ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

By pulse and chase experiments with [3H]leucine we have followed the time-course packaging of newly synthesized amylase in the zymogen granules of pig pancreas in vivo. In parallel, with a second group of pigs, we have followed the time-course release of newly synthesized amylase. The ratios of specific radioactivities of amylase in the zymogen granule over that of the homogenate indicated that substantial amounts of newly synthesized amylase had already reached the zymogen granule compartment at 50-min post-pulse. Specific radioactivity increased up to 180 min, then a plateau was obtained. In the juice with the other group of pigs, starting at 40 min postpulse, amylase specific radioactivity increased up to about 100 min, then slowly decreased in the next hours. These results show an asynchronism between packaging of newly synthesized amylase in the zymogen granule compartment and its release in the juice under resting conditions, supporting the concept of a partial bypass of the zymogen granule compartment.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The fluorescence and secretory response of calcium-chlorotetracycline were simultaneously and continuously measured in isolated perfused rat pancreata. Continuous vascular perfusion with 10 μM chlorotetracycline increased the fluorescence intensity exponentially. Continuous stimulation with higher nonphysiological doses of CCK (20 mU/ml) or ACh (10−6M induced (a) a gradual decrease in the Cacholorotetracycline fluorescence which increased to control after cessation of the stimulation, and (b) secretory response, consisting of an initial rapid ascent followed by a decline. On the other hand, continuous stimulation with a lower concentration of CCK (5 mUim1) or ACh (5 × 10−8M), which seems to be rather physiological, did not change the time course of the Ca-chlorotetracycline fluorescence increase, but it evoked a definite secretory response, consisting of an initial rapid ascent to a maximum followed by a descent to a sustained plateau. In a Ca2+-deficient environment, stimulation with 5 mU CCK/ml evoked only a small secretory response and a gradual insignificant decrease in the Ca-chlorotetracycline fluorescence. The present results may support the view that continuous stimulation with secretagogues at physiological concentrations does not cause dissociation of stored Ca2+from intracellular sites but does initiate secretion probably via the rise in [Ca2+], induced by the influx of extracellular Ca2+.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The current study examines the effects of somatocrinin (GRF) and somatostatin antiserum (ASS) alone and in combination on pancreatic growth. Twenty-four-day-old rats were injected daily S.C. at 10:00 and 16:30 h for 14 days with either saline or GRF (4 and 20 μg*kg−1). ASS was given i.p. every other day. Pancreatic weights and DNA, RNA, protein, amylase, and chymotrypsin total contents and concentrations were evaluated at the end of treatment. GRF alone was associated with significant decreases in pancreatic weight and contents of protein, amylase, and chymotrypsin but with significant increases in total DNA content indicating pancreatic atrophy and hyperplasia. ASS alone has a slight effect on DNA content but potentiates GRF given at the dose of 4 pg. kg-−1. Even though ASS reduced protein and enzyme contents, it prevented the large decreases observed with increasing doses of GRF. These data present for the first time effects of GRF and ASS on pancreatic growth and describe a strong interaction between the two products. It is yet too early to determine how these two substances work on the pancreatic acinar cells, but hypotheses on their possible mode of action are proposed.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Serum zinc levels were measured in sheep before and after total pancreatectomy, pancreatic duct ligation, alloxan treatment, and pancreatic biopsy. Values were elevated after each procedure, but only total pancreatectomy and pancreatic duct ligation caused a significant increase (t = 3.5, p <0.05; t = 2.8, p <0.05, respectively). These effects were not due to changes in serum proteins. The results are consistent with a model in which the pancreas removes zinc from blood and subsequently eliminates it via the pancreatic duct. Facilitation of intestinal absorption of zinc by pancreatic products and effects of insulin on serum zinc are less significant.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Minced neonatal pancreatic tissue from 3–6 canine littermates was placed in the peritoneal cavity of five alloxan diabetic dogs without separation of endocrine and exocrine tissue. Fasting blood glucose levels declined from a preimplant level of 211 ± 57 mg/dl to 111 ± 6 mg/dl. The maximum blood glucose following a glucose challenge declined from 387 ± 26 mg/dl to 175 ± 37 mg/dl. These levels were slightly higher than the 92 ± 6 mg/dl fasting and 140 ± 34 mg/dl maximum obtained in control dogs. Insulin levels before implant ranged from 6 to 11 μU/ml and showed no response to a glucose challenge. Insulin responses to a glucose challenge after implant were variable. Three of the dogs showed some hyperinsulinemia without hypoglycemia. Another dog showed a delayed insulin response of normal magnitude. Improvement in glucose tolerance lasted for 2–6 weeks. These results indicate that neonatal tissue can survive and function within the peritoneal cavity. It was not necessary to obtain isolated islets to achieve hormone secretion. However, additional purification may be needed to decrease the side effects of acinar enzymes.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Pancreatic insufficiency was induced in rats by a single injection of 50 μl oleic acid into the pancreatic duct over a period of 3 min. Exocrine tissue was destroyed within 3–6 days, and after 6 weeks the remaining pancreas equaled 2.7% of the original organ. The rats showed retardation of body weight in spite of normal food intake. After 7 weeks the fecal weight increased by 23%, and the fecal chymotrypsin activity decreased by 90% compared to controls. At this time plasma cholecystokinin (CCK) concentrations were significantly elevated. The amylase content in the remaining pancreas was reduced by 99%, and trypsin content was reduced by 93%. Unstimulated protein discharge from the remnant pancreas in vitro was threefold higher compared to secretion from control tissue. Thus a simple, reproducible model for inducing persistent pancreatic insufficiency was developed. To compensate for the loss of exocrine tissue, the remaining acinar cells adapt by a CCK-mediated increase in protein secretion.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Acinar cells were isolated by enzymatic digestion from normal pancreas and from azaserine-induced atypical acinar cell nodules and a transplant-able acinar cell carcinoma. Normal acinar cells were predominately binuclear, with abundant cytoplasm. They were 10–24 pm in diameter, with a size distribution skewed toward smaller sizes but with a peak at 18 μm. Cells were isolated from 41 enucleated nodules varying in weight from 1.1 to 200 mg. These cells were predominantly mononuclear, with a more uniform size than normal cells and a peak at 9 pm diameter. Cells from all nodules studied were grossly similar, and there was no relation between nodule size and the degree of mononucleation. Cells from the transplantable tumor were small, with little cytoplasm, and were almost exclusively mononuclear. The extent of binucleation in normal and microscopic atypical acinar cell nodules was also studied in sections from the pancreas of rats injected with azaserine 4 months before killing. Nuclear and cell counts in these sections confirmed that binucleation is more frequent in normal than in nodule tissue. These studies emphasize the high degree of binucleation found in normal pancreatic acinar cells. They demonstrate the feasibility of using cell separation techniques to obtain preparations of acinar cells from normal and neoplastic pancreatic tissue for studies of functional and morphological differences in these cells.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effects of epidermal growth factor (EGF) and somatostatin-14 (SS) on growth of Mia PaCa-2 cells in cell culture were examined. EGF had no effect on cell growth in sera containing media but significantly increased growth in sera-free media. The effect of EGF was complete within 18 h. SS added with EGF entirely eliminated the growth stimulation of EGF. SS added to cells in culture with sera inhibited their growth as well.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Pancreatic adenocarcinoma presents a clinical and experimental challenge because of its relative resistance to conventional modes of therapy. The present study explores a novel, biologically based approach to enhancing its chemosensitivity and to overcoming its chemoresistance in a panel of pancreatic adenocarcinoma cell lines (two human lines: PANC-1 and COLO-357; and two hamster lines: WD PaCa and PD PaCa). Difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase (ODC) that produces antiproliferative effects by polyamine depletion, was combined with the cyto-toxic agent doxorubicin (DOX) in vitro. The inhibitory effects of DFMO were cytostatic and roughly additive to those of DOX. Although the response to the combination varied as a function of the cell lines studied and the response to DFMO as a single agent, all cell lines studied showed some increased inhibition with the combination. The most striking enhancement was seen in our most DOX-resistant cell line, WD PaCa, and also in PANC-1, a relatively sensitive cell line. Thus, the combination of DFMO and DOX shows promise as an experimental approach to the problem of drug resistance and the limited chemosensitivity of pancreatic cancer.

ISSN:0885-3177    

出版商:OVID    

年代:1986

数据来源: OVID