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Biomedical subjects

M Okamoto

Publications and source records attributed to M Okamoto.

At least 973 records · Page 54Linked to original sources
PubMed1985

Isometric detrusor pressure in the male patient: a comparison between voluntary urethral sphincter contraction and forced penile compression techniques.

Different functions of detrusor contraction are estimated by measurement of maximum isometric detrusor pressure with voluntary urethral sphincter contraction and forced penile compression flow-stop techniques. Maximum isometric pressure curves with these 2 techniques consist of 2 and 3 phases, respectively. The first phase of each method is a linearly increasing curve whose slope seems to indicate the speed of isometric detrusor contractions. The second phase in the curve obtained by the voluntary flow-stop technique is considered to be an inhibitory phase, while that obtained by the forced technique is considered to be a continuing phase followed by a plateau, the third phase. The maximum isometric pressures obtained with the forced flow-stop technique were statistically higher than those obtained with the voluntary flow-stop technique in patients with enuresis and prostatic obstruction. Although in volunteers the maximum isometric pressure measured with the forced flow-stop technique showed higher values than that measured with the voluntary method there was no statistical difference. There was no statistical difference in the speed of detrusor contractions obtained with either technique in all of the patients except those with urethral stricture, in whom the speed of detrusor contraction measured with the forced flow-stop technique showed a lower value than that obtained with the voluntary method. We believe that the penile urethra distal to the stricture acts as a reservoir when urinary flow is poor. The forced flow-stop technique was necessary to measure maximum isometric pressure in patients with neurogenic bladder dysfunction, many of whom could not stop urinary flow voluntarily.

Adolescent↗
PubMed1985

Metastasis to the lingual lymph node in carcinoma of the tongue.

Lingual lymph nodes are occasionally found along the course of some lymph-vessels of the tongue. However, their existence has received little attention and metastasis of carcinoma of the tongue to them has not previously been reported. Three cases of carcinoma of the tongue with metastasis to the lingual lymph node are described and a discussion of the importance of such metastasis in the treatment of carcinoma of the tongue is presented.

Carcinoma, Squamous Cell↗
PubMed1985

Doppler echocardiographic features of ventricular septal rupture in myocardial infarction.

Doppler echocardiography was used to evaluate the features of interventricular septal rupture in six patients with acute myocardial infarction and to substantiate the hemodynamic data and morphologic findings at surgery or autopsy. Although echocardiographic visualization of the septal rupture was obtained in only two of the six patients, unusual Doppler flow signals were detected in the apical portion of the right ventricle in all six patients. Five patients had unusual flow signals during both systole and diastole; one had such signals only during systole. The location of these unusual flow signals coincided with the site of septal rupture confirmed at surgery or autopsy. The pattern of the flow signals in one cardiac cycle was very similar to that of the pressure difference between the left and right ventricular cavities. These findings indicate that the unusual flow signals represent the left to right shunt flows resulting from septal rupture. In conclusion, Doppler echocardiography may be a very useful tool for diagnosing interventricular septal rupture easily and noninvasively in patients with acute myocardial infarction.

Aged↗
PubMed1985

Synthesis of aldosterone by a reconstituted system of cytochrome P-45011 beta from bovine adrenocortical mitochondria.

When corticosterone was incubated with cytochrome P-45011 beta purified from bovine adrenocortical mitochondria in the presence of adrenodoxin, NADPH-adrenodoxin reductase and an NADPH generating system, aldosterone as well as 18-hydroxycorticosterone were formed with turnover numbers of 0.23 and 1.1 nmol/min/nmol P-450, respectively. Phospholipids extracted from adrenocortical mitochondria remarkably enhanced the activity of aldosterone formation by the cytochrome P-45011 beta-reconstituted system. The apparent Km and turnover number were estimated to be 6.9 microM and 2.0 nmol/min/nmol P-450 for aldosterone formation in the presence of the lipidic extract. When 18-hydroxycorticosterone was tested as a substrate, cytochrome P-45011 beta showed catalytic activity for aldosterone synthesis with an apparent Km and turnover number of 325 microM and 5.3 nmol/min/nmol P-450, respectively. Carbon monoxide and metyrapone inhibited the production of aldosterone from corticosterone and that from 18-hydroxycorticosterone. These results suggest that conversion of corticosterone and of 18-hydroxycorticosterone to aldosterone occurs through P-45011 beta-catalyzed reaction.

Adrenal Cortex↗
PubMed1985

Ethanol drug interaction with chlordiazepoxide and pentobarbital.

Drug interactions between ethanol and pentobarbital and ethanol and chlordiazepoxide were investigated utilizing mice. At the peak of oral ethanol (0-4 g/kg), either sodium pentobarbital (1-120 mg/kg) or chlordiazepoxide hydrochloride (2-400 mg/kg) was given intraperitoneally. Blood concentrations of ethanol, pentobarbital, chlordiazepoxide, and its pharmacologically active major metabolites were monitored utilizing either gas chromatography or high performance liquid chromatography. Lethality and loss-of-righting reflex were measured as indexes of behavioral drug interactions. It was evident from the isobolographic plot that the interactions between ethanol and pentobarbital and ethanol and chlordiazepoxide were more than additive. Interaction between ethanol and pentobarbital was greater than that between ethanol and chlordiazepoxide. Furthermore, with increasing ethanol pretreatment the shift in dose-response curves for the loss-of-righting reflex was affected more than the shift in dose-response curves for lethality. Blood concentration monitoring of each drug indicated that the rate of biotransformation of pentobarbital was significantly decreased; sequential biotransformation of chlordiazepoxide was also altered, resulting in a large accumulation of demethylchlordiazepoxide in the blood.

Animals↗
PubMed1985

A mutant of Chlamydomonas reinhardtii that lacks the flagellar outer dynein arm but can swim.

A new type of Chlamydomonas mutant, which lacks the outer dynein arm but can swim, was isolated. Sodium dodecyl sulphate/polyacrylamide gel electrophoresis showed that four of the ten high-molecular-weight bands of dynein present in the wild-type axoneme are missing or diminished in the mutant axoneme. The mutant has a swimming rate of about 35 micrometers/s and a flagellar beat frequency of about 25 Hz, both of which are about 1/2.5 to 1/3 of those of the wild type. The mutant flagella beat with an asymmetric, cilia-type pattern, similar to the forward-swimming mode of the flagellar beating pattern of the wild type. However, unlike wild-type flagella, the mutant flagella never beat with a symmetrical waveform: when the cells were stimulated by intense light, the mutant transiently stopped beating its flagella, whereas the wild-type cell transiently swam backwards with the two flagella beating with a symmetrical waveform. Both wild-type and mutant cells could be demembranated by Nonidet P40 and their swimming reactivated by addition of Mg-ATP in the virtual absence of Ca2+. Double reciprocal plots of the beat frequency against ATP concentrations showed a linear relationship for both strains, yielding maximal frequencies of 44 Hz (wild-type) and 23 Hz (mutant). The mutant axonemes can be reactivated only when the Ca2+ concentration is lower than 10(-6) M: at pCa4, the wild-type axonemes beat with a symmetrical waveform, but the mutant axonemes showed no movement. These findings indicate that the outer dynein arm is dispensable for flagellar beating of the asymmetric waveform (forward-swimming mode), but not for beating of the symmetrical waveform (backward-swimming mode), and thus suggest the importance of the outer dynein arm in the switching of flagellar waveforms.

Chlamydomonas↗
PubMed1985

Intracerebroventricular injection of 125I-salmon calcitonin in rats: fate, anorexia and hypocalcemia.

Intracerebroventricular (i.c.v.) injection of 19 pmol/rat or more of salmon calcitonin (sCT) or iodinated sCT suppressed spontaneous intake of food and water in a dose-dependent manner. Tail-whipping was a peculiar behavior which concomitantly developed, but no analgesia ensued from the doses tested (up to 62 pmol/rat). It was examined how the rise and fall pattern of these behavioral effects would correlate with the dispositional pattern of 125I-sCT. When the radioactive peptide was injected in anorectic doses via the i.c.v. route, the radioactivity was found to distribute throughout the brain, but not uniformly. In rats which showed a marked anorexia and tail-whipping behavior, distribution occurred in such a manner that it could be interpreted to reflect the regional and subcellular distribution pattern of sCT-specific binding sites. Even 3 hr after injection, the hypothalamus, the smallest region, retained the highest radioactivity corresponding to about 1% of the dose and at least one half of which was identified as the intact iodo-sCT. To be noted is the finding that sCT injected centrally will quickly enter the systemic circulation and peripherally induced long-lasting hypocalcemia, since the anorectic dose of sCT is considerably higher than the dose needed for the peripheral effect. It is concluded that most of the sCT after i.c.v. injection leaks into the systemic circulation, but the rest is retained rather selectively around the receptor in hypothalamic nuclei for a long time, leading to day-long suppression of feeding and drinking behavior.

Animals↗
PubMed1985

Light and electron microscopic immunohistochemistry on the localization of cytochrome P-450 of the side chain cleavage system and of cytochrome P-450 of 11 beta-hydroxylase in the bovine adrenal cortical cells.

In order to know the mechanism of steroid hormone biosynthesis, the localization of cytochromes P-450 of cholesterol side-chain cleavage enzymes (P-450SCC) and P-450 of 11 beta-hydroxylase (P-450(11)beta) were studied in bovine adrenal glands by light as well as electron microscopic immunohistochemistry, using monoclonal antibodies. With light microscopy the cytoplasm of the glomerulosa cells was faintly immunostained, while that of the fasciculata-reticularis cells was intensely immunostained by both monoclonal antibodies for cytochrome P-450SCC and cytochrome P-450(11)beta, though the capsular connective tissue cells and the adrenal medullary cells were entirely negative for these reactions. Electron microscopic immunohistochemistry revealed that the positive reaction products for cytochromes P-450 were present on the matrix side of the inner mitochondrial membrane including the tubulovesicular cristae of the cortical cells, and especially of the fasciculata and reticularis cells. The present results indicate that both cholesterol side-chain cleaving enzymes and 11 beta-hydroxylase are present in the inner mitochondrial membrane of bovine adrenal cortical cells.

Adrenal Cortex↗
PubMed1985

[Mitral regurgitation: detection and quantitative evaluation by two-dimensional Doppler echocardiography].

Mitral regurgitation was detected and quantitatively evaluated using two-dimensional Doppler-echocardiography. The subjects consisted of 74 cases having a variety of heart diseases, who underwent left ventriculography within one week before or after the Doppler study. Among 50 patients with mitral regurgitation confirmed by left ventriculography, the Doppler study detected mitral regurgitant flow signals in 46, for a sensitivity of 92%. Minimal mitral regurgitation in four cases could not be detected by Doppler studies. Twenty-four patients had no mitral regurgitation according to left ventriculography; all but one also had no mitral regurgitation by Doppler study, for a specificity of 96%. In one false positive case, typical mitral regurgitant flow signals were detected in an area localized within the left atrial cavity near the mitral valve orifice. The possibility remains that left ventriculography missed this minimal regurgitation. For quantitative assessment of mitral regurgitation, the following two methods were used. Three long-axis views through the lateral, middle and medial parts of the mitral valve, and a short-axis view at the level of the mitral orifice were imaged via the parasternal approach. The area where mitral regurgitant flow signals were detected was mapped on each cross-sectional echocardiogram, then the distance attained by the regurgitant flow from the mitral valve and the area covered by the regurgitant flow were determined. The maximal distance among the three long-axis views and the sum of the distances in these views was parallel to the severity of mitral regurgitation as assessed by left ventriculography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

[Clinical evaluation of cases of remission induction failure in acute myelogenous leukemia].

Among 73 patients who were admitted to our hospital between 1972 and 1983, 9 died before starting chemotherapy, 29 achieved complete remission (CR) with an initial regimen of induction chemotherapy, while the remaining 35 patients failed to achieve CR with this initial regimen. Patients with high initial WBC counts (greater than 100,000/cmm), old age, temperature (greater than 38 degrees C) and antecedent hematological disorders, were more prone to failure of remission induction therapy. Comparing CR patients and non-CR patients, there seemed to be no difference in sex distribution, initial platelet counts, initial LDH, percentage of blasts in the blood and bone marrow, the incidence of DIC and the regimen used for remission induction. According to Preisler's criteria, remission induction failure cases were further subdivided into various types and the numbers of each type were as follows: Type I (absolute drug resistance) 1, Type II (relative drug resistance) 16, Type III (regeneration failure) 0, Type IV (hypoplastic death) 6 and Type V (early death) 11. Among 18 M1 cases, 8 were Type II or Type V. Four out of 7 M2 cases belonged to Type II and all 3 M3 cases were Type V. Six out of the 35 remission induction failure patients entered CR with the 2nd chemotherapy regimen and 19 patients died during induction treatment with the initial induction regimen. Causes of death were infection (5 cases), bleeding (6 cases), infection and bleeding (3 cases) and organ failure (5 cases).

Adolescent↗