated similar metabolic activities when examined by a tracer uptake study using L-[14C]methionine, 2-deoxy-D-[14C]glucose and [3H]thymidine. [18F]FBPA may be a very promising PET tracer for melanoma imaging.

Animals↗

PubMed1992

Investigation of tumor metastatic potential with N-[18F]fluoroacetyl-D-glucosamine.

In order to investigate the metastatic potential of tumors in vivo by measuring hyaluronic acid metabolism, C57BL/6 mice with B16 melanoma variants and C3H/He mice with FM3A tumor variants were evaluated using N-[18F]fluoroacetyl-D-glucosamine (18F-GlcNFAc). The uptake of 18F-GlcNFAc was slightly higher (P less than 0.05) in B16-F10 tumors (high metastatic potential) than in B16-F1 (low metastatic potential). Analysis of metabolites showed that acid-insoluble fraction was the largest one in the liver by 60 min, whereas in the tumors, phosphates fraction was the major metabolite. Slower metabolism in tumors was suggested, and it may be one of the reasons for the difficulty of detecting the characteristics of their hyaluronic acid synthesis. 18F-GlcNFAc uptake by FM3A variants showed no significant correlation with their metastatic potential. In addition, N-acetyl-D-[1-14C]glucosamine, 2-deoxy-D-[1-14C]glucose and [6-3H]thymidine failed to demonstrate any difference between tumors' metastatic variants in vivo.

Acetylglucosamine↗

PubMed1992

Dose-responsive effect of radiotherapy on the tumor uptake of L-[methyl-11C]methionine; feasibility for monitoring recurrence of tumor.

The L-[methyl-11C]methionine [( 11C]Met) uptake by rat AH109A tumor was decreased irradiation-dose dependently from the control to 5, 10 and 20 Gy. After 10 Gy irradiation, the [11C]Met uptake decreased earlier than the tumor volume reduction, and later, it significantly increased earlier than the recurrent growth. Double tracer autoradiography with [14C]Met and 4-[18F]fluoroantipyrine showed a decrease in the [14C]Met tumor uptake without change of blood flow after irradiation. The [11C]Met uptake representing amino acid metabolism is a sensitive indicator for monitoring radiotherapeutic effect on tumor.

Animals↗

PubMed1992

Inhibition of corneal epithelial wound healing. A comparative study of mitomycin C and 5-fluorouracil.

PURPOSE: The purpose of this study is to assess the influence of the antiproliferative agents, 5-fluorouracil (5-FU) and mitomycin C (MMC), on the intact corneal epithelium and on epithelial wound healing in the rabbit cornea. METHODS: Using an eye cup made of polymethylmethacrylate, the intact rabbit corneas were bathed for 5 or 15 minutes with either MMC (in concentrations of 0.0016%, 0.008%, 0.04%, and 0.2%) or 5-FU (in concentrations of 1% and 5%). The same concentrations of MMC or 5-FU were applied to the cornea with the eye cup in which epithelial cells were mechanically removed. The contralateral fellow eyes, which were bathed in balanced salt solution in the eye cup, had the cornea intact or mechanically abraded and served as controls. Five to six animals were used only once for each concentration of MMC or 5-FU. RESULTS: Neither MMC nor 5-FU caused any discernible changes in the intact cornea of any of the eyes. The epithelial healing was retarded by mitomycin in a dose-related manner, and ID50 was calculated to be 0.06%. Five-fluorouracil 5% significantly delayed epithelial healing, but 1% failed to do so. Mitomycin C was estimated to be at least 125 times as potent as 5-FU in inhibiting corneal epithelial healing. CONCLUSION: These results indicate that particular care should be taken to minimize corneal contact with MMC in the clinical setting, particularly when epithelial defects are present.

Animals↗

PubMed1992

Active melanogenesis in non-S phase melanocytes in B16 melanomas in vivo investigated by double-tracer microautoradiography with 18F-fluorodopa and 3H-thymidine.

3,4-Dihydroxy-2-[18F]fluoro-L-phenylalanine (2-[18F]FDOPA) and [6-3H]thymidine ([3H]Thd) were simultaneously injected into mice transplanted with B16 melanomas of FM3A mammary carcinoma. Melanogenesis was differentiated from DNA synthesis in the mitotic cell cycle by monitoring grain distribution with double-tracer microautoradiography. The percentages of pigmented cells were inversely proportional to those of [3H]Thd-labelled cells, indicating that the greater the number of melanocytes, the smaller was the number of proliferating cells. The number of grains produced by 2-[18F]FDOPA in the [3H]Thd-unlabelled melanocytes was significantly higher (P < 0.001) than the numbers in the [3H]Thd-labelled melanocytes and in nonmelanocytes. The [3H]Thd-unlabelled non-melanocytes and FM3A cells showed the lowest accumulation of 2-[18F]DOPA, which may have resulted from the basic amino acid demand by malignant neoplasms via amino acid transport. The [3H]Thd-labelled cells, regardless of whether they were pigmented or not, had slightly more grains with 2-[18F]FDOPA than the [3H]Thd-unlabelled non-melanocytes (P < 0.05), which may have resulted from the enhanced amino acid requirement for proliferation. Melanogenesis appeared to be activated only in the non-S phase of the mitotic cycle in melanocytes.

Animals↗

PubMed1992

Age-dependent decrease in histamine H1 receptor in human brains revealed by PET.

Age-related changes in histamine H1 receptors were studied using [11C]pyrilamine or [11C]doxepin by positron emission tomography (PET). The frontal, parietal and temporal cortices showed age-related decreases in binding of approximately 13% per decade. In contrast, the thalamus showed no apparent decrease in binding during normal ageing because of its higher nonspecific binding. Post mortem studies also indicated that the nonspecific binding of [3H]pyrilamine in the thalamus was approximately 112% higher than that in the cortex. However, no significant decrease in histamine H1 receptors with age was observed by in vitro binding assays of autopsied human frontal cortex. Possible reasons are given for the larger effects of age observed in the PET study than in the in vitro post mortem binding study.

Adolescent↗

PubMed1992

Receptor autoradiography with 11C and [3H]-labelled ligands visualized by imaging plates.

The distribution of histamine H1, H3, dopamine D1 and D2 receptors in the brain was studied by receptor autoradiography using a high-sensitivity and high-resolution imaging plate system. [3H]Pyrilamine, [3H](R)alpha-methyl-histamine, [11C]SCH23390, and [11C]N-methylspiperone (or [11C]YM-09151-2) were used as ligands to identify H1, H3, D1 and D2 receptors, respectively. Two different receptors (dopamine D2 and histamine H3) could be also labelled simultaneously in a single cryostat-sliced section using [11C]N-methylspiperone and [3H](R)alpha-methylhistamine, respectively. The imaging plate system is useful for receptor autoradiography of positron emitter-labelled and tritium-labelled receptor-ligands because of its high sensitivity.

Animals↗

PubMed1992

Differential diagnosis of idiopathic fibrosis from malignant lymphadenopathy with PET and F-18 fluorodeoxyglucose.

Idiopathic fibrosis and malignant lymphoma were studied with positron emission tomography (PET) using 2-deoxy-2-[F-18]fluoro-D-glucose (F-18DG). Cases of retroperitoneal fibrosis and sclerosing peritonitis showed low F-18DG uptake with the mass/muscle radioactivity (M/M) ratio 2.0 and 1.9, respectively. A case of para-aortic adenopathy from malignant lymphoma showed high F-18DG uptake with the M/M ratio 9.4. F-18DG PET study may be useful for the differential diagnosis of idiopathic fibrosis and malignant lymphadenopathy.

Aged↗

PubMed1992

Positron emission tomography for treatment evaluation and recurrence detection compared with CT in long-term follow-up cases of lung cancer.

Two cases of lung cancer were studied with positron emission tomography (PET) using L-[methyl-C-11]methionine (C-11 Met) and CT scans five to six times during long-term follow-up after radiotherapy. In a large cell carcinoma with mediastinal invasion, C-11 Met tumor uptake showed a rapid decrease after radiotherapy, corresponding to clinical improvement, and detected recurrence at 11 months, as confirmed by biopsy. Tumor volume by CT showed no significant changes during this time. A squamous cell carcinoma of the superior sulcus (Pancoast type) showed rapid changes in C-11 Met tumor uptake and similar changes in tumor volume during two courses of radiotherapy and recurrence over a period of 25 months. PET evaluation of tumor viability seems to be valuable for treatment evaluation, and results match the tumor volume changes measured by CT.

Aged↗

PubMed1992

A unique in vivo assessment of 4-[10B]borono-L-phenylalanine in tumour tissues for boron neutron capture therapy of malignant melanomas using positron emission tomography and 4-borono-2-[18F]fluoro-L-phenylalanine.

A unique in vivo approach to assessing the concentrations of 4-[10B]borono-L-phenylalanine (L-BPA), a melanoma targeting compound for boron neutron capture therapy (BNCT), was investigated using L-BPA labelled with positron-emitting 18F (half-life = 110 min), i.e., 4-[10B]borono-2-[18F]fluoro-L-phenylalanine (L-[18F]FBPA). High melanoma uptake of L-[18F]FBPA was reduced slightly by competition with L-BPA in the two animal models of the murine B16 melanoma and the melanotic Greene's melanoma No. 179 in hamsters. In mice given L-[18F]FBPA and L-BPA, the concentrations of 10B in B16 estimated from 18F radioactivity were lower than those measured by inductively coupled plasma-atomic emission spectroscopy. Lower estimated values were dependent on the time after injection and on the loading dose of L-BPA. The estimated 10B concentrations for Green's melanomas were comparable to the measured values. Positron emission tomography (PET) using L-[18F]FBPA allowed Greene's melanomas to be clearly visualized. In conclusion, when L-[18F]FBPA is used as a probe for L-BPA in BNCT of malignant melanomas, the melanoma can be localized and the 10B concentrations in tissues can be assessed in vivo using 18F radioactivity by PET.

Animals↗

PubMed1992

Mapping of histamine H1 receptors in the human brain using [11C]pyrilamine and positron emission tomography.

We have studied the characteristics of carbon-11 labeled pyrilamine as a radioligand for investigating histamine H1 receptors in human brain with positron emission tomography (PET). [11C]Pyrilamine is distributed evenly in proportion to cerebral blood flow at initial PET images. Later (after 45-60 min), 11C radioactivity was observed at high concentrations in the frontal and temporal cortex, hippocampus, and thalamus, and at low concentrations in the cerebellum and pons. The regional distribution of the carbon-11 labeled compound in the brain corresponded well with that of the histamine H1 receptors determined in vitro in autopsied materials. In six controls, the frontal and temporal cortices/cerebellum ratio increased during the first 60 min to reach a value of 1.22 +/- 0.071. Intravenous administration of d-chlorpheniramine (5 mg) completely abolished the specific binding in vivo in the frontal cortex and temporal cortex (cortex/cerebellum ratio, 0.955 +/- 0.015). The availability of this method for measuring histamine H1 receptors in vivo in humans will facilitate studies on neurological and psychiatric disorders in which histamine H1 receptors are thought to be abnormal.

Adult↗

PubMed1992

Efficiency of grain production and latent image fading in F-18 micro-autoradiography.

In 18F micro-autoradiography using a frozen section method, the grain production was measured relative to the exposure time and radioactivity. The grain production increased until 6-hr exposure, but 7-hr or longer exposure induced a characteristic of latent image fading. However, the ratios of the efficiency of grain production between two different 18F-radioactivities (11.9 and 2.3 mBq/100 microns2) were constant over experimental exposure times, thus indicating that quantitative analysis by grain counting is preserved.

Animals↗

PubMed1992

Tumor radiotherapy monitoring with radioscintigraphy tracers: a comparative study with multiple-tracer technique.

A comparative multiple-tracer study was performed to assess the tracer feasibility of monitoring tumor radiotherapy. Metabolic tracers for glucose, amino acid, nucleic acid metabolism: F-18-FDG, C-14-Met, H-3-Thd, and F-18-FdUrd and conventional Ga-67 were compared in the same AH109A radiotherapy model using a new quadruple-tracer technique. F-18-FDG showed a large uptake change and a steady response to radiotherapy which is similar to Ga-67. F-18-FdUrd showed a rapid decrease, but the range of change in uptake was narrow. H-3-Thd and C-14-Met showed a rapid response to irradiation and a high sensitivity for monitoring radiotherapy, suggesting that if labeled with C-11, they may be feasible for PET study.

Animals↗

PubMed1992

Imaging of neurotransmitter receptors in the living human brain by positron emission tomography (PET).

More than 30 receptors or subtypes will be investigated in various neurological and psychiatric disorders using PET in the near future. However, the data obtained by PET should be carefully evaluated, because the PET method is based on the ligand-receptor binding in vivo. Extensive studies on animals and autopsied human brain samples are important to assess the significance of the findings revealed by PET technique to substantiate its validity.

Aging↗