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Biomedical subjects

Y Oda

Publications and source records attributed to Y Oda.

At least 595 records · Page 33Linked to original sources
PubMed1986

[Lymphoid adenohypophysitis, with special reference to 2 cases with sellar tumors spontaneously disappearing on the CT].

Lymphoid adenohypophysitis is an autoimmune disorder. Eighteen percent of the multipartums are reported to have autoantibodies to pituitary tissues. The symptoms in lymphoid adenohypophysitis, such as hypopituitarism and sellar tumors, exhibit spontaneous remission. The pituitary is a feasible target organ in other autoimmune diseases of the endocrine system. Of these patients, 19/287 showed a positive immune reaction with pituitary tissue antigens. Our three female patients with sellar and suprasellar mass were clinically diagnosed as having lymphoid adenohypophysitis, because of the spontaneous regression of tumors, or presence of immunologically and endocrinologically abnormal findings. The first case was a 31-year-old woman who had amenorrhea and galactorrhea syndrome for two years after delivery of her second child. CT scan revealed a supraseller enhanced mass lesion. She had concomitant signs of recurrent meningeal irritations. The number of cells in the CSF increased, though the protein concentration increased only slightly. During a one-year close observation, the suprasellar mass spontaneously regressed. The second patient was a 66-year-old woman. In 1945, she underwent hysterectomy and oophorectomy for appendicitis followed by adnexitis. She was admitted because of episodes of headache, vomiting and visual field defect in 1983. CT scan also showed a contrast enhanced mass in the suprasellar region. She had two episodes of high fever. After the treatment with antibiotics and anti-inflammatory agents for 4 months, the tumor disappeared. The third case was a 20-year-old female. She had neither neurological nor endocrinological abnormality, except for attacks of vertigo, nausea and vomiting.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

A new algorithm for voltage clamp by iteration: a learning control of a nonlinear neuronal system.

Voltage-clamp of excitable membrane allows the measurement of membrane currents associated with electrical potential changes across the membrane. However, it has been impossible in practice to apply the conventional analog feedback voltage-clamp circuits to single electrode voltage clamping in central neurons. The reason for this is that the feedback system becomes unstable because of the positive feedback required for compensation of capacitative loss through the wall of the microelectrode. Park et al. (1981) proposed a new iterative technique to solve this problem. It requires that the potential to be clamped repeats itself with little or no change. The amount of current needed to clamp the membrane potential is not determined at once, but in a step-wise, trial and error fashion in the course of a set of repetitions. Since the feedback loop is open in real time, the system has great stability, and this advantage can be exploited in single electrode preparations. The computation algorithm which calculates the current waveform based on the voltage deviation during the last trial is the central part of the iterative voltage-clamp system. In this paper, we propose a new algorithm, which has several theoretical and practical advantages over the original one proposed by Park et al. First, two parameters used in the new algorithm are predetermined by a current-clamp experiment. Second, the speed of convergence of the new algorithm is faster than that of the Park's original algorithm. This was shown by computer simulation of iterative voltage clamp of artificial membrane following Hodgkin-Huxley equations for squid axon membrane and Rall's compartment model for a neuron with dendrites. Finally, we offer proof that the new algorithm is certain to converge for the general cases of voltage-clamp experiments with active membrane properties, synaptic membranes, etc. Consequently, the new algorithm for iterative voltage clamp is very suitable for single electrode voltage clamp in the central neurons. The new algorithm has been successfully applied to voltage-clamp experiments on rubrospinal neurons of cats (Tsukahara, Murakami, Kawato, Oda, and Etoh, in preparation).

Animals↗
PubMed1985

A loss of uvrA function decreases the induction of the SOS functions recA and umuC by mitomycin C in Escherichia coli.

We have studied the levels of recA and umuC protein synthesis in Escherichia coli as a probe for regulatory and mechanistic events involved in mitomycin C mutagenesis. Both RecA and UmuC protein induction were greatly stimulated by mitomycin C in the wild-type strain, reached a peak at about 60 min for the recA gene, and at 90 min for the umuC gene, respectively, and maintained a plateau. The induction was blocked by recA and lexA(Ind-) mutations that conferred no mutagenesis on the cell. Mutation affecting uvrA protein markedly decreased induction of the recA gene as well as the umuC gene by mitomycin C. The results established that UvrA protein is involved in the induction of recA and umuC, and account, at least in part, for the mitomycin C nonmutability of uvrA mutants.

Bacterial Proteins↗
PubMed1985

Evaluation of the new system (umu-test) for the detection of environmental mutagens and carcinogens.

The umu operon in Escherichia coli is responsible for chemical and radiation mutagenesis, and the expression of the operon itself is inducible by these DNA-damaging agents. The principle of the umu-test is based on the ability of the DNA-damaging agents, most of which are potential carcinogens, to induce the umu operon. A plasmid (pSK1002) carrying a fused gene umuC'-'lacZ was introduced into Salmonella typhimurium TA1535. The strain TA1535/pSK1002 enabled us to monitor the levels of umu operon expression by measuring the beta-galactosidase activity in the cells produced by the fusion gene. Using this strain, a simple, inexpensive, and sensitive system, the umu-test, for the screening of environmental mutagens and carcinogens was developed. 38 chemicals with different structures and modes of action, including 31 known animal carcinogens, were examined by the test to evaluate the system. The threshold sensitivity of the umu-test was approximately equal to that of the Ames test for chemicals genotoxic in both tests. By the umu-test, using the single tester strain, we detect many types of DNA-damaging agents for which the Ames test requires several tester strains. Furthermore, the umu-test provides a potential practical advantage for the screening of various environmental samples containing amino acids and nutrients such as urine, serum and foods.

Animals↗
PubMed1985

Induction of umuC gene expression by nitrogen dioxide in Salmonella typhimurium.

Gaseous nitrogen dioxide (NO2) was found to induce umuC gene expression in Salmonella typhimurium carrying the umuC-lacZ fusion plasmid. The induction level of the umu operon responsible for inducible mutagenesis was measured by the level of beta-galactosidase in the cell, encoded by the fusion gene. NO2 gas was bubbled into bacterial suspensions at 10, 30 and 90 microliters/l for 30 min at a flow rate of 100 ml/min. Expression of the umuC gene varied with the concentration, flow rate and bubbling time of the NO2 gas. Although NO2 gas induces SOS functions, mutagenesis due to it was not detectable in Salmonella typhimurium TA100 and TA102. Nitric oxide gas (NO) did not induce any umuC gene expression.

DNA Repair↗
PubMed1985

Urinary diversion: anastomosis of the ureters into a sigmoid pouch and end-to-side sigmoidorectostomy.

From 1978 to 1982 bilateral ureterorectostomy and end-to-side sigmoidorectostomy were done following cystectomy for carcinoma of the bladder in 7 patients. No patient had recurrent pyelonephritis or ureterointestinal obstruction. Rectography showed the absence of rectoureteral reflux of contrast medium but rectosigmoid reflux appeared after injection of more than 150 ml. opaque solution. Adequate alkali therapy was performed in 2 patients with hyperchloremic acidosis. While there were some problems concerning the quality of urinary and fecal control achieved in our patients they were no worse than those of ordinary ureterosigmoidostomy. This operation might be recommended for patients in whom a collection appliance is unacceptable. However, before this surgical procedure can be performed the fact that the end result in terms of fecal urinary continence is unpredictable must be explained thoroughly to the patient.

Adult↗
PubMed1985

Sudden nocturnal death in young males from ventricular flutter.

Two young males who had no organic heart disease died unexpectedly during the night. In one patient, the monitor ECG showed a sinoatrial block and the electrophysiologic study revealed a sinoatrial conduction time at the upper limit of normal and a prolonged PA interval. The surface ECG showed left axis deviation. Ventricular ectopic beats were confined to the night when he died from ventricular flutter. The ECG of the other patient was normal except for the change in QRS configuration found when the preceding RR interval was prolonged, suggesting a phase 4 block in intraventricular conduction. He was completely free from arrhythmia except for the ventricular ectopic beats which developed around 9:00 p.m. and the ventricular flutter following an R-on-T type ventricular ectopic beat which resulted in death during the night. The autopsy showed no organic heart disease. ST elevation suggestive of acute ischemia was not found and the QT intervals were normal in both cases. No electrolyte imbalances were found. These 2 cases can be diagnosed as pokkuri disease which is well known in Japan. The victims are exclusively young males who have no apparent diseases to which death can be attributed.

Adult↗
PubMed1985

Monocyte chemiluminescence and macrophage precursors in the aged.

Age-related alterations in the host defense system have been vigorously investigated because of increased susceptibility to infection and neoplasms in the aged. Although monocyte-macrophages form a major part of the cellular defense against microorganisms, the majority of investigations has been limited to neutrophils and lymphocytes. The present study, designed to determine the influence of age on mononuclear phagocytes, revealed no significant decrease in the absolute number of blood monocytes, but did reveal a tendency for the chemiluminescence of blood monocytes to decrease (p less than 0.10) and a significant decrease in the numbers of macrophage precursors (p less than 0.05) in the aged (over 70 year old), in comparison with controls (under 40 years old). On the basis of these findings, functional alterations of monocyte-macrophages seem to participate in the increased susceptibility to infection in the aged.

Adult↗
PubMed1985

Randomness of base substitution mutations induced in the lacI gene of Escherichia coli by ionizing radiation.

The lacI system of Escherichia coli provides a method for monitoring mutational events at a large number of sites. Using this system, we have previously determined the mutational spectra for gamma-ray and beta-particle emissions resulting from the decay of tritium. Analysis of these mutational spectra reveals that base substitution mutations induced by ionizing radiation are distributed nearly randomly throughout the lacI gene and include all detectable substitution events. The distribution of ionizing radiation-induced mutagenesis is similar to the low frequency of occurrence mutational events induced by other SOS-dependent mutagens. The lack of an apparent nonrandom or high frequency of occurrence component seen with other SOS-dependent mutagens can be best explained as the result of the random interaction of ionizing radiation with the DNA bases leading to production of a variety of base substitutions.

Base Sequence↗
PubMed1985

[The study on Thomsen-Friedenreich antigen in bladder tumor].

The presence of Thomsen-Friedenreich antigen (T-Ag) against bladder mucosa in bladder tumor cases and control individuals was examined by the immunoperoxidase and the immunofluorescein method using labelled lectin. T-Ag was negative in all 15 cases of non-malignant bladder epithelium, and positive on the cell surface after sialidase treatment (cryptic T-Ag positive). In the 37 out of 72 bladder tumor cases, however, cryptic T-Ag was positive, and in the remaining 35 cases T-Ag was positive or negative after sialidase treatment. Furthermore 55 cases which had received the first treatment by TUR-Bt were investigated. Thirteen of the 31 cryptic T-Ag positive cases recurred during observation after operation whereas 22 of the 24 T-Ag positive or cryptic T-Ag negative cases recurred, the rate being significantly higher for the latter. In addition, the disease-free interval was absolutely longer in the cryptic T-Ag positive cases than in T-Ag positive or cryptic T-Ag negative cases. The exploration of T-Ag in bladder cancer may be valuable for predicting the clinical course after TUR-Bt.

Adult↗