Manifestation of fluorophore segmental motion in carbon dots in steady-state fluorescence experiments.

The steady state fluorescence anisotropy of carbon dot solutions of different viscosities η and its variation with temperature T has been investigated. The dependence of the anisotropy on T/η is shown to be described by the Perrin equation, which implies that Brownian rotational motion of carbon dots in solution is a basic mechanism of fluorescence depolarization. Peculiarities of the Perrin plot testify that the luminous entity ("fluorophore") responsible for carbon dot fluorescence displays noticeable segmental motions, which are independent of the overall rotational diffusion of the dots. The Perrin model fit to the experimental data yields the effective volumes of the fluorophore VF = 0.35 ± 0.15 nm3 and of the carbon dot as a whole VC = 10.5 ± 1.8 nm3. The rotational motions of the fluorophores are shown to be limited and spectrally dependent. A feasible nature of the fluorophores in question is discussed.

Effect of dark states on the fluorescence of carbon nanodots.

The nonlinear fluorescence properties of colloidal carbon dot solutions in glycerol were investigated at T = 298 K and 77 K. It was first found that the fluorescence intensity depended sublinearly on optical excitation intensity even at moderate excitation levels. With increasing excitation, the fluorescence signal shows a trend toward saturation, the latter being most pronounced at liquid nitrogen temperature. The relation between the fluorescence intensity and the excitation density was shown to be well approximated by the hyperbola equation. The behavior of the fluorescence intensity was theoretically described by a 3-level model that involves the singlet fluorescent state S1 and optically "dark" triplet state T1 of a carbon dot. The triplet states are almost inactive optically and manifest themselves in a very weak phosphorescence of the carbon dots that is several orders weaker than the fluorescence of the dots. The lifetimes of the triplet state were measured to be 0.75 ms at room temperature and 0.25 s at T = 77 K. Within the model used, the intersystem crossing (S1 → T1) lifetime in the carbon dots was estimated to be τIST ∼ 10-5 s at T = 77 K and τIST ∼ 10-6 s at T = 298 K.

Continuous symmetry of C60 fullerene and its derivatives.

Conventionally, the I(h) symmetry of fullerene C(60) is accepted, which is supported by numerous calculations. However, this conclusion results from the consideration of the molecule electron system, of its odd electrons in particular, in a closed-shell approximation without taking the electron spin into account. Passing to the open-shell approximation has led to both the energy and the symmetry lowering up to C(i). Seemingly contradicting to a high-symmetry pattern of experimental recording, particularly concerning the molecule electronic spectra, the finding is considered in this Article from the continuous symmetry viewpoint. Exploiting continuous symmetry measure and continuous symmetry level approaches, it was shown that formal C(i) symmetry of the molecule is by 99.99% I(h). A similar continuous symmetry analysis of the fullerene monoderivatives gives a reasonable explanation of a large variety of their optical spectra patterns within the framework of the same C(1) formal symmetry exhibiting a strong stability of the C(60) skeleton. TOC color pictures present chemical portrait of C(60) in terms of atomic chemical susceptibility (Sheka, E. Fullerenes: Nanochemistry, Nanomagnetism, Nanomedicine, Nanophotonics; CRC Press: Taylor and Francis Group, Boca Raton, 2011).

Frontonasal process-specific disruption of AP-2alpha results in postnatal midfacial hypoplasia, vascular anomalies, and nasal cavity defects.

A majority of the bones of the vertebrate cranial vault and craniofacial complex develop via intramembranous ossification, and are separated by fibrous sutures that undergo osteogenic differentiation in response to growth stimuli. Craniosynostosis is a common human birth defect that results from the premature bony fusion within skull sutures, and causes a myriad of complications including mental retardation and craniofacial anomalies. Synostosis of facial sutures has been reported to cause midfacial hypoplasia in some craniosynostosis cases, but most studies focus on cranial vault sutures. In this study, we have generated a mouse model of frontonasal suture synostosis and midfacial hypoplasia through the tissue-specific elimination of the AP-2alpha transcription factor. We report here the generation AP-2CRE, a frontonasal process (FNP)- and limb-specific CRE recombinase allele that is directed by human AP-2alpha promoter and enhancer elements. We used the AP-2CRE line in combination with the conditional AP-2alpha line to produce a new frontonasal knockout (FKO) mutant that lacks AP-2alpha in the FNP and limbs. FKO mice exhibit shortened snouts and wide-set eyes that become apparent at postnatal day 15. The most prominent defects in FKO snouts are (1) a lack of growth within the frontonasal sutures, and (2) a reduction in the snout vasculature. Additional defects are observed in the FKO nasal bones and sutures, the nasal cavity cartilage and bony projections, and the olfactory epithelium. The characteristics of the FKO mouse model are a unique combination of midfacial growth anomalies, and provide the first evidence that AP-2alpha is essential for appropriate postnatal craniofacial morphogenesis.

Peroxynitrite inhibits inducible (type 2) nitric oxide synthase in murine lung epithelial cells in vitro.

Peroxynitrite, formed by nitric oxide (NO) and superoxide, can alter protein function by nitrating amino acids such as tyrosine, cysteine, trytophan, or methionine. Inducible nitric oxide synthase (Type 2 NOS or iNOS) converts arginine to citrulline, releasing NO. We hypothesized that peroxynitrite could function as a negative feedback modulator of NO production by nitration of iNOS. Confluent cultures of the murine lung epithelial cell line, LA-4 were stimulated with cytokines to express iNOS, peroxynitrite was added, and the flasks sealed. After 3 h, NO in the headspace above the culture was sampled. Peroxynitrite caused a concentration-dependent decrease in NO. Similar results were obtained when 3-morpholinosydnonimine (SIN-1), a peroxynitrite generator, was added to the flasks. PAPA-NONOate, the NO generator, did not affect the headspace NO. Nitration of the iNOS was confirmed by detection of 3-nitrotyrosine by Western blotting. These data suggest a mechanism for inhibition of NO synthesis at inflammatory sites where iNOS, NO, and superoxide would be expected.

Inflammatory cytokines modulate eotaxin release by human lung fibroblast cell line.

Eotaxin, a potent eosinophil-specific chemotactic factor, is increased in the lower respiratory tract of asthma patients. Recently, lung fibroblasts have been reported to produce eotaxin and their activation can be modulated by inflammatory cytokines. To test the hypothesis that inflammatory cytokines modulate the eotaxin release from lung fibroblasts, we investigated the potential of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), or interferon-gamma (IFN-gamma) to induce the release of eotaxin and eotaxin mRNA by the human fetal lung fibroblast cell line, HFL-1, was evaluated. HFL-1 released eotaxin constitutively without stimulation, but IL-1beta or TNF-alpha stimulated eotaxin release in a dose- and time-dependent manner. IL-1beta or TNF-alpha treatment of HFL-1 also resulted in the augmented expression of eotaxin mRNA. Although IFN-gamma alone had negligible effect on eotaxin release and mRNA expression, IFN-gamma induced a significant, concentration-dependent attenuation of eotaxin release and eotaxin mRNA expression from HFL-1 stimulated with IL-1beta or TNF-alpha. These findings are consistent with the concept that lung fibroblast-derived eotaxin may in part be responsible for the eosinophil infiltration observed in the airways of asthmatic patients and that network of cytokines may modulate the eosinophil recruitment to the airways by stimulation of fibroblasts to release eotaxin.

Erythromycin modulates eosinophil chemotactic cytokine production by human lung fibroblasts in vitro.

Recent studies suggest that erythromycin can suppress the production of some cytokines and may be an effective treatment for asthma. Eosinophil chemotactic cytokines have been suggested to contribute to the pathogenesis of asthma by the recruitment of eosinophils. We hypothesized that erythromycin modulates eosinophil chemotactic cytokine production. To test the hypothesis, we evaluated the potential of erythromycin to modulate the release of eosinophil chemoattractants from the human lung fibroblast cell line HFL-1. HFL-1 released eotaxin, granulocyte-macrophage colony-stimulating factor, and regulated and normal T-cell expressed and presumably secreted (RANTES) in response to interleukin-1beta or tumor necrosis factor alpha. Erythromycin attenuated the release of these cytokines and eosinophil chemotactic activity by the HFL-1. The suppressive effect on eotaxin was the most marked of these cytokines. Erythromycin therapy also suppressed eotaxin mRNA significantly. These results suggest a mechanism that may account for the apparent beneficial action of macrolide antibiotics in the treatment of allergic airway disorders.

Reactive oxygen and nitrogen metabolites modulate fibronectin-induced fibroblast migration in vitro.

Nitration of proteins by peroxynitrite may alter protein function. We hypothesized that reactive nitrogen species modulate fibronectin-induced fibroblast migration. To test this hypothesis, we evaluated fibroblast migration induced by fibronectin incubated with and without peroxynitrite. Peroxynitrite attenuated fibronectin-induced fibroblast migration in a dose-dependent manner but did not attenuate complement-activated serum-induced fibroblast migration. The reducing agents, deferoxamine and dithiothreitol (DTT), and L-tyrosine reversed the inhibition by peroxynitrite. PAPA-NONOate, a nitric oxide (NO) donor, and superoxide generated by the action of xanthine oxidase on lumazine or xanthine, also showed an inhibitory effect on fibroblast migration. The peroxynitrite generator, 3-morpholinosydnonimine (SIN-1), caused a concentration-dependent inhibition of fibroblast migration. Peroxynitrite reduced fibronectin binding to fibroblasts and resulted in nitrotyrosine formation. These findings are consistent with nitration of tyrosine by peroxynitrite with subsequent inhibition of fibronectin binding to fibroblasts and suggest that peroxynitrite may play a role in regulation of fibroblast migration.

Helicobacter pylori and dyspepsia: a population-based study of the organism and host.

OBJECTIVE: The role of Helicobacter pylori (HP) infection in dyspepsia in the absence of peptic ulcer remains controversial. Specific attributes of the organism or the host response may be important. We aimed to determine whether HP infection overall, CagA status, serum gastrin, or serum pepsinogen levels are associated with dyspepsia in the community. METHODS: A self-report bowel disease questionnaire was mailed to a random sample of Olmsted County, Minnesota residents, aged 20-50 yr. All respondents who reported symptoms of dyspepsia or irritable bowel syndrome (cases) and all respondents without significant GI symptoms (controls) were invited to participate (n = 260). They were each assessed by a physician and their medical records reviewed. Serum was obtained to measure HP and CagA antibodies, pepsinogen I and II levels, and basal serum gastrin using validated assays. RESULTS: Of the 148 (57%) subjects who agreed to participate, 36 had dyspepsia (17 had ulcer-like dyspepsia), 35 had irritable bowel syndrome (IBS) without dyspepsia, and 77 were asymptomatic. The proportion who were seropositive for HP were 17% in dyspepsia (24% in ulcer-like dyspepsia), 20% in IBS, and 12% in asymptomatic controls. HP was not associated with dyspepsia, ulcer-like dyspepsia, or IBS after adjusting for age. Pepsinogen levels and serum gastrin were not associated with any of the conditions studied. However, CagA antibody positivity was associated with IBS (p < 0.05), and a borderline statistically significant association with dyspepsia was detected (p = 0.08). CONCLUSIONS: In this community, HP infection overall does not seem to explain dyspepsia, although the role of CagA-positive HP strains deserve further study.

Bradykinin stimulates eotaxin production by a human lung fibroblast cell line.

BACKGROUND: Bradykinin, a potent inflammatory peptide, is increased in the airways of allergic patients. Accompanying the elevated bradykinin levels are increases in both eosinophils and fibroblasts. Eotaxin, a potent eosinophil-specific chemotactic factor, is released by fibroblasts and increased in the lower respiratory tract of allergic patients. OBJECTIVE: We sought to test the hypothesis that lung fibro-blasts release eotaxin in response to bradykinin. METHODS: The potential of bradykinin to induce the release of eotaxin from the human lung fibroblast cell line HFL-1 was tested by cell culture and evaluation of the culture supernatant fluids and RNA for immunoreactive eotaxin and eotaxin messenger RNA. RESULTS: HFL-1 cells released eotaxin constitutively without stimulation, but bradykinin stimulated eotaxin release in a dose- and time-dependent manner and resulted in augmented expression of eotaxin messenger RNA. The release of eotaxin was sensitive to the action of glucocorticoids. Eosinophil chemotactic activity by HFL-1 supernatant fluids was inhibited by anti-human eotaxin-neutralizing antibody. Consistent with these results, inhibitors of bradykinin B2 receptors, but not bradykinin B1 receptors, inhibited bradykinin-induced eotaxin release. CONCLUSION: These data demonstrate that bradykinin may stimulate lung fibroblasts to release eotaxin and suggest the potential for this mechanism to be important in modulation of lung inflammation.

Changes in metabolism of TRH in euthyroid sick syndrome.

OBJECTIVE: The aim of this study was to examine the metabolism of a simple dose, intravenously administered TRH bolus of 200 microg, in patients with euthyroid sick syndrome (ESS). PATIENTS AND METHODS: A TRH test was performed on ten ESS patients and ten controls upon admission (d1) and after recovery (d2). Blood samples were collected at 0, 10, 20 and 30min after TRH injection. We analyzed the volume of distribution (V(d)), the plasma clearance rate (PCR), the fractional clearance rate (FCR), the half-life (t(1/2)) and the TSH response to the injection of TRH. RESULTS: All patients had lower tri-iodothyronine (T(3)) levels compared with controls (0.9 +/- 0. 1nmol/l vs 1.9 +/- 0.1 nmol/l; P < 0.0001; mean +/- S.D.; paired t-test). In addition, the V(d) (16.7 +/- 5.9/l vs 30.6 +/- 0.6/l; P < 0.0005) and PCR (2.0 +/- 0.80 l/min vs 3.3 +/- 0.25 l/min; P <0. 0005) were found statistically lowered in patients than in controls, whereas FCR (0.119 +/- 0.01 permin vs 0.110 +/- 0.01 per min; P < 0. 025) was found increased in patients as opposed to controls. The t(1/2) of exogenously administered TRH was increased in ESS compared with controls (7.2 +/- 0.7 min vs 6.3 +/- 0.6 min; P <0.005). TSH response to TRH was found significantly repressed at 10, 20 and 30 min after TRH injection. On d2, these findings had reverted to normal and no changes regarding the kinetics of TRH and the response of TSH could be detected between patients and controls. CONCLUSIONS: The results demonstrate an impairment of TRH metabolism in ESS. The findings may suggest altered enzymatic activity, responsible for TRH degradation in states of acute ESS. These changes might be involved in the pathogenesis of ESS and represent part of an adaptive mechanism to this syndrome.

Efficacy of conventional endoscopic disinfection and sterilization methods against Helicobacter pylori contamination.

BACKGROUND: Iatrogenic transmission of Helicobacter pylori via contaminated endoscopic devices is well documented. Despite the prevalence of this infectious agent, few controlled studies have investigated the major factors that impact on reprocessing of endoscopes contaminated with H. pylori. MATERIALS AND METHODS: An endoscope (Pentax) was contaminated with 108 cfu/ml of H. pylori in 5% bovine calf serum as standardized inoculum. The endoscope then was passed through one of eight arms (five repetitions per arm = 40 total runs), as follows: 1, recovery control (no cleaning or disinfection); 2, manual cleaning alone; 3-5, manual precleaning followed by either 10-, 20-, or 45-minute exposure to 2% glutaraldehyde and ethanol (ETOH) drying; 6, manual cleaning followed by automated reprocessing by STERIS System; 7 and 8, automated reprocessing by STERIS with and without active peracetic acid sterilant (wash-off control). Suction-biopsy channels and air-water channels were harvested for microbiological culture. RESULTS: Control runs recovered more than 1 x 106 cfu per site, confirming the viability of the test organism and the adequacy of the biological burden for challenge. When instruments underwent manual cleaning alone (without subsequent disinfection), test organisms remained in 40% of runs at the air-water site. Manual cleaning followed by 10-, 20-, or 45-minute glutaraldehyde exposure and ETOH drying removed all test organisms from all sites in all runs (i.e., 100% disinfection). The automated STERIS system with or without active peracetic acid sterilant also removed all test organisms from all sites in all runs, as did manual cleaning followed by STERIS use. CONCLUSION: Manual cleaning alone does not effectively remove H. pylori from an endoscope. Current joint association recommendations for minimal disinfection (manual cleaning followed by at least 20 minutes of immersion in glutaraldehyde and ETOH drying) are effective in preventing cross-transmission of H. pylori. Reprocessing using the automated STERIS system according to manufacturer's recommendations also is highly effective in sterilizing endoscopes contaminated with H. pylori.

Antimicrobial efficacy of endoscopic disinfection procedures: a controlled, multifactorial investigation.

BACKGROUND: Adequate disinfection of endoscopes is essential to prevent environmental and patient-to-patient transmission of infectious agents, but data from controlled studies are limited. Moreover, there is controversy regarding current guidelines for disinfection. We compared the antimicrobial efficacy of several endoscopic disinfection procedures controlling for multiple factors that affect reprocessing. METHODS: A colonoscope was contaminated with 10(8) CFU/mL of Enterococcus faecalis as a standardized inoculum. The colonoscope was passed through 1 of 16 study arms (5 reps/arm for a total of 80 runs) that were controlled for all possible combinations of the following variables: manual precleaning; 10-, 20-, or 45-minute glutaraldehyde exposure; air or ethanol drying; or automated reprocessing with peracetic acid (liquid sterilization system). Suction accessory channels and air-water channels were harvested for microbiologic culture. RESULTS: Control runs (no cleaning or disinfection) recovered more than 5 x 10(7) CFU/mL from each sampling site. When each processing variable was isolated independent of other variables, the benefits of manual precleaning, longer soak times, and ethanol drying were apparent. When factors were combined, manual precleaning followed by 20- and 45-minute glutaraldehyde exposure and ethanol drying removed all test organisms, as did processing with the liquid sterilization system. CONCLUSION: Although the initial cost is higher, the automated liquid sterilization system provides effective sterilization and minimizes worker exposure. In units where chemical disinfection is used, our results suggest that manual precleaning followed by at least 20-minute glutaraldehyde exposure and ethanol rinse drying are sufficient to achieve complete disinfection.

Characterization of Lyme meningitis and comparison with viral meningitis in children.

OBJECTIVES: The objectives of this study were to characterize Lyme meningitis (LM) in the pediatric population; to compare LM with viral meningitis (VM) with respect to epidemiology, history and physical examination, and laboratory data; and to provide means of early distinction of Lyme neuroborreliosis from other forms of aseptic meningitis. METHODS: This retrospective analysis involved children admitted to Alfred I. duPont Hospital for Children between 1990 and 1996 whose discharge diagnoses indicated viral or aseptic meningitis or Lyme disease. LM was defined as the presence of cerebrospinal fluid (CSF) pleocytosis with positive Lyme serology and/or erythema migrans. Patients were considered to have VM if they exhibited CSF pleocytosis and had a positive viral culture. Demographic, clinical, and laboratory data were collected for each patient, and patients with LM were compared with age-matched patients with VM. RESULTS: Of 179 patient records, 12 patients with LM and 10 patients with VM (all, >2 years old) were identified by using the above criteria. In comparing LM patients with VM patients, we noted no differences among demographic variables. Children with LM had significantly lower temperatures at the time of presentation. The presence of headache, neck pain, and malaise was similar for the two groups, but the duration of these symptoms was significantly longer among LM patients. Five children with LM had cranial neuropathies. All but 1 LM patient exhibited either papilledema, erythema migrans, or cranial neuropathy. These three findings were absent in the VM group. On CSF analysis, LM patients had fewer white blood cells (mean, 80/mm3 versus 301/mm3) and a significantly greater percentage of mononuclear cells than the VM patients. CONCLUSIONS: In this study, in a Lyme-endemic area, LM was about as common as VM in older children who were hospitalized with aseptic meningitis. Attention to pertinent epidemiologic and historical data, along with physical and CSF findings, allows early differentiation of LM from VM.

Effect of precollicular transection on audiogenic seizures in genetically epilepsy-prone rats.

Previous studies have demonstrated that generalized tonic-clonic seizures (GTCS) consisting of running/bouncing clonic and tonic extension can still be elicited in rats after brain transections which separate forebrain from brain stem, showing that forebrain circuitry is not required for GTCS. Inasmuch as sound-induced generalized tonic-clonic seizures in rodents are characterized by running-bouncing clonic and tonic convulsions, we have hypothesized that these are brain stem seizures that can occur independently of the forebrain. To test this hypothesis, we examined the response of two strains of genetically epilepsy-prone rats (GEPR-3s and GEPR-9s) to seizure-evoking auditory stimuli 3 h after a precollicular transection or sham surgery performed under ether anesthesia. In addition, the effect of a precollicular transection on audiogenic seizures was evaluated in normal rats made susceptible to such seizures by infusing NMDA into the inferior colliculus. Following the transection 58% of GEPR-9s displayed a sound-induced tonic-clonic convulsion and the remaining 42% exhibited a sound-induced seizure when subjected to stimulation 5 min after a subconvulsant dose of pentylenetetrazol (PTZ). While sham surgery and the precollicular transection both reduced sound-induced seizure severity in GEPR-3s, the full seizure response could be elicited by sound stimulation following a subconvulsant dose of PTZ. Moreover, the audiogenic seizures in normal rats rendered susceptible by NMDA were unaltered by the precollicular transection. These findings show that the anatomical circuitry required for generalized tonic-clonic seizures evoked by sound stimulation in rodents resides within the brain stem.

Independent cycles of exocrine pancreatic secretion, hormones and gastroduodenal motility in healthy fasting humans: reassessment of a complex partnership.

BACKGROUND: Interdigestive pancreatic secretion cycles in close association with the phases of the migrating motor complex (MMC) and release of regulatory hormones. The extrinsically denervated pancreas exhibits an intrinsic cyclic rhythm. We hypothesized that this intrinsic rhythm is normally present in the intact human pancreas. METHODS: 19 healthy males (age range 26-35 years) were studied after 12 h fasting. A manometry catheter was positioned with four pressure ports in the antrum and three in the duodenum, and motility was recorded for a complete MMC cycle or 5 h. Duodenal aspirates were sampled at 15-min intervals, and immediately analysed for amylase, lipase and chymotrypsin activities; enzyme outputs were calculated by standard marker perfusion techniques. Plasma levels of pancreatic polypeptide (PP) and motilin were also determined (RIA) at 15-min intervals. RESULTS: Output of amylase, lipase and chymotrypsin occurred in parallel. All phase III motility fronts were accompanied by a pancreatic secretory peak. However, in 12 subjects at least one secretory peak was observed without the concomitant occurrence of phase III. A total of 16 out of 51 secretory peaks identified across all subjects were independent (31%). These phase III-independent peaks of pancreatic secretion occurred in subjects with a longer MMC cycle (160 +/- 19 min vs 102 +/- 13 min, P < 0.05). Phase III-associated and -independent peaks had a similar magnitude (amylase output: 21.6 +/- 3.9 kUh-1 vs 21.1 +/- 2.8 kUh-1, respectively). Irrespective of MMC phases, antral but not duodenal motor activity was closely correlated with fluctuations of pancreatic secretion (P < 0.05). Cycling of PP and motilin were also closely coordinated with pancreatic enzymes, with a particularly tight link between endocrine and exocrine secretion from the pancreas. CONCLUSIONS: Peaks of pancreatic secretion invariably occur when a phase III motor activity occurs, but additional secretory peaks occur without a concomitant phase III. Interdigestive phasic pancreatic secretion is tightly coordinated with PP and motilin release as well as with antral motor activity. An intrinsic rhythm of the pancreas distinct from other cyclic activity may be present in healthy humans, expressed as peaks of pancreatic secretion independent of a motor phase III.

Prospective randomized comparison of stonetome combination catheter versus conventional endoscopic clearance of common bile duct.

OBJECTIVES: To assess the therapeutic efficacy and performance characteristics of a novel cannula that has recently become available for clearance of the common bile duct (CBD), combining a sphincterotome and retrieval balloon in a single instrument, and to compare it with the conventional approach. METHODS: Seventeen consecutive patients with signs of biliary obstruction were prospectively randomized to undergo evaluation and clearance of the CBD by combination catheter (Stonetome, Microvasive) or conventional sphincterotomy (Ultratome) with separate balloon sweep. In all cases, three sweeps of the CBD were made with an 11.5-mm retrieval balloon after sphincterotomy. Fluoroscopy time was measured, as was total time from initiation of sphincterotomy to removal of endoscope from the patient. The same endoscopist performed all procedures. RESULTS: Patient groups were matched with regard to age, gender, proportion with prior cholecystectomy, CBD diameter, and stone size. Patients were successfully treated by either approach. Use of the Stonetome combination catheter reduced mean fluoroscopy time by 52% (from 3.1 +/- 0.6 to 1.5 +/- 0.2 min), mean total time by 57% (from 11.3 +/- 2.2 to 4.9 +/- 1.1 min), and dosage of midazolam used for conscious sedation. CONCLUSIONS: The new combination catheter allows the elimination of one step in exchanging the sphincterotome for a retrieval balloon after sphincterotomy. Its efficacy in clearing the CBD is equal to that of our conventional approach. Use of the combined approach should minimize the risk of losing cannulation, reduce fluoroscopic exposure, and improve the overall efficiency of the procedure.

M1 muscarinic mechanisms regulate intestinal-phase gallbladder physiology in humans.

The contribution of muscarinic receptor subtypes to biliary control mechanisms is unclear. We investigated stimulated gallbladder function and release of associated hormones during M1-receptor blockade. Following a double-blind, randomized, crossover protocol, healthy volunteers each received placebo and telenzepine, a selective M1-receptor antagonist, as 2-h background infusion. Gallbladder contraction (by ultrasonography), bilirubin output, and release of cholecystokinin (CCK) and pancreatic polypeptide (PP) were assessed during increasing doses of endogenous (intraduodenal nutrient) and exogenous (hormonal) stimulation. All parameters were stimulated in a dose-dependent manner on placebo days. Contractile and secretory responses to low-dose caerulein (CCK analogue) were inhibited by 60-80% under telezepine, whereas high-dose (supraphysiological) stimulation overrode this effect. Similar inhibition was achieved during nutrient stimulation. CCK plasma levels rose during endogenous and exogenous stimulation but were unaffected by M1 blockade, whereas stimulated PP release was completely inhibited (> 100% decrease), reflecting suppressed vagal tone. Selective M1-receptor blockade inhibits the physiological response of the gallbladder in humans; this effect cannot be attributed to suppressed CCK release. Our findings support the hypothesis that CCK acts at the gallbladder via cholinergic nerves under physiological conditions. Viewed with our previous observations, nonselective antagonism of biliary function by atropine is primarily mediated through M1 muscarinic pathways.

M1-muscarinic mechanisms regulate interdigestive cycling of motor and secretory activity in human upper gut.

We determined the influence of M1-muscarinic pathways in modulating temporal cycling of motor and secretory activity in the fasting upper gut. Eight healthy subjects were studied on two separate days, following a double-blind, randomized protocol. Antroduodenal motility (migrating motor complex, MMC), pancreatic exocrine secretion (amylase, lipase, trypsin, chymotrypsin), and plasma levels of associated hormones [motilin, pancreatic polypeptide (PP)] were monitored for two consecutive cycles during background infusion of placebo or telenzepine, a selective M1-muscarinic receptor antagonist. On placebo days, pancreatic enzymes and hormones cycled in synchrony with motor activity, as expected. During M1 blockade, duodenal output of each enzyme was decreased by 85-90% in phase I and by > 90% in phase III. Similarly, plasma concentrations of hormones were decreased during all phases and cycling was absent. Despite the loss of these putative influences, intestinal motility continued to cycle, albeit in an altered fashion. Intermittent phase II activity was replaced by phase I quiescence, while phase III-like fronts were diminished (contraction frequency, amplitude, propagation velocity reduced 30-60%, duration not altered) but recurred at expected intervals (cycle length 105 +/- 14 min vs 109 +/- 12 in placebo). Gastric motor activity was virtually abolished. These data suggest or extend several working hypotheses: (1) Motilin is released and/or acts via cholinergic (M1-muscarinic) pathways to initiate antral, but not duodenal, phase III activity. (2) M1 receptors mediate all components of the gastric MMC and phase II activity throughout the gut, but intestinal phase III activity arises via alternate pathways. (3) M1-muscarinic mechanisms regulate interdigestive cycling of pancreatic enzymes and PP. (4) Secretions from the endocrine/exocrine pancreas are not primary mediators of intestinal motility.