Biomedical subjects
Publications and source records attributed to K Ishiwata.
Recombinant feline interferon-omega preparation (rFeIFN-omega, trade name: INTERCAT) showed good clinical efficacy on canine parvovirus infection both in an experimental trial with beagles, and in field trials.
We described a patient with encephalopathy associated with visceral larva migrans (VLM) caused by Ascaris suum. He suffered from drowsiness, quadriparesis, eosinophilia and elevated serum IgE levels. Brain magnetic resonance (MR) imaging revealed multiple cerebral cortical and white matter lesions. Serological tests indicated recent infection with A. suum. Pulse steroid therapy relieved the patient's central nervous system symptoms and marked improvement of lesions on brain MR images. We concluded that the encephalopathy in this patient was probably caused by VLM due to Ascaris suum.
We studied the tracer kinetics of three dopamine D2-like receptor ligands, [11C]raclopride ([11C]RAC), [11C]nemonapride ([11C]NEM) and [11C]N-methylspiperone ([11C]MSP), in anesthetized rats by tissue dissection, ex vivo ARG and PET in order to clarify their characteristics for PET imaging. The in vivo affinity of the three ligands for the striatum ([11C]MSP > [11C]NEM > [11C]RAC) obeyed the in vitro affinity for dopamine D2 receptors. The affinity of [11C]RAC and [11C]MSP for the cerebellum was very low, but the affinity of [11C]NEM for the cerebellum was compatible to that for the cortex and was not to be ignored. Also the affinity of [11C]MSP for the cortex was relatively high. [11C]RAC showed the highest selectivity. The striatal PET image with [11C]RAC was clearer than that with [11C]NEM or [11C]MSP, but the activity decreased much faster than that measured by tissue dissection because of the partial volume effect. The striatal activity with [11C]NEM remained high and that with [11C]MSP gradually increased. [11C]RAC and [11C]MSP, but not [11C]NEM, showed a high accumulation in the periorbital region.
The standard method of [11C]raclopride synthesis requires a large amount of its desmethyl precursor. We prepared [11C]raclopride by methylation of a small amount of desmethyl derivative (0.3-0.5 mg) with [11C]methyl iodide in a DMF solution containing NaH, with a decay-corrected radiochemical yield of 11-14% based on [11C]methyl iodide and with a specific activity of 48 TBq/mmol for 25 min from EOB. The reaction was reproducible and reliable.
This study evaluates the regional cerebral blood flow (CBF) with H2(15)O-PET and the distribution of central benzodiazepine receptor (BZR) with C-11 flumazenil (FMZ) by PET and I-123 iomazenil (IMZ) by SPECT in Alzheimer's disease (AD). In AD, whereas the CBF was diminished in the frontal, temporal, parietal, and occipital cortex, the distribution volume of FMZ and delayed activity of IMZ were relatively preserved in these cortices, suggesting that the BZR reduction, reflecting neuronal loss, is less prominent than the CBF suppression. The mini-mental state examination score (MMS) was weakly correlated with the CBF in the parietal cortex but not with BZR. It is speculated that the neuronal density reflected by BZR is less impaired than the neuronal function assessed with blood flow in the association cortex of AD. High correlation was found between the uptake of FMZ and the delayed activity of IMZ. The delayed image of IMZ-SPECT is clinically useful to evaluate the preservation of neuronal density in the affected temoporoparietal association cortex in AD.
An enzymatic synthesis of nca 6-[18F]fluoro-L-dopa has been developed. The process consists of a chemical synthesis of 4-[18F]fluorocatechol and its enzymatic reaction with beta-tyrosinase. The 4-[18F]fluorocatechol was prepared by nucleophilic aromatic substitution of the NO2 group on 6-nitroveratoraldehyde with [K/222]+18F-, followed by decarbonylation with tris(triphenylphosphine) rhodium(I) chloride and hydrolysis with hydroiodic acid. By C18 Sep-Pak purification, 4-[18F]fluorocatechol was obtained in ethanol with a radiochemical yield of 9.2%. An enzymatic reaction of 4-[18F]fluorocatechol, ammonium and pyruvate catalyzed by beta-tyrosinase in an ethanolic Tris-HCl buffer (pH 9.0) containing ascorbate gave within 5 min 6-[18F]fluoro-L-dopa with an approximate radiochemical yield of 60% without any isomers. The deproteinized reaction mixture was applied to a preparative reverse phase column, and the radiochemically and enantiomerically pure 6-[18F]fluoro-L-dopa was obtained with a radiochemical yield of 2.0% based on [18F]F- (decay-corrected). The synthesis time was 150 min from the EOB and the specific activity was > 200 GBq/micromol.
Ex vivo and in vitro autoradiography (ARG) with radioluminography is a useful technique to characterize newly developed 11C-labeled positron emission tomography (PET) tracers and to apply them to biological and pharmacological studies. In this report, we have described a method of evaluating the radioactivity distribution quantitatively in ex vivo and in vitro ARG using imaging plates and a dopamine D2-like receptor ligand [11C]nemonapride as a model compound. The photo-stimulated luminescence (PSL) values of the rat brain section provided by the imaging plates showed an excellent linear relationship with the radioactivity in a wide range under constant slice-thickness, although the PSL values slightly decreased with increasing slice-thickness both in ex vivo and in vitro ARG. The injection dose of 11C-tracers for ex vivo ARG was also discussed. We found saturable binding sites of [11C]nemonapride in the cortex besides the striatum both ex vivo and in vitro.
Radiolabeled nemonapride (NEM, YM-09151-2) is widely used as a representative dopamine D2-like receptor ligand in pharmacological and neurological studies, and 11C-labeled analog ([11C]NEM) has been developed for positron emission tomography (PET) studies. The aim of this study was to evaluate whether [11C]NEM binds in vivo to sigma receptors. [11C]NEM and one of six dopamine D2-like receptor ligands or seven sigma receptor ligands were co-injected into mice, and the regional brain uptake of [11C]NEM was measured by a tissue dissection method. The striatal uptake of [11C]NEM was reduced by D2-like receptor ligands, NEM, haloperidol, (+)-butaclamol, raclopride, and sulpiride, but not by a D4 receptor ligand clozapine. In the cortex and cerebellum the uptake was also reduced by D2-like receptor ligands with affinity for sigma receptors, but not by raclopride. Although none of seven sigma receptor ligands, SA6298, N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine hydrochloride (NE-100), (+)-pentazocine, R(-)-N-(3-phenyl-1-propyl)-1-phenyl-2-aminopropane hydrochloride ([-]-PPAP), (-)-pentazocine, R(+)-3-(3-hydroxyphenyl)-N-propylpiperidine hydrochloride ([+]-3-PPP), and (+)-N-allylnormetazocine hydrochloride ([+]-SKF 10047), blocked the striatal uptake, five of them with relatively higher affinity significantly reduced the [11C]NEM uptake by the cortex, and four of them reduced that by the cerebellum. We concluded that [11C]NEM binds in vivo not only to dopamine D2-like receptors in the striatum but also to sigma receptors in other regions such as cortex and cerebellum.
The potential of a 11C-labeled selective sigma1 receptor ligand, 1-(3,4-dimethoxyphenethyl)-4-[3-(3,4-dichlorophenyl)propyl]piperazine ([11C]SA6298), was evaluated as a positron emission tomography (PET) ligand for mapping sigma, receptors in the central nervous system and peripheral organs. [11C]SA6298 was synthesized by methylation of the desmethyl SA6298 with [11C]CH3I, with the decay-corrected radiochemical yield of 39 +/- 5% based on [11C]CH3I and with the specific activity of 53 +/- 17 TBq/mmol within 20 min from end of bombardment (EOB). In mice, the uptake of [11C]SA6298 was significantly decreased by carrier loading in the brain, liver, spleen, heart, lung, small intestine, and kidney in which sigma receptors are present as well as in the skeletal muscle. Pretreatment with SA6298 also blocked the uptake of [11C]SA6298 by these organs except for the small intestine, but significant displacement of [11C]SA6298 by posttreatment with SA6298 was observed only in the heart, lung, and muscle. In the blocking study with one of the eight sigma receptor ligands, including haloperidol, SA6298, NE-100, (+)-pentazocine, SA4503, (-)-pentazocine, (+)-3-PPP, and (+)-SKF 10,047 (in the order of the affinity for sigma1 receptor subtype), only SA6298 and an analog SA4503 significantly reduced the brain uptake of [11C]SA6298 to approximately 80% of the control, but the other six ligands did not. Peripherally, the uptake of [11C]SA6298 by the organs described above was decreased predominantly by SA6298 or SA4503, but the blocking effects of the other five ligands except for NE-100 depended on their affinity for sigma1 receptors. The saturable brain uptake of [11C]SA6298, approximately 20%, was also observed by tissue dissection method in rats and by PET in a cat. Ex vivo autoradiography of the rat brain showed a high uptake in the cortex and thalamus. In the cat brain a relatively high uptake was found in the cortex, thalamus, striatum, and cerebellum. These results have indicated a receptor-mediated uptake of the tracer to some extent in the brain and peripheral organs. However, the tracer has a limited potential for the PET study of the brain receptors because of a relatively high nonspecific binding.
The metabolic turnover of selenoprotein P (Sel P) and extracellular glutathione peroxidase (eGPx) in plasma was examined by HPLC-ICPMS, with the use of enriched Se, [82Se]selenite. [82Se]selenite was injected intravenously into rats at a dose of 25 micrograms 82Se kg-1 body weight, and the concentrations of labeled 82Se and naturally occurring 77Se in the serum, liver and kidneys were determined in samples obtained 1, 3, 6, 9, 12, 18 and 24 h after the injection. The distributions of both exogenous (labeled) 82Se and endogenous (naturally occurring) 77Se in serum, and supernatant fractions of the liver and kidneys were determined on a gel filtration column by HPLC-ICPMS. This dose was shown not to affect the constitutive levels of cellular GPx (cGPx), eGPx and Sel P. The labeled Se in Sel P increased soon after the injection, peaked at 6-9 h and then decreased, whereas that in eGPx continued increasing after 6 h post-injection and then throughout the remaining observation period in the bloodstream. These observations demonstrated the rapid and efficient incorporation of Se into Sel P in the liver and excretion into the plasma followed by the slow and steady incorporation of Se into eGPx in the kidneys and excretion into the plasma, with a minimal response of cGPx to selenite injection.
Analysis of carbon-11 labeled metabolites in plasma was carried out during positron emission tomography (PET) studies with a central benzodiazepine receptor ligand [11C]flumazenil ([11C]FMZ) in 24 human subjects (14-76 y.o.) including five normal volunteers and 19 patients with neurological disorders. Arterial plasma samples were obtained at 3, 5, 10, 15, 20, 30 and 60 min after i.v. injection of the tracer, and were analyzed by high-performance liquid chromatography. The rate of plasma [11C]FMZ degradation was associated with a large individual variation, but no significant difference was found in the degradation of [11C]FMZ either between male and female, young and old, or between normal subjects and patient groups. When the mean fraction of unchanged [11C]FMZ at each time point was used instead of individually measured metabolite data for the arterial input function, as much as a 30% error occurred in the distribution volume of the [11C]FMZ binding in the brain. These results indicate that the mean percentage of unchanged [11C]FMZ fraction in subjects cannot be used as the standardized value, and that the analysis of metabolites in plasma is necessary to determine the exact arterial input function for quantitative PET measurement.
In cats the global (gCBF) as well as the regional cerebral blood flow (rCBF) and blood pressure were measured before, during, and after noxious inward and outward rotations of normal and inflamed elbow joints. The animals were anesthetized with halothane and immobilized by gallamine triethiodide. The gCBF as well as the rCBF were measured using positron emission tomography (PET) with a camera specifically designed for use in small animals. Slow intravenous bolus injections of 15O-labeled water were followed by 3-min acquisition of regional radioactivity starting at the time of injection. In all experiments the gCBF as well as the blood pressure were increased by noxious inward-outward rotations of the normal and of the inflamed joint, whereas the blood pressure and the rCBF remained unchanged during bolus injections under control conditions (without any joint movement). Movements of the inflamed joint evoked significantly greater increases in blood pressure and gCBF than corresponding ones of the normal joint. These increases in gCBF were paralleled by increases in rCBF along the complete anterior to posterior axis of the brain. Again, the increases in rCBF were larger, more extensive and more uniform following the stimulation of the inflamed joint relative to the results obtained with stimulation of the normal joint. No significant laterality was seen, but when an atlas-based region of interest (ROI) analysis was carried out and when the individual variations in rCBF were removed with two-way ANOVA, significant differences were disclosed in rCBF between the stimulated condition and the resting condition in a large number of brain regions. In particular, noxious rotation of the normal (right) elbow joint induced a significant increase in rCBF over the cerebral cortex and in the right thalamus and hippocampus. The same stimulation of the (left) inflamed joint induced a significant increase in rCBF throughout the brain; the biggest increase being over the right posterior cortex. It is concluded that under the conditions of the present experiments the generally accepted autoregulation of the cerebral blood flow is not fully functioning, and various factors that may be responsible for this failure (which obscures rCBF differences) are discussed. The more pronounced increases in rCBF when moving inflamed joints instead of normal ones is thought to be a direct consequence of the peripheral sensitization of the articular nociceptors and the consequent central hyperexcitability induced in the articular nociceptive pathways.
N,N-Dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine (NE-100) was labeled with 11C in two different positions by the alkylation of an N-despropyl precursor with [11C]propyl iodide and of an O-desmethyl precursor with [11C]methyl iodide and was evaluated for the potential as a tracer for mapping sigma 1 receptors in the CNS and peripheral organs by PET. Following i.v. injection of [N-propyl-11C]NE-100 or [O-methyl-11C]NE-100 into mice, the two tracers showed similar tissue distribution patterns except for the liver and brain. With the coinjected carrier NE-100 or haloperidol, the uptake of [N-propyl-11C]NE-100 by the liver, pancreas and spleen was significantly decreased at 15 min after injection, whereas the effect was not significant for [O-methyl-11C]NE-100. The coinjection of NE-100 enhanced the brain uptake of the two tracers. Haloperidol also enhanced the brain uptake of [N-propyl-11C]NE-100, but not that of [O-methyl-11C]NE-100. The regional brain distribution assessed with [O-methyl-3H]NE-100 was consistent with the distribution pattern of the sigma receptors. Four sigma drugs reduced the regional brain uptake of [O-methyl-3H]NE-100 to 70%-90% of the control. In an ex vivo autoradiographic study of the rat brain, the uptake of [O-methyl-11C]NE-100 was blocked by carrier NE-100 or haloperidol (53%-59% of the control in the cortex), which suggests a receptor-specific distribution. These results show that [O-methyl-11C]NE-100 has limited potential as a PET ligand for mapping sigma 1 receptors in the peripheral organs and the CNS because of high nonspecific binding.
Recently several inbred strains of mice were found to be hyporesponsive to Interleukin (IL)-3 because of a 5-bp deletion in the intron 7 of the gene that encodes IL-3 receptor alpha subunit (IL-3R alpha). Due to this mutation, mast cells were not generated in vitro from bone marrow cells of these mice under the presence of IL-3. Intestinal mucosal mast cells, of which growth/differentiation is dependent on IL-3, are important effector cells in immune-mediated expulsion of intestinal nematodes, Stronglyoides spp. In the present study, therefore, we examined intestinal mast cell response and mucosal defence against Strongyloides venezuelensis in IL-3-hyporesponsive C58/J and A/J mice. After subcutaneous inoculation with 10,000 infective larvae, C58/J and IL-3-responsive C57BL/6 mice showed identical kinetic patterns of daily faecal egg output and intestinal mast cell response. When these mice were infected with 3000 L3 and, five weeks later, they were challenged by intraduodenal implantation of 800 S. venezuelensis adult worms, the timing of logarithmic decline of faecal egg count as well as intestinal mastocytosis was delayed for two days in C58/J mice. Kinetics of intestinal mastocytosis and faecal egg excretion after a primary and challenge infection in A/J mice, another IL-3-hyporesponsive strain, were identical with those seen in C58/J mice. These results suggest that intestinal mast cell response and mucosal defence against S. venezuelensis of the mutant mice were almost completely compensated in vivo. Possible mechanisms of induction of intestinal mast cell response in IL-3R alpha-defective mice are discussed.
Mast cell proteases in the tongue and jejunum of Mongolian gerbils (Meriones unguiculatus) were examined by enzyme-histochemical methods. Both trypsin-like (tryptase) and chymotrypsin-like (chymase) protease activities were demonstrated in mast cells in the tongue of fresh cryosections. When frozen sections of the tongue were post-fixed in various fixatives, those fixed in Carnoy's fluid showed strongest enzyme activities. Tryptase and chymase activities in paraffin sections of both tissues were well preserved when tissues were fixed in Carnoy's fluid at 4 degrees C for 15 min. However, enzyme activities in both tissues, especially in the tongue, were drastically reduced by longer fixation time and higher temperature. When Carnoy-fixed (4 degrees C for 15 min) paraffin sections were treated with heparinase I or chondroitinase ABC before enzyme-histochemical stainings for proteases, tryptase activities were lost entirely in the tongue and mostly in the jejunum by heparinase I digestion, and slightly in both organs by chondroitinase ABC digestion. In contrast, chymase activities at both sites were not influenced by these pretreatments. These results show that although mast cells in the tongue as well as in the jejunum of Mongolian gerbils contain both tryptase and chymase activities, their stability to fixations is variable among organs so that tissue fixation conditions are crucial for the preservation. At least some part of the stability of mast cell proteases is dependent on the proteoglycans present in mast cell granules.
OBJECTIVES: To examine the effect of chronic exposure to welding fumes on pulmonary function by a direct estimate of fumes accumulated in the lungs. METHODS: The strength of the residual magnetic field of externally magnetised lungs (LMF) was used as an estimate of fumes accumulated in the lungs. The results of forced spirometry manoeuvres obtained in 143 of 153 male welders in the original sample were cross sectionally evaluated according to LMF. Seven conventional forced spirogram indices and two time domain spirogram indices were used as pulmonary function indices, and height squared proportional correction was performed when necessary. RESULTS: The distribution of LMF values was considerably skewed towards positive. There was a weak but significant positive relation between age and log transformed LMF. Obstructive pulmonary function indices correlated well with LMF. After adjustment for age and smoking, however, a significant association with LMF was only found with percentage rate of forced expiratory volume in one second (FEV1%) divided by forced vital capacity (FVC) and mu, and average component of assumed time constant distribution of lung peripheral units. Neither FVC nor vital capacity (VC), as indices of restrictive disorders, showed a significant association with LMF. Based on the results of multiple regression analyses, a 0.6% decrease in FEV1% and 0.039 unit increase in mu were expected for each doubling of LMF. CONCLUSION: Obstructive changes in pulmonary function were found to be related to level of cumulative exposure to welding fume in male Japanese arc welders after controlling for age and smoking, assuming that LMF adequately reflects accumulation of welding fumes in the lungs.
The clinical effects of recombinant feline interferon-omega (rFeIFN-omega), produced in silkworm by recombinant baculovirus, were examined in 3-4 month-old beagle dogs given an experimental canine parvovirus type-2 (CPV-2) infection. Clinical symptoms, such as pyrexia, vomiting, anorexia and diarrhea, were observed on day 4 after oral inoculation of 10(7) TCID50 of CPV-2 (cc 238 strain) in almost all the inoculated dogs. From day 4, rFeIFN-omega (1 mega units/kg/day) or physiological saline was administered intravenously to infected dogs for 3 consecutive days. Seven out of 17 dogs treated with physiological saline showed hemorrhagic diarrhea and continuously expressed severe clinical enteritis; one dog died with a large amount of hemorrhagic rice-water stool on day 6 after viral exposure. In contrast, 4 out of 12 dogs treated with rFeIFN-omega showed severe clinical enteritis associated with intermittent diarrhea. Scoring of fecal condition revealed that treatment with rFeIFN-omega significantly shifted the enteritis from a severe to mild form. Furthermore, rFeIFN-omega administered in the morning decreased the number of dogs expressing clinical enteritis in the evening suggesting a rapid effect. Vomiting and anorexia were also improved by treatment with rFeIFN-omega. These results suggest that rFeIFN-omega can reduce severe enteritis caused by CPV-2 infection in dogs.
Gnathostoma doloresi, a nematode parasite producing ulcerative and/or granulomatous lesions in the gastric wall of domestic pigs and wild boars (Sus scrofa leucomystax) throughout southeastern Asia, is an important zoonosis causing cutaneous larva migrans in humans. Patients infected with G. doloresi have been found yearly in the vicinity of Miyazaki Prefecture, Japan. Adult nematodes were found in 31 of 32 wild boars captured at two different geographic locations in the prefecture, a location in the high mountains and one at sea level. The parasite-free animal had gastric lesions typical of a previous infection with this parasite. The nematode intensities were higher in wild boars caught in the mountains than those caught at near sea level. The extremely high prevalence of G. doloresi in wild boars indicates that the life cycle of this parasite is well established in this area of Japan.