Search PubMed⌕ Search

Biomedical subjects

M Sawada

Publications and source records attributed to M Sawada.

At least 523 records · Page 29Linked to original sources
PubMed1981

Modulation of arterial muscle contraction in Aplysia by glycine and neuron R14.

Glycine and electrical activity in neuron R14 both enhance the contractility of the anterior aorta of the gastropod Aplysia californica. Glycine and R14 do not seem to cause contraction directly, change membrane permeabilities or alter junctional potentials occurring in the muscle fibers, yet they increase the force of contractions induced by other means. Modulation of muscle contraction is a new function for glycine.

Animals↗
PubMed1981

Unusual concentration of urine and prevention of polydipsia by fungal prenylphenols in DOCA hypertensive rats.

When deoxycorticosterone acetate (DOCA)-loaded uninephrectomized rats were fed on standard laboratory pellet diet and 1% saline for 5 weeks, caloric homeostasis became abnormal resulting in (a) hyperlipidemia, (b) cholesterol deposit in the heart, (c) significant reduction of triglycerides in the aorta, heart and liver and (d) a 60% increase in the cardiac free fatty acids (FFA) on one hand and a 50% reduction of the hepatic FFA on the other. These facts suggest that the hypertension severely reduces hepatic lipogenesis, whereas the cardiovascular system depends much more on FFA as a metabolic fuel than on glucose. This idea is supported by the deficiency in total body potassium (K) and decrease in serum immunoreactive insulin (IRI) which occur in the hypertension. These alterations were attenuated by the fungal prenylphenols, 4-0-methylascochlorin (MAC) and ascofuranone (AF). The protective effect seems to be partly attributable to the counteraction to DOCA. In addition, the agents caused a specific increase of renal water reabsorption. MAC treatment resulted in a particularly marked reduction of saline intake and excretion of unusually thick urine with 2.8 times higher sodium (Na) concentration than in the DOCA/saline control rats.

Animals↗
PubMed1981

The number of ribosomal RNA genes in Mycoplasma capricolum.

We have examined the number of rRNA genes in Mycoplasma capricolum (KID) by hybridization of Bg/II-, EcoRI- and Xbal-digests of DNA to [3'-32P] 16S, 23S and 5S rRNAs according to the Southern procedure (1975). All the restriction gels gave two radioactive bands with three kinds of rRNA. Furthermore, band positions were indistinguishable from one another when 16S, 23S and 5S rRNAs were used as probes, indicating that each band contains sequences corresponding to the 3'-termini of 16S, 23S and 5S rRNAs. It is thus concluded that Mycoplasma capricolum chromosome carries at least two sets of genes for 16S, 23S and 5S rRNAs.

DNA Restriction Enzymes↗
PubMed1981

Alteration of cholesterol metabolism by 4-O-methylascochlorin in rats.

The effect of 4-O-methylascochlorin (MAC), an experimental hypocholesterolemic agent, on cholesterol metabolism was investigated in rats in two separate experiments. The administration of MAC for 2 and 6 consecutive weeks at daily doses of 100-135 mg/kg resulted in reduction in serum cholesterol levels of 16% after 2 weeks of treatment in the first experiment, and 13% after 6 weeks in the second experiment in comparison to the corresponding controls. MAC administered at a daily dose of 100 mg/kg for 2 weeks showed a significant increase in the biliary excretion of bile acids and cholesterol in bile-duct cannulated rats with or without the administration of taurocholate. In the second experiment, MAC treatment for 6 weeks produced a marked increase in the fecal output of acidic sterols during a 2 to 6-week period. MAC treatment also further enhanced hepatic cholesterol 7 alpha-hydroxylase in the rats. Therefore, it appears that the mechanism of serum cholesterol lowering due to MAC is related to the enhancement of hepatic bile acid synthesis and the increase in biliary and fecal excretion of bile acids.

Animals↗
PubMed1981

Histochemical study of the efferent nervous system in the guinea pig inner ear.

The efferent nervous system of the guinea pig inner ear is histochemically investigated. Remarkable activity of alkaline phosphatase and acetylcholinesterase is demonstrated by Burstone's (1958) azo dye method and Koelle's (1949) method as modified by Gomori (1952) respectively. The distribution pattern of both enzymes in the efferent nervous system is entirely similar. The intraganglionic spiral bundles, fascicles of the osseous spiral lamina and efferent plexus of the organ of Corti reacted intensely for both enzymes. Afferent nerve fibers give no histochemical reaction for both alkaline phosphatase and acetylcholinesterase. However, spiral and vestibular ganglion cells are rich in both enzymes, though they belong to the afferent nervous system. The significance of both enzymes in the nervous system of the guinea pig inner ear is briefly discussed.

Acetylcholinesterase↗
PubMed1981

The usefulness of thallium-201 myocardial perfusion scintigraphy in the diagnosis of chronic cor pulmonale.

To open up the possibility of exact clinical diagnoses of chronic cor pulmonale, we performed thallium-201 myocardial perfusion scintigraphy on patients with chronic pulmonary disease. From the thallium activity in the left ventricle (plus ventricular septum) and right ventricle counted scintigraphically, we determined the thallium activity ratio of left to right ventricle (TAR). The intra- and inter-observer variations of this ratio were negligible. We compared TAR with pulmonary hemodynamic findings and with left to right ventricular mass ratio measured at autopsy, and obtained the following results. 1) Left to right ventricular mass ratio determined in 11 autopsied patients by the method of Fulton et al. was closely correlated with TAR values (r = 0.90, p less than 0.001). 2) In patients with chronic pulmonary disease, there were highly significant exponential inverse correlations between TAR and pulmonary arterial mean pressure, total pulmonary vascular resistance and right ventricular systolic pressure the the coefficients of -0.75, 0.72 or -0.77, respectively (p less than 0.001). These results suggested the possibility that the severity of pulmonary circulatory disturbance may be ascertained non-invasively by TAR measurement. Thus, thallium-201 myocardial perfusion scintigraphy is able to reveal non-invasively right ventricular hypertrophy in patients with chronic pulmonary disease, and it might be a useful means of clinically diagnosing chronic cor pulmonale. If TAR obtained from scintigrams is smaller than 2, the patient concerned may possibly have right ventricular hypertrophy and he or she may be diagnosed as having chronic cor pulmonale.

Adult↗
PubMed1981

Kinetic analysis of the action of chemical modulators on neuromuscular transmission.

The kinetics of the direct action of 4-aminopyridine (4AP) and streptomycin (SM) on the mechanism of transmitter release were studied by recording the endplate potentials from curarized frog muscles using conventional microelectrode techniques, and by calculating the fractional release from the store of available acetylcholine quanta from the experiments with tetanic rundown during short train stimulations. To explain the tremendous facilitatory effect of 4AP on the fractional release and the antagonistic interaction of SM thereupon, it was postulated that 4AP and SM modify the transmitter output by combining with the Ca-dependent process X; i.e., 4AP and SM compete for the occupancy of the X site. A combination of 4AP or SM presumably modifies allosterically the action of the Ca-X complex, resulting in a profound augmentation of the evoked release of the available transmitter with the former and its depression with the latter. The theoretically derived equations from the above assumptions agreed reasonably well with the results obtained.

4-Aminopyridine↗
PubMed1981

[Effects of cis-platinum diammine dichloride on yolk sac tumor transplanted in nude mice (author's transl)].

Effects of new anticancer drug Cis-platinum dichloride (CPDD) on yolk sac tumor were studied. Human yolk sac tumor serially transplanted in BALB/c nude mice (YST-1) was used as material in this experiment. Two administration methods of CPDD were examined and compared. 1) CPDD 5 mg/kg X 1 day X 4 2) CPDD i mg/kg X 5 days X 4. Tumor size was measured and serum AFP of nude mice was determined by radioimmunoassay method during experiments. At the end of experiments, treated tumor was resected and examined by light and electron microscopy. Results as follows: 1. CPDD was active in regressing yolk sac tumor at doses of 5 mg/kg given as a single treatment and doses of 1 mg/kg given daily for five days. It appeared that CPDD showed higher activity against tumors by daily injections at doses of 1 mg/kg. 2. Close correlation was recognized between tumor size and serum AFP of nude mice ((r = 0.93, p less than 0.001). Serum AFP of tumor-bearing nude mice revealed to be a useful marker of yolk sac tumor also in nude mice as in human patient. 3. Effect of CPDD on tumor cells was confirmed by light and electron microscopy.

Animals↗
PubMed1980

Ionic mechanism of inhibition of long duration in Aplysia synapse.

In the abdominal ganglion of Aplysia kurodai, three neurons were identified that responded with inhibition of long duration (ILD) to a single stimulation of the siphon nerve and to bath and iontophoretic application of dopamine. The ILD is a long-lasting (15-60 sec) hyperpolarizing potential, typically associated with a conductance increase but with a reversal potential, typically negative than the potassium equilibrium potential. Exchange of half the external chloride with acetate induced no change in the ILD. The ILD was reduced in amplitude in the presence of 0.1 normal K+ in the external medium and enhanced in two times normal K+ solution. The ILD amplitude, but not conductance, was progressively impaired by cooling and by the metabolic inhibitors ouabain and strophanthidin. These results suggest that the ILD is composed of an increase in K++ conductance and activity of the electrogenic Na-pump. theophylline potentiated the ILD, especially its duration. Furthermore, bath application of dibutyryl cAMP augmented the amplitude of the synaptically elicited ILD and the dopamine responses by 30% over controls without any effect on the change in membrane conductance. Intracellularly injected cAMP also increased the ILD, but 5'-AMP showed no such effect. These data suggest that dopamine acts on the ILD neurons by increasing K+ conductance and the activity of the electrogenic Na-pump and that cAMP might selectively stimulate the pump component of the ILD.

Animals↗
PubMed1980

The fiber arrangement of the pathological human tympanic membrane.

Remarkable morphological changes of the fiber arrangement was observed in the middle lamina propria of the pathological human tympanic membranes. These changes were present mainly in the middle zone of the pars tensa. There were several fibers running in entirely different directions among the regularly arranged radial and circular fibers. These abnormal fibers had a tendency of forming fiber bundles of varying sizes and lengths. It is stressed that the normal fiber arrangement was undoubtedly disordered in the healing process of the inflamed middle lamina propria of the human tympanic membrane.

Aged↗
PubMed1980

Correction of alar deformity in cleft lip by marginal incision.

A surgical technique is described for correcting the drooping alar rim associated with cleft lip. An incision is made on the cleft-side alar rim such that the rims will be symmetrical. After extensive undermining between the dorsal skin and alar cartilages, a suspension suture is positioned so as to pull the drooping point of the nostril rim in an anteromediocranial direction to the septovestibular junction on the normal side. The upper and lateral walls of the nasal vestibule, together with the alar cartilage, are fixed to the dorsal skin in a pushed-back position using a special technique. For the nose to retain its corrected shape, it is important that hematoma does not develop and that the chondrovestibular flap be fixed to the dorsal skin under adequate pressure and over a wide area.

Adolescent↗
PubMed1980

Microbial degradation of a macrotetrolide miticide in soil.

Macrotetrolide, a miticide consisting of tetranactin, trinactin, and dinactin, was readily biodegradable and hence did not accumulate in soil. [U-C]macrotetrolide was rapidly degraded via its constituent hydroxycarboxylic acids to carbon dioxide and water. In culture media, however, the mixture was hydrolyzed to homononactic and nonactic acids by three strains of Bacillus sp. and two of Micrococcus sp. The latter strains were able to hydrolyze 500 mug of the antibiotic per ml within a few days and to grow in the presence of 4,000 mug of the antibiotic per ml. However, they were unable to assimilate the constituent acids which accumulated in the culture medium.

Journal Article↗