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Biomedical subjects

A Wada

Publications and source records attributed to A Wada.

At least 487 records · Page 27Linked to original sources
PubMed1981

Conformational studies of Escherichia coli ribosomes with the use of acridine orange as a probe.

The interaction of E. coli vacant ribosomes with acridine orange (AO) was studied, to obtain conformational information about rRNAs in ribosomes. Acridine orange binds to an RNA in two different modes: cooperative outside binding with stacking of bound AO's and intercalation between nucleotide bases. Free 16S and 23S rRNAs have almost identical affinities to AO. At 1 mM Mg2+, AO can achieve stacking binding on about 40% of rRNA phosphate groups. The number of stacking binding sites falls to about 1/3 in the 30S subunit in comparison with free 16S rRNA. In the 50S subunit, the number of stacking binding sites is only 1/5 in comparison with free 23S rRNA. Mg2+ ions are more inhibitory for the binding of AO to ribosomes than to free rRNAs. The strength of stacking binding appears to be more markedly reduced by Mg2+ in active ribosomes than in rRNAs. "Tight couple" 70S particles are less accessible for stacking binding than free subunits. The 30S subunits that have irreversibly lost the capability for 70S formation under low Mg2+ conditions have an affinity to AO that is very different from that of active 30S but similar to that of free rRNA, though the number of stacking binding sites is little changed by the inactivation. 70S and 30S ribosomes with stacking bound AO's have normal sedimentation constants, but the 50S subunits reversibly form aggregates.

Acridine Orange↗
PubMed1981

Leiomyosarcoma of the pancreas. Report of a case and review of the literature.

A case of leiomyosarcoma of the pancreas, occurring in a 44-year-old male, is reported. With a preoperative diagnosis of cystadenocarcinoma, the patient underwent surgical resection of a cystic tumor in the head of the pancreas. There were no metastases noted at the time. The resected specimen was diagnosed histologically as a smooth muscle tumor originating from the pancreas. It was seemingly benign on the basis of the mitotic counts and the degree of cellular atypism. However, the tumor proved to be malignant; the patient died with metastases to the liver. The tumor at autopsy also had few mitoses (0-1/10 hpf). The previously reported cases were reviewed and the limitations of histological diagnosis in assessing malignant potential of smooth muscle tumors are discussed.

Adult↗
PubMed1980

Surgical adjuvant chemotherapy with mitomycin C and cyclophosphamide in Japanese patients with breast cancer.

A controlled trial of surgical adjuvant chemotherapy for breast cancer was carried out using 551 Japanese patients. Single or combined treatment with mitomycin C (0.2 mg/kg i.v. three times within five days postoperatively) and cyclophosphamide (100 mg postoperatively daily for four months or longer) was used after radical surgery. In patients of the chemotherapy group with one to three lymph nodes involved in the axilla, the five-year cancer-free survival rate was 84.8% compared with 57.3% in the control group (P < 0.05), and the five-year cumulative recurrence in distant sites was 5.1% compared with 31.1% in the control (P < 0.05). The effectiveness of chemotherapy was much less marked in patients without nodal metastasis and with four or more nodes involved. Histologically, scirrhous cancer was the type that responded most favorably to chemotherapy, even in patients without axillary involvement. Premenopausal patients benefited more than postmenopausal patients from chemotherapy. A combination of mitomycin C and cyclophosphamide was more effective than their use singly. The present chemotherapy regimen was effective primarily in moderately advanced stages of breast cancer with decreased incidence of distant metastasis.

Adenocarcinoma, Scirrhous↗
PubMed1980

Adenosquamous carcinoma of the pancreas: a clinicopathologic study and report of three cases.

Among 27 surgically resected carcinomas of the pancreas, 3 cases were diagnosed histologically as adenosquamous carcinoma (11.1%). This is the highest rate among the medical literature we reviewed. Since a very small focus of squamous cell carcinoma was detected through close observation in 1 case, it would seem that this sort of pancreatic tumor could be more common than is ordinarily expected. From the histologic studies of these 3 cases, it seems likely that the preexisting adenocarcinoma partially underwent malignant transformation into a malignant squamous component. When the different modes of spread of these two histologic elements are compared, the adenocarcinomatous element seems to be more invasive and more likely to metastasize than does squamous cell carcinoma.

Adenocarcinoma↗
PubMed1980

Multidimensional spectroscopic data correlation in the conformation transition of biological macromolecules.

A computerized spectrophotometer system which is capable of simultaneously obtaining three spectral dimensions, that is, the absorbance, the circular dichroism and the fluorescence intensity, from one sample solution has been developed for the purpose of attaining a higher resolving power in the study of conformational transitions of biological macromolecules. Measurement conditions, such as the wavelength, the temperature, pH or the concentration of reagents in the sample solution, can be scanned according to a sequence that is set just prior to the measurement. A computer-driven micro-injector and a pH electrode directly immersed in the sample solution make it possible to obtain a titration curve in parallel to the optical measurement. All the data taken are stored on a magnetic disk for later retrieval. They can be processed and displayed in any required form. The helix-coil transitions of a polynucleotide caused by temperature and those of a polypeptide caused by pH, and the denaturation of proteins caused by guanidine hydrochloride, were studied by this measuring system. The continuous plotting of transition profiles and the correlation diagrams among different spectral dimensions has proved to be a good way of demonstrating the existence of different modes of transition.

Circular Dichroism↗
PubMed1980

Dielectric dispersion of alternating copolymers of maleic acid.

Dielectric dispersions of three kinds of copolymers of maleic acid, poly (maleic acid-co-methyl vinyl ether) (PMAMVE), poly(maleic add-co-ethyl vinyl ether) (PMAEVE) and poly (maleic acid-co-styrene) (PMAST), were measured by use of a pseudorandom noise dielectric spectrometer. A large dielectric increment was observed in the low frequency region (10-20 Hz), and was explained in terms of our theory of ion fluctuation. When these copolymers were neutralized with mixtures of NaOH and Ca(OH)2 by changing their ratio, enhancement of the static dielectric increment was observed in the intermediate ratios of both ion species. This phenomenon was analyzed by modifying our. theory of ion fluctuation to the case of alternating copolymers. Quantitative agreement with experimental results was obtained by using values of parameters representing binding energies and mutual repulsion, which are chosen to fit the calculated degree of ion binding to the experimental data on activities of Na+ and Ca2+ ions. At large fractions of divalent ions, the increment, relaxation time and specific viscosity were found to decrease sharply due to chelation by divalent ions.

Journal Article↗
PubMed1980

Fine structure in the thermal denaturation of DNA: high temperature-resolution spectrophotometric studies.

Fine structures which appear in the optical melting profile of DNA are examined from both the experimental and theoretical aspects. After a brief historical survey of the DNA melting experiments during the pre-fine-structure era in Section II, the high temperature-resolution experimental techniques which are essential to the investigation of fine structure are described in Section III. Then, the current status of the high-resolution study is reviewed first by a phenomenological description of the melting profile (Section IV) and then of the refolding profile (Section V), where a general idea about the cooperatively melting region and several factors affecting it is given. Sections VI and VII are devoted to the review of current theoretical works. Several well-established theoretical frameworks which correlate the base sequence with the melting phenomena are examined in terms of their rigorousness and usefulness. The molecular thermodynamic parameters concerning the DNA melting which have been evaluated by several research groups are compared and discussed. Finally, in Section VIII, current ideas on the correlation between the fine structure and genetic functions and genetic maps are reviewed. Some future problems relating to the fine structure are also discussed.

Animals↗
PubMed1980

An approach to the genesis of idiopathic cardiomyopathy.

The turnover of cholesterol of red blood cells in healthy hamsters was faster than that in cardiomyopathic hamsters. The uptake of 2-deoxy-D-glucose by heart cells was more rapid in the diseased hamsters compared with that of the healthy ones. Freeze-etch study of heart cells disclosed a difference of membrane structure between the two groups. Results of lactate content in hearts with nonexercised and exercised hamsters of both the diseased and healthy groups revealed the retention of lactate in the diseased hearts, even in a nonexercised state. Electron microscopic findings confirmed that an increased hypoxic condition caused by exercise aggravates the diseaes in the cardiomyopathic hamsters. These two conditions, membrane abnormality and hypoxia, probably play a role fundamental to the genesis of the disease, because hypoxia in the cellular level may well be caused by membrane abnormality.

Animals↗
PubMed1979

Ductal carcinoma of the pancreas. Rationales for total pancreatectomy.

In order to evaluate total pancreatectomy as a surgical procedure for ductal carcinoma of the pancreas, a histopathological analysis was made on 18 resected specimens with special regard to the pattern of cancer growth in the pancreatic tissue. In five of them there was no lymphatic involvement or extrapancreatic invasion, but cancer extended continuously to the tail along with the pancreatic ducts and reached the end of the ducts in three cases. All 11 patients treated with Whipple's procedure died of recurrence, while of four total pancreatectomized patients, one with continuously invasive cancer to the end of the pancreatic duct has been living more than eight years postoperatively. We believe that total pancreatectomy for this type of "intraductal spreading cancer" without invasion beyond the pancreas is indicated as a radical procedure.

Aged↗