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Biomedical subjects

A Yamaguchi

Publications and source records attributed to A Yamaguchi.

At least 721 records · Page 40Linked to original sources
PubMed1986

[A case of intussusception due to intestinal metastasis of renal carcinoma].

Adult intussusceptions due to metastatic intestinal-tumor are very rare. A 71-year-old man with an intussusception due to intestinal metastasis of renal carcinoma is reported. To our knowledge, this is the third such patient in the Japanese literature. The patient was suffered from an intestinal obstruction six months after his renal carcinoma was detected. Laparotomy was performed, revealing that he had developed a jejunojejunal intussusception due to metastasis of renal carcinoma. The early diagnosis of metastatic intestinal tumor is difficult. It is important to bear in mind that patients with malignant tumor may already have metastasis.

Adenocarcinoma↗
PubMed1986

[A study of malignancy in gastro-intestinal carcinoids with special reference to the association of the prognosis and peptide hormone or oncofetal protein producing pattern].

It is difficult to differentiate malignant carcinoid tumors from benign ones early in the course of the illness. We investigated retrospectively a series of thirty-nine gastro-intestinal carcinoids not only for primary tumor anatomic site, macroscopic type, tumor size, histological depth, vessel invasion and mitosis, but also for peptide, ectopic hormone and oncofetal proteins by immunohistochemistry. Carcinoids primary in the appendix or rectum rarely metastasize, but those primary in the stomach or colon grow rapidly. Those greater than 2 cm in diameter and Borrmann's type had a poor prognosis. Carcinoids with deep penetration, vessel invasion or mitosis easily metastasize to lymph nodes or to the liver. Peptide hormone producing carcinoids were present in 21 of 39 (54%) tumors, but there were no correlation between the prognosis and peptide hormone producing patterns. Carcinoids producing carcinoembryonic antigen (CEA) were demonstrated in 11 of 37 (29%) tumors. These tumors were greater in size, more deeply penetrating and had more remarkable vessel invasion and mitosis than CEA non-producing ones. These results show that CEA producing carcinoids grow rapidly and easily metastasize. We concluded that these findings in carcinoid tissue appeared to be a reliable markers for metastasis and poor prognosis.

Carcinoembryonic Antigen↗
PubMed1985

Energetics of tetracycline efflux system encoded by Tn10 in Escherichia coli.

Tritiated tetracycline was actively accumulated in inverted membrane vesicles prepared from Escherichia coli W3104rif, which has a transposon, Tn10, on the plasmid, R388, by means of a protonmotive force when NADH was added as an energy source. The tetracycline accumulation was reduced to about one-half the full value on the addition of a cation/proton-exchange ionophore, nigericin. In contrast, remarkable stimulation of the tetracycline accumulation was observed with a K+-specific ionophore, valinomycin. The accumulation of [3H]tetracycline could also be driven by an artificially imposed interior-acidic pH gradient (delta pH), but not, however, by an artificially imposed interior-positive membrane potential (delta psi). These results strongly indicate that the plasmid-encoded tetracycline transport was mainly due to an electrically neutral proton/tetracycline antiport system.

Biological Transport↗
PubMed1985

Difference in pathway of Escherichia coli outer membrane permeation between penicillins and cephalosporins.

The differences in the outer membrane permeation between two major subgroups of beta-lactam antibiotics were studied. The permeation of cephalosporins was closely related to porin channels in the outer membrane. In contrast, the outer membrane permeation of penicillins did not decrease in porin-deficient mutants and, in Rd-type mutants, their permeability became proportional to the hydrophobicity of the molecules. The activation enthalpy of the penicillin permeation was significantly larger than that of cephalosporins. These observations indicate that penicillins can use the hydrophobic region for the major route of outer membrane passage whereas the cephalosporin permeation is restricted to the pathway via the porin pore.

Ampicillin↗
PubMed1985

Effect of cetiedil on platelet aggregation and thromboxane synthesis.

Cetiedil was found to inhibit platelet aggregation and thromboxane synthesis induced by thrombin and arachidonic acid. When platelets were activated by thrombin, half maximal inhibition (ED50 effective dose of cetiedil necessary for 50% inhibition) for platelet aggregation was 100 microM while that for thromboxane B2 (TXB2) production was 50 microM. When arachidonic acid was used, the ED50 for platelet aggregation was 100 microM while that for TXB2 production was 150 microM. The presence of calcium ions did not affect on the inhibitory effects of cetiedil. The cAMP level in platelets did not increase after incubation with cetiedil. Cetiedil appears to inhibit the activation of platelets related to thromboxane synthesis.

Antisickling Agents↗
PubMed1985

Uptake of horseradish peroxidase by bone cells during endochondral bone development.

To investigate the mechanisms whereby bone cells absorb organic bone-matrix components during endochondral bone development, rat humeri were examined, employing horseradish peroxidase as a soluble protein tracer. Intravenously-injected peroxidase filled the osteoid layer and penetrated into the osteocyte lacunae and canaliculi, but did not enter the mineralized bone matrix. Whereas osteocytes rarely took up exogenous peroxidase, osteoblasts and osteoclasts actively endocytosed peroxidase in pinocytotic coated vesicles, tubular structures, and vacuoles. They also formed endocytotic vacuoles containing peroxidase in the Golgi area. The Golgi apparatus and dense bodies of these bone cells were, however, free of reaction products. Osteoclast ruffled borders were responsible for peroxidase absorption. In the osteoblast, osteocyte and osteoclast, endogenous peroxidatic reaction was detected only in mitochondria and not in other membrane-bounded vesicles and bodies. These results strongly suggest that both osteoblasts and osteoclasts participate in the resorption of bone-matrix organic components during bone remodelling.

Animals↗
PubMed1985

1 alpha,25-dihydroxyvitamin D3 receptors and their action in embryonic chick chondrocytes.

The role of vitamin D in the maturation of epiphyseal chondrocytes was investigated in the developing chick embryo. Cartilage tissues were divided into two parts: resting cartilage and growth cartilage. A cytosol component to which 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) is specifically bound first appeared in the growth cartilage on day 15, rapidly increased, and attained a maximum on day 19. The calcium content of the growth cartilage also began to increase on day 15 and continued to increase in parallel with the 1 alpha,25(OH)2D3 receptor levels. Glycosaminoglycan (GAG) synthesis by the growth cartilage cells increased from day 11-17 and rapidly declined thereafter reciprocally with the increase in calcium and receptor levels. In the resting cartilage, no cytosol receptor for 1 alpha,25(OH)2D3 was detected up to hatching time. The calcium content and GAG synthesis in the resting cartilage were very low and did not change appreciably throughout development. No receptor-like macromolecule for 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) was recognized in either the resting or growth cartilage. 1 alpha,25(OH)2D3 added to the culture of chondrocytes from the epiphyseal growth cartilage inhibited GAG synthesis and stimulated its release from the cell layer into the medium in a dose-dependent manner. These in vitro effects of 1 alpha,25(OH)2D3 were not observed in chondrocytes obtained from 13-day-old growth cartilage and 19-day-old resting cartilage. 25-Hydroxyvitamin D3 and 24R,25(OH)2D3 had no effect on chondrocytes in any of the preparations. These results suggest that 1 alpha, 25 (OH)2D3 is directly involved in the maturation of chondrocytes and possibly in the calcification of growth cartilage.

Animals↗
PubMed1985

Intrasinusal pyelocalicotomy with lower pole nephrotomy for removal of renal stones.

A small renal sinus often limits exposure of the intrarenal pelvis and restrains the sinus approach for removal of renal stones. For 14 such cases, we used a lower pole nephrotomy combined with extended pyelolithotomy. Incision of the renal parenchyma through the intersegmental avascular plane greatly facilitated exposure of the intrarenal collecting system and enabled stone removal through the longitudinal incision of the collecting system. The indication for operative technique and results of the procedure are described.

Humans↗
PubMed1985

Carcinosarcoma of the prostate.

The present report describes a rare prostatic tumor occurring in a 78-year-old Japanese male. The histological features were those of carcinosarcoma involving an adenocarcinoma and a chondrosarcoma, with metastasis to the liver. The carcinomatous component stained positively for prostatic acid phosphatase (PAP) by an immunoperoxidase technique. The literature is reviewed.

Adenocarcinoma↗
PubMed1985

Effect of hypophysectomy on cyclic 3',5'-nucleotidemetabolizing enzymes in the rat thyroid gland.

Adenylate cyclase and cyclic AMP phosphodiesterase activities in the thyroid gland were significantly reduced after hypophysectomy, followed by a gradual restoration of the enzyme activities to the levels seen in sham-operated rats whereas a slight and persistent reduction was evident in guanylate cyclase and cyclic GMP phosphodiesterase activities in the same tissue. These changes in enzyme activities were restored by TSH administration but not by ACTH. The recovery of activity produced by TSH administration was inhibited by cycloheximide. Hypophysectomy, or TSH and cycloheximide administration, did not produce any significant changes in the concentrations of calmodulin, suggesting that the alteration of these enzyme activities is not induced by a decrease in the concentration of calmodulin. Since forskolin activation of adenylate cyclase did not restore the reduced activity in the hypophysectomized rat thyroid to the level found in the sham-operated control rat thyroid, we conclude that there is a reduction of the amount of enzyme after hypophysectomy rather than a change of the active site on adenylate cyclase. The spontaneous restoration of adenylate cyclase and cyclic AMP phosphodiesterase activities after hypophysectomy implies that cyclic AMP-metabolizing enzymes are responsive to an autoregulatory mechanism in thyroid follicular cells.

3',5'-Cyclic-AMP Phosphodiesterases↗