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Biomedical subjects

K Iwasa

Publications and source records attributed to K Iwasa.

At least 19 recordsLinked to original sources
PubMed1992

Transformations of (+-)-salsolinol into optically active O- and/or N-methylated derivatives by several Papaveraceae plants and their tissue-cultured cells.

(+-)-Salsolinol [3], a substance possibly inducing parkinsonism, was biotransformed into optically active O- and/or N-methylated salsolinols 5, 6, and 7 by several Papaveraceae plants and tissue-culture cells derived from these plants. The bioconversion of racemic salsolinol into optically active tetrahydroisoquinolines has never been shown to occur, either in animals or in plants.

Biotransformation↗
PubMed1992

[Prevention of postoperative recurrence of hepatocellular carcinoma by adjuvant locoregional chemotherapy].

Postoperative adjuvant locoregional chemotherapy was performed on patients who underwent hepatic resection for hepatocellular carcinoma with permeation of tumor into portal vein and/or into hepatic vein and/or intrahepatic metastasis to prevent recurrence. Twenty patients received intra-hepato-arterial infusion of chemotherapeutic drugs or Lipiodol, or transcatheter arterial embolization as adjuvant therapy, and 25 patients did not receive the therapy. There was no significant difference in the recurrence rate between the two groups, and disease-free-survival would not be improved significantly by adjuvant therapy. But the disease-free-survival was improved in patients who underwent relative noncurative hepatectomies. Median duration from the hepatic resection to the recurrence was prolonged by adjuvant therapy, but no significant difference was noted between the two groups. Serious hepatic injury was a side effect of adjuvant therapy in one patient. Therefore great care was necessary when performing the therapy. Further study on choice of the drugs and methods was considered necessary to obtain more effective therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Pentagastrin-stimulated histamine release and acid secretion from the totally isolated vascularly perfused rat stomach.

This study was performed to examine the effect of cAMP levels on histamine release in the isolated rat stomach. Pentagastrin-induced histamine release was unaffected by phosphodiesterase inhibition, and pentagastrin itself had no phosphodiesterase-like effect. The results support previous observations showing that histamine is likely to be the mediator of the acid secretagogue effect of (penta) gastrin.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Ultrastructure of the red pulp in spleen innervation in horse and pig.

The innervation of the red pulp in the spleen of horse and pig was investigated by electron microscopy. In addition, the neurilemma was studied by immunohistochemistry specific for S-100 protein. In the pig, a large population of smooth-muscle cells extending from the smooth-muscle trabeculae was present in the red pulp. The cytoplasmic processes of reticular cells enwrapped the smooth-muscle cells, and nerve fibres were distributed between the smooth-muscle cells and the reticular cells. The nerve terminals clustered toward the facing of the smooth-muscle cells. Nerve fibres and terminals were not disclosed within the sheathed artery. Immunohistochemically the neurilemma showed a reaction positive for S-100 protein. In the horse, no smooth-muscle cells were noted in the red pulp. The nerve fibres terminated around the cytoplasmic processes of the reticular cells. Nerve fibres and terminals were disclosed within the sheathed artery, and the terminals contained both large and small dense-cored vesicles. Immunohistochemically the neurilemma showed a reaction negative for S-100 protein. These findings support the presence of the axon-bearing reticular cells described earlier in the horse spleen.

Animals↗
PubMed1991

Carbohydrate histochemistry of bovine duodenal glands.

The complex carbohydrates in the bovine duodenal glands were examined histochemically using 5 peroxidase-labeled lectins to achieve a better knowledge of their glycoprotein profiles. The presence of at least 2 different cell types and secretion of neutral mucin were observed in the bovine duodenal glands. The duodenal gland cells located in the central area of the lobules contained neutral glycoproteins with different saccharide residues as beta-D-gal-(1-3)-D-galNAc, alpha-D-galNAc, beta-(1-4)-D-glcNAc, NeuNAc and D-galNAc. The other cell types located in the peripheral area of the lobules contained alpha-L-Fuc, alpha-D-galNAc, beta-(1-4)-D-glcNAc, NeuNAc and D-galNAc. These findings seemed to be characteristic of a unique digestive process of the ruminant.

Animals↗
PubMed1991

[Flow cytometric analysis of DNA ploidy pattern in advanced gastric cancer and its relationship with prognosis].

Cell nuclear DNA content was determined by flow cytometric analysis in 270 patients with advanced gastric cancer. Aneuploid DNA content was observed in 150 patients (55.6%). The DNA ploidy pattern was the third significantly prognostic factor behind peritoneal dissemination and liver metastasis in Cox regression multivariate analysis. About the relationship between DNA ploidy pattern and other prognostic factors, peritoneal dissemination and wall invasion ratio of aneuploid were significantly higher than those of diploid (p less than 0.01). Five-year survival rate of diploidy patients was significantly higher than that of aneuploidy patients. In stage I, five-year survival rate of patients with diploid tumor was 83.3% and that of patients with aneuploid tumor was 70.0%. In stage II, that of patients with diploid tumor was 81.3% and that of patients with aneuploid tumor was 66.7%. In stage III, that of patients with diploid tumor was 71.2% and that of patients with aneuploid tumor was 25.1%. In stage IV, that of patients with diploid tumor was 31.6% and that of patients with aneuploid tumor was 2.6%. Furthermore in the curative case, that of patients with diploid tumor was 77.2% and that of patients with aneuploid tumor was 48.2%. Aneuploid case has significantly worse prognosis in curative operation.

Adult↗
PubMed1990

Anomalous caudal vena cava passing through the vertebral canal in a calf.

A 15-day-old female Holstein-Friesian calf with an anomalous caudal vena cava was examined macroscopically, roentgenologically, and histologically. The calf, weighing 43 kg, had severe scoliosis. A common renal vein merged into a single venous trunk formed by the union of the left and right common iliac veins. The trunk entered the vertebral canal through the left intervertebral foramen formed by the last (13th) thoracic and the first lumbar vertebrae. The trunk continued along the ventral side of the narrowing spinal cord inside the canal, and then ran out the left intervertebral foramen formed by the 8th and 9th thoracic vertebrae and emptied via the right azygos vein into the cranial vena cava. In contrast, the hepatic vein passed through the foramen vena cava independently of the trunk and entered the right atrium directly. The pathogenesis of the present anomaly may be explained as follows: The right subcardinal vein, failing to make connection with the liver, shunted directly into the right azygos vein derived from the right supracardinal vein. The body axis began to curve before ossification of the vertebrae occurred. Consequently, the developing right supracardinal vein, located close to the spinal cord, is thought to have become enclosed in the vertebrae with the spinal cord during the early fetal stages.

Animals↗
PubMed1990

A retrospective study on the efficacy of cervical lymph node dissection in well-differentiated carcinoma of the thyroid.

The management of cervical lymph node metastases in well-differentiated carcinoma of the thyroid is controversial. In our department, from 1963 to 1972, node plucking was performed only in patients with cervical lymphadenopathy whereas, from 1973 to 1983, modified radical neck dissection was therapeutically or electively performed. In order to determine whether the more extensive dissection is adequate, a retrospective analysis was performed using two groups of patients who were managed differently with regard to the treatment of cervical lymph node metastases. From this series of 206 patients with more than five years follow-up, it was found that the rates of survival and lymph node recurrence did not differ between the two groups. However, since the well-differentiated carcinoma of the thyroid has relatively indolent biological behaviour, further long-term follow-up seems to be necessary for demonstrating the efficacy of neck dissection.

Adolescent↗
PubMed1989

Glucagon antagonists: contribution to binding and activity of the amino-terminal sequence 1-5, position 12, and the putative alpha-helical segment 19-27.

Glucagon binding to and recognition by its cell surface receptor is the necessary first step in the cascade of events leading to the activation of adenylate cyclase by the hormone. It has long been presumed that glucagon adopts an ordered conformation upon binding to its membrane-bound receptor. A recent model of this three-dimensional structure based on biophysical data, predicts beta-turns at positions 2-5, 10-13, and 15-18, and an alpha-helical region between residues 19-27. Our approach in the design of antagonists of glucagon was to elucidate the steric and electronic features that stabilize these secondary structures to obtain analogs that bind with high affinity to the receptor but do not activate adenylate cyclase. Nineteen glucagon analogs incorporating structural changes at the amino-terminal sequence 1-5, at positions 9 and 12, and at the carboxyl-terminal helical region were synthesized. Des-His1-[Glu9]glucagon amide was recently shown to be a competitive inhibitor. Our synthetic studies in combination with this modification have resulted in seven new glucagon antagonists. The implications for the structural and conformational properties required for binding and activity of glucagon and the glucagon peptide family are discussed.

Adenylyl Cyclases↗
PubMed1989

Protective effect of vitamin E on spinal cord injury by compression and concurrent lipid peroxidation.

Studies were made on the influence of vitamin E on the effects of compression injury of the spinal cord associated with ischemia in rats. The motor disturbance induced by spinal cord injury was greatly reduced by vitamin E supplementation. After injury, the spinal cord evoked potentials showed greater recovery of both amplitude and latency in the vitamin E-supplemented group than in the control group. Spinal cord blood flow was promptly restored and remained normal after injury in the vitamin E-supplemented group, but was significantly decreased from 3 h after injury in the control group. Thiobarbituric acid (TBA)--reactive substances in the spinal cord was immediately increased by compression injury in both groups, and after injury it persisted at a high value for 24 h in the control group, but decreased within 1 h in the vitamin E-supplemented group. Pathological examination of the spinal cord showed less damage, such as bleeding and edema, in the vitamin E-supplemented group than in the control group. Vitamin E may have protective effects on the spinal cord by inhibiting damage induced by lipid peroxidation and/or by sustaining the blood flow by maintaining the normal metabolism of arachidonic acid.

Animals↗
PubMed1989

Clinical considerations and biochemical basis of prognosis of cervical spinal cord injury.

A total of 118 patients with cervical spinal cord injury were studied to determine the neurologic improvement achieved by either conservative or surgical treatment. Useful recovery was observed in 55% of the patients with incomplete cord injuries, but in none of those with complete cord injuries. There was no significant difference between the treatment groups regarding neurologic improvement. In experimental studies on rats, the increased levels of lipid peroxides and thromboxane after spinal cord injury were found to be proportional to the magnitude of injury. These evidences suggest that spinal cord injury is directly related with the magnitude of injury, and the prognosis is determined entirely at the time of injury.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Activation by curare of acetylcholine receptor channels in a murine skeletal muscle cell line.

Curare action on nicotinic acetylcholine receptors has a number of facets, of which the best known is competitive antagonism. Here we describe the weak agonist action of 10(-5) M curare on the murine skeletal muscle cell line, G8. Although curare induces no depolarization in G8 cells, single-channel recordings reveal short-lived curare-induced currents. A feature of these brief events is the multiplicity of conductance levels (of the four levels with conductances of 48, 37, 14, and 6 pS, none had a lifetime greater than 1.5 ms). Most well-resolved events (about 17% of which are to a subconductance) last less than 0.5 ms, with activation occurring predominantly as isolated events rather than in bursts. Agonism is not, however, a high probability action for curare: calculations based on the frequency of events at half-saturating conditions suggest that curare-induced channel openings occur during less than 1% of acetylcholine receptor-curare binding episodes. The outcome is (a) an agonist action too feeble to perturb the membrane voltage and (b) a powerful competitive antagonist action.

Animals↗
PubMed1989

Seven-legged calf--dipygus with an extra foreleg at the pelvic region.

A male Holstein-Friesian calf with seven legs was examined macroscopically and radiographically. External features included two normal forelimbs, two normal hindlimbs (lateral hindlimbs), and two abnormal hindlimbs (medial hindlimbs) which were underdeveloped. Also, a rudimentary forelimb, which was attached to the pelvic region, was observed between both the medial hindlimbs. It consisted of an underdeveloped humerus, a duplicated ulna, several carpal bones, a partially duplicated metacarpal bone and three digits with three hoofs. This leg was connected with two sets of coxae by a irregular-shaped bone considered the vestigial vertebrae and ribs. Two penises and scrotums, three kidneys and testes were also observed. This calf is the first case of dipygus associated with pygopagus parasiticus in cattle. Based on these findings, the pathogenesis of this rare anomaly was briefly discussed from an embryological point of view.

Abnormalities, Multiple↗