Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 523 records · Page 29Linked to original sources

PubMed1991

[Effects of long-term low dose radiation--relationship between chromosomal translocation and the cellular oncogenes].

To clarify the late effects of long-term exposure to low doses of radiation, chromosomal aberrations in the lymphocytes of radiological technologists (RT) were analyzed by the trypsin G-banding method. Structural aberrations were identified in 384 (2.5%) of 15,442 cells analyzed from 53 RT as compared to 177 (1.6%) of 11,136 cells from 36 healthy controls. Most of structural aberrations in both groups was translocations, and this frequency was significantly higher in the RT than in the controls. Translocations of chromosomes, such as Nos. 1, 2, 7 and 14 in RT and Nos. 1, 3, 7 and 14 in controls, was observed in over 7% of the cells. 7/14 translocations were the most frequent reciprocal translocations in RT. However, the frequency of 7/14 translocations was not significantly different between the RT and controls. In these cases, most of the break points were localized in band 14q11-12 and 7q32-36. At the chromosomal sites which were related to the sites of ski, abl, myb, mos, myc, N-myc oncogenes, very low incidences of translocation were detected in RT. However, none of the RT demonstrated abnormal clones of cells with identical chromosomal aberrations.

Chromosomes, Human↗

PubMed1991

[Somatosensory evoked potential and brain temperature in the Mongolian gerbil during whole body hyperthermia].

Somatosensory evoked potentials (SEP) have been applied to many men and several animals with cerebral ischemia. But in the Mongolian gerbil, one of the most common models of cerebral infarction, the wave form and the latency of SEP have been studied by few authors. In this report, we studied the effects of hyperthermia on SEP in the gerbil. Six gerbils weighting 40 to 50g were anesthetized and heated with ultra-red ray. Brain and rectal temperatures were continuously monitored. The brain temperature changed from 35 degrees C to 42 degrees C during heating, then returned to 37 degrees C with cooling. Typical SEP peaks have been labelled according to their positive or negative character and their sequential latency determination. The latency of the major positive voltage deflection, P1, was 9.97 +/- 9.94 ms at 37 degrees C. The negative deflection before P1 has been labelled as N0 and the negative waves after P1 and N1 and N2. Peak latency of SEP was significantly reduced gradually during hyperthermia, and increased gradually with recooling. The correlation between the latency of SEP and the brain temperature was very close. Our results emphasize the importance of measurement of SEP during hyperthermia as a monitor of the brain temperature and during experiment for maintenance of the body temperature at 37 degrees C.

Animals↗

PubMed1991

[Evaluation of radiation therapy in pediatric brain stem glioma by computed tomography: CT findings and tumor response to radiotherapy].

The effects of radiation therapy on 29 brain stem gliomas in childhood were evaluated by computed tomography (CT). The patients received radiation of 2 Gy/day as a single fraction, 5 day a week with a total dose of 40 to 60 Gy. Initial CT findings of brain stem gliomas were divided into two types: diffuse and localized. Of 29 children, 5 had localized and 24 had diffuse tumor. Histological diagnoses were available for 18 patients, 4 with localized and 14 with diffuse tumor. All of the localized tumors were astrocytomas and diffuse tumors included 13 anaplastic gliomas (glioblastomas), 3 anaplastic astrocytomas, and one astrocytoma. Complete response or partial response to radiation therapy was observed on CT in 100% (5/5) of the localized tumors and 46% (11/13) of the diffuse tumors at the first evaluation. Contrary to expectation, low-grade gliomas responded much better to radiation therapy than high-grade gliomas. The response rates were 80% (4/5) in astrocytoma, 67% (2/3) in anaplastic astrocytoma, and 38% (5/13) in anaplastic glioma. In the follow-up CT after radiation therapy, a delayed effect was observed in only one of the 24 diffuse tumors. Nine of 10 children who had a re-irradiation following the recurrence experienced very little benefit. None of the patients with localized tumors have shown evidence of tumor progression or recurrence, and the quality of their life has been excellent. On the other hand, all of the patients with diffuse tumor died within 20 months after initial treatment. The results of this study suggest that radiation therapy is beneficial for localized tumors but not for diffuse tumors, and new treatments need to be developed for diffuse tumors.

Adolescent↗

PubMed1990

Prokaryotic genetic code.

The prokaryotic genetic code has been influenced by directional mutation pressure (GC/AT pressure) that has been exerted on the entire genome. This pressure affects the synonymous codon choice, the amino acid composition of proteins and tRNA anticodons. Unassigned codons would have been produced in bacteria with extremely high GC or AT genomes by deleting certain codons and the corresponding tRNAs. A high AT pressure together with genomic economization led to a change in assignment of the UGA codon, from stop to tryptophan, in Mycoplasma.

Anticodon↗

PubMed1990

[Differential diagnosis between pancreatic ductal adenocarcinoma and chronic pancreatitis with thin slice table incremental CE-CT].

Thin slice table incremental CE-CT was performed on 18 patients considered to have pancreatic carcinoma, 13 patients with chronic pancreatitis, and 19 patients with a normal pancreas. Each patient underwent precontrast CT scanning and delayed scanning. Computed tomography was performed with a high-speed scanner, a TCT 900s. First, precontrast CT scanning was initiated at the level of the top of the right diaphragm, and the scan sequence was performed to include the liver and pancreas at contiguous 10 mm intervals. Second, a bolus of 50-60 mL of 300 mgI/mL iopamidol was delivered intravenously by hand injection via a peripheral arm vein, and subsequent injections were administered during table incrementation with 2-second interscan delay, and the scan sequence was obtained at contiguous 5 mm intervals with a scan speed of 1-second. Delayed scanning was performed 1-2 minutes later after 12 images had been obtained by thin slice table incremental CE-CT scanning. The average CT numbers were calculated for each lesion by precontrast CT scanning, thin slice table incremental CE-CT scanning, and delayed scanning. For the patients with pancreatic carcinoma, the average CT numbers were 41.6HU +/- 6.4HU, 69.6HU +/- 10.4HU, and 86.2HU +/- 14.7HU by precontrast CT scanning, thin slice table incremental CE-CT scanning, and delayed scanning, respectively. While for the patients with chronic pancreatitis, the average CT numbers were 50.0HU +/- 5.0HU, 94.3HU +/- 13.3HU, and 82.5HU +/- 11.6HU, respectively, and for those with a normal pancreas, the average CT numbers were 51.3HU +/- 5.7HU, 93.5HU +/- 7.6HU, and 82.0HU +/- 11.6HU, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Intraductal, Noninfiltrating↗

PubMed1990

Structure of (R)-tetrahydro-2-furancarboxylic acid monohydrate.

C5H10O4, Mr = 134.31, monoclinic, P2(1), a = 11.670 (2), b = 6.177 (3), c = 10.704 (2) A, beta = 115.11 (2) degrees, V = 698.7 (4) A3, Z = 4, Dm = 1.26, Dx = 1.28 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 9.69 cm-1, F(000) = 288, room temperature, R = 0.046 for 1047 reflections with [Fo[ greater than 3 sigma(F). There are two independent molecules of the title compound in the crystal. No twofold symmetry is observed in the tetrahydrofuran rings. Hydrogen bonds between water molecules and carboxylic acid groups stabilize the crystal structure.

Furans↗

PubMed1990

Symptomatic cerebrospinal fluid dissemination of cerebral glioblastoma. Computed tomographic findings in 11 cases.

Computed tomography (CT) findings in eleven patients with symptomatic cerebrospinal fluid (CSF) dissemination from cerebral glioblastoma were analyzed and, in seven cases subsequently autopsied, they were compared with histological observations. Each patient had multiple CT abnormalities including periventricular enhancement (5/11), subarachnoid enhancement (10/11) and progressive hydrocephalus (7/9) by cranial CT, and small filling defects with or without block (5/5) by CT myelography. The areas that showed periventricular or subarachnoid enhancement on CT were confirmed to have macroscopically detectable seeding at autopsy. On the other hand, microscopic deposits were more widely distributed than the enhancement suggested, and were hardly visualized on CT. In association with subarachnoid seeding, we found low-density lesions on CT which had resulted from ischemia or reinvasion of adjacent structures by disseminated glioblastoma and resulting parenchymal edema. By cranial CT, subarachnoid enhancement seems to be a very reliable sign of CSF seeding, whereas periventricular enhancement due to CSF metastases should be carefully distinguished from that due to periventricular tumor infiltration. CT myelography is capable of revealing minute metastatic spinal deposits and may be helpful for ruling out spinal seeding as well as its precise evaluation.

Adult↗

PubMed1990

Focal pachygyria with unusual vascular anomaly.

A case of focal pachygyria with an unusual vascular anomaly is reported. Preoperative magnetic resonance imaging demonstrated few and broad gyri, and an abnormally thickened cortex of the right frontal lobe. In addition, T2-weighted imaging showed a high intensity lesion beneath the thickened cortex. In the pachygyric cortex, the peripheral portions of the arteries were tortuous and irregularly dilated, and prominent deep medullary veins were found draining into the subependymal veins. Histological examination revealed a decreased number of neurons with no tendency towards lamination, and degenerative changes with gliosis in the white matter. These findings suggest that the etiology of this anomaly may be gradual perfusion failure restricted to the territory of the anomalous vessels through the period of neuronal migration to the post-migratory, perinatal stage.

Cerebral Angiography↗

PubMed1990

The differences in human spinal motoneuron excitability during the foreperiod of a motor task.

Changes in excitability of the spinal motoneuron pool during the foreperiod, which was fixed at 0.8 s, in simple and choice reaction time experiments using ankle dorsiflexion and plantar flexion were studied in fourteen healthy normal subjects by combining the visually guided tracking and H-reflex testing methods. Almost all cases showed a significant facilitation in the soleus H-reflex within the time interval between 100 and 300 ms after a warning signal (Phase I), irrespective of movement direction and task modality. The pretibial H-reflex was also facilitated. On the other hand, variable effects were noted in the later half of the foreperiod, particularly within the 200 ms prior to the response signal (Phase II). Using a simple reaction task with dorsiflexion, six cases showed no changes in the soleus H-reflex, while four others showed statistically significant inhibitory changes and the remaining four showed facilitation. The inhibition and facilitation were often accompanied with very weak and unintended EMG activities in the pretibial and So1 muscles respectively. A similar finding was obtained in the simple plantar flexion task and the choice reaction task with dorsiflexion or plantar flexion. We suggest that the facilitation at Phase I represents a perceptual orienting response to a warning signal and the effects seen in Phase II represent the difference in the waiting attitude of each subject anticipating initiation of the coming task, or the preparatory "set" which primed the spinal motor structure in a biased position.

Action Potentials↗

PubMed1990

Ciclosporin treatment in children with steroid-dependent nephrotic syndrome.

We report our experience with ciclosporin (CS) treatment in 18 children with steroid-dependent nephrotic syndrome. CS was started at 3-5 mg/kg per day after the patients had attained remission with steroid therapy, and was adjusted to maintain a trough blood level of between 250 and 600 ng/ml, being administered for 6 months. Although 1 patient dropped out of the study because of renal dysfunction, the remaining 17 children completed the full trial. No relapse occurred during the 6-month period of CS treatment, and it was possible to discontinue steroid therapy in all patients. However, after discontinuation of CS treatment, nephrotic syndrome relapsed in 16 patients and 14 again had frequent relapses and became steroid-dependent, as before CS treatment. The effect of CS in maintaining remission from steroid-dependent nephrotic syndrome was thus dependent on continuation of CS treatment. Although several side-effects occurred during CS treatment, they were not so serious as to necessitate discontinuation of treatment, except in 1 patient, and all of these side effects were reversible. CS is therefore a new agent for the management of children with steroid-dependent nephrotic syndrome in place of corticosteroid and alkylating agents, although long-term maintenance therapy may be necessary for maintaining longer remission.

Adolescent↗

PubMed1990

Induction of antitumor activity in macrophages by mycoplasmas in concert with interferon.

The in vitro growth of tumor cells infected with mycoplasmas was suppressed by macrophages pretreated with interferon (IFN), but the growth of mycoplasma-free tumor cells was not suppressed. Pretreatment of macrophages with IFN plus mycoplasmas or their soluble factors either simultaneously or sequentially, IFN first and mycoplasmas second, but not in the reverse order, was effective in activating macrophages to suppress the growth of mycoplasma-free tumor cells. Macrophages from C3H/HeJ mice (which respond only slightly to lipopolysaccharide) were activated by IFN plus mycoplasmas or their soluble factor, and their action was not influenced by the addition of a lipopolysaccharide-neutralizing agent, polymyxin B. These results suggest that the macrophage-activating agent in mycoplasmas does not mimic lipopolysaccharide. The administration of mycoplasmas plus IFN to mice with ascitic or solid tumors resulted in the reduction of tumor growth. The survival rate of tumor-bearing mice was improved by the administration of mycoplasmas, and this was synergistically enhanced by the addition of IFN. These results indicate (a) that mycoplasmas can be useful as a biological response modifier, and (b) that care should be taken to prevent contamination with mycoplasmas in experiments on macrophage activation.

Animals↗

PubMed1990

A case of tuberculous pericarditis--use of adenosine deaminase activity (ADA) in early diagnosis.

Pericardial tuberculosis is rare, and because of the difficulty in isolating the causative organism, the diagnosis is often missed. Adenosine deaminase, an enzyme associated with purine metabolism, shows markedly high levels of activity in tuberculous effusion. We report a case of tuberculous pericarditis diagnosed by high levels of adenosine deaminase activity, and where the pericardial fluid cultures revealed acid-fast organisms.

Adenosine Deaminase↗

PubMed1990

Mid-mediastinal parathyroid lesions: preoperative localization and surgical approach in two cases.

Although hyperfunctioning mediastinal parathyroid lesions that require median sternotomy or thoracotomy for removal are occasionally present, the majority are located in the anterior mediastinum closely associated with the thymus. Only eight cases of ectopic hyperfunctioning parathyroid tumors in the middle mediastinum have been reported. We experienced two cases of either persistent or recurrent hyperparathyroidism in which abnormal parathyroid tissue was located in the aorticopulmonary window. One of the patients had a parathyroid adenoma and the other had metastatic lesions of parathyroid carcinoma. In both cases, thallium scanning proved useful in identifying the lesions while computed tomography scan was effective for mediastinal three-dimensional localization. In one case, single photon emission computed tomography imaging with thallium proved beneficial for both identification and localization of the middle mediastinal lesion. The surgical approach used in both cases was different. In one case, left thoracotomy was performed, after which the ligamentum arteriosum was divided, and an adenoma anterior to the left main bronchus and posterior to the left pulmonary artery removed. In the other case, two metastatic tumors of parathyroid carcinoma anterior to the right main bronchus and posterior to the right pulmonary artery were resected through a median sternotomy and opening of the pericardium.

Adenoma↗

PubMed1990

Anti-tumor-promoting activity of derivatives of abieslactone, a natural triterpenoid isolated from several Abies genus.

Abiesenonic acid methyl ester (AVB-I acid methyl ester), a triterpenoid compound prepared from abieslactone, suppressed tumor promoter-induced phenomena in vitro and in vivo; i.e., AVB-I acid methyl ester inhibited 12-o-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32Pi-incorporation into phospholipids of cultured cells and the promoting action of TPA on skin tumor formation in mice initiated with 7,12-dimethylbenz[a]anthracene.

Animals↗

PubMed1990

Metabolic deactivation of furylfuramide by cytochrome P450 in human and rat liver microsomes.

Metabolic deactivation of furylfuramide by human and rat liver microsomal cytochrome P450 enzymes has been investigated in a system measuring induction of umu gene expression response in Salmonella typhimurium TA1535/pSK1002. Both human and rat liver microsomes catalyzed the metabolism of furylfuramide to inactive form(s) that are incapable of inducing umu gene expression in the tester strain. The reaction required an NADPH-generating system and molecular oxygen and was inhibited by carbon monoxide, suggesting that a cytochrome P450-linked mono-oxygenase system is prerequisite for the deactivation reaction. With liver microsomes from variously pretreated rats, 3-methylcholanthrene was found to be a powerful inducer for the furylfuramide-metabolizing activity, and antibodies raised against rat P450IA1(BNF-B, c) and P450IA2(ISF-G, d) inhibited the microsomal activity. Human liver microsomal furylfuramide-metabolizing activity was also inhibited significantly by anti-P450IA2 IgG but weakly by anti-P450IA1 IgG. In liver microsomes prepared from seven different human samples, the activities of deactivation of furylfuramide were found to correlate with the amounts of immunoreactive protein related to rat P450IA2 and with the monooxygenase activities of metabolic activation of 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoline (MeIQ) and of ethoxyresorufin O-deethylation. These results suggest that P450IA1 and P450IA2 in rats, and P450PA (IA2, the phenacetin O-deethylase and ortholog of rat P450IA2) in humans are the major enzymes involved in the deactivation of furylfuramide in liver microsomes. The metabolic studies involving HPLC analysis of products followed by spectrophotometric examination have also suggested that furylfuramide can be degraded very rapidly through the aerobic metabolism by liver microsomes.

Animals↗

PubMed1990

Tetrahymena actin: copolymerization with skeletal muscle actin and interactions with muscle actin-binding proteins.

We have previously shown that actin from Tetrahymena pyriformis has a very divergent primary structure (Hirono, M., Endoh, H., Okada, N., Numata, O., & Watanabe, Y. (1987) J. Mol. Biol. 194, 181-192) and that though it shares essential properties with skeletal muscle actin, it does not interact at all with phalloidin or DNase I (Hirono, M., Kumagai, Y., Numata, O., & Watanabe, Y. (1989) Proc. Natl. Acad. Sci. U.S. 86, 75-79). In this study, we investigated the copolymerization of this actin with skeletal muscle actin by direct observation of the heteropolymers formed from the two actins by means of electron microscopy. We also examined the binding of actin-binding proteins from skeletal muscle or smooth muscle to Tetrahymena actin by means of a cosedimentation assay. The results show that (i) Tetrahymena actin copolymerizes with skeletal muscle actin and that (ii) muscle myosin subfragment 1 binds to it in the absence of ATP, like skeletal muscle actin. However, it was also shown that (iii) muscle alpha-actinin hardly binds to Tetrahymena actin and that (iv) muscle tropomyosin does not bind to it at all. The results show that Tetrahymena actin has both properties similar and dissimilar to those of skeletal muscle actin.

Actinin↗

PubMed1990

Bacterial aetiology of infantile diarrhoea in Papua New Guinea.

Bacterial examination of stools of children with diarrhoea was carried out at Port Moresby, Papua New Guinea, where little information is available concerning the causative bacteria of diarrhoea. Shigellae, enterotoxigenic Escherichia coli, Bacillus cereus, Staphylococcus aureus, Campylobacter jejuni, and Aeromonas hydrophila were isolated with the decreasing frequency in that order. Among these, enterotoxigenic E. coli and C. jejuni were isolated for the first time in this country. Although Vibrio parahaemolyticus was recovered from sea water, no cases suffering from this organism were found.

Bacterial Infections↗

PubMed1990

10-year follow-up of young male patients with mild hypertension.

In 1977, 92 male patients with mild hypertension (persistent diastolic blood pressure between 90 and 104 mmHg) were found from among 1608 men aged between 18 and 40 years old who were employees of an industrial company. Of these, 81 patients were followed-up for 10 years. After that time, blood pressures (BP) of 44.4% of the mild hypertensive patients became normotensive (group N); BP of 22.2% remained mild hypertensive (group M); and BP of 33.4% increased to higher levels than the starting BP (group H). Higher levels of systolic and diastolic BP, a higher incidence of family history of hypertension, a higher voltage of SV1 + RV5 on ECG and a lower concentration of serum triglycerides at the starting point were risk factors for the progression to higher levels of hypertension. Body weights of patients in group H increased significantly during the follow-up period. These results indicate that male mild hypertensive patients with the above-mentioned risk factors should be followed carefully, especially with regard to increased body weights.

Adolescent↗