Chronic pancreatitis: A diagnostic dilemma

Typical clinical symptoms of chronic pancreatitis are vague and non-specific and therefore diagnostic tests are required, none of which provide absolute diagnostic certainly, especially in the early stages of disease. Recently-published guidelines bring much needed structure to the diagnostic work-up of patients with suspected chronic pancreatitis. In addition, novel diagnostic modalities bring promise for the future. The assessment and diagnosis of pancreatic exocrine insufficiency remains challenging and this review contests the accepted perspective that steatorrhea only occurs with > 90% destruction of the gland.     

Performance of a rapid antigen test for the diagnosis of congenital malaria

OBJECTIVE: To assess the performance of OptiMAL, a rapid malaria antigen capture dipstick, in diagnosing congenital malaria. METHODS: Live newborns aged 0-3 days, delivered at Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria between August 2004 and January 2005, were screened for malaria parasitaemia with an immunochromatographic test (OptiMAL) and blood film microscopy. OptiMAL detects plasmodium lactate dehydrogenase (pLDH). RESULTS: Twenty-one of 192 newborns (10.9%) were diagnosed with congenital malaria by blood film microscopy. The OptiMAL test was negative in all infants. CONCLUSION: OptiMAL rapid malaria antigen capture dipstick might not be useful for diagnosing malaria parasitaemia in newborns. Blood film microscopy remains the gold standard for the diagnosis of congenital malaria.     

Tranexamic acid for treatment of postpartum haemorrhage

Postpartum haemorrhage remains the leading cause of maternal mortality globally. Mortality and severe morbidity due to postpartum haemorrhage is highest in lower-resource settings. Tranexamic acid is an anti-fibrinolytic drug that has been in use in humans for nearly five decades. It is a structural analogue of lysine that binds irreversibly to plasminogen, thereby inhibiting the binding of plasmin to fibrin. This in turn inhibits fibrinolysis, thus stabilizing blood clots. Tranexamic acid has been shown to improve outcomes in trauma-related bleeding. New research has shown that early use of tranexamic acid (within 3 hours of birth), in addition to standard care, safely reduces deaths due to bleeding in women with clinically diagnosed postpartum haemorrhage, regardless of the mode of birth.     

Acetaminophen-induced liver damage in mice: Effects of some medicinal plants on the oxidative defense system

Paracetamol (acetaminophen, PCM) is widely used as an over-the-counter analgesic and antipyretic drug. Intake of a large dose of PCM may result in severe hepatic necrosis. Oxidative stress mediated by oxidative capacities of the PCM metabolite (N-acetyl-p-benzoquinoneimine (NAPQI), is considered as the main cause of hepatotoxicity of PCM. This work therefore seeks to induce liver damage in mice using single dose (25 0mg/kg) of acetaminophen and to evaluate the possible protective effects of administration (100mg/kg) of some medicinal plants (Kigelia africana, Calotropis procera, Hibiscus sabdariffa and Alchornea cordifolia) on PCM-induced liver damage in mice. The alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activities were determined in the plasma of mice. Equally, comparative effects of these plants on lipid peroxidation product thiobarbituric reacting substances (TBARS) and some antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), gluthathione peroxidase (GPx), and delta-aminolevulinate dehydratase (delta-ALA-D) activities, were also evaluated in the mouse liver homogenate. Paracetamol caused liver damage as evident by statistically significant (P<0.05) increased in plasma activities of AST and ALT. There were general statistically significant losses in the activities of SOD, GPx, CAT, and delta-ALA-D and an increase in TBARS in the liver of paracetamol-treated group compared with the control group. However, all the tested plants except Calotropis procera were able to counteract these effects. The present results suggest that these plants can act as hepatoprotectives against paracetamol toxicity and that the mechanism by which they do this is by acting as antioxidants.     

In-vitro evaluation of anti-trichomonal activities of Eugenia uniflora leaf

Eugenia uniflora, used ethnomedically in some tropical countries as an anti-infective, has shown anti-malarial and anti-trypanocidal activities. Therefore using bioactivity guided fractionation, anti-trichomonal activity of E. uniflora leaf was investigated. Anti-trichomonal activities of leaf methanol extract and its fractions against Trichomonas gallinae as well as their cytotoxicities using an in vitro haemaglutination assay were determined. Anti-trichomonacidal activities of the extract improved on purification up to a stage. Subfractions E(2-5) had LC(50) and LC(90) values of 4.77 - 5.28, 18.49 - 25.00 and 4.53 - 5.18, 18.32 - 19.07 μg/ml at 24 and 48 hrs, respectively that were better than those of metronidazole. Further purification of E(2-5) led to loss of activity suggesting that the active components were probably working synergistically and additively. Demonstration of low haemaglutination titre values of 0.00 - 5.33 by methanolic extract and its partition fractions suggested their low toxicity profile. The established safety of the leaf indicated that its anti-trichomonal activity was not due to non-specific cytotoxicity, hence could be used in ethnomedicine as an anti-trichomonal agent.     

Synthesis and cytotoxic activities of some 2-Arylnaphtho[2,3-d]oxazole-4,9-dione derivatives on androgen-dependent (LNCaP) and androgen-independent (PC3) human prostate cancer cell lines

The synthesis of five 2-arylnaphtho[2,3-d]oxazole-4,9-dione derivatives was accomplished by refluxing 2-amino-3-bromo-1,4-naphthoquinone with appropriate benzoyl chloride analogs at elevated temperatures. In vitro anticancer evaluation of these compounds was performed on androgen-dependent, LNCaP, and androgen-independent, PC3, human prostate cancer cell lines. In general, these compounds displayed slightly stronger cytotoxicity on the androgen-dependent LNCaP than on the androgen-independent PC3 prostate cancer cell lines. The meta-substituted 2-(3-Chloro-phenyl)-naphtho[2,3-d]oxazole-4,9-dione (10) appear to display the best cytotoxicity on both cell lines with an IC(50) of 0.03 μM on LNCaP and 0.08 μM on PC3 after 5 days of exposure.     

Phosphatidylinositol-4-phosphate-5-kinase alpha deficiency alters dynamics of glucose-stimulated insulin release to improve glucohomeostasis and decrease obesity in mice

OBJECTIVE

Phosphatidylinositol-4-phosphate-5-kinase (PI4P5K) has been proposed to facilitate regulated exocytosis and specifically insulin secretion by generating phosphatidylinositol-4,5-bisphosphate (PIP₂). We sought to examine the role of the α isoform of PI4P5K in glucohomeostasis and insulin secretion.

RESEARCH DESIGN AND METHODS

The response of PI4P5Kα^−/− mice to glucose challenge and a type 2-like diabetes-inducing high-fat diet was examined in vivo. Glucose-stimulated responses and PI4P5Kα^−/− pancreatic islets and β-cells were characterized in culture.

RESULTS

We show that PI4P5Kα^−/− mice exhibit increased first-phase insulin release and improved glucose clearance, and resist high-fat diet-induced development of type 2-like diabetes and obesity. PI4P5Kα^−/− pancreatic islets cultured in vitro exhibited decreased numbers of insulin granules docked at the plasma membrane and released less insulin under quiescent conditions, but then secreted similar amounts of insulin on glucose stimulation. Stimulation-dependent PIP₂ depletion occurred on the plasma membrane of the PI4P5Kα^−/− pancreatic β-cells, accompanied by a near-total loss of cortical F-actin, which was already decreased in the PI4P5Kα^−/− β-cells under resting conditions.

CONCLUSIONS

Our findings suggest that PI4P5Kα plays a complex role in restricting insulin release from pancreatic β-cells through helping to maintain plasma membrane PIP₂ levels and integrity of the actin cytoskeleton under both basal and stimulatory conditions. The increased first-phase glucose-stimulated release of insulin observed on the normal diet may underlie the partial protection against the elevated serum glucose and obesity seen in type 2 diabetes-like model systems.Failure of pancreatic β-cells to release adequate amounts of insulin contributes to the onset of type 2 diabetes and obesity (1). Elevated serum glucose transported into pancreatic β-cells is metabolized to increase cytosolic ATP levels, which then promote closure of ATP-sensitive K⁺ (KATP) channels, causing membrane depolarization. Membrane depolarization triggers opening of L-type Ca²⁺ channels, influx of Ca²⁺, and exocytosis. The first phase of exocytosis entails fusion of primed insulin granules predocked at the plasma membrane (2). A second phase involving mobilization of distal insulin vesicles occurs after approximately 10 min (3), preceded by actin cytoskeletal reorganization (4–6) and generation of lipid second messengers (7,8). The majority of type 2 diabetes is only weakly associated with specific genetic defects and is characterized by inadequate release of insulin, in addition to insulin resistance exhibited by fat and muscle target cells. Prolonged stimulation of β-cells by elevated levels of glucose, such as is encountered in the typical western-style high-fat diet, eventually suffices to trigger changes in insulin secretion in many individuals with otherwise seemingly normal physiology and genetics.Lipid kinases and their phosphoinositide products play important roles in secretory vesicle trafficking (9). Type I phosphatidylinositol-4-phosphate-5-kinases (PI4P5Ks) α, β, and γ generate the signaling lipid phosphatidylinositol-4,5-bisphosphate (PIP₂). Elegant studies in neurons and neuroendocrine cells on the role of PI4P5Kγ (10,11) and PIP₂ (12–14) have revealed that PIP₂ generation at the plasma membrane is critical during regulated exocytosis. PIP₂ directly facilitates some types of Ca⁺⁺ signaling (15,16), recruits proteins that facilitate the fusion process (13,14), and is required for docked secretory vesicles to undergo priming to become part of the ready-releasable pool and then fuse into the plasma membrane (10,11). Although less well understood mechanistically, decreased levels of PIP₂ have also been shown to inhibit insulin secretion in pancreatic β-cell model systems (7,17–19).However, PIP₂ also carries out functions that potentially oppose regulated exocytosis (20). First, PIP₂ supports the open state of the KATP channel (21,22); thus, because it is ATP-driven closure of the KATP channel that triggers secretion, PIP₂ deficiency might be anticipated to decrease K⁺ efflux, triggering membrane depolarization and thus increasing Ca⁺⁺ currents, resulting in increased secretion (23–25). In support of this model, expression of a dominant-negative isoform of PI4P5K to lower levels of PIP₂ changes the responsiveness of mutant KATP channels with decreased ATP sensitivity. However, expression of the dominant-negative PI4P5K does not alter function of wild-type (WT) KATP channels, suggesting that under normal physiologic conditions, the level of PIP₂ on the plasma membrane is not high enough to strongly affect KATP channel activity (26). PIP₂ has also been suggested to restrain fusion of docked vesicles by inhibiting SNARE complex function (14,27), with the restraint being alleviated through sequestration of the PIP₂ by Syntaxin-1 (14) or Ca²⁺-triggered PIP₂ destruction (28).Taken together, the action of PIP₂ is complex, and both its synthesis and its turnover are required at different steps in the fusion process.Another function undertaken by PIP₂ is to promote assembly of actin filaments (F-actin) (29,30). F-actin at the periphery of the cell (cortical F-actin) has also been proposed to have both positive and negative regulatory functions in exocytosis. Cortical F-actin has been proposed to act as a barrier to block access of undocked secretory vesicles to the plasma membrane; consistent with this model, cortical F-actin is disassembled during regulatory exocytosis events (31), and pharmacologic agents that disassemble F-actin enhance movement of insulin granules to the plasma membrane and insulin release, whereas agents that stabilize the actin cytoskeleton decrease insulin release (4,18,32–34). F-actin may also affect SNARE complex function by binding to and inhibiting Syntaxin-4 function in a glucose stimulation-relieved manner (32,33). To further complicate matters, F-actin can also undertake a positive role in regulated exocytosis by mediating translocation of more internal secretory vesicles to the periphery, particularly in poorly granulated or recently degranulated cells (4,35). Thus, dynamic regulation of the actin cytoskeleton is also important in the progression of regulated exocytosis and can play positive or negative roles depending on the setting.Changes in PIP₂ and cortical F-actin can have positive and negative effects on the secretory process, making it difficult a priori to predict the outcomes of their physiologic and experimental manipulation. Critically, individual PI4P5K isoforms may generate subpools of PIP₂ that regulate distinct components of the fusion process. Deletion of PI4P5Kγ markedly decreases levels of PIP₂ at the plasma membrane in resting neurons and neuroendocrine cells, and inhibits secretion at the stage of vesicle priming and fusion without notable effect on the actin cytoskeleton (10,11). In contrast, deletion of PI4P5Kα increases mast cell degranulation triggered by cross-linking of the IgE receptor, accompanied by minor decreases in cellular PIP₂, but significantly increased levels of Ca²⁺ signaling and decreased levels of total F-actin (36). PI4P5Kα knockdown using RNAi has also been reported to alter Ca²⁺ signaling, disrupt F-actin, and affect insulin release in a pancreatic β-cell line (37).This report examines insulin secretion in PI4P5Kα^−/− mice and finds that first-phase insulin release is augmented, and on a high-fat diet, fasting and stimulated serum insulin levels are even more elevated, conferring faster glucose clearance and resistance to the development of obesity. In this setting, K⁺ and Ca⁺⁺ signaling is seemingly normal; in contrast, the determinative factor seems to be a dramatic stimulation-dependent loss of PIP₂ at the plasma membrane that leads to reorganization of the actin cytoskeleton resulting in a near-total loss of cortical F-actin and decreased numbers of insulin granules docked at the plasma membrane.     

Lead exposure increases oxidative stress in the gastric mucosa of HCl/ethanol-exposed rats

AIM To investigate the role of reactive oxygen species in the ulcer-aggravating effect of lead in albino rats.METHODS Albino Wistar rats were randomly divided into three groups and treated orally with 100 mg/L (low dose) or 5000 mg/L (high dose) of lead acetate for 15 wk. A third group received saline and served as control.At the end of wk 15, colorimetric assays were applied to determine the concentrations of total protein and nitrite, the activities of the oxidative enzymes catalase and superoxide dismutase, and lipid peroxidation in homogenized gastric mucosal samples.RESULTS Exposure of rats to lead significantly increased the gastric mucosal damage caused by acidified ethanol. Although the basal gastric acid secretory rate was not significantly altered, the maximal response of the stomach to histamine was significantly higher in the lead-exposed animals than in the unexposed control group. Exposure to low and high levels of lead significantly increased gastric lipid peroxidation to 183.2% ± 12.7% and 226.1% ± 6.8% of control values respectively (P ＜ 0.0). On the other hand, lead exposure significantly decreased catalase and superoxide dismutase (SOD) activities and the amount of nitrite in gastric mucosal samples.CONCLUSION Lead increases the formation of gastric ulcers by interfering with the oxidative metabolism in the stomach.