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Biomedical subjects

M Mikami

Publications and source records attributed to M Mikami.

At least 109 records · Page 6Linked to original sources
PubMed1990

Antithrombogenic pO2 sensor for continuous intravascular oxygen monitoring.

An antithrombogenic oxygen partial pressure sensor (Anthron pO2 sensor) was produced by coating a hydrophilic heparinized polymer (Anthron) on an etched epoxy composite ultramicroelectrode (microhole electrode). From in vitro tests, both the response time and stability were satisfactory under the conditions of a 20 microns thickness of Anthron coating and a depth up to 100 microns for the microhole. Additionally, results of in vitro tests without systemic heparinization demonstrated that a stable real time measurement of the intravascular oxygen partial pressure value was possible for a long period without thrombus formation or adhesion of blood components on the electrode surface of the Anthron pO2 sensor. Moreover, the measured data agreed with those from the blood gas analyser. Due to the thick thrombus formation on the electrode surface, the control (non-coated) sensor was unable to measure the intravascular oxygen partial pressure even for a short period of time.

Animals↗
PubMed1990

[Estimation of left ventricular diastolic characteristics in patients with myocardial ischemia by pulsed Doppler echocardiography: transmitral blood flow velocity in postextrasystolic beats].

To investigate diastolic dynamics of the left ventricle in postextrasystolic (PES) beats during myocardial ischemia induced by rapid atrial pacing (RAP), transmitral blood flow velocity was evaluated using pulsed Doppler echocardiography in 13 subjects. The subjects consisted of eight patients with ischemic heart disease and five healthy subjects. An atrial extrasystole was artificially induced before and immediately after RAP, while the transmitral flow velocity was recorded continuously. The ratio of the early peak diastolic velocity to the peak atrial velocity (A/E) on PES beat was less than that in a basic beat without an extrasystole. The A/E increased in the PES beat in four patients who experienced myocardial ischemia; whereas, other patients and the normals showed a decrease in the A/E in the PES beat even after RAP. These findings indicated that left ventricular dynamics coupled with left atrial contraction are quite different in myocardial ischemic and nonischemic situations, and that postextrasystolic potentiation may be a useful means of detecting the ventricular diastolic dysfunction.

Blood Flow Velocity↗
PubMed1990

[Establishment and characterization of a human chorionic gonadotropin (hCG) producing cell line (RTSG) from an ovarian epithelial cancer].

A new cell line designated RTSG established in vitro from the pleural effusion of a patient with metastatic ovarian epithelial cancer has been subcultured 46 times for more than 2 years. The cells grew in a monolayered sheet, showing a tendency to pile up, with the population doubling in 48 hrs. Electron-microscopically, desmosomes were characteristically observed, suggesting the cells were of epithelial origin. Chromosomal analysis revealed aneuploidy with a tetraploid mode. The heterotransplanted tumors in nude mice were histopathologically classified as a poorly differentiated adenocarcinoma, whereas the original tumor consisted mainly of mucinous and serous cystadenocarcinoma and only partly of poorly differentiated adenocarcinoma. The cells secreted hCG (38.8 mIU/day/10(6) cells) and beta-hCG (6.1 ng/day/10(6) cells) in spent medium. Immunocytologic +-and-histochemical staining for tumor markers of the original tumor, the cultured cells and the transplanted tumors also revealed the localization of not only hCG and beta-hCG but also CA19-9 and CA-125 whose values had been elevated in the preoperative serum (hCG: 10 mIU/ml, CA19-9: 6,400 U/ml, CA-125: 225 U/ml). Results of PAS, Alcian-blue and Mucicarmine strains indicated that most of the PAS-positive substances in the cultured cells and the transplanted tumors were consistent with glycogen while the original tumor mainly contained mucin except for the lesion of poorly differentiated adenocarcinoma with glycogen. These results suggested that the cultured cells might originate from poorly differentiated adenocarcinoma cells in the original tumor.

Adenocarcinoma↗
PubMed1990

[Continuous monitoring of coronary sinus oxygen saturation during pacing loading in patients with syndrome X].

To determine whether patients with syndrome X suffer from myocardial ischemia, coronary sinus oxygen saturation was continuously measured during pacing loading in 31 patients. Subjects were categorized by groups as syndrome X (11 patients), effort angina (14), and old myocardial infarction and valvular heart disease (6). Pacing loading induced evidence of ischemia in all syndrome X patients and in eight of the 11 patients with effort angina, while there was no such evidence in those with old myocardial infarction and valvular heart disease. Coronary sinus oxygen saturation in syndrome X decreased significantly from 44.2 +/- 5.8% to 33.5 +/- 4.4% (p less than 0.01), and it decreased from 47.0 +/- 4.9% to 31.2 +/- 4.0% (p less than 0.01) in effort angina with induced ischemic evidence, indicating that a significant reduction in coronary sinus oxygen saturation reflects the presence of myocardial ischemia. In the group with old myocardial infarction and valvular heart disease, coronary sinus oxygen saturation remained nearly unchanged during pacing. The pattern of depression of coronary sinus oxygen saturation during pacing was steeper in effort angina than in syndrome X. Therefore, we conclude that, although syndrome-X may not be a homogeneous group of patients, most of them may develop myocardial ischemia due to reduced vasodilator reserves of the small coronary artery.

Adolescent↗
PubMed1990

[Estimation of myocardial oxygen extraction dynamics in effort angina by continuous measurement of coronary venous saturation].

To estimate myocardial oxygen extraction dynamics in the situation of increased myocardial oxygen requirement, we made a continuous measurement of coronary venous oxygen saturation (CSO2-Sat) using the fiberoptic catheter system and a measurement of myocardial lactate extraction ratio (MLER) in 14 patients. Ten patients showed ischemic ST depression and/or anginal episodes during the pacing loading, while 4 patients did not. Although transient decreases in CSO2-Sat were observed in the non-ischemic 4 patients immediately after the initiation of pacing or with the increase in pacing rate. CSO2-Sat and MLER remained almost unchanged from the start of pacing to the time of maximal pacing. However, in the 10 patients who developed ischemia, CSO2-Sat fell from 39.5 +/- 1.8% before pacing to 32.9 +/- 2.8% at the time of maximal pacing (p less than 0.05), with an average decrease of 6.6 +/- 2.8%. Data of MLER obviously indicated the appearance of myocardial ischemia (32.1 +/- 4.7% to 9.2 +/- 10.3%, p less than 0.05). These findings suggest that myocardial oxygen extraction will increase transiently or continuously to meet the myocardial oxygen demand when increase in coronary blood flow is limited. Continuous measurement of coronary venous saturation may be useful for the early detection of myocardial ischemia.

Adult↗
PubMed1989

Menstrual cycle-associated alteration of sulfogalactosylceramide in human uterine endometrium: possible induction of glycolipid sulfation by sex steroid hormones.

The human uterine endometrium is a tissue in which cell proliferation and differentiation are strictly controlled by sex steroid hormones, and these hormone-controlled cellular events occurring in association with the menstrual cycle of the uterine endometrium should be accompanied by characteristic molecular and metabolic changes. To characterize the menstrual cycle at the molecular level, we analyzed the glycolipids of human uterine endometrium in the proliferative and secretory phases of the menstrual cycle. Neutral glycosphingolipids from uterine endometrium comprised globo-series glycosphingolipids, such as GlcCer, LacCer, Gb3Cer, and Gb4Cer, and the relative concentrations remained constant in the two phases. However, in the case of acidic glycosphingolipids, although the concentrations of sialoglycosphingolipids remained at constant levels in the two phases, sulfatide, I3-SulfoGalCer, dramatically increased from the proliferative to the secretory phase, amounting to 7-17 nmol/g dry weight in the proliferative phase and 115-245 nmol/g dry weight in the secretory phase. Since sulfatide was the only glycolipid that changed in association with the menstrual cycle, it is likely that the sulfotransferase responsible for the synthesis of sulfatide might be induced by sex steroid hormones, estrogen and progesterone, and that sulfatide might play an essential biological role in the secretory phase of the menstrual cycle in the uterine endometrium.

Cerebrosides↗
PubMed1989

Effect of a synthetic progestin on ventilatory response to hypoxia in anesthetized rats.

Effects on ventilatory responses to progressive isocapnic hypoxia of a synthetic potent progestin, chlormadinone acetate (CMA), were determined in the halothane-anesthetized male rat. Ventilation during the breathing of hyperoxic gas was largely unaffected by treatment with CMA when carotid chemoreceptor afferents were kept intact. The sensitivity to hypoxia evaluated by hyperbolic regression analysis of the response curve did not differ between the control and CMA groups. The reduction of ventilation after bilateral section of the carotid sinus nerve (CSN) in hyperoxia was less severe in CMA-treated than in untreated animals. Furthermore, the CMA-treated rats showed a larger increase in ventilation during the hypoxia test and a lower PO2 break point for ventilatory depression. Inhibition of hypoxic ventilatory depression by CMA persisted even after the denervation of CSN. We conclude that exogenous progestin likely protects regulatory mechanism(s) for respiration against hypoxic depression through a stimulating action independent of carotid chemoreceptor afferents and without a change in the sensitivity of the ventilatory response to hypoxia.

Afferent Pathways↗
PubMed1989

Evaluation of antithrombogenic thermodilution catheter.

In order to prevent the complications accompanied with pulmonary-artery (Swan-Ganz) catheterization, we have developed an antithrombogenic coating, tradenamed Anthron. Anthron-coated thermodilution catheters show excellent antithrombogenicity due to continuous release of heparin from its surface to the blood stream in animal experiments. As controls, a poly (vinyl chloride) thermodilution catheter was evaluated in the similar manner. All of Anthron-coated thermodilution catheters were completely free from thrombus formation and kept excellent sensing functions for more than 3 days, while in control catheters severe thrombus formations were found both on the surfaces of the catheters and blood vessels. The sensing functions of the control catheters deteriorated with passage of time because of the deposition of the blood constituents on the thermistor.

Animals↗
PubMed1989

Respiration effect of synthetic progestin in small doses in normal men.

Twelve healthy men were studied to determine the effect of ventilatory stimulation with chlormadinone acetate (CMA), a potent synthetic progesterone, in small doses (5 mg/day), on arterial blood gas levels. Using a randomized, double-blind, crossover trial, one week of CMA administration caused a significant reduction in arterial CO2 tension (PaCO2) by 4.1 +/- 2.9 (SD) mm Hg. The magnitude of the fall in PaCO2 was about the same as that obtained with dose of 50 mg per day in our previous study. The results indicate that the dosages of progestin and the effect of the drug on ventilation were not in parallel, and it may provide the idea that larger doses of progestin would not necessarily be required to stimulate ventilation.

Adult↗
PubMed1989

[Transfer of bacterial drug resistance factor in artificial dental plaque].

Transfer of drug resistance factor was examined using so-called artificial dental plaque. Clinically isolated specimens of Enterococcus faecalis showing various kind of drug resistance were used as the donors. Streptococcus mutans BHT strain was used as the recipient and the plaque former. S. mutans formed artificial dental plaque on the surface of glass sticks after 7 to 10 day cultivation in brain heart infusion medium containing 5% sucrose. Each strain of E. faecalis was added to the plaque culture and co-cultured further 24 hours. Colonies were formed on drug-containing plates by 5 different mixed cultures with the frequencies of 10(-5)-10(-6) (kanamycin, KM) and 10(-4)-10(-8) (erythromycin, EM). Since these values were higher than that of the mutation frequency, we conclude that the resistant sublines were formed by a genetic transfer. Plasmid DNA derived from some transferred sublines was electrophoreted and the patterns were compared with those from the donor and the recipient. One KM-resistant subline showed a new band at the point of 40 kb which was not found in the plasmid DNA from the donor. It is suggested that the plasmid containing KM-resistance gene was modified molucularly. Sublines without new plasmid band were obtained also. There may be technical problems with it, or the transferred gene may be incorporated in a chromosome. Considering above results, the effect of bacterial transferable genes on oral hygiene were discussed.

Dental Plaque↗
PubMed1989

[Indications for home oxygen therapy in cases of sleep oxygen desaturation].

Home oxygen therapy is now considered indicated in cases of severe sleep oxygen desaturation. To explore whether we could choose cases with severe sleep desaturation by measurement of waking physiological parameters, we examined the relationship between arterial blood gases, lung functions and pulmonary artery pressure while awake and the degree of sleep oxygen desaturation in 21 patients with chronic obstructive pulmonary disease and 22 cases with a past history of pulmonary tuberculosis. There were significant correlations between waking PaO2, PaCO2 and pulmonary artery mean pressure and sleep lowest SaO2, respectively, whereas no significant relation was found between %VC or FEV1.0% and sleep lowest SaO2. However, we found wide ranges of PaO2 and PaCO2 in cases who had 10 min or more with SaO2 below 85% during sleep. This was also true in the patients who underwent 60 min or more with SaO2 below 85% while a sleep. These results suggest that it may be difficult to find out the indications for cases with severe sleep desaturation by evaluation of arterial blood gases while awake.

Aged↗
PubMed1989

[A case of esophageal rupture confirmed by chest CT: characteristic changes in chest radiographs].

A 67-year-old woman was admitted to our hospital with chest pain and dyspnea which occurred suddenly after vomiting. She was well until admission except for cholelithiasis and hypertension which had been pointed out 3 years earlier. Arterial blood gas analysis showed hypoxemia without hypercapnea. Chest X-ray examination on admission revealed intra-mediastinal air with a niveau behind the heart which compressed the vasculature of the left lower lobe and a small amount of air in the regions adjacent to the trachea, left main bronchus and aortic arch. The serial chest radiographs showed pneumomediastinum, subcutaneous emphysema, pneumothorax and pleural effusion in that order within 16 hours after the onset. The diagnosis of esophageal rupture was made by CT scan of the chest performed after oral administration of Gastrografin, which demonstrated extravasation of contrast medium into the mediastinum. Surgical treatment including eversion stripping and esophagogastrostomy was performed 23 hours after the onset. Pathological examination of the removed specimens revealed a rupture of the lower portion of the esophagus originated in the gastric ulcer of the cardia. In spite of intensive care, she died 45 days after surgery because of renal failure. It was considered that the most important point in the early diagnosis of esophageal rupture was to suspect this disease based on the gastric symptoms followed by the respiratory symptoms and to demonstrate pneumomediastinum in chest X-ray. Chest CT scan performed after the oral administration of contrast medium could be an useful and non-invasive diagnostic procedure.

Aged↗
PubMed1989

[A case of left atrial ball thrombus observed in a patient with combined valvular heart disease, accompanying anomalous coronary venous run].

A 53-year woman, who had been under observation for combined valvular heart disease, was admitted to our hospital for further examination of embolic episodes to brain and kidney. Echocardiographic examination showed the evidence of free-moving ball thrombus in the left atrium, and emergent cardiac catheterization following the echocardiography confirmed the diagnosis of it as well as mitral stenosis, aortic regurgitation with stenosis, and tricuspid regurgitation. In addition, coronary angiography disclosed the anomalous coronary venous run. With these findings, the cause of embolic episodes was found to be due to the thrombus in the left atrium. In the surgery performed a ball thrombus of 40 x 35 x 36 mm and a mural thrombus of 15 x 35 x 20 mm in size in the left atrium were detected and removed, and both mitral and aortic valves were replaced to artificial ones. She had a good hospital course after the surgery and discharged without any complication. In this report, we discussed a case of left atrial thrombus observed in a combined valvular heart disease, with 29 literatures reported in our country.

Coronary Vessel Anomalies↗
PubMed1988

Obese patients with sleep apnea syndrome treated by progesterone.

Two obese patients with sleep apnea syndrome were administered chlormadinone acetate (CMA), a synthetic progesterone, known as a potent respiratory stimulant to augment load compensation response as well as CO2 chemosensitivity. Before CMA administration, both cases showed normal chemosensitivity of hypoxic and hypercapnic ventilatory responses (HVR and HCVR) at daytime, although marked oxygen desaturation with sleep apnea was observed. During CMA administration for 7 days, HVR, HCVR and occlusion pressure response to flow-resistive loading were altogether augmented. In one case obstructive sleep apnea (OSA) was altered to obstructive hypopnea, and in the other case central apnea disappeared completely, resulting in remarkable improvement of oxygen desaturation at sleep and daytime somnolence in both cases. We conclude that CMA might be useful in the treatment of sleep apnea syndrome.

Adolescent↗