Fentanyl but Not Morphine or Buprenorphine Improves the Severity of Necrotizing Acute Pancreatitis in Rats.

Opioids are widely used for the pain management of acute pancreatitis (AP), but their impact on disease progression is unclear. Therefore, our aim was to study the effects of clinically relevant opioids on the severity of experimental AP. Various doses of fentanyl, morphine, or buprenorphine were administered as pre- and/or post-treatments in rats. Necrotizing AP was induced by the intraperitoneal injection of L-ornithine-HCl or intra-ductal injection of Na-taurocholate, while intraperitoneal caerulein administration caused edematous AP. Disease severity was determined by laboratory and histological measurements. Mu opioid receptor (MOR) expression and function was assessed in control and AP animals. MOR was expressed in both the pancreas and brain. The pancreatic expression and function of MOR were reduced in AP. Fentanyl post-treatment reduced necrotizing AP severity, whereas pre-treatment exacerbated it. Fentanyl did not affect the outcome of edematous AP. Morphine decreased vacuolization in edematous AP, while buprenorphine pre-treatment increased pancreatic edema during AP. The overall effects of morphine on disease severity were negligible. In conclusion, the type, dosing, administration route, and timing of opioid treatment can influence the effects of opioids on AP severity. Fentanyl post-treatment proved to be beneficial in AP. Clinical studies are needed to determine which opioids are best in AP.

Mislocalization of CFTR expression in acute pancreatitis and the beneficial effect of VX-661 + VX-770 treatment on disease severity.

Cystic fibrosis transmembrane conductance regulator (CFTR) has an essential role in maintaining pancreatic ductal function. Impaired CFTR function can trigger acute pancreatitis (AP) and exacerbate disease severity. We aimed to investigate the localization and expression of CFTR during AP, and determined the effects of a CFTR corrector (VX-661) and potentiator (VX-770) on disease severity. AP was induced in FVB/n mice by 6-10 hourly intraperitoneal injections of 50 µg/kg cerulein. Some mice were pre-treated with five to six daily injections of 2 mg/kg VX-661 + VX-770. Control animals were administered physiological saline instead of cerulein and dimethyl sulfoxide instead of VX compounds. AP severity was determined by measuring laboratory and histological parameters; CFTR and CK19 expression was measured. Activity of ion transporters was followed by intracellular pH or fluid secretion measurement of isolated pancreatic intra-/interlobular ducts. Cerulein-induced AP severity was greatest between 12 and 24 h. CFTR mRNA expression was significantly increased 24 h after AP induction. Immunohistochemistry demonstrated disturbed staining morphology of CFTR and CK19 proteins in AP. Mislocalization of CFTR protein was observed from 6 h, while expression increased at 24 h compared to control. Ductal HCO3- transport activity was significantly increased 6 h after AP induction. AP mice pre-treatment with VX-661 + VX-770 significantly reduced the extent of tissue damage by about 20-30%, but other parameters were unchanged. Interestingly, VX-661 + VX-770 in vitro administration significantly increased the fluid secretion of ducts derived from AP animals. This study described the course of the CFTR expression and mislocalization in cerulein-induced AP. Our results suggest that the beneficial effects of CFTR correctors and potentiators should be further investigated in AP. KEY POINTS: Cystic fibrosis transmembrane conductance regulator (CFTR) is an important ion channel in epithelial cells. Its malfunction has several serious consequences, like developing or aggravating acute pancreatitis (AP). Here, the localization and expression of CFTR during cerulein-induced AP in mice were investigated and the effects of CFTR corrector (VX-661) and a potentiator (VX-770) on disease severity were determined. CFTR mRNA expression was significantly increased and mislocalization of CFTR protein was observed in AP compared to the control group. Interestingly, pre-treatment of AP mice with VX-661 + VX-770 significantly reduced the extent of pancreatic tissue damage by 20-30%. In vitro administration of VX-661 + VX-770 significantly increased the fluid secretion of ducts derived from AP animals. Based on these results, the utilization of CFTR correctors and potentiators should be further investigated in AP.

A novel, protective role of ursodeoxycholate in bile-induced pancreatic ductal injury.

We have previously shown that chenodeoxycholic acid (CDCA) strongly inhibits pancreatic ductal HCO3 (-) secretion through the destruction of mitochondrial function, which may have significance in the pathomechanism of acute pancreatitis (AP). Ursodeoxycholic acid (UDCA) is known to protect the mitochondria against hydrophobic bile acids and has an ameliorating effect on cell death. Therefore, our aim was to investigate the effect of UDCA pretreatment on CDCA-induced pancreatic ductal injury. Guinea pig intrainterlobular pancreatic ducts were isolated by collagenase digestion. Ducts were treated with UDCA for 5 and 24 h, and the effect of CDCA on intracellular Ca(2+) concentration ([Ca(2+)]i), intracellular pH (pHi), morphological and functional changes of mitochondria, and the rate of apoptosis were investigated. AP was induced in rat by retrograde intraductal injection of CDCA (0.5%), and the disease severity of pancreatitis was assessed by measuring standard laboratory and histological parameters. Twenty-four-hour pretreatment of pancreatic ducts with 0.5 mM UDCA significantly reduced the rate of ATP depletion, mitochondrial injury, and cell death induced by 1 mM CDCA and completely prevented the inhibitory effect of CDCA on acid-base transporters. UDCA pretreatment had no effect on CDCA-induced Ca(2+) signaling. Oral administration of UDCA (250 mg/kg) markedly reduced the severity of CDCA-induced AP. Our results clearly demonstrate that UDCA 1) suppresses the CDCA-induced pancreatic ductal injury by reducing apoptosis and mitochondrial damage and 2) reduces the severity of CDCA-induced AP. The protective effect of UDCA against hydrophobic bile acids may represent a novel therapeutic target in the treatment of biliary AP.

Alcohol disrupts levels and function of the cystic fibrosis transmembrane conductance regulator to promote development of pancreatitis.

BACKGROUND & AIMS: Excessive consumption of ethanol is one of the most common causes of acute and chronic pancreatitis. Alterations to the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) also cause pancreatitis. However, little is known about the role of CFTR in the pathogenesis of alcohol-induced pancreatitis. METHODS: We measured CFTR activity based on chloride concentrations in sweat from patients with cystic fibrosis, patients admitted to the emergency department because of excessive alcohol consumption, and healthy volunteers. We measured CFTR levels and localization in pancreatic tissues and in patients with acute or chronic pancreatitis induced by alcohol. We studied the effects of ethanol, fatty acids, and fatty acid ethyl esters on secretion of pancreatic fluid and HCO3(-), levels and function of CFTR, and exchange of Cl(-) for HCO3(-) in pancreatic cell lines as well as in tissues from guinea pigs and CFTR knockout mice after administration of alcohol. RESULTS: Chloride concentrations increased in sweat samples from patients who acutely abused alcohol but not in samples from healthy volunteers, indicating that alcohol affects CFTR function. Pancreatic tissues from patients with acute or chronic pancreatitis had lower levels of CFTR than tissues from healthy volunteers. Alcohol and fatty acids inhibited secretion of fluid and HCO3(-), as well as CFTR activity, in pancreatic ductal epithelial cells. These effects were mediated by sustained increases in concentrations of intracellular calcium and adenosine 3',5'-cyclic monophosphate, depletion of adenosine triphosphate, and depolarization of mitochondrial membranes. In pancreatic cell lines and pancreatic tissues of mice and guinea pigs, administration of ethanol reduced expression of CFTR messenger RNA, reduced the stability of CFTR at the cell surface, and disrupted folding of CFTR at the endoplasmic reticulum. CFTR knockout mice given ethanol or fatty acids developed more severe pancreatitis than mice not given ethanol or fatty acids. CONCLUSIONS: Based on studies of human, mouse, and guinea pig pancreata, alcohol disrupts expression and localization of the CFTR. This appears to contribute to development of pancreatitis. Strategies to increase CFTR levels or function might be used to treat alcohol-associated pancreatitis.

Postconditioning in major vascular surgery: prevention of renal failure.

BACKGROUND: Postconditioning is a novel reperfusion technique to reduce ischemia-reperfusion injuries. The aim of the study was to investigate this method in an animal model of lower limb revascularization for purpose of preventing postoperative renal failure. METHODS: Bilateral lower limb ischemia was induced in male Wistar rats for 3 hours by infrarenal aorta clamping under narcosis. Revascularization was allowed by declamping the aorta. Postconditioning (additional 10 sec reocclusion, 10 sec reperfusion in 6 cycles) was induced at the onset of revascularization. Myocyte injury and renal function changes were assessed 4, 24 and 72 hours postoperatively. Hemodynamic monitoring was performed by invasive arterial blood pressure registering and a kidney surface laser Doppler flowmeter. RESULTS: Muscle viability studies showed no significant improvement with the use of postconditioning in terms of ischemic rhabdomyolysis (4 h: ischemia-reperfusion (IR) group: 42.93 ± 19.20% vs. postconditioned (PostC) group: 43.27 ± 27.13%). At the same time, renal functional laboratory tests and kidney myoglobin immunohistochemistry demonstrated significantly less expressed kidney injury in postconditioned animals (renal failure index: 4 h: IR: 2.37 ± 1.43 mM vs. PostC: 0.92 ± 0.32 mM; 24 h: IR: 1.53 ± 0.45 mM vs. PostC: 0.77 ± 0.34 mM; 72 h: IR: 1.51 ± 0.36 mM vs. PostC: 0.43 ± 0.28 mM), while systemic hemodynamics and kidney microcirculation significantly improved (calculated reperfusion area: IR: 82.31 ± 12.23% vs. PostC: 99.01 ± 2.76%), and arterial blood gas analysis showed a lesser extent systemic acidic load after revascularization (a defined relative base excess parameter: 1(st) s: IR: 2.25 ± 1.14 vs. PostC: 1.80 ± 0.66; 2(nd) s: IR: 2.14 ± 1.44 vs. PostC: 2.44 ± 1.14, 3(rd) s: IR: 3.99 ± 3.09 vs. PostC: 2.07 ± 0.82; 4(th) s: IR: 3.28 ± 0.32 vs. PostC: 2.05 ± 0.56). CONCLUSIONS: The results suggest a protective role for postconditioning in major vascular surgeries against renal complications through a possible alternative release of nephrotoxic agents and exerting a positive effect on hemodynamic stability.

Recent advances in the investigation of pancreatic inflammation induced by large doses of basic amino acids in rodents.

It has been known for approximately 30 years that large doses of the semi-essential basic amino acid L-arginine induce severe pancreatic inflammation in rats. Recently, it has been demonstrated that L-arginine can also induce pancreatitis in mice. Moreover, other basic amino acids like L-ornithine and L-lysine can cause exocrine pancreatic damage without affecting the endocrine parenchyma and the ducts in rats. The utilization of these noninvasive severe basic amino acid-induced pancreatitis models is becoming increasingly popular and appreciated as these models nicely reproduce most laboratory and morphological features of human pancreatitis. Consequently, the investigation of basic amino acid-induced pancreatitis may offer us a better understanding of the pathogenesis and possible treatment options of the human disease.

The role of pancreatic ductal secretion in protection against acute pancreatitis in mice*.

OBJECTIVES: A common potentially fatal disease of the pancreas is acute pancreatitis, for which there is no treatment. Most studies of this disorder focus on the damage to acinar cells since they are assumed to be the primary target of multiple stressors affecting the pancreas. However, increasing evidence suggests that the ducts may also have a crucial role in induction of the disease. To test this hypothesis, we sought to determine the specific role of the duct in the induction of acute pancreatitis using well-established disease models and mice with deletion of the Na/H exchanger regulatory factor-1 that have selectively impaired ductal function. DESIGN: Randomized animal study. SETTING: Animal research laboratory. SUBJECTS: Wild-type and Na/H exchanger regulatory factor-1 knockout mice. INTERVENTIONS: Acute necrotizing pancreatitis was induced by i.p. administration of cerulein or by intraductal administration of sodium taurocholate. The pancreatic expression of Na/H exchanger regulatory factor-1 and cystic fibrosis transmembrane conductance regulator (a key player in the control of ductal secretion) was analyzed by immunohistochemistry. In vivo pancreatic ductal secretion was studied in anesthetized mice. Functions of pancreatic acinar and ductal cells as well as inflammatory cells were analyzed in vitro. MEASUREMENTS AND MAIN RESULTS: Deletion of Na/H exchanger regulatory factor-1 resulted in gross mislocalization of cystic fibrosis transmembrane conductance regulator, causing marked reduction in pancreatic ductal fluid and bicarbonate secretion. Importantly, deletion of Na/H exchanger regulatory factor-1 had no deleterious effect on functions of acinar and inflammatory cells. Deletion of Na/H exchanger regulatory factor-1, which specifically impaired ductal function, increased the severity of acute pancreatitis in the two mouse models tested. CONCLUSIONS: Our findings provide the first direct evidence for the crucial role of ductal secretion in protecting the pancreas from acute pancreatitis and strongly suggest that improved ductal function should be an important modality in prevention and treatment of the disease.

Therapeutic option for managing lung injury induced by infrarenal aortic cross-clamping.

BACKGROUND: Operations on the infrarenal aorta can cause ischemic-reperfusion (IR) injury in local tissues, which could result in remote organ (e.g., lung) damage. Treatment of such injuries remains an unresolved problem. OBJECTIVES: Our aim was to reduce remote lung damage after lower limb IR by means of postconditioning. MATERIALS AND METHODS: Male Wistar rats were divided into three groups: Sham-operated, IR, and Postconditioned (PostC). In the latter two groups rats underwent 180 min of exclusion of the infrarenal aorta. The reperfusion time was 4 h. Serum-free radical levels, tumor necrosis factor-α and interleukin-6 concentrations, histologic changes in the lung, wet/dry-ratio, myeloperoxidase activity, heat shock protein 72 level and blood gas changes were investigated. RESULTS: Postconditioning reduced histological damage in the lung (P < 0.05). Free radical levels and tumor necrosis factor-α concentrations were significantly lower in the PostC group than in the IR group (P < 0.05 and P < 0.01, respectively). Interleukin-6 concentrations did not significantly differ in the PostC group. Compared with the IR group, lung myeloperoxidase activity was lower in the PostC group. Decreased pulmonary heat shock protein 72 level was observed in the PostC group compared with the IR group and the wet/dry-ratio was also significantly lower in the PostC group (P < 0.05). A noticeably higher arterial pO2 level was manifest in the PostC group after 2 and 4 h of reperfusion (P < 0.05). CONCLUSIONS: Postconditioning reduced lung damage under experimental conditions, in the early period of reperfusion after lower limb IR injury.

[Postconditioning can reduce long-term lung injury after lower limb ischemia-reperfusion]. / Alsó végtagi ischaemiás-reperfusiós károsodás hosszú távú tüdoszövodményeinek megelozése posztkondicionálással.

INTRODUCTION: Operation on the infrarenal aorta could cause ischemic-reperfusion (IR) injury in local tissues and remote organs (e.g. the lung). OBJECTIVES: Our aim was to reduce long-term lung damage, after lower limb IR with postconditioning. MATERIALS AND METHODS: Male Wistar rats underwent 180 minutes of bilateral lower limb ischemia. Animals were divided into three groups: Sham-operated, IR, Postconditioned (PostC) and further to two subgroups according to reperfusion time: 24 h and 72 h. Serum free radical and IL-6 levels, histological changes, Wet/Dry (W/D) ratio, tissue myeloperoxidase (MPO) activity and Hsp72 levels were investigated. RESULTS: Postconditioning can reduce histological changes in the lung. Free radical levels are significantly lower in PostC groups than in IR groups (42.9 ± 8.0 vs. 6.4 ± 3.4; 27.3 ± 4.4 vs. 8.3 ± 4.0 RLU%; p < 0.05). IL-6 level (238.4 ± 31.1 vs. 209.1 ± 18.8; 190.0 ± 8.8 vs. 187.0 ± 14.9 pg/ml) and Hsp72 expression did not show any significant difference. Compared to the IR group, lung MPO activity did not change in the PostC groups. W/D ratio in PostC groups is significantly lower at all measured time-points (68% vs. 65%; 72% vs. 68%; p < 0.05). CONCLUSION: Postconditioning may reduce long-term damages of the lung after lower limb ischemic-reperfusion injury.

The anti-inflammatory effect of dimethyl trisulfide in experimental acute pancreatitis.

Various organosulfur compounds, such as dimethyl trisulfide (DMTS), display anti-inflammatory properties. We aimed to examine the effects of DMTS on acute pancreatitis (AP) and its mechanism of action in both in vivo and in vitro studies. AP was induced in FVB/n mice or Wistar rats by caerulein, ethanol-palmitoleic acid, or L-ornithine-HCl. DMTS treatments were administered subcutaneously. AP severity was assessed by pancreatic histological scoring, pancreatic water content, and myeloperoxidase activity measurements. The behaviour of animals was followed. Pancreatic heat shock protein 72 (HSP72) expression, sulfide, and protein persulfidation were measured. In vitro acinar viability, intracellular Ca2+ concentration, and reactive oxygen species production were determined. DMTS dose-dependently decreased the severity of AP. It declined the pancreatic infiltration of leukocytes and cellular damage in mice. DMTS upregulated the HSP72 expression during AP and elevated serum sulfide and low molecular weight persulfide levels. DMTS exhibited cytoprotection against hydrogen peroxide and AP-inducing agents. It has antioxidant properties and modulates physiological but not pathophysiological Ca2+ signalling. Generally, DMTS ameliorated AP severity and protected pancreatic acinar cells. Our findings indicate that DMTS is a sulfur donor with anti-inflammatory and antioxidant effects, and organosulfur compounds require further investigation into this potentially lethal disease.

[Remote ischemic conditioning: short-term effects on rat liver ischemic-reperfusion injury]. / Távoli szervi kondicionálás: rövid távú hepatoprotectiv hatások patkánymodellben.

INTRODUCTION: Several techniques have been developed to reduce ischemic-reperfusion injury. A novel method is the remote ischemic perconditioning, applied parallel with target organ ischemia. AIM: The aim of the study was to determine the extent of liver ischemic-reperfusion injury via the application of this novel method. METHODS: Male Wistar rats (n = 30, 10/group) were subjected to 60-minute partial liver ischemia and 60-minute reperfusion. Rats in the perconditioned group received conditioning treatment during the last 40 minutes of liver ischemia by infrarenal aortic clamping. Hepatic and lower limb microcirculation was monitored by laser Doppler flowmeter during reperfusion. After reperfusion, liver samples were taken for routine histological examination and redox-state assessment. Serum transaminase activities and liver tissue heat-shock protein-72 expression were measured. RESULTS: Parameters of microcirculation showed significant (p<0.05) improvement in the perconditioned group in comparison with the control. Besides the significant improvement observed in the serum alanine amino-transferase activities, significantly milder tissue injury was detected histologically in the liver sections of the perconditioned group. Moreover, significant improvement was found in the redox-state parameters. CONCLUSION: Perconditioning may be a reasonable possibility to reduce liver ischemic-reperfusion injury.

Blood-brain barrier dysfunction in L-ornithine induced acute pancreatitis in rats and the direct effect of L-ornithine on cultured brain endothelial cells.

BACKGROUND: In severe acute pancreatitis (AP) the CNS is affected manifesting in neurological symptoms. Earlier research from our laboratory showed blood-brain barrier (BBB) permeability elevation in a taurocholate-induced AP model. Here we aimed to further explore BBB changes in AP using a different, non-invasive in vivo model induced by L-ornithine. Our goal was also to identify whether L-ornithine, a cationic amino acid, has a direct effect on brain endothelial cells in vitro contributing to the observed BBB changes. METHODS: AP was induced in rats by the intraperitoneal administration of L-ornithine-HCl. Vessel permeability and the gene expression of the primary transporter of L-ornithine, cationic amino acid transporter-1 (Cat-1) in the brain cortex, pancreas, liver and lung were determined. Ultrastructural changes were followed by transmission electron microscopy. The direct effect of L-ornithine was tested on primary rat brain endothelial cells and a triple co-culture model of the BBB. Viability and barrier integrity, including permeability and TEER, nitrogen monoxide (NO) and reactive oxygen species (ROS) production and NF-κB translocation were measured. Fluorescent staining for claudin-5, occludin, ZO-1, ß-catenin, cell adhesion molecules Icam-1 and Vcam-1 and mitochondria was performed. Cell surface charge was measured by laser Doppler velocimetry. RESULTS: In the L-ornithine-induced AP model vessel permeability for fluorescein and Cat-1 expression levels were elevated in the brain cortex and pancreas. On the ultrastructural level surface glycocalyx and mitochondrial damage, tight junction and basal membrane alterations, and glial edema were observed. L-ornithine decreased cell impedance and elevated the BBB model permeability in vitro. Discontinuity in the surface glycocalyx labeling and immunostaining of junctional proteins, cytoplasmic redistribution of ZO-1 and ß-catenin, and elevation of Vcam-1 expression were measured. ROS production was increased and mitochondrial network was damaged without NF-κB, NO production or mitochondrial membrane potential alterations. Similar ultrastructural changes were seen in L-ornithine treated brain endothelial cells as in vivo. The basal negative zeta potential of brain endothelial cells became more positive after L-ornithine treatment. CONCLUSION: We demonstrated BBB damage in the L-ornithine-induced rat AP model suggesting a general, AP model independent effect. L-ornithine induced oxidative stress, decreased barrier integrity and altered BBB morphology in a culture BBB model. These data suggest a direct effect of the cationic L-ornithine on brain endothelium. Endothelial surface glycocalyx injury was revealed both in vivo and in vitro, as an additional novel component of the BBB-related pathological changes in AP.

Kynurenic Acid and Its Analogue SZR-72 Ameliorate the Severity of Experimental Acute Necrotizing Pancreatitis.

The pathophysiology of acute pancreatitis (AP) is not well understood, and the disease does not have specific therapy. Tryptophan metabolite L-kynurenic acid (KYNA) and its synthetic analogue SZR-72 are antagonists of the N-methyl-D-aspartate receptor (NMDAR) and have immune modulatory roles in several inflammatory diseases. Our aims were to investigate the effects of KYNA and SZR-72 on experimental AP and to reveal their possible mode of action. AP was induced by intraperitoneal (i.p.) injection of L-ornithine-HCl (LO) in SPRD rats. Animals were pretreated with 75-300 mg/kg KYNA or SZR-72. Control animals were injected with physiological saline instead of LO, KYNA and/or SZR-72. Laboratory and histological parameters, as well as pancreatic and systemic circulation were measured to evaluate AP severity. Pancreatic heat shock protein-72 and IL-1ß were measured by western blot and ELISA, respectively. Pancreatic expression of NMDAR1 was investigated by RT-PCR and immunohistochemistry. Viability of isolated pancreatic acinar cells in response to LO, KYNA, SZR-72 and/or NMDA administration was assessed by propidium-iodide assay. The effects of LO and/or SZR-72 on neutrophil granulocyte function was also studied. Almost all investigated laboratory and histological parameters of AP were significantly reduced by administration of 300 mg/kg KYNA or SZR-72, whereas the 150 mg/kg or 75 mg/kg doses were less or not effective, respectively. The decreased pancreatic microcirculation was also improved in the AP groups treated with 300 mg/kg KYNA or SZR-72. Interestingly, pancreatic heat shock protein-72 expression was significantly increased by administration of SZR-72, KYNA and/or LO. mRNA and protein expression of NMDAR1 was detected in pancreatic tissue. LO treatment caused acinar cell toxicity which was reversed by 250 µM KYNA or SZR-72. Treatment of acini with NMDA (25, 250, 2000 µM) did not influence the effects of KYNA or SZR-72. Moreover, SZR-72 reduced LO-induced H2O2 production of neutrophil granulocytes. KYNA and SZR-72 have dose-dependent protective effects on LO-induced AP or acinar toxicity which seem to be independent of pancreatic NMDA receptors. Furthermore, SZR-72 treatment suppressed AP-induced activation of neutrophil granulocytes. This study suggests that administration of KYNA and its derivative could be beneficial in AP.

Foveal and perifoveal retinal thickness measured by OCT in diabetic patients after phacoemulsification cataract surgery.

PURPOSE: The aim of the study was to measure the change of the foveal and perifoveal thickness of the retina in diabetic patients after uneventful phacoemulsification and PC-IOL implantation. METHODS: Retinal thickness values of the foveal and perifoveal (fovea + 3.0 mm, fovea + 6.0 mm) sectors and the minimum values were measured in a prospective study using optical coherence tomography (OCT) in 18 eyes of 18 diabetic patients who underwent cataract surgery. Phacoemulsification and "in the bag" implantation of a foldable posterior chamber intraocular lens (PC-IOL) was performed under topical anaesthesia. Data were collected one day before the operation, and postoperatively at 1, 7, 30, and 60 days. Contralateral eyes of each patient served as controls. Student's t-test was used for statistical analysis, and p < 0.05 value was considered significant. RESULTS: No significant change of the thickness values could be measured one day after surgery. However, a significant increase could be detected on the postoperative 7, 30, and 60 days in the perifoveal 3.0 mm and 6.0 mm sectors either calculated alone or averaged together with the foveal values. The initial (preoperative) average value of 232.7 +/- 3.5 microm (mean +/- SEM, n=144) in the 6.0 mm perifoveal region increased to 246.0 +/- 8.2 microm (mean +/- SEM, n=120, p < 0.05) one week, to 249.9 +/- 5 1 microm (n=112, p < 0.01) one month, and to 249.5_+6.2 pm (n=104, p < 0.01) 2 months after surgery, which proved to be significant. DISCUSSION: Our results indicate that diabetes did not influence significantly the thickening of the macular regions after uncomplicated cataract surgery. However, the postoperative perifoveal macular thickness change was found to be nonsignificantly higher in the diabetic group compared to the nondiabetic group, which might be attributed to the high sensitivity of the OCT method.

The acidity and self-catalyzed lactonization of l-gulonic acid: Thermodynamic, kinetic and computational study.

Lactonization and proton dissociation of sugar acids take place simultaneously in acidic aqueous solutions. The protonation-deprotonation processes are always fast, whilst the formation and hydrolysis of γ- and δ-lactones are usually slower. Thus, both thermodynamic and kinetic information are required for the complete understanding of these reactions. The protonation constant (Kp) of l-gulonate (Gul-) was determined from potentiometric and polarimetric measurements, while the individual lactonization constants (KL,γ and KL,δ) for l-gulonic acid (HGul) were obtained via13C NMR experiments. The applicability of this method was proven by measuring these well-known constants for d-gluconic acid (HGluc) and by comparing them to literature data. l-gulonic acid γ-lactone (γ-HGul) has remarkable stability in contrast with δ-HGul as well as γ- and δ-HGluc. The polarimetric measurement implies that the main factor responsible for the enhanced stability of γ-HGul is that its hydrolysis is much slower than that of δ-HGul. This higher stability of the γ-HGul ring over its δ-isomer was also confirmed by quantum chemical calculations. A new confirmed feature of the reaction is that in parallel to H3O+, HGul also catalyzes the formation and reverse hydrolytic processes of γ-HGul, similarly to other general acid catalysts.

Bidirectional Relationship Between Reduced Blood pH and Acute Pancreatitis: A Translational Study of Their Noxious Combination.

Acute pancreatitis (AP) is often accompanied by alterations in the acid-base balance, but how blood pH influences the outcome of AP is largely unknown. We studied the association between blood pH and the outcome of AP with meta-analysis of clinical trials, and aimed to discover the causative relationship between blood pH and AP in animal models. PubMed, EMBASE, and Cochrane Controlled Trials Registry databases were searched from inception to January 2017. Human studies reporting systemic pH status and outcomes (mortality rate, severity scores, and length of hospital stay) of patient groups with AP were included in the analyses. We developed a new mouse model of chronic metabolic acidosis (MA) and induced mild or severe AP in the mice. Besides laboratory blood testing, the extent of pancreatic edema, necrosis, and leukocyte infiltration were assessed in tissue sections of the mice. Thirteen studies reported sufficient data in patient groups with AP (n = 2,311). Meta-analysis revealed markedly higher mortality, elevated severity scores, and longer hospital stay in AP patients with lower blood pH or base excess (P < 0.001 for all studied outcomes). Meta-regression analysis showed significant negative correlation between blood pH and mortality in severe AP. In our mouse model, pre-existing MA deteriorated the pancreatic damage in mild and severe AP and, vice versa, severe AP further decreased the blood pH of mice with MA. In conclusion, MA worsens the outcome of AP, while severe AP augments the decrease of blood pH. The discovery of this vicious metabolic cycle opens up new therapeutic possibilities in AP.

Ductal Mucus Obstruction and Reduced Fluid Secretion Are Early Defects in Chronic Pancreatitis.

Objective: Defective mucus production in the pancreas may be an important factor in the initiation and progression of chronic pancreatitis (CP), therefore we aimed to (i) investigate the qualitative and quantitative changes of mucus both in human CP and in an experimental pancreatitis model and (ii) to correlate the mucus phenotype with epithelial ion transport function. Design: Utilizing human tissue samples and a murine model of cerulein induced CP we measured pancreatic ductal mucus content by morphometric analysis and the relative expression of different mucins in health and disease. Pancreatic fluid secretion in CP model was measured in vivo by magnetic resonance cholangiopancreatography (MRCP) and in vitro on cultured pancreatic ducts. Time-changes of ductal secretory function were correlated to those of the mucin production. Results: We demonstrate increased mucus content in the small pancreatic ducts in CP. Secretory mucins MUC6 and MUC5B were upregulated in human, Muc6 in mouse CP. In vivo and in vitro fluid secretion was decreased in cerulein-induced CP. Analysis of time-course changes showed that impaired ductal ion transport is paralleled by increased Muc6 expression. Conclusion: Mucus accumulation in the small ducts is a combined effect of mucus hypersecretion and epithelial fluid secretion defect, which may lead to ductal obstruction. These results suggest that imbalance of mucus homeostasis may have an important role in the early-phase development of CP, which may have novel diagnostic and therapeutic implications.

The Importance of Aquaporin 1 in Pancreatitis and Its Relation to the CFTR Cl- Channel.

Aquaporins (AQPs) facilitate the transepithelial water flow involved in epithelial fluid secretion in numerous tissues; however, their function in the pancreas is less characterized. Acute pancreatitis (AP) is a serious disorder in which specific treatment is still not possible. Accumulating evidence indicate that decreased pancreatic ductal fluid secretion plays an essential role in AP; therefore, the aim of this study was to investigate the physiological and pathophysiological role of AQPs in the pancreas. Expression and localization of AQPs were investigated by real-time PCR and immunocytochemistry, whereas osmotic transmembrane water permeability was estimated by the dye dilution technique, in Capan-1 cells. The presence of AQP1 and CFTR in the mice and human pancreas were investigated by immunohistochemistry. Pancreatic ductal HCO3- and fluid secretion were studied on pancreatic ducts isolated from wild-type (WT) and AQP1 knock out (KO) mice using microfluorometry and videomicroscopy, respectively. In vivo pancreatic fluid secretion was estimated by magnetic resonance imaging. AP was induced by intraperitoneal injection of cerulein and disease severity was assessed by measuring biochemical and histological parameters. In the mice, the presence of AQP1 was detected throughout the whole plasma membrane of the ductal cells and its expression highly depends on the presence of CFTR Cl- channel. In contrast, the expression of AQP1 is mainly localized to the apical membrane of ductal cells in the human pancreas. Bile acid treatment dose- and time-dependently decreased mRNA and protein expression of AQP1 and reduced expression of this channel was also demonstrated in patients suffering from acute and chronic pancreatitis. HCO3- and fluid secretion significantly decreased in AQP1 KO versus WT mice and the absence of AQP1 also worsened the severity of pancreatitis. Our results suggest that AQP1 plays an essential role in pancreatic ductal fluid and HCO3- secretion and decreased expression of the channel alters fluid secretion which probably contribute to increased susceptibility of the pancreas to inflammation.

Relationship between visual field sensitivity and retinal nerve fiber layer thickness as measured by optical coherence tomography.

PURPOSE: To evaluate the strength and pattern of the relationship between visual field (VF) sensitivity and retinal nerve fiber layer (RNFL) thickness as measured by StratusOCT (Carl Zeiss Meditec, Inc., Dublin, CA). METHODS: Three hundred eleven subjects--45 normal, 102 with preperimetric glaucoma (PPG), and 164 with primary open-angle glaucoma (POAG)--were enrolled in this cross-sectional study. The relationship between RNFL thickness and VF sensitivity, expressed as mean deviation (MD) and mean sensitivity (MS), were evaluated with linear and nonlinear regression models, and the coefficient of determination (R(2)) was calculated. The association between RNFL/VF was described by bivariate Pearson correlation coefficients. RESULTS: The correlation of RNFL and the VF parameters MS and MD in normal and PPG eyes was not significant. In POAG eyes, RNFL and both MS (r = 0.733) and MD (r = 0.718) correlated significantly. Linear regression plots of MS or MD against RNFL thickness demonstrated a negligible degree of determination in normal (R(2) = 0.0378 and 0.0121, respectively) and PPG groups (R(2) = 0.0215 and 0.0151, respectively), whereas their relationship fit a curvilinear regression model (R(2) = 0.6947 and 0.723) in the POAG group. Receiver operating characteristic (ROC) curves describing the VF parameters and average RNFL thickness (AVG) were evaluated to differentiate PPG from POAG eyes. Repeated analysis with the best-performing test parameter, pattern standard deviation (PSD) (AUROC = 0.937) with a cutoff of 1.9 dB, showed that regression profiles in the POAG group with PSD >1.9 dB maintained a strong curvilinear RNFL/VF relationship, whereas those with PSD <1.9 dB exhibited a relationship almost indistinguishable from the PPG group. CONCLUSIONS: Evaluation of the structure-function relationship in normal subjects and those with PPG or POAG showed strong curvilinear regression in POAG eyes with PSD >1.9 dB and RNFL AVG thickness below 70 microm, whereas no correlation was detectable above these values.

Modeling long-term diabetes and related complications in rats.

INTRODUCTION: Accurate preclinical modeling of diabetic complications such as retinopathy, nephropathy and neuropathy is crucial to enable the development of novel preventative therapies. The aims of this study were to establish a model of long-term diabetes with sustained medium scale hyperglycemia and characterize the pathological changes detectable after 4months, with particular respect to dependence on the degree of hyperglycemia. METHODS: Streptozotocin-induced diabetic CFY rats were subjected to four different insulin substitution protocols to achieve different levels of glycemic control (Diabetic 1-4 groups). Eyes were investigated by ophthalmoscopy, kidney function by urine analysis, and neuropathy by functional tests. Retinal and renal morphological evaluations were performed by histology, immuno-histochemistry and electron microscopy. RESULTS: Rats of the Diabetic 3 group showed massive hyperglycemia-dependent anterior segment neovascularization, enhanced total retinal score and retinal apoptotic cell number, degeneration of dopaminergic amacrine cells, increased glomerular PAS-positivity, altered excreted total protein/creatinine ratio and cold allodynia, parallel with medium scale hyperglycemia (blood glucose level between 22 and 25mmol/L) and satisfying state of health. DISCUSSION: We established a treatment protocol in rats enabling complex investigation of diabetic retinopathy, nephropathy and neuropathy on a long-term period. Clearly hyperglycemic dependent parameters of these complications serve as good outcome measures for preclinical trials. Our results provide a useful basis for designing studies for testing preventative treatments as well as other translational medical research in this field.