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Biomedical subjects

C C Chen

Publications and source records attributed to C C Chen.

At least 703 records · Page 39Linked to original sources
PubMed1979

Regeneration of human liver after hepatic lobectomy studied by repeated liver scanning and repeated needle biopsy.

Regeneration of the residual lobe of the liver after hepatic lobectomy in humans was studied by repeated liver scanning in seven noncirrhotic and three cirrhotic patients. Each patient was studied for several months during the study which lasted from 1-12 years. Regeneration was apparent in noncirrhotic liver remnants following hepatic lobectomy. In the case of a long standing, space occupying lesions such as benign giant cysts, the liver remnant would complete its regeneration process rather early, usually within a few months of hepatic lobectomy. In hepatoma cases, however, regeneration of the residual lobe after hepatic resection usually took five or six months for completion. On the contrary, no definite increase in the size of the liver remnant was seen on repeated liver scanning in cirrhotic patients. Histologic study of the residual lobe was repeated on needle biopsy specimens in two noncirrhotic and four cirrhotic patients. Regenerative hyperplasia of liver cells with large hyperchromatic, or double nuclei never seen in the preresection liver appeared in the liver remnant five, 11, and 27 days after hepatic lobectomy in noncirrhotic patients. In cirrhotics, however, there were no histologic changes between the preresection liver and the postresection remnant studied three, five, 15, 40 days or even two years and 8 months after hepatic lobectomy.

Biopsy, Needle↗
PubMed1978

Evidence for lack of phosphatidic acid and phospholipase D activity in milk.

Phosphatidic acid could not be demonstrated when milk was assayed for phospholipase D activity even when lecithin was added. The concentration of "free" choline in milk remained the same before and after addition of lecithin. However, phosphatidic acid and an increased concentration of "free" choline were demonstrated when cabbage phospholipase D was added to raw milk. The concentration of phosphatidic acid and "free" choline in milk increased appreciably when both lecithin and cabbage phospholipase D were added to raw milk. Phospholipase D activity in milk was assayed at 23.5 C, pH 5.6, in the presence of 10% vol/vol of diethyl ether and .015M calcium chloride. "Free" choline was determined by adjusting the acid whey from milk to pH 11 and adding a freshly prepared 3% methanolic solution of ammonium reineckate. The precipitated choline reineckate was washed, dissolved in acetone, and its absorbance measured at 520 nm. The absence or presence of phosphatidic acid was shown by thin-layer chromatography. These results refute a previous report which proposed that both phosphatidic acid and phospholipase D were in milk.

Animals↗
PubMed1978

Comparison of thioredoxin reductases from Novikoff ascites hepatoma cells and normal liver of rats.

Adult rat liver contained variant forms of thioredoxin reductase with isoelectric points at pH 4.9 and at approximately pH 4.7 compared to pH 5.1 for the enzyme from Novikoff ascites hepatoma. Fetal and regenerating liver contained only the form with the isoelectric point at pH 4.9. All three enzymes precipitated with and were inhibited by a rabbit antibody to purified enzyme from Novikoff tumor.

Animals↗
PubMed1977

Phosphorylation of nuclear proteins in rat regenerating liver.

In studies of the phosphorylated proteins in rat liver and Walker-256, it was established that the ratio of various fractions of P-N linkages to P-O linkages varies from 0.6 to 3.1. In rat regenerating liver nuclei, the ratio of P-N and P-O varies with time after partial hepatectomy. Using [3H]-lysine and 32Pi, it is shown that phosphoryllysine forms in some new and, presumably, some preexisting H1 molecules. Using [3H]histidine and 32Pi, it is shown that phosphohistidine forms exclusively in preexisting H4. The half-life of H4 phosphohistidine appears to be about 2 h.

Animals↗
PubMed1977

In vitro development of plants from microspores of rice.

Rice (Oryza sativa L., 2n=24) anthers containing microspores in the early-uninucleate to first-mitosis stages were induced successfully to develop into plants in vitro through an intermediary step of callus formation. Callus initiation occurred with highest frequency in anthers containing mid-uninucleate imcrospores. The callus derived from different stages of microspore development differed in the potential to differentiate into plants. The plants regenerated from pollen callus were predominantly haploid or diploid; polyploid and aneuploid plants were relatively infrequent. The first division of the uninucleate microspores was asymmetrical, resulting in the formation of large vegetative and small generative nuclei. The vegetative nucleus divided repeatedly and assumed the major role in the formation of callus, whereas the generative nucleus degenerated rapidly. Simultaneous division of the two nuclei was observed in a few pollen grains. Nuclear fusion during the very initial stages of pollen development was postulated to account for the occurrence of the diploid and polyploid plants.

Cell Differentiation↗
PubMed1977

Purification of thioredoxin reductase from the Novikoff rat tumor.

Thioredoxin reductase (E.C.1.6.4.5.) has been purified to about 95% homogeneity from the Novikoff ascites rat tumor. The enzyme contained two subunits of approximately 58,000 daltons, with one FAD per subunit. The amino acid analysis is reported. An immunoadsorbent was prepared and used for affinity chromatography in order to improve the yield of the enzyme.

Amino Acids↗