Guide wire-assisted cannulation for the prevention of post-ERCP pancreatitis: a systematic review and meta-analysis.

BACKGROUND AND STUDY AIMS: Cannulation techniques are recognized to be important in causing post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). However, considerable controversy exists about the usefulness of the guide wire-assisted cannulation technique for the prevention of PEP. This systematic review of randomized controlled trials (RCTs) aimed to compare the guide wire-assisted cannulation technique with the contrast-assisted cannulation technique. METHODS: CENTRAL, MEDLINE, EMBASE, CINAHL, and abstracts from Digestive Disease Week and the United European Gastroenterology Week were searched up to February 2012 for RCTs comparing the guide wire-assisted ERCP cannulation technique with the conventional contrast-assisted ERCP cannulation technique. The risk of bias was assessed, and outcomes were pooled by meta-analysis (random-effects model). The primary outcome measure was PEP. Secondary outcome measures included severity of PEP, primary common bile duct (CBD) cannulation success, overall CBD cannulation success, precut sphincterotomy, and other ERCP-related complications. RESULTS: In total, 12 RCTs (3450 patients) were included. The guide wire-assisted cannulation technique significantly reduced PEP compared with the contrast-assisted cannulation technique (risk ratio [RR] 0.51, 95 % confidence interval [CI] 0.32 - 0.82). In addition, the guide wire-assisted cannulation technique was associated with greater primary cannulation success (RR 1.07, 95 %CI 1.00 - 1.15), fewer precut sphincterotomies (RR 0.75, 95 %CI 0.60 - 0.95), and no increase in other ERCP-related complications. Subgroup analyses indicated that this significant risk reduction in PEP with the guide wire-assisted cannulation technique existed only in "non-crossover" trials (RR 0.22, 95 %CI 0.12 - 0.42). The results were robust in sensitivity analyses. CONCLUSION: Compared with the contrast-assisted cannulation technique, the guide wire-assisted cannulation technique increases the primary cannulation rate and reduces the risk of PEP, and therefore appears to be the most appropriate first-line cannulation technique.

Declining Use of Corticosteroids for Crohn's Disease Has Implications for Study Recruitment: Results of a Pilot Randomized Controlled Trial.

BACKGROUND: Corticosteroids (CS) have been used extensively to induce remission in Crohn's disease (CD); however, they are associated with severe side effects. We hypothesized that the administration of an exclusive enteral nutrition (EEN) formula to CS would lead to increased CD remission rates and to decreased CS-related adverse events. We proposed to undertake a pilot study comparing EEN and CS therapy to CS alone to assess decrease symptoms and inflammatory markers over 6 weeks. AIM: The overall aim was to assess study feasibility based on recruitment rates and acceptability of treatment in arms involving EEN. METHODS: The pilot study intended to recruit 100 adult patients with active CD who had been prescribed CS to induce remission as part of their care. The patients were randomized to one of three arms: (i) standard-dose CS; (ii) standard-dose CS plus EEN (Modulen 1.5 kcal); or (iii) short-course CS plus EEN. RESULTS: A total of 2009 CD patients attending gastroenterology clinics were screened from October 2018 to November 2019. Prednisone was prescribed to only 6.8% (27/399) of patients with active CD attending outpatient clinics. Of the remaining 372 patients with active CD, 34.8% (139/399) started or escalated immunosuppressant or biologics, 49.6% (198/399) underwent further investigation and 8.8% (35/399) were offered an alternative treatment (e.g., antibiotics, surgery or investigational agents in clinical trials). Only three patients were enrolled in the study (recruitment rate 11%; 3/27), and the study was terminated for poor recruitment. CONCLUSION: The apparent decline in use of CS for treatment of CD has implications for CS use as an entry criterion for clinical trials.

Membrane flux through the pore formed by a fusogenic viral envelope protein during cell fusion.

We have investigated the mechanism of cell fusion mediated by HA, the fusogenic hemagglutinin of the Influenza viral envelope. Single erythrocytes (RBCs) were attached to fibroblasts expressing the HA on their cell surface, and fusion of the paired cells was triggered by rapid acidification. The RBC membrane was stained with fluorescent lipid, and the fusion-induced escape of lipid into the fibroblast was observed by quantitative image analysis. At the same time, the formation of an aqueous connection (i.e., the fusion pore) between the two cells was monitored electrically. Within minutes after acidification, an electrical conductance between the two cells appeared abruptly as the fusion pore opened, and then increased gradually as the pore dilated. Later, fluorescent lipid diffused into the fibroblast, approaching equilibrium over the next 5-20 min. No lipid flux was seen while the pore conductance remained 0.5 nS or less. Evidently lipid flux requires a threshold pore size. Our finding suggests that the smallest and earliest fusion pores are surrounded by a ring of protein. A fusion pore expands by breaking this ring and recruiting lipid into its circumference.

Rhythmic exocytosis stimulated by GnRH-induced calcium oscillations in rat gonadotropes.

In pituitary gonadotropes, gonadotropin-releasing hormone (GnRH) induces the rhythmic release of Ca2+ from an inositol 1,4,5-trisphosphate (IP3)-sensitive store. Simultaneous measurement of the concentration of cytosolic free Ca2+ ([Ca2+]i) and exocytosis in single identified gonadotropes showed that each elevation of [Ca2+]i induced a burst of exocytosis. These phenomena were largely suppressed by buffering of [Ca2+]i but persisted in the absence of extracellular Ca2+. Activation of voltage-gated Ca2+ channels by brief depolarizations seldom supplied enough Ca2+ for exocytosis, but [Ca2+]i elevations induced by photolysis of caged IP3 did trigger exocytosis, confirming that GnRH-stimulated gonadotropic hormone secretion is closely coupled to intracellular Ca2+ release. Agonist-induced oscillations of [Ca2+]i in secretory cells may be a mechanism to optimize the secretory output while avoiding the toxic effects of sustained elevation of [Ca2+]i.

The 100 most cited manuscripts in head and neck cancer: a bibliometric analysis.

OBJECTIVE: This study aimed to highlight the key studies that have led to the current understanding and treatment of head and neck cancer. METHOD: The Thomson Reuters Web of Science database was used to identify relevant manuscripts. The results were ranked according to the number of citations. The 100 most cited papers were analysed. RESULTS: A total of 63 538 eligible papers were returned. The median number of citations was 626. The most cited paper compared radiotherapy with and without cetuximab (3205 citations). The New England Journal of Medicine had the most citations (23 514), and the USA had the greatest number of publications (n = 66). The most common topics of publication were the treatment (n = 45) and basic science (n = 19) of head and neck cancer, followed by the role of human papillomavirus (n = 16). CONCLUSION: This analysis highlighted key articles that influenced head and neck cancer research and treatment. It serves as a guide as to what makes a 'citable' paper in this field.

Local Ca2+ release from internal stores controls exocytosis in pituitary gonadotrophs.

Exocytosis and the cell-averaged cytosolic [Ca2+], [Ca2+]i, were tracked in single gonadotrophs. Cells released 100 granules/s at 1 microM = [Ca2+]i when gonadotropin-releasing hormone (GnRH) activated IP3-mediated Ca2+ release from internal stores, but only 1 granule/s when [Ca2+]i was raised uniformly to 1 microM by other means. Strong exocytosis was then seen only at higher [Ca2+]i (half-maximal at 16 microM). Parallel second messengers did not contribute to GnRH-induced exocytosis, because IP3 alone was as effective as GnRH, and because even GnRH failed to trigger rapid exocytosis when the [Ca2+]i rise was blunted by EGTA. When [Ca2+]i was released from stores, exocytosis depended on [Ca2+]i rising rapidly, as if governed by Ca2+ flux into the cytosol. We suggest that IP3 releases Ca2+ selectively from subsurface cisternae, raising [Ca2+] near exocytic sites 5-fold above the cell average.

Alpha-latrotoxin stimulates inward current, rise in cytosolic calcium concentration, and exocytosis in at pituitary gonadotropes.

Alpha-latrotoxin (LTX) from the black widow spider venom, stimulates neurotransmitter release from neuronal cells via Ca2+ -dependent as well as Ca2+ -independent mechanisms. In some peptide-secreting endocrine cells, however, LTX stimulates hormone release mainly via a Ca2+ -independent mechanism. Here we investigated the action of LTX in rat pituitary gonadotropes that secrete the peptide, LH. Using the patch-clamp technique in conjunction with the fluorescent Ca2+ indicator (indo-1) to simultaneously measure the cytosolic Ca2+ concentration ([Ca2+]i) and ionic current, we showed that LTX elicited bursts of inward current that were accompanied by [Ca2+]i elevations. In the presence of a physiological concentration of extracellular Ca2+, the unitary conductance of the LTX-induced current was about 300 pS, and only about 6.4% of the current was carried by Ca2+. The LTX-induced current was occasionally followed by intracellular Ca2+ release. At [Ca2+]i of 1 microM or more, exocytosis (detected by membrane capacitance measurement) was consistently triggered, and it was frequently followed by endocytosis. Thus, LTX triggers Ca2+ -dependent exocytosis in gonadotropes via extracellular Ca2+ entry as well as intracellular Ca2+ release. In approximately 25% of the cells, LTX could also trigger a slow exocytosis in the absence of [Ca2+]i elevation. Therefore, LTX has both Ca2+ -dependent and Ca2+ -independent actions in gonadotropes.

Propoxyphene and norpropoxyphene: influence of diet and fluid on plasma levels.

The influence of various test meals and ingested fluid volumes on the bioavailability and pharmacokinetics of propoxyphene and its major metabolite norporpoxyphene has been studied in healthy human subjects. The absorption of drug was delayed by all test meals, but the overall efficiency of absorption was either not affected or was slightly increased. Increased fluid volume intake decreased propoxyphene bioavailability. Plasma levels of metabolite correlated well with levels of unchanged drug, particularly in the first 2 hr after dosing, but were not markedly influenced by treatments.

Variation in terminal morphology and presynaptic inhibition at crustacean neuromuscular junctions.

Synaptic terminals of excitatory and inhibitory neurons supplying muscle fibers in leg muscles of crabs (Pachygrapsus crassipes and Hyas areneus) were investigated with light and electron microscopy. Terminals responsible for large excitatory postsynaptic potentials (EPSPs) at low frequencies of activation had a compact configuration with clusters of terminal boutons radiating from the main axon branch. Terminals responsible for small EPSPs had a more diffuse organization, with boutons often arranged in series along thin axon branches. Inhibitory neurons, when activated, produced both presynaptic and postsynaptic inhibitory effects, with the former being more potent at low frequencies of activation. Presynaptic inhibition was variable in magnitude but was generally strong in fibers with large EPSPs. Representative terminals from regions of strong and weak presynaptic inhibition were identified by activity-dependent uptake of horseradish peroxidase, serially sectioned, and reconstructed from electron micrographs. Both regions were found to contain axo-axonal synapses from inhibitory to excitatory terminals, with a larger number in the region of strong presynaptic inhibition. In addition, axo-axonal synapses were more uniformly distributed in the latter region. The number of inhibitory presynaptic dense bars (active zones) was somewhat higher in the region of weak inhibition, but larger individual dense bars occurred in the region of strong inhibition. Possible factors contributing to the differences in strength of inhibition include: (1) morphology and electrical properties of terminals; and (2) high probability of transmission at a relatively small number of inhibitory synapses during low frequency activation in the region of strong inhibition.

Quisqualate agonists occlude kainate-induced current in cultured striatal neurons.

We employed the whole cell patch-clamp technique to examine the ionic currents induced via activation of kainate/quisqualate receptors on striatal neurons in primary culture when N-methyl-D-aspartate receptors were blocked by selective antagonists. Bath perfusion of 10 microM-1 mM each of quisqualate, glutamate, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (a selective quisqualate agonist) or kainate, induced only a sustained current, but more rapid application by pressure ejection of each of the first three agonists (but not kainate) also activated a rapidly desensitizing current. The current induced by a near-saturating concentration of kainate (1 mM) was, on average, 16-fold larger than the maximum sustained current induced by quisqualate (10 microM), or 7.5-fold larger than that induced by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (100 microM) or glutamate (100 microM). When kainate (100 microM-10 mM) was co-applied with each of the agonists (1 microM-1 mM), the sustained current was not the algebraic sum of the currents activated by kainate or the other agonist alone; rather, the kainate-induced current was increasingly occluded by co-application with increasing concentrations of another agonist. The potency to occlude kainate-induced current had a rank order of quisqualate greater than alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate approximately glutamate; although at sufficiently high concentrations all three agonists could occlude the kainate-induced current completely. When kainate and quisqualate were co-applied during the continued presence of quisqualate, the onset of the kainate-induced sustained current was dramatically slowed. However, the steady-state occlusion by quisqualate could be abolished when the ratio kainate to quisqualate was raised to 100:1; therefore, the occlusion appears to involve a competition between kainate and quisqualate at some shared receptor binding sites which have a higher affinity for quisqualate than kainate.

Pharmacokinetics of fluvastatin after single and multiple doses in normal volunteers.

The pharmacokinetics of fluvastatin, a potent inhibitor of hydroxymethylglutaryl-CoA reductase and thus cholesterol synthesis, have been studied in 24 normal male volunteers who received [3H] fluvastatin in three different studies: a single-dose study using oral doses of 2 or 10 mg, an absolute bioavailability study using doses of 2 mg intravenously or 10 mg orally, and a multiple-dose study using 40 mg orally once daily for 6 days. Serial blood and plasma samples and complete urine and feces were collected and analyzed for total radioactivity as well as for intact fluvastatin. Fluvastatin was rapidly and almost completely (greater than 90%) absorbed from the gastrointestinal tract, although the estimated bioavailability from the 2- and 10-mg doses was only 19 to 29% because of extensive first-pass metabolism. Fluvastatin pharmacokinetics appeared to be linear over the 2- to 10-mg dose range, as indicated by dose-proportional blood levels of total radioactivity and the parent drug. Absorbed fluvastatin was completely metabolized before excretion, the biliary/fecal route being the major excretory pathway. The recovery of radioactivity after a single dose was virtually complete within 120 hours. The terminal half-lives of fluvastatin and total radioactivity averaged 0.5 to 1 hour and 55 to 71 hours, respectively, whereas the total body clearance of fluvastatin was 0.97 L/hour/kg. Repeated oral administration of 40-mg doses of [3H]fluvastatin resulted in no time-related change in pharmacokinetic characteristics, but this dose yielded greater than proportional increases in circulating levels of the parent drug, thus suggesting a saturable first-pass effect on fluvastatin.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of compound 58-112, a potential skeletal muscle relaxant, in man.

The pharmacokinetics of 4-[(3-methoxyphenyl)methyl] -2,2,6,6-tetramethyl-1-oxa-4-aza-2,6-disilacyclohexane (Sandoz compound 58-112), a new chemical entity with a unique myotonolytic effect, was studied in 12 healthy male volunteers who received an oral dose of 50 or 100 mg of the 14C-labeled drug. Serial blood and breath samples and complete urine and feces were collected for 120 hours after dosing. All samples were analyzed for total radioactivity while the blood and urine were also assayed for unchanged compound 58-112. Measurable blood radioactivity levels were observed at 0.5 hour, and peak concentrations were attained at 1 to 2 hours after dosing. The absorption of the radioactive doses was complete and appeared linear in the 50-100 mg range, as indicated by blood 14C levels that were proportional to the dose. The 50- and 100-mg doses also resulted in virtually identical excretion patterns, with 95 per cent of the administered radioactivity recovered within 9 hours, almost exclusively in the urine. However, the disproportionately higher blood concentrations of unchanged compound 58-112 after the 100-mg dose could suggest saturable presystemic metabolism in the liver. Simultaneous fitting of all data in the 100-mg dose study to a pharmacokinetic model showed that unchanged compound 58-112 was distributed into a central and a peripheral compartment and was eliminated entirely by metabolism, the distribution and elimination half-lives being 0.5 and 3.9 hours, respectively. The metabolite(s) was distributed into one homogeneous space, and its elimination half-life was 0.1 hour, with a renal:fecal clearance ratio of approximately 96:4.

Focal labeling of axonal terminals with active synapses recorded by an extracellular macro-patch electrode.

A technique to label active synaptic terminals, whose electrophysiology had been monitored by a macro-patch electrode, was developed for a crustacean neuromuscular preparation. The active synaptic terminals were labeled by release-dependent uptake of horseradish peroxidase (HRP) into synaptic vesicles. The focal labeling technique involved the following steps: (1) locating a site where evoked synaptic currents could be recorded at a subset of neuromuscular synapses by a macro-patch electrode; (2) reducing synaptic transmission by bathing the preparation in a solution containing low [Ca2+] and high [Mg2+]; (3) introducing HRP as an extracellular marker into the solution bathing the preparation; (4) restoring synaptic release focally by ejection of a solution containing Ca2+ from the macro-patch electrode. The muscle fibre with labeled synapses was fixed for electron microscopy and processed for HRP histochemistry. The distribution of HRP-labeled vesicles was documented by electron microscopy and semi-serial sectioning. A significant increase in labeled vesicles was found within a maximum radius of 10-15 micron from the lumen of the macro-path electrode. This maximum radius of labeling set an upper limit to the number of active synapses recorded by the macro-patch electrode.

Phosphoinositides and GTP binding proteins involved in muscarinic generation of hippocampal rhythmic slow activity.

We examined the role of phosphoinositide turnover in muscarinic rhythmic slow activity (RSA; also called theta) in rat CA3 pyramidal neurons. Pre-incubation of hippocampal slices in pertussis toxin (which inhibits some GTP-binding proteins) or in Li+ (which blocks inositol phosphate degradation, and thereby decreases the resynthesis of phosphoinositides), prevented the induction of RSA by carbachol. Phorbol esters, which can activate protein kinase C (PKC) directly, did not induce RSA but inhibited muscarinic RSA. We infer that muscarinic RSA involves a GTP-binding protein linked increase in phosphoinositide turnover, while the activation of PKC may have a negative feedback role.

Pharmacokinetics of orally administered tizanidine in healthy volunteers.

The pharmacokinetics of tizanidine, a new centrally acting muscle relaxant, have been studied in 18 normal male volunteers who received orally a single 5 mg dose, a single 20 mg dose, or repeated administration of 4 mg every 8 hr for 13 doses of [14C]tizanidine. Serial blood and breath samples and complete urine and feces were collected and analyzed for total radioactivity as well as intact tizanidine. Tizanidine was rapidly and almost completely absorbed from the gastrointestinal tract, although the estimated bioavailability was only 21% due to extensive first-pass metabolism. The pharmacokinetics of tizanidine appeared to be linear in the 0-20 mg dose range, as indicated by the dose-proportional blood levels of total radioactivity as well as of parent drug. Absorbed tizanidine was almost completely metabolized before excretion, the major excretory route being via the kidneys. The terminal half-lives of tizanidine and radioactivity were ca 3 hr and 61 hr, respectively, and 76%-77% of the administered radioactivity was recovered within 120 hr. Repeated administration of [14C]tizanidine resulted in no apparent change in pharmacokinetic characteristics. During the 4 mg q 8 hr regimen, blood levels of tizanidine reached steady state after only 2 or 3 doses, whereas those of total radioactivity approached steady state after approximately 4 days. The degree of accumulation of radioactivity, unlike that of parent drug, was inconsistent with the terminal half-life, but instead implied a shorter effective half-life of ca. 16 hr. It appears that the terminal phase of the blood radioactivity profile represents a metabolite that is reversibly bound to and slowly released from a specific tissue depot, and that this binding involves a finite amount of drug regardless of the dose. The oral administration of [14C]tizanidine prescribed in the present study was safe and well tolerated.

High-throughput quantification of the anti-leukemia drug STI571 (Gleevec) and its main metabolite (CGP 74588) in human plasma using liquid chromatography-tandem mass spectrometry.

The signal transduction inhibitor STI571 (formerly known as CGP 57148B) or Gleevec received fast track approval by the US Food and Drug Administration (FDA) for treatment of chronic myeloid leukemia (CML). STI571 is a revolutionary and promising new oral therapy for CML, which functions at the molecular level with high specificity. The dramatic improvement in efficacy compared to existing treatments prompted an equally profound increase in the pace of development of Gleevec. The duration from first dose in man to completion of the New Drug Application (NDA) filing was approximately 2.6 years. In order to support all pharmacokinetics studies with sufficient speed to meet various target dates, a semi-automated procedure using protein precipitation was developed and validated. A Tomtec Quadra 96 (Model 320) and a protein precipitation step in a 96-well plate format were utilized. A Sciex API 3000 triple quadrupole mass spectrometer with an atmospheric pressure chemical ionization interface operated in positive ion mode was used for detection. The method proved to be rugged and allowed the simultaneous quantification of STI571 and its main metabolite (CGP 74588) in human plasma. Herein, assay development, validation, and representative concentration-time profiles obtained from clinical studies are presented.

Prednisolone bioavailability in the dog.

With a fasted dog as an animal model, the bioavailability and pharmacokinetics of prednisolone were studied following rapid intravenous injection and oral dosing of a prednisolone sodium phosphate solution and also following oral doses of prednisolone as tablets and a slurry. Hydrolysis of the phosphate ester to prednisolone in the body is extremely rapid and complete, thus permitting accurate calculation of the distribution volume of prednisolone. Enteral absorption of prednisolone from a slurry is superior to that from prednisolone tablets and from a prednisolone sodium phosphate solution. Reduced absorption from tablets, compared to the slurry, is probably due to tablet disintegration characteristics; reduced absorption from the solution is probably due to poor membrane permeability of the ionized drug. Information obtained from a single animal may indicate the need for expanded studies in humans.

Theophylline bioavailability in the dog.

The bioavailability of theophylline following single oral doses of a theophylline capsule, a theophylline tablet, and an aminophylline tablet in beagle dogs was compared against an intravenous standard. Plasma theophylline levels after oral and intravenous drug administration were described by the one-compartment open model. The onset of theophylline absorption from the oral products was rapid. While the theophylline tablet showed a slower absorption rate than the capsule or the aminophylline tablet, all three products appeared to be completely bioavailable.

Biliary excretion of [14C]temazepam and its metabolites in the rat.

The excretion of temazepam and its N-desmethyl metabolite, oxazepam, and their respective O-conjugates was examined following a single intravenous dose of [14C]temazepam to two groups of bile fistula rats, with and without bile replenishment to the animals via duodenal cannulae. During an 8-hr collection period, the two groups produced virtually identical bile volumes, and there were no significant differences between them in the amount of total radioactivity, free temazepam, or the identified metabolites in the bile, as determined by TLC and liquid scintillation counting. Elimination of the radioactive dose was rapid during 0-8 hr, with a half-life of approximately 1 hr. Approximately 85-90% of the administered radioactivity was recovered in the bile: less than 1% as free temazepam, 3% as oxazepam, and approximately 10% as their O-conjugates.

Binding of fluvastatin to blood cells and plasma proteins.

The binding of fluvastatin, an inhibitor of hydroxymethylglutaryl coenzyme A reductase, to plasma proteins and red blood cells of rat, dog, and human in vitro was determined by ultrafiltration. Additionally, the stereospecificity of fluvastatin binding to proteins and the potential interaction between fluvastatin and the highly protein bound drugs warfarin, salicylic acid, and glyburide were investigated. Only a small fraction of fluvastatin in blood was taken up by the blood cells, amounting to 19-33% in the rat and < or = 15% in dog and humans. The plasma:blood fluvastatin ratio in these species at 37 degrees C was > or = 1.4. In human blood, this ratio was temperature independent. In the plasma concentration range 25-50,000 ng/mL, fluvastatin was > or = 98% bound to proteins. The binding was concentration dependent in the rat, but not in the dog and human. Both enantiomers of fluvastatin were > 99% bound in normal human plasma, the binding of each being unaffected by the presence of the other. A major fluvastatin-binding protein in human plasma was albumin, whereas binding to alpha 1-acid glycoprotein was relatively weak and concentration dependent. At therapeutic concentrations in normal human plasma, the protein binding of fluvastatin (0.1 microgram/mL) was unaffected by warfarin (1-10 micrograms/mL), salicylic acid (50-150 micrograms/mL), and glyburide (0.1-1 micrograms/mL). Similarly, fluvastatin had no influence on the binding of these compounds. In diluted human albumin solution (29 microM), bound fluvastatin was displaced by all three co-solutes tested.(ABSTRACT TRUNCATED AT 250 WORDS)