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Biomedical subjects

S Takeda

Publications and source records attributed to S Takeda.

At least 631 records · Page 35Linked to original sources
PubMed1990

[Dissolution of silver and copper from Ag-Cu binary alloys under dynamic conditions].

Ag-Cu binary alloys containing 5-30% copper were subjected to dynamic extraction at 200 rpm and 37 degrees C to simulate the functional movement in the oral environment. Extraction was carried out in Eagle's minimum essential medium every two weeks for 18 weeks. The corrosion products were examined by the separation of extracts with a 0.22 micron filter. Significant dissolution of copper occurred with increasing copper content, but the increase in silver dissolution was slight. The amount of copper in the filtrate was the same as that in the extract, but no silver was detected in the filtrate. Therefore, dynamic extraction accelerated the dissolution of copper from the Ag-Cu binary alloys and thus lowered the corrosion resistance.

Copper↗
PubMed1990

[In vitro metal dissolution under various extraction conditions].

Dissolution of components from pure Ni, pure Ti, NiTi alloy and 316 L stainless steel was examined in Eagle's minimum essential medium to evaluate the effects of dynamic condition, pH, extraction period and filtration on the corrosion behaviour. Extraction medium was pH 3.5, 7.0 and 9.5. Extraction was done under static and gyrating conditions of 160 rpm, 200 rpm and 230 rpm for 3 and 7 days. Under static conditions, nickel was eluted from pure Ni and NiTi alloy at pH 3.5. Nickel and iron were slightly eluted from 316 L stainless steel at pH 3.5. However, dissolution of components from alloys was greater under dynamic conditions and with longer extraction periods. Dissolution of components, particularly of nickel at pH 3.5, was the highest from pure Ni, NiTi alloy and 316 L stainless steel. Following filtration with a 0.22 micron filter, the amount of metal decreased. Titanium was not detected in the filtrate under the conditions tested. The finding that a considerable amount of nickel was detected in the extract and filtrate indicated that the element was present in both a soluble and particulate form, especially at pH 3.5. The present results demonstrate that extraction under dynamic conditions is useful for investigating the degradation of metallic materials for medical and dental use.

Corrosion↗
PubMed1990

[Corrosion behavior of Ag-Pd binary alloys under dynamic conditions and its cytotoxicity (in vitro)].

Ag-Pd binary alloys with various palladium contents were extracted in Eagle's minimum essential medium by dynamic extraction at 200 rpm at 37 degrees C. The extracts were filtered through a 0.22 microns cellulose acetate filter, and the silver and palladium amount of the extracts and filtrates as dissolved metallic elements was measured with atomic absorption spectroscopy. Extracts and filtrates were also used in cultivation of L-929 cells to study in vitro cytotoxicity. An increase in the palladium content of the alloy resulted in decreased silver dissolution and increased palladium dissolution. The amount of palladium in the filtrates increased as the extraction period was extended, but the amount of silver was negligible in all filtrates. Extracts which had been extracted for 1 day showed strong cytotoxicity in pure Ag. However, the addition of palladium at a weight percent of more than 40% decreased cytotoxicity almost to the control level. Filtrate which had been extracted for 1 or 3 days was noncytotoxic in all alloys. However, the filtrate which had been extracted for 5 or 7 days showed cytotoxicity, which was especially strong in high-palladium alloys. These results demonstrate that extraction using a dynamic method appears to be useful in the investigation of their corrosion and biocompatibility.

Biocompatible Materials↗
PubMed1990

[Antitumor activities of orally administered 7-con-0-methylnogarol (TUT-7)].

We estimated antitumor activity of TUT-7 following p.o. administration using animal tumor models and human tumor xenografts. In mouse L 1210 leukemia system, antitumor activity of TUT-7 administered orally was as good as that by i.v. administration. Treatment involving schedules of every 4-days or daily administration was much more effective than single treatment. Therapiotic indices of this compound administered both p.o. or i.v. routes, were better than that of adriamycin administered i.v.. TUT-7 showed antitumor activities against various mouse tumors (L 1210 leukemia, P 388 leukemia, colon 38 adenocarcinoma, B 16 melanoma), LX-1 human tumor xenografts, and Yoshida sarcoma in rat. Base on above results, we concluded that oral administration is one of the useful route of TUT-7 administration.

Administration, Oral↗
PubMed1990

[Clinical and pathological studies on two patients with adult-onset nemaline myopathy].

Clinical and pathological findings of two patients, a 44-year-old male and a 54-year-old female, with adult-onset nemaline myopathy were described. Both patients showed normal motor development through their childhood; Patient 1 ran fast and was involved in powerful heavy labor until the age of 40, and Patient 2 was in good health until 49, when they began to have progressive muscle weakness. They had no family history of neuromuscular diseases. On neurological examination, they had moderate muscle weakness and atrophy in their limb-girdle and paravertebral muscles. Because paravertebral and neck muscles were preferentially involved, they had difficulty in holding the head straight up. They stood in a lordotic posture. They had neither high-arched palate nor facio-skeletal abnormalities which were common findings in congenital nemaline myopathy. Serum enzymes derived from muscle were normal and needle electromyography showed myogenic and neurogenic changes in both patients. On CT scan of the skeletal muscles, the paravertebral muscles were markedly decreased in density suggesting advanced fat tissue replacement in large areas. In patient 2 who was in more advanced stage, the quadriceps femoris, hamstrings and soleus muscles also showed the similar CT findings. Light microscopic examination of biopsied biceps brachii (Patient 1) and quadriceps femoris (Patient 2) demonstrated abundant rod-like structures in the majority of type 1 fibers. In both patients, there was a marked variation in fiber size. Type 1 fibers were atrophic and type 2C fibers increased in number.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Endocrine effects of hypotension induced by nicardipine in rabbits].

Endocrine effects of hypotension induced by nicardipine, a calcium antagonist, were studied in 18 male rabbits under halothane anesthesia. They were randomly divided into two groups; nicardipine (group N; n = 10) and controls (group C; n = 8). No change was noted in plasma catecholamines in group C throughout the experiment, but plasma renin activity decreased progressively. During and after induced hypotension, in group N, plasma epinephrine was significantly higher than the control value. The highest level of plasma epinephrine was seven times of the control value during 30 minutes after induction of hypotension. Plasma norepinephrine of group N was significantly higher than the controls. The maximum increase occurred 60 minutes after induction of hypotension. Plasma renin activity of group N was significantly higher than the control value. Compared with the control value (15.1 +/- 1.8 ng.ml-1.hr-1), plasma renin activity was activated 30 and 60 minutes after induction of hypotension (55.5 +/- 6.0 ng.ml-1.hr-1, P less than 0.001, 50.3 +/- 7.1 ng.ml-1.hr-1, P less than 0.01, respectively). In conclusion, our data show that hypotension by nicardipine activates the renin-angiotensin-sympathetic system.

Animals↗
PubMed1990

[Problems associated with radical neck dissection in patients with tongue carcinoma: four cases of stage I tongue carcinoma that recurred in the cervical area after the dissection].

Reported are four cases of a stage I tongue carcinoma which recurred in the cervical area after a radical neck dissection (RND). In all cases, the primary lesion was controlled with radium needle implants. Clinically, these tumors manifested endophytic growth and, histologically, had a high malignant grading. In most cases, a latent lymph metastasis appeared within 6 months after initial treatment and an early metastatic lesion developed beyond the capsule of the node. The site of cervical recurrences was located in non treated areas that were outside the range of the RND.

Aged↗
PubMed1990

[An elderly case of recurrent craniopharyngioma suffering from hemorrhage].

A case of a 63-year-old female with craniopharyngioma is reported. She first suffered from occult pituitary apoplexy and had recurrent enlargement and characteristic changes of a tumor during short periods. This patient was hospitalized after suddenly developing bitemporal hemianopsia. An intra-and suprasellar hematoma was revealed on computed tomography (CT) and magnetic resonance imaging (MRI). At the first operation, the hematoma was removed totally by the transsphenoidal approach, but tumor tissues were not identified. During the following 12 months, operations were repeated three times due to the recurrence and/or enlargement of a tumor associated with visual symptoms. Pathological diagnosis was squamous-type craniopharyngioma without any malignancy. Microscopic appearance of the tumor apparently changed during the clinical course. The characteristic findings were revealed respectively on MRI and CT. On the first preoperative MRI, a lesion of diffuse high signal intensity was observed on both T1 and T2 weighted images. At the second operation, the lesion was also revealed as having high signal intensity on T1 and T2 weighted images but the tumor had a large cyst with serous-yellowish fluid contents. A differential diagnosis was made on CT. At the third and fourth operations, the tumor was solid and had atheromatous contents. The lesion was revealed as having low signal intensity on T1 image and high on T2 respectively. Occult pituitary apoplexy with intra and suprasellar hemorrhage is very rare in cases of craniopharyngioma and only nine cases have been reported until now. It is also interesting with this high-aged patient that repeated recurrence and/or enlargement of a tumor with different microscopic appearances occurred during such short periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Craniopharyngioma↗
PubMed1990

[Plasma and red blood cell cyanide concentrations during hypotension induced by sodium nitroprusside or by a nitroprusside-trimetaphan mixture in rabbits].

Plasma and red blood cells cyanide concentrations during hypotension induced by sodium nitroprusside and a nitroprusside-trimetaphan mixture were studied in 29 male rabbits under halothane anesthesia. They were randomly divided into three groups; Nitroprusside (group N; n = 10), A nitroprusside-trimetaphan mixture (group M; n = 10), Controls (group C; n = 9). No changes were noted in plasma and red blood cells cyanide concentrations in group C throughout the experiment. During and after induced hypotension, in group N, plasma cyanide concentration was significantly higher than the control value. The maximum increase occurred 60min after induction of hypotension and the highest concentration of plasma cyanide was six times the control value. In contrast, in group M, plasma cyanide concentration was unchanged from the control value. However, during and after induced hypotension, red blood cells cyanide concentrations of group N and group M were significantly higher compared with the control values. Red blood cells concentrations of cyanide increased for 30 and 60 min during induced hypotension in group N (27.11 +/- 3.9 micrograms.ml-1, P less than 0.001, 46, 73 +/- 4.7 micrograms.ml-1, P less than 0.001, respectively) and in group M (0.31 +/- 0.05 micrograms.ml-1, P less than 0.05, 0.29 +/- 0.03 micrograms.ml-1, P less than 0.05, respectively). In conclusion, the data suggest that a nitroprusside-trimetaphan mixture is a safe method for hypotensive anesthesia.

Animals↗
PubMed1990

Genetically defined membrane-bound and soluble alkaline phosphatases of the silkworm: their discrete localization and properties.

In the midgut tissue of the silkworm, Bombyx mori, alkaline phosphatase isozymes, membrane-bound (m-ALP) and soluble (s-ALP) forms are controlled by non-allelic genes on the same chromosome. We purified and characterized both ALPs to elucidate their possible functions and to compare with mammalian ALPs. Both forms were found to be similar Mr = 68,000 in gel permeation chromatography and as a single subunit as a monomer in SDS-polyacrylamide gel electrophoresis with Mr = 58,000 for m-ALP and Mr = 61,000 for s-ALP. The pH optima of ALPs were 10.9 (m-ALP) and 9.8 (s-ALP), and the former was extremely stable even in pH 10-12 which accords with the physiological milieu in Bombyx midgut lumen. Both ALPs had similar substrate specificities. L-cysteine inhibited strongly both ALPs, but inhibitory effects of L-phenylalanine, L-homoarginine, and L-leucine were undetectable for s-ALP and very weak for m-ALP. The antibody raised against purified m-ALP recognized m-ALP but not purified s-ALP and vice versa. Rocket-immunoassay showed that m-ALP was distributed in similar levels along the length of midgut except for the most anterior portion. Seventy percent of s-ALP activity existed in the last one-third of midgut. Immunohistochemical study revealed that the m-ALP was localized at the brush border of columnar cells in the middle and posterior midgut epithelia. In contrast, the s-ALP was localized at the apical surface of goblet cells through the length of midgut. We detected ATPase activity in the purified s-ALP preparation; Mg2+ was essential for the ATPase activity and the activity also increased with KHCO3 but not with KCl. The solubilization test of m- ALP with various agents was attempted and the relationship between m-ALP and the digestive fluid-ALP was discussed.

Alkaline Phosphatase↗
PubMed1990

[A case of stage III ovarian carcinoma successfully treated with oral etoposide].

A 49-year-old woman with stage III ovarian cancer (undifferentiated adenocarcinoma), who refused combination chemotherapy for postoperative residual tumor, were successfully treated with daily oral etoposide in the outpatient clinic. The etoposide (50 mg/day) was first given orally and then a dose of etoposide was decreased to 25 mg/day because of alopecia and gastrointestinal toxicity. After seven months of treatment, the complete remission was confirmed by the second look laparotomy, and cytology of peritoneal surface revealed no signs of adenocarcinoma. This case suggests that daily oral etoposide therapy might be the alternative as a first-line and second-line chemotherapy of ovarian cancer in the outpatient clinic.

Adenocarcinoma↗
PubMed1989

[Metabolic clearance rate of oxytocin in human subjects].

Oxytocin metabolism seems to occur mainly in the kidney and the liver. Placental cystine amino peptidase (CAP), which inactivates oxytocin by cleavage of the bond between the N-terminal cystine residue and adjacent tyrosine, rises progressively with advancing gestation. The role of CAP in oxytocin metabolism is not clear. To clarify this issue, the authors measure oxytocin metabolic clearance rate(MCR) by the constant infusion of 3mU/min and 6 mU/min synthetic oxytocin in 14 adult subjects: 5 pregnant women (38 approximately 41 weeks gestation), 4 puerperal women and 5 nonpregnant women. Oxytocin MCR (mean +/- SE) during infusion of 3 mU/min was 20.9 +/- 2.6 ml/kg/min in pregnant women; 16.9 +/ 2.4 ml/kg/min in puerperal women; 19.7 +/- 3.3 ml/kg/min in pregnant women. Oxytocin MCR during infusion of 6 mU/min was 22.1 +/- 3.3 ml/kg/min in pregnant women and 22.7 +/- 3.1 ml/kg/min in nonpregnant women. These values were statistically similar. Mean (+/- SE) CAP values were 143.5 +/- 7.8 mU/ml in pregnant women, 60.8 +/- 3.0 mU/ml in puerperal women, and 13.8 +/- 2.7 mU/ml in nonpregnant women. CAP levels in pregnant women were significantly higher than others. 3H-oxytocin degradation was studied in vitro in pooled plasma of pregnant and nonpregnant women. 85% of original 3H-oxytocin was destroyed in pregnant plasma during 1 hour but only below 10% was destroyed in nonpregnant plasma in 2 hours. These results suggest that CAP in pregnant women may not play a role in the inactivation of oxytocin in vivo, thus differing from its role in vitro.

Adult↗
PubMed1989

Nuclear GTP-binding proteins of Swiss 3T3 cells.

The GTP-binding proteins of Swiss 3T3 cell nuclei were analyzed by filter binding assay and UV cross-linking analysis. The results showed the presence of multiple GTP-binding proteins in the nuclei. Scatchard analysis revealed that the Kd value for GTP binding to high-affinity components was 69 nM, that to low-affinity components being 2.7 microM. The GTP-binding activities of some nuclear proteins were found to change significantly in response to the growth conditions of the cells. During culture of cells in medium without serum, the GTP-binding activity of a 140 kDa protein clearly decreased, whereas that of a 40 kDa protein increased.

Animals↗