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Z C Zhang

Publications and source records attributed to Z C Zhang.

25 records · Page 2Linked to original sources
PubMed1988

Vasopressin, phorbol diesters and serum elicit choline glycerophospholipid hydrolysis and diacylglycerol formation in nontransformed cells: transformed derivatives do not respond.

REF52, a rat embryo cell line, and several transformed derivatives were used to examine the lipid-related events associated with agonist treatment (phorbol diesters, vasopressin, fetal bovine serum). Exposure of cells, prelabeled with [3H]glycerol, to TPA (12-O-tetradecanoylphorbol 13-acetate) resulted in 3-4-fold increase in the amount of intracellular diacyl[3H]glycerols as early as 10 min after treatment. Continued incubation (up to 60 min) revealed that the diacyl[3H]glycerol formed was under dynamic metabolic regulation as shown by the production of triacyl[3H]glycerols and free [3H]glycerol. Serum and vasopressin likewise induced the generation of intracellular diacyl[3H]glycerol, thereby illustrating that physiological agents provoke a similar reaction. In the three SV-40-transformed variants examined, the diacylglycerol generative-response to TPA, serum and vasopressin, was greatly diminished or totally absent. Experiments employing REF52 cells prelabeled with [3H]choline demonstrated that both TPA and vasopressin induce the hydrolysis of cellular choline-containing glycerophospholipids; this was measured by both a decrease in cell-associated phosphatidylcholine radioactivity and an increase in the production of water-soluble [3H]choline-containing metabolites in the culture medium. 92-97% of the tritium released to the medium was identified as [3H]choline. Vasopressin treatment of REF52 cells prelabeled with [3H]arachidonic acid elicited an increase of more than 11-fold in the amount of cellular diacyl[3H]glycerol and a concomitant release of arachidonic acid to the culture medium that was 12-fold higher than controls. These data demonstrate that tumor-promoting phorbol esters (agonists of protein kinase C), serum and vasopressin, increase the levels of cellular diacylglycerol by stimulating the hydrolysis of choline-containing glycerophospholipids. This agonist-directed mechanism is inoperable in transformed cells. Further, collateral with vasopressin-induced phosphatidylcholine hydrolysis, the cellular release of arachidonic acid occurs. The participation of these lipid-related responses in the signaling of agonist-directed events and their relation to cellular homeostasis is currently being explored.

Animals↗
PubMed1988

[Pathologic study and prognostic factors in 28 patients with ovarian immature teratoma].

28 patients with ovarian immature teratoma were studied pathologically. Neoplasms with other germ cell elements were excluded. The ages ranged from 11 to 38. 71% were women under 25 years. Each primary tumor and metastatic lesion was graded histologically according to the criteria of Norris. Of these 28 cases, 11 were grade I; 11 grade II; and 6 grade III. The study showed that the stage of primary tumor is closely related to the prognosis. The likelihood of recurrence and metastasis could be determined by the grade of the primary tumor. The recurrence rate of grade I, II, and III were 0%, 44% and 100%, respectively. It also showed that the addition of hysterectomy and contralateral adnexectomy for grades II and III lesions did not improve the survival. One patient had been operated for 3 times to remove recurrences in the abdominal cavity and liver in a period of 25 months. The first and second recurrent tumors were grade III, but the third one was grade II showing that the immature teratoma tends to mature, but this conversion needs time. The authors support the opinion that repeated operations to remove the recurrences may improve the survival.

Adolescent↗
PubMed1987

Modification of serum, pancreatic, and microbial lipase activities by phorbol diesters.

The influence of phorbol diesters on the in vitro hydrolysis of diacylglycerols was examined using enzymes from rat serum, porcine pancreas, and Rhizopus delemar. Two main phenomena were observed: 12-O-tetradecanoylphorbol-13-acetate (TPA), when added to the enzyme assay system, stimulated 2- to 3-fold the hydrolysis of [9,10-3H]dioleoylglycerol by serum lipase. The hydrolysis of dioleoylglycerol by either pancreatic or R. delemar lipase was, on the other hand, inhibited by TPA. A 50% inhibition of the pancreatic and R. delemar enzymes was attained with 10 and 2.0 microM TPA, respectively. The pattern of enzyme stimulation (rat serum), with regard to increasing TPA concentrations, was hyperbolic. Stimulation was not influenced by Triton X-100, but it was highly dependent on the structure of the phorbol ester: TPA greater than phorbol didecanoate greater than tetradecanoylphorbol. Phorbol dibutyrate, phorbol acetate, myristic acid, and mezerein were without influence. Lipase activity was inhibited most strongly by TPA and the nonpromoter 4-O-methyl-TPA; the weaker promoter, phorbol dibutyrate, was relatively inactive. The inhibition of R. delemar lipase by TPA was reversible. Collectively, these data show that phorbol diesters can interact with enzymes other than protein kinase C. It is believed, by virtue of their structural similarity to diacylglycerols, that phorbol diesters may serve directly as intracellular regulators of lipid metabolism. In such a manner phorbol esters could sustain or attenuate the second messenger signal by modifying diacylglycerol metabolism, a manifestation of the pleiotropic action.

Animals↗