Biomedical subjects
Publications and source records attributed to T Kadota.
We present a case of a xanthogranuloma of the lateral ventricle choroid plexus in association with focal areas of abnormal T2 signal in the tegmentum of the pons as well as within the middle cerebellar peduncles. The characteristic MR appearance of this rare entity is described along with a pathologic basis suggesting an association with posterior fossa lesions.
Whole liver scanning during artery-dominant phase using spiral CT was performed in 14 patients with 17 histologically proven well-differentiated HCCs, which were not depicted by hepatic digital subtraction angiography but by CT during arterial portography. The density of HCC relative to the liver was evaluated with conventional precontrast CT, spiral CT, and following conventional CT during the equilibrium phase. Comparison between spiral CT and magnetic resonance (MR) imaging of dynamic contrast studies was also investigated. Four tumors of 17 HCCs (24%) were shown as a high-density area by the artery-dominant phase using spiral CT. Consequently, the total sensitivity of these three kinds of CT techniques was elevated to 82%. The sensitivity of dynamic MR imaging was slightly greater than that of spiral CT. However, spiral CT sometimes made the diagnosis more conspicuous by it's good spatial resolution. Our results indicate that spiral CT has a potential benefit in the detection of hypovascular well-differentiated HCC, and MR imaging and spiral CT may be complement each other.
Almitrine bismesylate is known to be an anti-hypoxemic agent that acts via the enhancement of hypoxic pulmonary vasoconstriction. However, screening for this class of compounds has been minimal, owing, in part, to a lack of convenient hypoxemic models in small animals. The present study was designed to establish a convenient model of hypoxemia induced by bleomycin and to evaluate anti-hypoxemic agents including a newly synthesized compound. TEI-7322, 2-allylamino-4-tert-butyl-amino-7-methyl-7H-pyrrolo[2,3- d]pyrimidine hydrochloride by using this model. Bleomycin was intratracheally instilled into rats. After 3 weeks, the arterial blood gas pressures were monitored in the animals in the conscious state. Then, prednisolone, doxapram, almitrine or TEI-7322 was administered to the bleomycin-treated rats to monitor changes in arterial blood gas pressures. Bleomycin-treated rats showed a decrease in the arterial blood O2 pressure (PaO2). The blood CO2 pressure (PaCO2) increased, along with an increase in the alveolar-arterial oxygen difference (AaDO2). These blood gas pressures in bleomycin-treated rats were not affected by treatment with prednisolone. Doxapram decreased the PaCO2 but did not change the PaO2. However, administration of almitrine or TEI-7322 significantly improved the PaO2 of bleomycin-treated rats with a decrease in the PaCO2. In conclusion, (1) bleomycin-induced lung injury causes hypoxemia in rats, probably resulting from ventilation-perfusion inequality; thus this model may be useful for evaluating anti-hypoxemic agents; and (2) TEI-7322, as well as almitrine, showed anti-hypoxemic effects in this model with different properties from those of doxapram, possibly due to improvement of ventilation-perfusion inequality, indicating that TEI-7322 may be a potent candidate for the treatment of hypoxemia.
By recording the locomotor activity rhythm of hagfish, Eptatretus burgeri, in which surgical lesions of the pretectal areas were made, we searched for the route of light information from the eyes to the circadian pacemaker, which is considered to be located in the preoptic nucleus. The entrainment of circadian activity rhythm to the light dark cycle, under 12 h light/12 h dark (12L:12D) was lost in animals whose pretectum was ablated with a pair of scissors and the animals then showed a free-running rhythm. Destruction of the pretectal areas with a high-frequency lesion generator also caused a free-running rhythm under 12L:12D. These findings indicate that retinal information may entrain the circadian rhythm via the pretectal areas, which have retinofugal connections.
We investigated the development of substance P immunoreactivity in mouse vomeronasal organs in embryos, juveniles, and adults. In all stages, substance P fibers were found in the receptor-free epithelial area, but never in the neuroepithelium. Substance P fibers were found sparsely in the lamina propria of 15-day-old embryos. Although buds of the vomeronasal glands in the cavernous tissue were observed in 17-day-old embryos, and gradually grew in size and numbers, the substance P fibers around them decreased after about the 13th day. Thus, substance P may be a trophic factor for the development of the vomeronasal glands in the cavernous tissue. We first recognized substance P fibers reaching the surface of the receptor-free epithelium in 13-day-old pups. In 21-day-old mice, substance P fibers were as well developed as in adult mice. Considering the development of the substance P fibers in the receptor-free epithelium and the cavernous tissue, they probably cause the vasodilation of the cavernous tissue via local axon reflexes. These structures may then act as a defense system, eliminating noxious stimulus substances sucked into the vomeronasal organ.
Crotaline snakes, which have infrared-sensitive pit organs, provide a good model for linking neuron morphology with sensory modality. In the trigeminal ganglion of the habu, Trimeresurus flavoviridis, cells positive for calcitonin gene-related peptide-like (CGRP) immunoreactivity were found to be of two types, darkly stained and lightly stained. They were pseudo-unipolar, having an axon divided into stem, peripheral branch, and central branch, all of which were 1 micron or less in diameter. Other, CGRP-negative cells in the ganglion were also pseudo-unipolar, but much larger. In configuration, some of the positive cells were similar to the neurons with A-delta fibers, and others to the neurons with C fibers that have been reported by other workers. On the basis of their distribution and density, and physiological studies by other workers, the CGRP-positive cells were judged to be not part of the infrared-receptive system, but to be involved in the transmission of nociception in small fibers.
To determine if superoxide radicals (O2-) and related metabolites are generated in extradermal tissues of burned animals, 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazol [1,2-å]pyrazin-3-one (MCLA) was infused intravenously into rats, and change in the chemiluminescence (CL) intensity of the small intestine was determined by using a sensitive photodetector. When animals were challenged with burn stress of 40% total body surface area (TBSA), the CL intensity of the intestine gradually increased, reaching a maximum within 1 hour and remaining elevated for up to 3 hours. Pretreatment of animals with a long-acting superoxide dismutase (SOD) derivative (SM-SOD) significantly inhibited the increase in CL intensity. Administration of SM-SOD immediately after inducing burn injury also significantly inhibited the increase in CL. These results suggest that superoxide radicals are generated in extradermal tissues, such as the small intestine, in the early stage after burn injury.
Two kinds of oligopeptides, based on the amino acid sequences of No. 217-232 and 374-387 of a rat dopamine transporter, were designed and chemically synthesized. Five clones of the monoclonal antibodies against these peptides were produced with the in vitro immunization method. Two of them have recognized a protein of M(r) approximately 85,000 in a synaptosomal fraction of the rat striatum. It is probable that the protein M(r) approximately 85,000 corresponds to a dopamine transporter in the nerve terminal of the dopamine neurons in the striatum. The expression of dopamine transporter was immunohistochemically examined with these antibodies in PC12h cells. The immunoreactivity was detected on the surface membrane of the cells.
Amplification of the c-myc gene in the human promyelocytic leukemia cell line HL-60 is considered to be one of the major causes of its malignant phenotype. It is also well known since the establishment of the cell line that a culture of HL-60 cells contains a small but fixed percentage of spontaneously differentiated cells. We show that the spontaneous differentiation could be a result of extensive losses of amplified c-myc genes by the findings: (a) the spontaneously differentiated HL-60 cells express Mac-1 (CR3, CD11b/CD18) antigen, irreversibly stop the uptake of [3H]thymidine, and die by apoptosis; (b) these cells, when isolated, and when the copy number of c-myc genes is precisely quantitated, show extensive losses of c-myc genes; and (c) low concentrations of hydroxyurea increase the percentage of spontaneously differentiated cells in which the number of c-myc genes is further decreased. A simple theoretical consideration suggests that an active elimination process(es) must be operating besides the stochastic losses of the extrachromosomally amplified c-myc genes by unequal partition at mitosis.
Immunohistochemical fluorescent double labeling revealed the coexistence of galanin and substance P in nerve fibers in the mouse nasal mucosa. At the base of and in the epithelium, all galanin fibers also contained substance P, but around the blood vessels and glands, most of them did not. Since substance P fibers in the nasal mucosa originate from the trigeminal ganglion, these results suggest that galanin fibers in the submucosal region originate from ganglia other than the trigeminal.
In 47 patients with liver cirrhosis, we performed dynamic MRI with a multisection FLASH technique that enabled us to obtain 13 T 1-weighted images of the entire liver within a single breath hold. Computed tomographic arterial portography (CTAP), US, CT, angiography (AOG) and MRI (spin echo [SE] and dynamic MRI) were performed in all 47 patients. Except for cyst, hemangioma and metastatic tumor, 104 focal nodules less than 3 cm in diameter were detected. These 104 focal lesions were divided into three groups according to the pattern of CTAP: 69 portal supply negative, 11 portal supply decreased, and 24 portal supply normal. In the portal supply negative group, 63 lesions (91%) were detected by dynamic MRI, which was superior to other modalities (US 77%, CT 41%, AOG 70%, MRI-SE 61%). The superiority of dynamic MRI resulted from its excellent ability to detect liver lesions less than 1 cm in diameter. We confirmed histologically that dynamic MRI had almost the same ability to detect hepatocellular carcinoma (HCC) as CTAP. Dynamic MRI should be clinically useful as a noninvasive examination for the detection of HCC.
We describe a rare case of cervical canal stenosis at the level of the atlas, presenting with cervical myelopathy as an initial symptom. A 55-year-old man was admitted to our hospital with a 4-month history of gait disturbance and clumsiness in both hands. He had no history of trauma, and showed left-sided hemihyperesthesia and mild quadriplegia with exaggerated deep tendon reflexes. Plain cervical tomography revealed marked spinal canal stenosis, with the diameter of 8.0 mm at the level of the atlas. Magnetic resonance imaging demonstrated severe compression of the spinal cord at the atlas, with an extensive high intensity area indicating edema on T2-weighted images. The patient showed an excellent recovery after laminectomy of the atlas combined with decompression of the lower posterior fossa of the foramen magnum and dural plasty.
We administered selective intra-arterial chemotherapy consisting of a combination of etoposide and cisplatin to 20 patients with malignant glioma (seven with recurrent and six with enlarged tumors after initial treatment, and seven newly diagnosed patients). Evaluation of efficacy was based on computed tomographic and magnetic resonance imaging findings. In the process of establishing a safe technique for superselective intra-arterial chemotherapy, we encountered cerebrovascular accidents in two patients (after etoposide in one and after etoposide plus cisplatin in the other). In these two cases, 100 mg/m2 of etoposide and 100 mg/m2 of cisplatin were delivered via the horizontal segment of the middle cerebral artery (M1) or the tip of the basilar artery, with the infusion time reduced to 20 minutes. Thereafter, the etoposide was diluted, and the doses of both drugs were reduced to 80 or 50 mg/m2, and finally to 60 mg/m2, and both were infused over 60 minutes. In addition, for prevention of local spasm, papaverine hydrochloride and nicardipine were given via the same catheter at 5-minute intervals during administration of etoposide and cisplatin. No complications developed in the later cases. Thereafter, selective intra-arterial infusion of etoposide and cisplatin into the anterior cerebral artery, middle cerebral artery, posterior cerebral artery, or the basilar artery for malignant gliomas in the basal ganglia, internal capsule, and brainstem--a procedure generally considered risky in terms of potential complications--was performed safely, with tolerable side effects. Computed tomography and magnetic resonance imaging indicated improvement in 13 patients, including four whose tumors completely disappeared. This method of intra-arterial chemotherapy may be useful as an adjuvant treatment for malignant glioma.
Recently we introduced a small Picture Archiving Communication System (PACS) for handling CT and MRI data. Our experience with this system has been useful in identifying potential problems in a clinical setting. Since the use of PACS raises both medical and social concerns, it cannot be instituted without addressing concerns related to the reliability and security issues. Although PACS is useful in the management of medical images, there are concerns about their reliability and security in a clinical setting. Reliability encompassed image quality, timeliness of the reports, and the PACS to the Radiological Information System (RIS) interface including the retrieval of the previously obtained images. The security of the patient's medical data is also essential.
Coated vesicles (CVs) isolated from bovine striatal tissue were examined to determine whether they are associated with dopamine signal systems consisting of dopamine D1 and D2 receptors, G proteins, and adenylate cyclase. Dopamine receptors in CVs were characterized by a dopamine D1 receptor antagonist, [3H]SCH 23390, and a dopamine D2 receptor antagonist, [3H]-spiroperidol. The bindings of both ligands were specifically saturable and reversible with a dissociation constant (KD) of 0.65 and 0.5 nM, respectively. Dopaminergic antagonists and agonists inhibited the specific bindings of [3H]SCH 23390 and [3H]spiroperidol in a stereoselective and concentration-dependent manner with an appropriate rank order potency for dopamine D1 or D2 receptors. The regulations of the agonist binding by guanyl-5-ylimidodiphosphate were observed. ADP ribosylation of the CVs with [32P]NAD demonstrated predominant labeling of bands of M(r) 47,000-52,000, 42,000-45,000, and 40,000-39,000, which corresponded to the known molecular weights of the alpha subunits of Gs and Gi proteins. The presence of alpha and beta subunits of G proteins in the CVs was also confirmed by immunoblotting assay. Adenylate cyclase activity, which was stimulated by SKF 38393 and inhibited by dopamine D2 receptor agonists, was present in the CVs. These findings suggest that the dopamine D1 and D2 receptors in the CVs couple with adenylate cyclase via Gs/Gi protein.
PURPOSE: To evaluate the potential role of three-dimensional (3D) computed tomography (CT) in assessment of pleural invasion by peripheral bronchogenic carcinoma. MATERIALS AND METHODS: Twenty-four-second helical CT scans were obtained during a single breath hold in 42 consecutive patients with peripheral bronchogenic carcinoma. Conventional two-dimensional (2D) images and 3D reconstruction images were reviewed independently by three blinded observers, who reached a decision by consensus. All patients underwent surgical resection of the tumor, and CT findings were correlated with the findings in pathologic specimens. RESULTS: Twelve patients had visceral pleural invasion, five had parietal pleural invasion, and 25 had no evidence of pleural invasion. Visceral pleural invasion was identified on 2D CT images in two patients and on 3D reconstructions in 11. Parietal pleural invasion was identified on 2D CT images in two patients and on 3D reconstructions in three. CONCLUSION: 3D reconstruction imaging is superior to conventional 2D CT in assessment of pleural invasion by peripheral bronchogenic carcinoma.
Paclitaxel, an antineoplastic agent, was given to Crj: CD (SD) rats of both sexes at 38, 50, 65 and 85 mg/kg by single intravenous administration to investigate its acute toxicity. The results obtained are summarized as follows: 1. Tachypnea and decreased activity with prone position were noted for vehicle and all paclitaxel groups, and alopecia for all paclitaxel groups. 2. Deaths occurred for one out of 5 males and 2 out of 5 females at 85 mg/kg. One female died of respiratory insufficiency induced by vehicle on Day 0. One female and one male died of the systemic toxicity of paclitaxel such as hypoplasia of the bone marrow and lymphoid depletion of lymphatic organs on Days 6 and 12, respectively. 3. On Days 4 and 5, all paclitaxel groups showed decreases of reticulocyte and white blood cell counts, as well as decrease of differential count of neutrophils. These changes were generally recovered by a week after dosing. 4. Histopathological examinations revealed atrophy of the thymic medulla, hypoplasia of the bone marrow and lymphoid depletion of the spleen for a few males at 85 mg/kg, and hypospermatogenesis and tubular atrophy of the testes for all paclitaxel groups. Based on these results, 85 mg/kg of paclitaxel was lethal to rats, and hematopoietic, lymphoid and male reproductive systems were primarily affected under this condition.
Paclitaxel, an antineoplastic agent, was intravenously given to Crj:CD (SD) rats of both sexes at 0 (saline), 0 (vehicle), 1.0 (low dose), 3.3 (intermediate dose) and 10.0 (high dose) mg/kg at five-day interval over one-month period (6 times in total) to investigate its repeated dose toxicity and the reversibility of toxic effects. The results obtained are summarized as follows: 1. Decreased activity with prone position was observed for high dose and vehicle groups, and alopecia was seen for many high dose rats. Body weight gain and food intake were suppressed for high and intermediate dose groups. No deaths occurred. 2. Red blood cell count, hemoglobin, hematocrit, white blood cell count, relative neutrophil count, platelet count and reticulocyte count were decreased for high dose groups. Red blood cells count was also decreased for intermediate dose groups. 3. Thymic atrophy, splenic hematopoiesis, bone marrow hypoplasia, testicular atrophy with suppression of spermatogenesis and tubular atrophy, and epididymal atrophy were observed for high dose rats. 4. Above-described changes excluding the findings on the testis and epididymis for high dose rats were shown to be generally reversible. Based on these results, the no-toxic effect dose of paclitaxel was estimated to be 1.0 mg/kg in rats under this study condition.