Ionophore A23187 can mimick the changes in membrane permeability that occur during acetylcholine-stimulation of pancreatic acinar secretion

Acetylcholine (ACh) released from vagal terminals increases the permeability of the pancreatic acinar membrane to Na⁺ and Ca²⁺ ions. In this report, we compare the induced changes in intracellular Na⁺ and Ca²⁺ electrode potentials (E_Na and E_Ca) due to ACh-stimulation of acini with those observed during stimulation with the calcium ionophore, A23187, which mimicks the action of ACh on pancreatic secretion. Stimulation with ACh concentrations varying from 10^–8 to 10^–5 M and with A23187 concentrations of 10^–6 and 10^–5 M caused parallel increases in cytosolic Ca²⁺ and Na⁺ ([Ca]_i, [Na]_i). The magnitude of the increases in [Ca]_i and [Na]_i due to A23187-stimulation further indicate that when presented with a calcium challenge the acinar cells continue to regulate [Ca]_i close to physiological levels and suggest that the observed increases in ionized calcium could reflect much larger increases in complexed Ca²⁺. ACh-stimulation following removal of either extracellular Na⁺ or Ca²⁺ ions, eliminated the intracellular increases found when the removed ions is present, but did not affect the increases usually found with the other ion. The independence of the permeability changes to either the presence of Ca²⁺ or Na⁺ indicates the ACh-induced currents carried by Na⁺ and Ca²⁺ are also independent. The selective translocation of Na⁺ and Ca²⁺ during acetylcholine-stimulation in a manner analogous to the changes observed when ionophore A23187 was used as stimulus, indicates the ability of the activated acinar membrane to function as an ionophore.     

Investigating Population Risk Factors of Pancreatic Cancer by Evaluation of Optical Markers in the Duodenal Mucosa

Pancreatic cancer screening has been hampered by the high rate of complications associated with interrogating the pancreas. The closest non-invasively accessible mucosa available for pancreatic cancer screening is the periampullary duodenal tissue. Our earlier report has shown the potential of using optical markers to interrogate this tissue for the presence of pancreatic cancer. In this study, we report a larger data set of low-coherence enhanced backscattering (LEBS) and elastic light scattering fingerprinting (ELF) optical markers from the periampullary duodenal mucosa. Optical measurements from biopsy samples were acquired from a total of 203 patients with varying clinical classification including healthy controls, a family history of pancreatic cancer, pancreatitis, mucinous cystic precursor lesions, pancreatic cancer, and other pancreatic malignancies. Evaluation of the performance of an independent testing set for discriminating healthy control patients from pancreatic cancer patients showed a 95% sensitivity, 71% specificity, and 85% area under the receiver operator characteristic (AUROC) curve. Importantly, this performance was uncompromised for detecting potentially curable stages of the disease. Additionally, optical markers in higher risk populations such as family history and pancreatitis had values between those of healthy control and pancreatic cancer patients, thus allowing for future investigations of screening from these high risk groups.     

肝门阻断和再开放对兔胰腺功能的影响

目的：观察肝门阻断（HVO）及再开放（HVR）后胰腺内外分泌功能的改变。方法：选择健康日本大耳白兔25只，体重2.3-3.0 kg，分别于HVO前、HVO 10、20 min及HVR后（10、30、60、120 min）不同时点取血，并在HVO前、HVO 20 min、HVR后120 min 3个时点取胰腺组织，电镜下观察其超微结构的变化。结果：HVO时，血浆葡萄糖、胰岛素水平及一氧化氮代谢产物（NO₂^-/NO₃^-）含量均明显低于阻断前，胰高血糖素/胰岛素及丙二醛（MDA）浓度显著高于阻断前（P<0.05或P<0.01），并随阻断时间延长而加重；血浆淀粉酶、脂肪酶、游离脂肪酸水平则无明显差异（P>0.05）；胰岛细胞的线粒体肿胀、粗面内质网扩张，细胞核形态、结构基本正常，而胰腺腺泡细胞变化则不明显。HVR后上述差异逐渐不明显，至120min才接近阻断前水平。结论：急性肝门阻断和再开放对胰腺内分泌功能有较大的影响。     

兔急性肾功能衰竭时胰腺形态与功能及自由基、一氧化氮的变化

目的：探讨家兔急性肾功能衰竭（ARF）时胰腺的变化及机制。 方法： 60只家兔均分为4组。ARF模型1组：皮下注射1%HgCl2（1.3 mL/kg）；ARF模型2组：肌肉注射50%甘油（10 mL/kg）；以等量生理盐水代替HgCl2或甘油分别作为对照1、2组。24 h后，经Aeroset型全自动生化分析仪测定血清BUN、Cre及胰淀粉酶（AMY）活性；以放射免疫法检测血清胰岛素（INS）水平；制作胰腺病理切片，观察其组织等变化；制备10%胰匀浆，检测自由基及一氧化氮（NO）水平的变化。 结果： ARF时胰腺细胞有空泡变性、坏死等改变。ARF模型1、2组血清AMY活性均显著高于相应对照组，血清INS水平显著低于相应对照组（P<0.05，P<0.01）；胰匀浆MDA、NO2-/NO3-含量及NOS活性高于对照组，SOD活性低于对照组（P<0.05，P<0.01）。 结论： 兔急性肾功能衰竭时，胰腺可发生形态及功能变化，其机制可能与自由基损伤及NO升高有关。     

Mutagenicity,antioxidant potential,and antimutagenic activity against hydrogen peroxide of cashew (Anacardium occidentale) apple juice and cajuina

Fresh and processed cashew (Anacardium occidentale) apple juice (CAJ) are among the most popular drinks in Brazil. Besides their nutritional benefits, these juices have antibacterial and antitumor potential. The chemical constituents of both the fresh juice and the processed juice (cajuina) were analyzed and characterized as complex mixtures containing high concentrations of vitamin C, various carotenoids, phenolic compounds, and metals. In the present study, these beverages exhibited direct and rat liver S9-mediated mutagenicity in the Salmonella/microsome assay with strains TA97a, TA98, and TA100, which detect frameshifts and base pair substitution. No mutagenicity was observed with strain TA102, which detects oxidative and alkylating mutagens and active forms of oxygen. Both CAJ and cajuina showed antioxidant activity as determined by a total radical-trapping potential assay. To test whether this antioxidant potential might result in antimutagenesis, we used a variation of the Salmonella/microsome assay that included pre-, co-, and posttreatment of hydrogen peroxide-exposed Salmonella typhimurium strain TA102 with the juices. CAJ and cajuina protected strain TA102 against mutation by oxidative damage in co- and posttreatments. The antimutagenic effects during cotreatment with hydrogen peroxide may be due to scavenging free radicals and complexing extracellular mutagenic compounds. The protective effects in posttreatment may be due to stimulation of repair and/or reversion of DNA damage. The results indicate that CAJ and cajuina have mutagenic, radical-trapping, antimutagenic, and comutagenic activity and that these properties can be related to the chemical constituents of the juices.     

Masked excitatory action of noradrenaline on rat islet β-cells via activation of phospholipase C

The effect of noradrenaline (NE) on rat islet -cells was examined. NE reduced insulin secretion from rat islets exposed to extracellular solutions containing glucose at 5.5 or 16.6 mM. In islets treated with pertussis toxin (PTX), however, NE increased insulin secretion. The NE-induced augmentation of insulin secretion was inhibited by prazosin. In intact islets, NE increased phospholipase C (PLC) activity, an effect that was prevented by treatment of islets with U-73122. NE elevated intracellular [Ca²⁺] ([Ca²⁺]_i) in isolated -cells independently of PTX. Although this NE effect was inhibited by prazosin, phenylephrine did not mimic it. The [Ca²⁺]_i response to NE was also prevented by the treatment of cells with U-73122. NE produced depolarization of -cells followed by nifedipine-sensitive action potentials. NE reduced the whole-cell membrane currents through ATP-sensitive K⁺ channels (K_ATP), responsible for the depolarization. This NE effect was prevented by treatment of -cells with U-73122 or BAPTA/AM. Although at least some of our results imply the presence of ₁-adrenoceptors, -cells were not stained by a polyclonal IgG antibody recognizing all adrenergic ₁-receptor subtypes so far identified. These results suggest that an interaction of NE with an unknown type of receptor activates rat islet -cells via a PLC-dependent signal pathway. This effect is, however, masked by the inhibitory action via a PTX-sensitive pathway also activated by NE.     

Changes in element concentrations induced by agonist in pig pancreatic acinar cells

 Changes in electrolytes of pig pancreatic acinar cells following application of gastrin-cholecystokinin (CCK) were investigated using the technique of X-ray microanalysis of hydrated and dehydrated sections of freshly frozen pancreas. After stimulation by CCK (10^–9 M), Na and Cl increased significantly in the cytoplasm [Na, from 10 mmol/kg wet wt. (48 mmol/kg dry wt.) to 19 mmol/kg (95 mmol/kg); Cl, from 22 mmol/kg (105 mmol/kg) to 49 mmol/kg (245 mmol/kg)] as well as in the luminal interspace [Na, from 53 mmol/kg (189 mmol/kg) to 65 mmol/kg (283 mmol/kg); Cl, from 65 mmol/kg (232 mmol/kg) to 102 mmol/kg (443 mmol/kg)]. In the secretory granules Cl increased significantly from 30 mmol/kg (86 mmol/kg) to 67 mmol/kg (203 mmol/kg). K decreased significantly from 120 mmol/kg (571 mmol/kg) to 81 mmol/kg (405 mmol/kg) in the cytoplasm, while both increased from 38 mmol/kg (109 mmol/kg) to 58 mmol/kg (176 mmol/kg) in the granules and from 46 mmol/kg (164 mmol/kg) to 48 mmol/kg (209 mmol/kg) in the luminal interspace. Ca increased significantly in the cytoplasm as well as in the luminal interspace, and decreased significantly in the secretory granules. CCK evoked Ca release from secretory granules in the secretory pole of acinar cells. The values were measured from dehydrated sections, and agreed well with those from hydrated sections. The effect of furosemide, an inhibitor of the Na⁺-K⁺-2Cl^–co-transporter, on the ion transport of acinar cell was studied. When furosemide (10^–5 M) was added to the external solution, the cytoplasmic Cl and Ca concentrations decreased significantly, while there was a little decrease in Na and K concentrations under the secretory condition. These results indicate that Na⁺-K⁺-2Cl^–co-transport, and Na⁺, Cl^–and K⁺ exits into the lumen are involved in the mechanism of ion secretion in pig pancreatic acinar cells. Received: 17 January 1996 / Accepted: 12 March 1996     

Radiation therapy for pancreatic cancer: eleven year experience at the JCRT

Radiation therapy (XRT) for 41 patients with unresectable pancreatic cancer resulted in a median survival of 7.0 months. There was no difference in median survival for patients receiving external beam alone (3500 to 5600 cGy) (n = 28), intraoperative (IORT) boost plus external beam (5040 to 6750 cGy) (n = 9), or a gold-198 implant +/- external beam radiation (n = 4). A pilot study using orthovoltage IORT boost indicates no acute toxicity with doses of 1250 to 1750 cGy. Serious late damage has not been observed in any patients followed to 2 years. Local recurrence in patients treated post-operatively after "radical" surgery occurred in one of 10 (10%). This adjuvant treatment is safe and appears to improve local control rates compared to historical data, but survival is still poor. The median survival for the post-operative group is 10 months; three patients are alive without disease 8 months to 8.3 years after treatment.     

Roberts铜盐法测定蔗汁葡聚糖含量的热效应——淀粉对受热蔗汁葡聚糖测定的影响

作者从研究中发现:用Roberts铜盐法测定蔗汁样本葡聚糖含量时,所得结果与蔗汁的受热有关,受热蔗汁的测定值高于真实值,作者将这种现象暂称为Roberts铜盐法测定蔗汁样本葡聚糖含量的热效应。研究表明:蔗汁中的淀粉是引起热效应的重要因素。本文最后提出了一种由淀粉引起的热效应的可行校正方法。     

Trends in Vitamin C Consumption in the United States: 1999–2018

Low intakes of fruits and vegetables have resulted in suboptimal intakes of several micronutrients, including vitamin C. This cross-sectional study used data from 84,902 children/adults (≥1 y) who completed a 24-h dietary recall as part of the United States National Health and Nutrition Examination Survey (1999–2018). Mean vitamin C intakes from foods/beverages were calculated as were trends in major food/beverage sources of vitamin C. Percentages below the Estimated Average Requirement (EAR) were estimated. Overall, mean vitamin C consumption declined by 23% (97–75 mg/d; p-value for trend < 0.001). 100% fruit juice was the leading source of vitamin C (25.6% of total or 21.7mg/d), but this declined by 48% (25–13 mg/d; p-value for trend < 0.001). Whole fruit increased among children/adolescents (+75.8%;10–17 mg/d; p-value for trend < 0.001), but not adults, while the vegetable contribution was generally unchanged. The proportion of the population below the EAR increased by 23.8% on a relative scale or 9 percentage points on an absolute scale (38.3–47.4%). Declines in vitamin C intake is driven largely by decreases in fruit juice coupled with modest increases in whole fruit. Due to associations between vitamin C intake and numerous health outcomes these trends warrant careful monitoring moving forward.