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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 1,135 records · Page 63Linked to original sources
PubMed1991

Determinations of organ doses and effective dose equivalents from computed tomographic examination.

The organ or tissue doses were determined with a phantom measurement for 12 types of CT scanners widely used in Japan. Two types of thermoluminescent dosimeters were used for the dose determinations in a Rando woman phantom. The effective dose equivalents recommended by the International Commission on Radiological Protection were calculated using the measured organ or tissue doses. It was found that the CT scanners currently available give quite different organ or tissue doses. When selecting the optimum technical factors for scanning, therefore, it is important to take into consideration the balance of the image quality and the radiation exposure to patients.

Female↗
PubMed1991

Effect of vitamin B6 deficiency on glycogen metabolism in the skeletal muscle, heart, and liver of rats.

The effect of vitamin B6 deficiency was studied on glycogen metabolism in the gastrocnemius muscle, heart, and liver of rats. The glycogen phosphorylase activities in the gastrocnemius muscle and heart but not in the liver of vitamin B6-deficient rats were significantly decreased. The decrease in the enzyme activity in the gastrocnemius muscle was due to decrease in the amount of enzyme. The glycogen content of the muscle of vitamin B6-deficient rats was higher than that of the controls, but the glycogen content of the liver was similar in the two groups. These data suggest that glycogen degradation was impaired in the muscle but not the liver of vitamin B6-deficient rats.

Animals↗
PubMed1991

Effect of pyridoxine-deficiency on degradation of cytosolic aspartate aminotransferase in rat liver lysosomes.

Highly purified lysosomes were isolated from the livers of control and pyridoxine-deficient rats. The calculation of the lysosomal protein contents indicated that the livers of both groups of rats contain virtually the same amounts of the lysosomal proteins (12.0 and 13.0 mg lysosomal proteins/g liver proteins for the control and pyridoxine-deficient rats, respectively). The immunoblotting of the lysosomal proteins with anti-cytosolic aspartate aminotransferase (cAspAT) showed 46 kDa band, corresponding to the subunit molecular weight of cAspAT, as well as the bands representing degradative intermediates of cAspAT. The relative amounts of the immuno-reactive substances were estimated by scanning the immuno-stained bands and measuring the densitometric tracings. It was found that the lysosomes in the pyridoxine-deficient rat liver contain almost twice as much cAspAT and its degradative intermediates as those in the control rat liver. On the basis of these observations, it was concluded that the increased rate of degradation of cAspAT in the liver of the pyridoxine-deficient rats is brought about by the increased rate of sequestration of cAspAT into lysosomes.

Animals↗
PubMed1991

[Utilization of D-histidine by the derivative strain TA100 of Salmonella typhimurium LT 2].

In general, wild-type gram-negative enteric bacteria are not able to utilize D-amino acids as the precursors of respective L-amino acids. We found, however, that an L-histidine auxotroph mutant, TA100, derived from Salmonella typhimurium strain LT 2 and used in the Ames test, showed a biphasic growth curve in the presence of both L- and D-histidine at concentrations of 5 micrograms/ml and 100 micrograms/ml, respectively. L-histidine may be utilized preferentially and then, after a short lag, D-histidine may be utilized. The short lag time is therefore considered to be the time required for induction of such an enzyme that converts D-histidine to L-histidine and for uptake of D-histidine by the bacterial cells.

Culture Media↗
PubMed1991

Poststatin, a new inhibitor of prolyl endopeptidase, produced by Streptomyces viridochromogenes MH534-30F3. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

Poststatin, a new inhibitor of prolyl endopeptidase (PEP) was discovered in the fermentation broth of Streptomyces viridochromogenes MH534-30F3. It was purified by Diaion HP-20, Sephadex LH-20 and YMC-gel (ODS-A) column chromatography and then isolated as a colorless powder. Poststatin has the molecular formula C26H47N5O7. The IC50 value of poststatin against the PEP of partially purified porcine kidney was 0.03 microgram/ml. It has low acute toxicity. No deaths occured after iv injection of 250 mg/kg of this agent to mice.

Amino Acid Sequence↗
PubMed1991

Rapid and sensitive chemiluminescent enzyme immunoassay for measuring tumor markers.

We developed a chemiluminescent enzyme immunoassay (CLEIA) to quantify such tumor markers as carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), CA19-9, and CA125. We used a novel chemiluminescent substrate, a derivative of 1,2-dioxetane phosphate (AMPPD), to measure alkaline phosphatase as a labeling enzyme to Fab' fragments of antibody. Regardless of the solid phase, i.e., polystyrene beads (6 mm diameter) or ferrite-coated particles (0.3 microns diameter), the standard curves within the dynamic ranges of the conventional RIA or enzyme immunoassay (EIA) were linear in all cases except for those with AFP. Use of the ferrite particles further shortens the immunoreaction, so the assay can be performed in 30 min. In addition, the relationships between concentrations of the marker and chemiluminescent signals for CA19-9, CA125, and CEA were linear up to concentrations about 10-fold greater than the ordinary dynamic ranges. Intra- and interassay CVs (averages for individual analyte) were 2.2%-4.9% and 2.0%-5.8%, respectively. In an analysis of serum samples, results of the CLEIA correlated reasonably well with those of RIA or EIA. The lower limit of detection by CLEIA with ferrite particles was 390 arb. units/L for CA19-9, 990 arb. units/L for CA125, 0.06 micrograms/L for CEA, and 0.03 micrograms/L for AFP. Thus, the sensitivity increased to between two- and 10-fold that of RIA or colorimetric EIA, depending on the analytes.

Adamantane↗
PubMed1991

Human complement regulatory proteins expressed on mouse A9 cells containing a human chromosome 1.

The structural genes of human complement regulatory proteins are clustered on chromosome 1 at position q3.2. Human chromosome 1 was transferred into a mouse fibroblast cell line, A9 [designated as A9(neo-1)], and the surface expression of its gene products participating in complement regulation, namely C3b/C4b receptor (CR1, CD35), decay-accelerating factor (DAF, CD55), membrane co-factor protein (MCP, CD46) and C3d/EB virus receptor (CR2, CD21), were assessed using respective monoclonal antibodies by flow cytometry. CR1 became positive within 7 days of culture. MCP appeared in a small population of cells by Day 3 and, together with DAF, began to increase on Day 7. CR2 appeared on Day 14. The order of the expression was CR1 greater than DAF = MCP greater than CR2. On Day 42, however, all became negative except for MCP, which was markedly diminished. These human regulatory proteins were specifically associated with the presence of human chromosome 1, since none of them were expressed on human chromosome 12-transferred A9 cells [A9(neo-12)]. Intact A9 and A9(neo-12) cells activated human complement via the alternative pathway. The activation of this pathway was suppressed in the A9(neo-1) cells that expressed CR1, DAF and MCP. Slight protective activity was still observed in the 42-day cultured A9(neo-1) cells expressing only trace MCP. These results suggest that human complement regulators, expressed via the transferred human chromosome 1, can protect heterologous cells from complement, overcoming their ability to activate the human alternative pathway.

Animals↗
PubMed1991

Effect of oxiracetam on cerebrovascular impairment in rats.

The effect of oxiracetam (CGP 21690E, CAS 62613-82-5) on cerebrovascular impairment was investigated in rats. 1. After injection of tranylcypromine (a MAO inhibitor), spontaneously hypertensive rats (SHR) which had been previously infused with norepinephrine (NE) for 14 days displayed stroke-related behaviour including kangaroo-like posture, seizures and death. Administration of oxiracetam at doses of 400 and 800 mg/kg/d p.o. for 14 days before tranylcypromine injection inhibited the stroke-related behaviour. 2. Bilateral common carotid and vertebral artery occlusion induced electroencephalogram (EEG) flattening, the EEG recovering gradually after re-perfusion of cerebral blood flow. Oxiracetam administered after the re-perfusion at a dose of 100 mg/kg, i.v. accelerated the recovery. This facilitatory effect was not seen when either piracetam (50 and 100 mg/kg i.v.) or idebenone (50 and 100 mg/kg i.v.) were administered. 3. Occlusion of middle cerebral artery produced cerebral infarction and disturbed the circadian rhythm of spontaneous motor activity with an relative increase of activity in the light period. Treatment with oxiracetam (400 mg/kg/d p.o.) for 14 days after the occlusion showed a tendency to an improvement in the disturbed circadian rhythm but did not influence the size of brain infarction. From these results, oxiracetam is thought to have a protective effect in cerebrovascular impairment.

Animals↗
PubMed1991

[Experimental studies on the effects of superoxide dismutase on warm ischemic-reperfusion injury of the lung].

Transient impairment of the transplanted lung in early postoperative period is one of difficult problems in lung transplantation. It is likely that reperfusion injury of the warm ischemic lung is contributory. The purpose of this study is to evaluate the effects of superoxide dismutase (SOD) on reperfusion injury of warm ischemic lung. Thirty mongrel dogs were divided into four groups. In group I (n = 6), the left lung with complete hilar stripping was placed in warm ischemic state under deflation for 1 hour. In group II (n = 9), the left lung with complete hilar stripping was kept in warm ischemic condition under inflation. Group III (n = 6) animals with same manipulation as group I received superoxide dismutase (SOD 20 mg/kg) before reperfusion. Group IV (n = 9) animals underwent same manipulation as group II and received SOD (20 mg/kg) before reperfusion. Before warm ischemia, immediately after reperfusion, and 1 and 2 hours, blood gases, left pulmonary vascular resistance were measured under the occlusion of right pulmonary artery. Extra vascular lung water content (EVLW) was measured at autopsy and lung was processed for histology. In group II, III and IV, blood gases and EVLW showed significantly better values than group I. In group I and III, left pulmonary vascular resistance increased prominently after reperfusion, however did not change in group II and IV. From these results, we concluded that inflated lung reduced the extent of pulmonary edema after reperfusion and SOD was effective in preventing warm ischemic damage even in deflated lung.

Animals↗
PubMed1991

[A combined operation of coronary revascularization, abdominal aortic aneurysmectomy and femoro-popliteal bypass].

A 71-year-old male with abdominal aortic aneurysm, coronary artery disease and obstructive peripheral arteriosclerosis successfully underwent a combined operation of coronary artery bypass grafting (CABG), replacement of abdominal aortic aneurysm and femoro-popliteal bypass. In this combined operation, the right gastroepiploic artery (GEA) is suitable as a bypass graft, because a laparotomy is required for abdominal aortic aneurysmectomy. And the usage of arterial grafts such as GEA and the left internal thoracic artery (LITA) is reasonable in terms of avoiding hazardous proximal anastomosis and reducing the operating time.

Aged↗
PubMed1991

[Blood gas changes after laparoscopy].

Blood gas changes after laparoscopy under general anesthesia were examined. Thirty-six ASA I or II women were allocated to one of the two groups: carbon dioxide was used for pneumoperitoneum in group C and nitrous oxide in group N. Anesthesia was maintained with enflurane, buprenorphine, and supplemental midazolam. Arterial blood gases were measured in patients breathing room air. A significant fall in PaO2 (from 92.8 mmHg to 71.5 mmHg) was observed 5 minutes after extubation in group N as compared with the preoperative level and with group C, but there is no change in PaO2 in group C. PaCO2 showed no significant changes in both groups. In 6 out of 36 patients, PaO2 decreased below 60 mmHg. Possible causes of the difference between the two groups are diffusion hypoxia produced by nitrous oxide, gas embolism, or postoperative hyperventilation in response to hypercarbia during laparoscopy by carbon dioxide insufflation, and the last one is most probable. This may have prevented hypoxia in group C.

Adult↗
PubMed1991

[A case of left main bronchial rupture due to bronchocath tube].

A 68-year-old woman underwent a right upper lobectomy for lung cancer. After resection, we noticed the left main bronchial rupture due to bronchocath tube (polyvinyl chloride double lumen tube). The lesion of the rupture was repaired by interrupted sutures with 4-0 prolene. Subsequent course of the patient was uneventful. Tracheobronchial rupture is rare complication of intubation with polyvinyl chloride double lumen tube. There are 6 cases of this complication last five years in Japan. The cause and prevention of this complications are described. It is important to use an adequate tube size, to prevent malposition of the tube and overinflation of the bronchial balloon.

Aged↗
PubMed1991

[Long-term prognosis of Crohn's disease].

Two hundred and three patients with Crohn's disease seen at our clinics and affiliated centers from April 1973 to August 1988 were followed for 4.4 +/- 3.2 years (mean +/- SD), in order to evaluate the prognosis of Crohn's disease in Japan. These 203 patients (142 males and 61 females) fulfilled the following criteria; 1) they have been followed at the outpatients clinic for more than six months or 2) they have been admitted to us for more than a month. Of these, 83 (40.9%) had ileitis, 60 (29.6%) ileocolitis, 25 (12.3%) colitis, 15 (7.5%) miscellaneous types and the remaining 20 (9.9%) had undergone bowel resection. Cumulative survival rate and cumulative probability of surgery were calculated by life table method. Cumulative survival rate in these patients was compared with expected survival rate of sex and age matched general population. Cumulative survival rates five and ten years after diagnosis were 98.9% and 98.9%, respectively. There were no significant differences in the survival rates between two groups. Cumulative probability of surgery five and ten years after onset of symptoms were 16.2% and 39.1%, respectively. Cumulative probability of surgery five and ten years after diagnosis were 25.9% and 46.9%, respectively. From these results, the prognosis of Japanese patients with Crohn's disease appears to superior to that in European and American literatures.

Adult↗
PubMed1991

[Studies on nonthyroidal illness after heart surgery].

The concentrations of pituitary hormones (TSH and PRL), thyroid hormones (free-T4 and free-T3), thyroid hormone binding protein (TBG) and lipids (TG and FFA) in the blood were measured in order to examine the physiology of nonthyroidal illnesses that occurred as a result of heart surgery as well as their effects on the pituitary and thyroid glands. The subjects of the study consisted of 30 adults with congenital and acquired heart disease. Blood concentrations of TSH, PRL, free-T4, free-T3, and TBG decreased, and those of FFA increased, on the 2nd day following surgery. On the 2nd day following surgery, the decrease in the concentrations of free-T4 and free-T3 in the blood were considered due to a decrease in secretion of T4 from the thyroid gland, as well as due to a decrease in the activity of iodothyronine 5'-deiodinase in the peripheral organs. In the 3rd week following surgery, the concentrations of these items returned to their original values on the day prior to surgery.

Adult↗
PubMed1991

[Serum cholesterol levels in normal subjects taking into consideration the accuracy of the measuring system].

Serum cholesterol levels were determined in 5,843 normal subjects aged zero to seventy years. The accuracy of our assay method was checked by Standard Reference Material 909 and Certified Reference Serum, both of which were supplied by the National Bureau of Standards. Reference values of serum cholesterol were confirmed for each age group. That of male subjects in the 15-20 year age group was within a range of 109-203 mg/dl, and that of female subjects in the 20-25 year age group was within a range of 133-215 mg/dl. Therefore, among normal subjects, the above-mentioned age groups had the lowest serum cholesterol levels. Serum cholesterol levels increased with age in both male and female subjects. The upper limit of cholesterol levels was 248 mg/dl for males in the 50-60 year age group and 284 mg/dl for females in the same age group. We observed the necessity of paying consideration those changes which occur with aging, in the determination of reference values of serum cholesterol. Our findings also showed that serum cholesterol levels remained nearly constant in male subjects of all age groups over a period of 25 years. However, we found mean levels in female subjects in the 50-70 year age groups to be significantly elevated, when compared with those observed in persons in the same age group of 25 years previous. We also found that the mean cholesterol level in girls aged 12 years was higher than that of boys the same age.

Adolescent↗
PubMed1991

[Metastases to the mediastinal lymph nodes in a series of two-hundred-consecutive operations for primary lung cancer].

We examined the characteristics of lymph nodes metastases to the mediastinum on cases of two-hundred-consecutive operations for primary lung cancer from October of 1987 to May of 1990, comparing the intraoperative macroscopic diagnosis of lymph nodes to the histologic reports. The purpose of this study is to know how important the mediastinal dissection is and how many cases resulting in vain are hidden behind it. Thirty three cases were excluded because of limited operation or other reasons. Remaining a hundred sixty seven cases were divided on the basis of lymph node metastasis into following 5 groups. Forty three cases (26%), of which N2 disease was correctly diagnosed macroscopically, true positive for N2, were classified into group A. Sixteen cases (10%), group B, in which we failed to detect N2 positive from dissected specimens during operation, was considered to be false negative for N2, thirty one cases of N1 disease (18%), were classified into group C and thirteen cases of N0 disease (8%) into group D with false positive of lymph node prediction for metastasis. Sixty four cases of N0 disease (40%) were classified into group E, true negative for N0 prediction, which were correctly detected by macroscopic appearance of lymph nodes. Nine cases had only mediastinal lymph nodes metastases without hilar and lobar lymph node. Almost of them with this skip phenomenon occurred in the patients with adenocarcinoma in the upper lobe. It could be concluded that we dissected the mediastinal lymph nodes in this series, salvaging one N2 disease of ten cases and wasting our efforts four cases of those cases, in vain.

Adenocarcinoma↗