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Biomedical subjects

K Iwasa

Publications and source records attributed to K Iwasa.

At least 73 records · Page 4Linked to original sources
PubMed1994

Ultracytochemistry of glycoconjugates in pig duodenal gland.

To elucidate the ultrastructure, glycoprotein profile and site of glycosylation of glandular cells in relation to the functional polarity of the organelles, swine duodenal tissue was embedded in glycol methacrylate and subsequently stained for periodic acid thiocarbohydrazide silver proteinate (PA-TCH-SP), high iron diamine (HID)-TCH-SP, low iron diamine (LID)-TCH-SP, ninhydrin T-TCH-SP and five peroxidase-labeled lectins. The secretory granules in the duodenal gland cells were electron lucent with a 200 nm to 500 nm electrondense core. Glycoconjugates were confined to the secretory granules and elements of the Golgi complex. Protein activity was located only in the electron dense core. Achivementestic staining pattern for Concanavalin A (Con A), peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I), wheat germ agglutinin (WGA) and soybean agglutinin (SBA) was observed in stained secretory granules and the Golgi apparatus. A few cis cisternae were stained with SBA and UEA-I. Trans cisternae were stained with WGA and PNA. Con A reacted with seromucous granules and rough endoplasmic reticulum. These observational findings suggest that these are seromucous cells. The Golgi apparatus is the site of glycosylation and can be divided into two distinct compartments.

Animals↗
PubMed1994

Two distinct types of reticular cells in the pig sheathed artery.

The morphology of reticular cells of the sheathed arteries, in the red pulp of pig spleen, was studied by using transmission electron microscopy; and their histochemical reactivity with periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP). The phagocytic ability was evaluated by injecting colloidal carbon into the splenic artery. Reticular cells of the sheathed arteries were classified as type I and type II cells. Type I cells have a nucleus with scanty chromatin, and the cytoplasm reacts positively to PA-TCH-SP. The PA-TCH-SP-positive granules are considered to be subunits of beta-glycogen particles based on their morphological features. Type II cells have a nucleus with abundant chromatin and are not stained by PA-TCH-SP. Both types of reticular cells are connected with reticular fibers. Results of the colloidal carbon injection showed that type I reticular cells did not ingest carbon particles during the time frame of the experiment, whereas type II reticular cells are phagocytic and ingested carbon.

Animals↗
PubMed1994

Scanning electron microscopical observation of the intramitochondrial body in the bovine corpus luteum during pregnancy and after parturition.

Large luteal cells of the bovine pregnant luteum can be characterized as steroid-producing cells. Mitochondria of these cells contained intramitochondrial bodies (IMB). The three-dimensional structure of the IMB and the degenerative process of luteal cells were as follows: 1) The IMBs were globular or oval, 0.1 to 1.5 microns in diameter. Their outer surfaces were coarse but their cut surfaces were uniform. Their outer surfaces changed from rough to smooth during pregnancy. 2) At the late stage of pregnancy, the large luteal cells lost their cytoplasmic processes, showing the first sign of degeneration at the cell level in such a way that their mitochondrial cristae transformed from tubular to laminar, and that they contained accumulated lipid droplets. 3) After parturition, the IMBs came out from degenerating large luteal cells, and were conveyed by lymphatic capillaries.

Animals↗
PubMed1993

Father-son testicular cancer.

Testicular tumors in closely related family members are rare. We report a case of familial testicular cancer occurring in father-son pairs. The father had teratocarcinoma and his son developed pure seminoma. The association of a genetic factor in the etiology of testicular malignancy is discussed.

Adult↗
PubMed1993

Cervico-pectoral ectopia cordis in two Holstein calves.

Two Holstein calves affected with cervico-pectoral ectopia cordis, a male (No. 1) delivered stillborn and a female (No. 2) died 1 hour after birth, were examined macroscopically and radiographically to assess the severity and elucidate the teratogenesis of the anomaly. The heart of one calf was covered by the intact pericardium and skin and displaced to the caudalmost portion of the ventrocervical region, just cranial to an enlarged thoracic inlet. The cranial vena cava and the vena azygos were duplicated. The sternum was bilaterally divided into two parts fused only at the xyphoid process and was semicircular. The heart of the other calf, covered solely by the pericardium, was exposed ventrally from an oval opening in the body wall just cranial to a defective Y-shaped sternum. In both calves, the arterial branching pattern from the aortic arch was intermediate between the patterns of the dog and pig, and in each case a single pulmonary vein emptied into the left atrium. Pronounced or slight torticollis, cleft palate, and abnormalities in the urogenital system were also found. From an embryological perspective, cervical and pectoral ectopia cordis have a common pathogenesis; the cervical type occurs at a slightly earlier fetal stage than the pectoral type.

Animals↗
PubMed1993

Nonmuscle arterial constriction after subarachnoid hemorrhage: role of growth factors derived from platelets.

Recent studies have shown that myofibroblasts cultured from spastic arteries after subarachnoid hemorrhage (SAH) can produce contractile forces and that cerebrospinal fluid obtained from SAH patients accelerates this contraction. Myofibroblast-populated collagen lattices were used to evaluate the roles of polypeptide growth factors considered to be released from intraluminal accumulated platelets. The myofibroblasts, obtained at autopsy from human cerebral arteries of victims of vasospasm, caused contractile forces by compacting collagen fibrils in the matrix. Transforming growth factor beta 1 (TGF-beta 1) and platelet-derived growth factors aa and bb (PDGFaa and PDGFbb) accelerated this contraction in a dose-dependent manner. In the presence of TGF-beta 1 at 1 or 10 ng/ml, PDGFaa at 10 ng/ml, or PDGFbb at 10 ng/ml, lattice areas were reduced to 69.5 +/- 1.9% (mean +/- standard deviation) (P < 0.001), 63.3 +/- 0.4% (P < 0.001), 66.5 +/- 3.0% (P < 0.01), or 74.4 +/- 1.7% (P < 0.01) of the control on Day 6, respectively. The combination of subthreshold doses of TGF-beta 1 and PDGFaa created a stimulatory effect that appeared to act synergistically. Furthermore, myofibroblast-populated collagen lattices made with cells preincubated with TGF-beta 1 showed more rapid compaction with or without the presence of stimulants such as post-SAH cerebrospinal fluid. These results suggest that, in addition to other possible factors in the post-SAH cerebrospinal fluid, growth factors derived from accumulated platelets may play an important role in arterial constriction caused by nonmuscle components after SAH, by single or multiple mechanisms.

Arteries↗
PubMed1993

Electron microscopic studies on reticular fibers in the pig sheathed artery and splenic cords.

The reticular fibers of the capillary sheath and splenic cord were studied in the pig spleen by transmission electron microscopy to reveal their components and the presence of sialic acid in the amorphous ground substance. Collagen fibrils, elastic fibers, microfibrils, nerve fibers and smooth muscle cells were observed in the reticular fibers of the splenic cord, while only microfibrils were recognized in the reticular fibers of the capillary sheath. The binding of LFA lectin to the splenic cord was stronger than the capillary sheath. These findings may suggest that the reticular fibers of the splenic cord include numerous functional elements and perform an important role during contraction or dilation of the spleen. On the other hand, it seems to be reasonable to term the capillary sheath as "capillary basement membranous reticular tissue", since the reticular fiber of the capillary sheath resembles the basement membrane of the capillary in its components.

Animals↗
PubMed1993

Three-dimensional structure of dog Sertoli cells: a computer-aided reconstruction from serial semi-thin sections.

The three-dimensional structure of the Sertoli cell in the Korean Jindo dog was investigated by scanning and transmission electron microscopy. Additionally, type-A and type-B Sertoli cells were simulated by three-dimensional computer graphic imaging to clarify the anatomical relationship between Sertoli cell and germ cells. Descriptions in the present study are based on examination of the reconstructed type-A cells at stages IV, V and VI of the spermiogenetic cycle and stages VII, VIII and IX of the reconstructed type-B Sertoli cells. Morphologically, three types of Sertoli cell processes were evident: 1) flat club-like, elliptical processes bifurcating and trifurcating randomly; 2) slender cord-like, tubular processes; and 3) sheet-like processes. The sheet-like processes rested upon more than half the surface of each round spermatid located in the proximity of the Sertoli cell. Curiously, just before spermiation, the apical club-like processes shifted from their initial position at the spermatid head and subsequently covered the disengaged residual body, after which the residual body was no longer evident in the tubule. Though the mechanism for this elimination is not known, the process suggests a reciprocity between the Sertoli and germ cells. An anatomical dissimilarity between type-A and type-B Sertoli cells appeared in the apical region, with the apical club-like processes of the type-B Sertoli cell given off by sheet-like processes as well as by the Sertoli column. At the base of all Sertoli cells, sophisticated sheet-like processes paralleled the basal lamina, tenaciously adhering end-to-end to the sheet-like processes of adjacent Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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↗