摘要:

Pancreatic enzyme secretion in rats has been shown to be stimulated differentially by the intestinal hormones secretin and cholecystokinin. Since it is unknown if activation of neural mechanisms have similar effects, it was the aim of the present study to examine in anesthetized rats the output of the pancreatic enzymes amylase, lipase, trypsin, and chymotrypsin before (15 min), during, and after (30 min each) vagal stimulation (5 ms, 10 V) with different frequencies (0.5, 5, 10, and 50 Hz). At 5 Hz, a maximal stimulation of all four enzymes was observed, with a peak towards the end of the vagal stimulation period. At 0.5 Hz, amylase, trypsin, and chymotrypsin were released not only in smaller quantities but also in a different time pattern (trypsin and chymotrypsin), with a maximum early during vagal stimulation. Lipase secretion remained unchanged at 0.5 Hz. At 10 Hz, the output of amylase, lipase, and trypsin was quantitatively less compared to 5 Hz. In contrast to stimulation at 0.5 and 5 Hz, the maximal enzyme output was reached after cessation of vagal stimulation (amylase and lipase). Chymotrypsin release did not change in response to vagal stimulation at 10 Hz. A frequency of 50 Hz had no influence on the secretion of any of the four enzymes determined. These data demonstrate that activation of the vagus nerves can lead to a differential release of pancreatic enzymes. The exact regulatory mechanisms of action are as yet unknown and remain to be determined.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Current evidence suggests that carbonic anhydrase II (CA II) is produced by pancreatic duct cells but not by pancreatic acinar or islet cells. The aim of this study was to determine whether CA II homologous RNA and CA I1 immunoreactive protein are produced by cell lines established from human pancreatic adenocarcinomas. A 1.7-Kb CA II homologous RNA was detected in poly(A+) RNA isolated from normal human pancreas, normal human liver, and to varying degrees in the cell lines examined. The CA II immunoreactivity corresponding to approximately 30 kD (consistent with the established molecular mass of CA II) was also detected by immunoblotting in normal human pancreas, normal human liver, and some of the cell lines. We also found that the levels of CA II homologous RNA increase in the pancreatic adenocarcinoma cell lines following treatment with the differentiating agent, retinoic acid.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Serum androstenedione and testosterone levels were measured in 39 male patients with pancreatic cancer, and compared with the values obtained from 37 male patients with chronic pancreatitis or benign obstructive jaundice, and with those from 36 male patients with other gastrointestinal malignancies. Mean androstenedione values were significantly higher in the pancreatic cancer patients when compared to both control groups, and mean testosterone levels were significantly lower. The testosterone/androstenedione ratio was calculated and was also found to be significantly lower in the patients with pancreatic cancer. There was no difference in this ratio or in the androstenedione or testosterone levels when comparing both control groups. In two patients with stage I pancreatic cancer, serum androstenedione and testosterone levels were significantly altered, and returned to normal values after successful resection. These results confirm previous findings indicating that there is signifcant derangement in the androgen profile of patients with pancreatic cancer.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Serum apolipoprotein A-I measurement was compared in alcoholic patients according to presence or absence of chronic pancreatitis and liver fibrosis. Among alcoholic patients without liver disease, apolipoprotein A-I was significantly lower in patients with chronic pancreatitis (157 ± 70 mg/dl) than in patients without pancreatitis (209 ± 74 mg/dl, p < 0.001). In cirrhotic patients, apolipoprotein A-I was lower in patients with chronic pancreatitis (82 ± 35 mg/dl) than in patients without pancreatitis (102 ± 45 mg/dl), but this difference was not significant. The decrease of serum apolipoprotein A-I was independent of nutritional parameters whether or not there was cirrhosis. Immunohistochemical study of pancreatic samples with chronic pancreatitis showed that apolipoprotein A-I was located in the pancreatic fibrosis whereas lobules were unstained. This study suggests that apolipoprotein A-I is trapped by the pancreatic extracellular matrix and that this sequestration might explain, in part, the decrease of the serum apolipoprotein A-I.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The aim of this study was to compare the diameter of the main pancreatic duct measured by ultrasonography (US) and endoscopic pancreatography (ERCP) in cases of chronic pancreatitis and to evaluate the ability of US to gauge the dilation of the main duct accurately enough to do a side-to-side wirsungo-jejunostomy. Sixty-one measurements were recorded in 50 patients (47 men and 3 women; age: 43.7 ± 10 years). In 11 cases, two measurements were made at an interval of more than one year. US always preceded ERCP. The measurements were compared in only 43 cases (71%), because evaluation by US was inaccurate in 14 cases (23%) and by ERCP in nine cases (15%). The mean value of the diameter measured by US was 4.30 ± 3.01 mm, and by ERCP, 5.52 ± 3.08 mm (mean t SD). When the diameter assessed by US (y) was ⩾ 3 mm, the diameter assessed by ERCP (x) was always ⩾4 mm. The value of x could be determined from y by the equation:x = y + 1.2 mm (r = 0.91, p < 0.05)The difference between x and y was constant and did not depend on the size of the duct. It could be owing to the hyperechogenicity of the duct walls. We conclude that US is a reliable way to assess the dilation of the main pancreatic duct and might be an acceptable method of judging whether a side-to-side wirsungo-jejunostomy can be performed.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Prolonged, continuous exposure of the islets of Langerhans to highglucose concentrations results in desensitization of the beta cell to glucosestimulation. This study tested the ability of a sulphonylurea to stimulate insulinsecretion in this setting. Normal isolated rat islets were cultured for 18–20 h inRPMI-1640 with 300 mg/dl glucose to induce desensitization or with 100 mg/dl as a control. Islets were then placed into a perifusion system and perifused with 60 mg/dl glucose followed by a stimulus. After preincubation at 300 mg/dl, asignificant 50% suppression of glucose-induced insulin secretion compared with secretion in the control group preincubated at 100 mg/dl glucose was observed (p < 0.025–0.001). This confirmed the occurrence of desensitizationto glucose in this in vitro model. In contrast, stimulation of insulin secretion by glyburide (500 ng/ml) was unaffected compared with control. We also tested whether glyburide corrects the defective response to glucose stimulation inglucose-desensitized islets. Control islets (preincubated at 100 mg/dl) were stimulated with 300 mg/dl glucose or with this glucose concentration plus glyburide. Peak incremental insulin responses were similar (0.81 ± 0.07 and 0.77± 0.12 μU/ml.islet). After preincubation at 300 mg/dl, perifusion with 300mg/dl glucose alone or with glyburide was associated with smaller, but similar, peak insulin responses (0.53 ± 0.13 and 0.62 ± 0.06 μU/ml.islet). In conclusion, islets in which the insulin-secretory response is compromised by desensitization to glucose are nevertheless completely responsive to the direct stimulatory effects of a sulphonylurea. However, the sulphonylurea does not correct the defect in glucose-induced insulin secretion.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This study describes the sequential morphological changes in pancreaticislets from 1-, 6-, and 18-month-old male eSS rats, as compared to aged-matched control animals. Spontaneous diabetes mellitus was confirmed in 6- and 18-month-old eSS rats after an oral glucose tolerance test. Lightmicroscopic immunocytochemical and morphometric techniques were used to study islet-cell populations. The pancreas was normal, and the morphometric methods did not reveal significant changes in islets from 1-month-old rats. However, 6-month-old eSS animals showed disruption of islet architecture and fibrosis in the stroma. The volume density (Vvi) of endocrine tissue and the Vvi and percentage of B cells were increased, whereas the Vvi of exocrinetissue and the Vvi and percentage of A cells were diminished. Eighteen month-old eSS rats also exhibited conspicuous islet lesions. Nevertheless, the Vvi of endocrine tissue and the Vvi and percentage of B cells were diminished, while the Vvi of exocrine tissue and the Vvi and percentage of D cells were increased. Our results provide further quantitative evidence for the sequentialmor phological events occurring in the pancreatic islets of a useful animalmodel of diabetes mellitus.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Novel islet cell, duct cell, and acinar cell markers have been identified by monoclonal autoantibodies (Maab) derived from prediabetic BB rats. Spleen cells from two rats that both developed diabetes after splenectomy were fused with mouse myeloma cells. A cellular immunoradiometric assay for differential reactivity toward the surface of two closely related, insulin- and noninsulin-producing rat islet tumor cell lines was used to select and clone several IgM-producing hybridomas. The supernatants were finally characterized by two-color immunofluorescence with islet hormone antisera on frozen sections of human, monkey, and rat pancreas. Maab EB52 stained PP cells, but also few A cells on rat pancreas. Maab CA812 identified a subpopulation of islet D cellson rat, human, and monkey pancreas. Although the CA81 Zreactive antigen and somatostatin were coexpressed in most D cells in adult rat pancreas, only a few islet D cells were stained in the newborn pancreas. The CA812-reactiveantigen was not detected in somatostatin-producing cells in the duct epithelium. Maab H37 and IF5 selectively stained acinar cells in rat, human, and monkey pancreas, whereas Maab DA39 identified the rat ductal epithelium including the scattered endocrine cells of the ducts. In summary, B lymphocytes producing autoantibodies to pancreatic endocrine, exocrine, and ductal markers are present in prediabetic BB rats and can be detected by use of transformed pluripotent islet cells as target. Such B lymphocytes can be immortalizedto produce monoclonal antibodies to study their role in insulin dependent diabetes mellitus pathogenesis and to clarify the development of the pancreas.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Northern blot hybridization established that metallothionein (MT)mRNA levels were dramatically elevated in the rat pancreas following injection of Cd or Zn salts. To determine which pancreatic cell types express the MT gene, Northern blot hybridization analysis of RNA from preparations enriched for acini, in situ hybridization, and immunocytochemistry were used. RNA from pancreatic acini of Zn-treated rats contained high levels of MT mRNA. In control rats, in situ hybridization suggested very low levels of MT mRNA in both exocrine and endocrine cells in the pancreas, but these levels were dramatically increased in both these cell populations following metal injection. In contrast, levels of insulin-I mRNA in the endocrine cells were not affected by metal injection. A similar result with MT mRNA was obtained in mouse and chicken pancreas using Northern blot and in situ hybridization. Immunocyto chemistry detected MT in the rat acinar cell cytoplasm following metal injection. Although inconsistent with in situ hybridization studies and immunocytochemical analysis of exocrine cells, immunocytochemistry for MT indicated a uniform staining pattern of islet cells that was unaffected by metal treatment. These results establish that metal ion induction of the MT genes in pancreasoccurs in both endocrine and exocrine cells, which suggests that this proteinhas diverse physiologic functions in this organ.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Geranyl-geranyl acetone (GGA), a new acyclic polyisoprenoid, anti-ulcer drug appears to exert its beneficial effect by stimulating bicarbonate secretion from the stomach and pancreas. Its efficacy in Stimulating pancreatic bicarbonate is particularly striking, and this study was designed to examine the mechanism for this action. Since it is structurally similar to the side chain of the prostaglandin molecule, its ability to stimulate bicarbonate secretion could be a direct one. On the other hand, the magnitude of pancreatic bicarbonate response (about 50% of maximal response to secretin) suggests it might act by releasing secretin. Two types of experiments were performed in dogs with pancreatic fistulas: first, secretagogue interactions were examined by studying the effect of intraduodenal GGA (8 mg/kg) or its carrier (control) on the dose response curves to exogenous secretin and cholecystokinin octapeptide (CCK-8); second, the effect of graded doses of intraduodenal GGA on pancreatic bicarbonate and plasma secretin-like immunoreactivity (SLI) responses was tested directly. Pancreatic bicarbonate responses (micromoles per 30 min) were to secretin doses of 32, 125, and 500 ng/kg/h. Without and with GGA, responses were 74 ± 27, 952 ± 215, and 2,000 ± 425 and 599 ± 110, 1,624 ± 472, and 2,129 ± 398 ng/kg/h, respectively. Similarly, the bicarbonate responses to CCK-8 were augmented. Basal plasma SLI was 1.5*0.6 pM/ml. Peak plasma SLI in response to 2, 4, and 8 mg of GGA intraduodenally were6.8 ± 0.7, 8.9 ± 3.1, and 19.6 ± 2.7 pM/ml, respectively. It is concluded that GGA is a potent stimulant of pancreatic bicarbonate secretion, and this action appears to be mediated by the release of duodenal secretin.

ISSN:0885-3177    

出版商:OVID    

年代:1990

数据来源: OVID