Nutrient-induced spatial patterning of human duodenal motor function

The spatiotemporal patterning of duodenal motor function has been evaluated comprehensively for the first time in humans, with a novel 21-lumen manometric assembly. In nine young, healthy volunteers (6 male, 3 female), duodenal motility was recorded during fasting and three 45-min intraduodenal (ID) nutrient infusion periods (Intralipid at 0.25, 0.5, and 1.5 kcal/min). Pressures were recorded along the length of the duodenum with an array of 18 sideholes at 1.5-cm intervals. Pressure patterns were compared for the final 20 min of each of the four periods. Compared with fasting, ID lipid was associated with regional variation in pressure wave (PW) sequences, with fewer proximally and more distally; this was not observed during fasting (P < 0.001). During fasting and all rates of lipid infusion, most (87-90%) PW sequences were short (1.5-4.5 cm), with a small number (2-4%) of 10.5 cm or longer. At all times, antegrade PW sequences occurred more frequently than retrograde sequences over all distances examined (3, 4.5, and >6 cm), and the proportion of antegrade sequences increased with greater PW sequence length (P = 0.0001). Increasing ID lipid rates appeared to produce dose-related suppression of PW sequences (P < 0.001). The frequency and spatial patterning of human duodenal motor function show substantial variability in response to different nutrient delivery rates. These complex patterns are likely to be involved in duodenal modulation of flow and gastric emptying rate.

The in vitro activity of ABT773, a new ketolide antimicrobial agent

The in vitro activity of ABT773, a ketolide antimicrobial agent, was investigated and compared with those of seven other antibiotics. Type strains and 733 Gram-positive, Gram-negative and anaerobic isolates of clinical origin and four CHLAMYDIA: isolates were used. The activity of ABT773 was very similar to that of telithromycin, the other ketolide tested. The MIC(90) was < or = 0.5 mg/L for all bacteria examined except methicillin-resistant Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Haemophilus influenzae and BACTEROIDES: spp. The antichlamydial activity of ABT773 was greater than that of telithromycin, erythromycin and ciprofloxacin. Neither an increase in the size of the inoculm nor the addition of human serum had any marked affect on the in vitro activity of ABT773.

Repression of tax-mediated human t-lymphotropic virus type 1 transcription by inducible cAMP early repressor (ICER) protein in peripheral blood mononuclear cells

Human T-lymphotropic virus type 1 (HTLV-1) infection causes adult T-cell leukemia and is characterized by long periods of clinical latency with low levels of viral production. Transcription of HTLV-1 is controlled through sequences in the promoter and enhancer regions of the long terminal repeat of the integrated provirus. Important among these sequences are three 21 bp imperfect repeats responsive to the viral oncogenic protein Tax (TRE). Members of the CREB/ATF-1/CREM family of transcription factors bind to TRE-1 and are critical for HTLV-1 transcription. Other less studied family members include the inducible cAMP early repressor (ICER) proteins. ICER proteins lack phosphorylation and activation domains and are potent inhibitors of transcription. The ability of ICER to bind TRE-1 and its effects on HTLV-1 Tax mediated transcription have not been studied in the natural cell targets of the virus, peripheral blood mononuclear cells (PBMC). We show that ICER mRNA levels are low in quiescent PBMC, but rise and remain elevated for up to 18 hr after mitogenic stimulation of these cells. Electrophoretic mobility shift assays using recombinant Tax and ICER demonstrate that ICER binds TRE-1 and that binding is increased in the presence of Tax. Furthermore, over expression of ICER IIgamma suppressed Tax-mediated transcription whereas an anti-sense ICER II plasmid designed to block endogenous ICER enhanced Tax-mediated transcription in activated PBMC. Together our data indicate that ICER inhibits Tax-mediated transcription in activated PBMC and suggest a role for ICER in maintenance of HTLV-1 persistence.

Evaluation of the Oxoid Aura image system for measuring zones of inhibition with the disc diffusion technique

In this study the Oxoid Aura image antibiotic sensitivity test system, used as a stand-alone device, was compared with manual zone measurement and use of a template, for the determination of sensitivities. An overall correlation coefficient of 0.99 was observed for zone diameters measured using the Aura image system and zones measured manually, when the differences between zones were within 3 mm; 5.4% of zones showed a difference in zone diameter between manual and automated measurement of >3 mm. The results obtained using the template method for interpretation were less reliable than zone measurement, with cefuroxime and ampicillin tested against Enterobacteriaceae and Acinetobacter spp. When linked to a laboratory patient database, the bar code and disc identification facilities avoided errors that were associated with manual data entry.

Tentative minimum inhibitory concentration and zone diameter breakpoints for moxifloxacin using BSAC criteria

Tentative MIC and zone diameter breakpoints were determined for moxifloxacin using BSAC criteria. An MIC breakpoint of < or =1 mg/L, denoting sensitivity, is suggested for Enterobacteriaceae, staphylococci, haemophili, moraxellae, pneumococci and enterococci. For pseudomonads high and low breakpoints of 4 mg/L and 1 mg/L are suggested to allow for an intermediate category of sensitivity. A 1 microg moxifloxacin disc content is suggested for testing all of the organisms previously mentioned, except pseudomonads, for which a 5 microg disc is needed to discriminate between the intermediate and sensitive populations. Corresponding zone diameter breakpoints for a 1 microg disc are > or = 20 mm for Enterobacteriaceae and staphylococci, 18 mm for the respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) and 15 mm for enterococci. For Pseudomonas aeruginosa with a 5 microg disc, three bands are suggested for interpretation, that of > or = 25 mm (sensitive), 18-24 mm (intermediate) and < or = 17 mm (resistant).

A study to determine the pharmacokinetics and inflammatory fluid penetration of gatifloxacin following a single oral dose

A single 400 mg oral dose of gatifloxacin was given to each of nine healthy male volunteers and the concentrations of the drug in plasma, cantharidine-induced inflammatory fluid and urine were measured over the following 24 h. The mean peak concentration in plasma of 4. 1 mg/L was attained at a mean time of 1.8 h post dose. The mean peak concentration in inflammatory fluid was 3.6 mg/L and was attained at a mean time of 4.2 h post dose. The mean plasma elimination half-life of gatifloxacin was 6.8 h and that in inflammatory fluid was 7.2 h. The mean penetration into the inflammatory fluid was 117%. Recovery of drug from urine during the first 24 h post dose was 65% of that administered. Our data suggest that gatifloxacin dosed at 400 mg od should be adequate to treat systemic infections caused by most bacterial species.

The in-vitro activity and tentative breakpoint of gemifloxacin, a new fluoroquinolone

The in-vitro activity of gemifloxacin, a new fluoroquinolone, against a wide range (c. 700) of recent clinical isolates, was compared with that of three other fluoroquinolones and other relevant agents. Gemifloxacin inhibited 90% of the Enterobacteriaceae strains at 0.5 mg/L or less, exceptions being Serratia spp. (MIC(90) 1 mg/L) and strains possessing a putative mechanism of resistance to fluoroquinolones. Ninety per cent of Pseudomonas aeruginosa were inhibited by 4 mg/L. Gemifloxacin had good activity against respiratory pathogens, with 90% of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis being inhibited by 0.06 mg/L or less. Staphylococcus aureus (MSSA) were highly susceptible (MIC(90) 0.06 mg/L) but MRSA less susceptible (MIC(90) 8 mg/L) to gemifloxacin. Enterococcus spp. were markedly more susceptible to the study agent than to ciprofloxacin. Gemifloxacin showed good activity against Bacteroides fragilis (MIC(90) 0.5 mg/L) and anaerobic cocci. A tentative in-vitro breakpoint of 0.5 mg/L was studied using a 1 microg disc content for all genera except Pseudomonas where a 5 microg disc content was employed. The false sensitivity reporting rate was 0.5% and false resistance rate was 6.0%, which was considered acceptable. In conclusion, gemifloxacin is a highly active fluoroquinolone that should prove clinically useful in the treatment of a wide range of infections. Susceptibility testing criteria have been developed that should prove robust in a clinical laboratory.

Pharmacokinetics and inflammatory-fluid penetration of moxifloxacin following oral or intravenous administration

A single 400-mg oral or intravenous (i.v.) dose of moxifloxacin was given to each of eight healthy male volunteers, and 6 weeks later the dose was administered by the other route. The concentrations of the drug in plasma, cantharidin-induced inflammatory fluid, and urine were measured over the subsequent 24 h. The mean maximum concentrations observed in plasma were 4.98 microg/ml after oral dosing and 5.09 microg/ml after i.v. dosing. The mean maximum concentrations attained in the inflammatory fluid were 2.62 and 3.23 microg/ml, respectively. The mean elimination half-lives from plasma were 8.32 and 8.17 h, respectively. The overall penetration into the inflammatory fluid was 103.4 and 104.2%. Over 24 h 15% of the drug was recovered in the urine when administered by either route.

Effects of age on concentrations of plasma cholecystokinin, glucagon-like peptide 1, and peptide YY and their relation to appetite and pyloric motility

BACKGROUND

Aging is associated with a decrease in appetite and a slowing of gastric emptying. The gastrointestinal hormones cholecystokinin (CCK), glucagon-like peptide 1 (GLP-1), and peptide YY (PYY) may mediate these changes.

OBJECTIVE

We investigated whether aging influenced the secretion of CCK, GLP-1, and PYY and their effects on appetite and pyloric motility.

DESIGN

Eight healthy older (65-80 y) and 7 younger (20-34 y) men received isoenergetic (12.1 kJ/min) intraduodenal infusions of lipid and glucose for 120 min on separate days. Plasma CCK, GLP-1, and PYY concentrations were measured.

RESULTS

Plasma CCK concentrations were higher in older than in younger subjects (P = 0.004) as a result of higher baseline values (4.7+/-0.2 compared with 3.2+/-0.2 pmol/L; P < 0.0001) and a greater rise during lipid infusion (increase from baseline: 7.1+/-0.5 compared with 5.3+/-0.6 pmol/L; P = 0.048). Plasma GLP-1 and PYY concentrations were not significantly different between groups. The decrease in hunger during intraduodenal lipid infusion was inversely related to the increase in CCK, GLP-1, and PYY in younger but not older subjects. During intraduodenal lipid infusion, the increase in isolated pyloric pressure wave (IPPW) frequency was positively related to GLP-1 and PYY and the increase in IPPW amplitude was positively related to CCK in older but not younger subjects, whereas the increase in IPPW amplitude and pyloric tone was negatively related to GLP-1 and PYY in younger subjects.

CONCLUSIONS

Human aging is associated with increased CCK concentrations, which may contribute to the slowing of gastric emptying, mediated by increased pyloric motility. The role of increased plasma CCK concentrations in mediating the age-related decrease in appetite remains to be established.

Bactericidal properties of moxifloxacin and post-antibiotic effect

The time-kill kinetics and post-antibiotic effect (PAE) of moxifloxacin were studied for strains of Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Staphylococcus aureus and Escherichia coli. Moxifloxacin had a bactericidal effect against all strains tested, with the least rapid bactericidal effect being against S. pyogenes and the most rapid effect against S. aureus and E. coli. The PAE of moxifloxacin was similar to that of other fluoroquinolones and increased with increasing concentration. No association was found between the bactericidal effect of moxifloxacin and the duration of PAE. Gram-positive and gram-negative organisms were also exposed to concentrations of moxifloxacin, sparfloxacin and amoxycillin that simulated the drug concentrations obtained in human serum after standard oral dosing schedules. Simulation of moxifloxacin concentrations in human serum reduced viable counts more effectively and more rapidly than shown in time-kill experiments; in contrast, sparfloxacin and amoxycillin were less effective than when constant concentrations of these antibacterials were used.

Validation of a novel luminal flow velocimeter with video fluoroscopy and manometry in the human esophagus

There is currently no ideal method for concurrently assessing intraluminal pressures and flows in humans with high temporal resolution. We have developed and assessed the performance of a novel fiber-optic laser-Doppler velocimeter, mounted in a multichannel manometric assembly. Velocimeter recordings were compared with concurrent fluoroscopy and manometry following 50 barium swallows in healthy subjects. During these swallows, the velocimeter sensor was situated in either the proximal (24 swallows) or the distal (26 swallows) esophagus. It signaled intraluminal flow following 46 of 50 swallows. A greater mean number of deflections were recorded in the distal compared with the proximal esophagus (4. 3 vs. 2.4, P = 0.001). The maximal flow velocity recorded did not differ between the proximal and distal esophagus (76.7 vs. 73.8 mm/s). No velocimeter signals commenced after fluoroscopic lumen occlusion. The velocimeter signals were closely temporally related to fluoroscopic barium flow. Upward catheter movement on swallowing sometimes appeared to cause a velocimeter signal. Manometrically "normal" swallows were no different from "abnormal" swallows in the number and velocity of deflections recorded by the velocimeter. This novel instrument measures intraluminal flow velocity and pressures concurrently, thus enabling direct study of pressure-flow relationships. Flow patterns differed between the proximal and distal esophagus.

Physiological changes in blood glucose do not affect gastric compliance and perception in normal subjects

Marked hyperglycemia (blood glucose approximately 14 mmol/l) slows gastric emptying and affects the perception of sensations arising from the gut. Elevation of blood glucose within the physiological range also slows gastric emptying. This study aimed to determine whether physiological changes in blood glucose affect proximal gastric compliance and/or the perception of gastric distension in the fasting state. Paired studies were conducted in 10 fasting healthy volunteers. On a single day, isovolumetric and isobaric distensions of the proximal stomach were performed using an electronic barostat while the blood glucose concentration was maintained at 4 and 9 mmol/l in random order. Sensations were quantified using visual analog scales. The blood glucose concentration had no effect on the pressure-volume relationship during either isovolumetric or isobaric distensions or the perception of gastric distension. At both blood glucose concentrations, the perceptions of fullness, nausea, bloating, and abdominal discomfort, but not hunger or desire to eat, were related to intrabag volume (P </= 0.002) and pressure (P </= 0.01). We conclude that, in the fasted state, elevations of blood glucose within the physiological range do not affect proximal gastric compliance or the perception of gastric distension.

The concentrations of clinafloxacin in alveolar macrophages, epithelial lining fluid, bronchial mucosa and serum after administration of single 200 mg oral doses to patients undergoing fibre-optic bronchoscopy

The concentrations of clinafloxacin were measured in serum, bronchial mucosa, alveolar macrophages and epithelial lining fluid after single 200 mg oral doses of clinafloxacin had been administered to 15 subjects who were undergoing bronchoscopy. Concentrations were measured using a microbiological assay method. Mean concentrations in serum, bronchial mucosa, alveolar macrophages and epithelial lining fluid at a mean of 1.27 h post-dose were 1.54, 2.65, 15.60 and 2.71 mg/L respectively. These site concentrations exceeded the MIC90 for common respiratory pathogens and indicate that clinafloxacin is likely to be effective in the treatment of a wide range of respiratory tract infections.

Study to assess the reliability of a disc diffusion method for determining the sensitivity of gram-positive pathogens to dalfopristin/quinupristin

A standardized method of disc testing the sensitivity of gram-positive pathogens to dalfopristin/quinupristin was developed, and then 'field tested' in ten centres in the UK. For a 15 microg disc, zone diameter breakpoints of 20 mm and 15 mm are suggested when organisms are tested on Iso-Sensitest agar and Iso-Sensitest agar supplemented with 5% whole horse blood, respectively.

The in-vitro activity of HMR 3647, a new ketolide antimicrobial agent

The in-vitro activity of HMR 3647, a novel ketolide, was investigated in comparison with those of erythromycin A, roxithromycin, clarithromycin (14-membered ring macrolides), amoxycillin-clavulanate and ciprofloxacin against 719 recent clinical Gram-positive, Gram-negative and anaerobic isolates and type cultures. HMR 3647 generally demonstrated greater activity than the other compounds with MIC90s of < or =0.5 mg/L, except for Staphylococcus epidermidis (MIC90 > 128 mg/L), Haemophilus influenzae (MIC90 = 2 mg/L), Enterococcus faecalis (MIC90 = 2 mg/L), Enterococcus faecium (MIC90 = 1 mg/L) and the anaerobes, Bacteroides fragilis (MIC90 = 2 mg/L) and Clostridium difficile (MIC90 = 1 mg/L). In general, an increase in the size of the inoculum from 10(4) to 10(6) cfu on selected strains had little effect on the MICs of HMR 3647. Additionally, the in-vitro activity of HMR 3647 was not affected by the presence of either 20 or 70% (v/v) human serum. The antichlamydial activity of HMR 3647 was generally greater than that of commonly used antichlamydial antimicrobials.

The in-vitro activity of linezolid (U-100766) and tentative breakpoints

The in-vitro activity of linezolid, a novel oxazolidinone, was investigated in comparison with those of amoxycillin, cefuroxime, quinupristin/dalfopristin, trovafloxacin and vancomycin against 420 recent Gram-positive and anaerobic clinical isolates. Linezolid was equally active (MIC90 1 mg/L) against methicillin-susceptible and -resistant Staphylococcus aureus. It demonstrated uniform activity against streptococci and enterococci and no cross-resistance with other agents. The time-kill kinetic data demonstrated that the in-vitro activity of linezolid was predominantly bacteriostatic; slow bactericidal activity was only observed at the higher concentration with streptococci. An increase in inoculum from 10(4) to 10(6) cfu on selected strains had little effect on the MICs (MIC90 within one dilution step) of linezolid and an increase in inoculum from 10(5) to 10(7) cfu/mL had no notable effect on the in-vitro bactericidal activity. A tentative linezolid breakpoint of 2 mg/L was chosen after analysis of distribution of susceptibilities.

The effect of the cellular stress response on human T-lymphotropic virus type I envelope protein expression

In this report the influence of the cellular stress response in mediating changes in human T-lymphotropic virus type I (HTLV-I) viral envelope (Env) protein metabolism is determined. Previously, we reported that induction of the cellular stress response enhanced HTLV-I-mediated syncytia formation following induction of the cellular stress response in persistently infected lymphocytes. In this study, we show that the increase in HTLV-I-mediated syncytia formation following stress response induction is a result of increased cell surface expression of viral Env protein (gp46). Cellular stress in MT 2.6 cells did not alter the turnover of intracellular Env protein (gp68) as no changes in viral protein half-life were demonstrated as compared to non-stressed cells. However, Env expression in stressed cells treated with a protein synthesis inhibitor (cycloheximide) indicates the effect is mediated through increased translation of viral Env protein.

Effects of meal volume and posture on gastric emptying of solids and appetite

The effects of volume and posture on gastric emptying and intragastric distribution of a solid meal and appetite were evaluated. Eight normal volunteers were studied on four occasions, on each of which a meal comprising ground beef mixed with tomato sauce of either 650 g ("large") or 217 g ("small") was eaten. Two studies were performed while the subject was lying in the left lateral decubitus position, and two studies were performed while the subject was sitting so that in each subject data were available for both meals and in both postures. Hunger and fullness were evaluated using a visual analog questionnaire. In both postures and after both meals, gastric emptying approximated a linear pattern after an initial lag phase. The lag phase was shorter for the large meal when compared with the small meal [sitting: large 13 +/- 5 vs. small 29 +/- 7 min; left lateral: large 16 +/- 3 vs. small 24 +/- 3 min, F(1, 7) = 46.3, P < 0.0005]. In both postures the contents of the total [F(1,7) = 1794.5, P < 0.0001], proximal [F(1,7) = 203.7, P < 0.0001], and distal [F(1,7) = 231.5, P < 0.0001] stomach were greater after the large meal when compared with the small meal. Although the 50% emptying time was greater with the large than the small meal [F(1,7) = 40.8, P < 0.001], the postlag emptying rate (g/min) was more rapid with the large meal [sitting: large 1.7 +/- 0.2 vs. small 1.1 +/- 0. 1 g/min; left lateral: large 1.8 +/- 0.1 vs. small 1.3 +/- 0.04 g/min, F(1,7) = 44.7, P < 0.0005]. There was a significant interaction between meal volume and posture for retention in the distal stomach [F(1,7) = 7.14, P < 0.05]. Contrasts were used to evaluate the effects of volume and posture between the four studies and demonstrated an effect of posture for the large [F(1,21) = 18.7, P < 0.005] but not the small [F(1,21) = 0.30, P = 0.60] meal so that the retention was greater in the sitting when compared with the left lateral position. The magnitude of the postprandial increase in fullness [F(1,7) = 7.8, P < 0.05] and reduction in hunger [F(1,7) = 5.9, P < 0.05] was greater with the large meal. We conclude that meal volume has a major effect on gastric emptying; in contrast posture has only a minor impact on intragastric meal distribution, which is observed only after a large meal, and no effect on gastric emptying.

Physiological changes in blood glucose affect appetite and pyloric motility during intraduodenal lipid infusion

We evaluated the effects of varying blood glucose concentration within the normal postprandial range and its interaction with small intestinal nutrients on antropyloric motility and appetite. Eight healthy males (19-40 yr) underwent paired studies, with a blood glucose level of 5 or 8 mmol/l. Manometry and visual analog scales were used to assess motility and appetite, during fasting and intraduodenal lipid infusion (1.5 kcal/min). In the fasting state, antral waves were suppressed at 8 mmol/l compared with 5 mmol/l (P = 0.018). However, pyloric motility was no different between the two blood glucose concentrations. Hunger was no different at 5 mmol/l compared with 8 mmol/l, but fullness was greater at 8 mmol/l (P = 0. 01). During intraduodenal lipid infusion, antral waves were suppressed (P < 0.035) and isolated pyloric pressure waves (IPPWs) were stimulated (P < 0.02) compared with during the fasting state, with no difference between blood glucose concentrations, although the temporal patterning of IPPWs varied between blood glucose concentrations. The amplitude of IPPWs was greater at 5 mmol/l compared with 8 mmol/l (P < 0.001), and hunger decreased at 8 mmol/l compared with 5 mmol/l (P = 0.02). We conclude that "physiological" hyperglycemia modifies gastric motor and sensory function and that synergy exists between blood glucose concentration and small intestinal nutrients in modulating gastric motility and appetite.

Comparison of the modified Stokes' method of susceptibility testing with results obtained using MIC methods and British Society of Antimicrobial Chemotherapy breakpoints

The majority of clinical microbiology laboratories in the UK use comparative disc diffusion methods based on the Stokes' method to determine antibiotic susceptibility. The technical validity of the results obtained from the modified Stokes' method of disc testing and how they relate to MIC data are not known. We studied susceptibility testing using a modified Stokes' disc diffusion method for a wide range of clinical isolates against which MICs had been determined by collaborators not involved with the disc testing evaluation. Results indicated that for 1301 organism-antibiotic combinations the number of major errors (where resistant strains were reported as sensitive) was 21/468 (4.4%) and the number of minor errors (where sensitive strains were reported as resistant) was 14/713 (1.9%) using ciprofloxacin breakpoints of 0.5 and 2 mg/L. There was good correlation between the disc susceptibility test and the MIC for 119 isolates of Enterobacteriaceae tested with the exception of Serratia spp. Excluding Serratia spp. the number of major errors for Enterobacteriaceae was 1/200 (0.5%). Data revealed 2/25 (8%) major errors for Pseudomonas aeruginosa and 1/45 (2.2%) for Acinetobacter spp. Haemophilus influenzae showed a number of unexpected categorization errors. The modified Stokes' method performed accurately for Staphylococcus aureus and coagulase-negative staphylococci when tested for susceptibility to gentamicin, erythromycin, teicoplanin and vancomycin. No major errors were reported for Streptococcus pneumoniae and beta-haemolytic streptococci. Problems occurred with the detection of antibiotic resistance in Enterococcus spp. Major errors were seen for ampicillin (2/12 strains), teicoplanin (5/6 strains) and vancomycin (5/13 strains) using a 30 microg disc but only 1/13 strains using a 5 microg disc. Overall, from our data, the modified Stokes' disc diffusion antibiotic susceptibility test showed an unacceptable number of major errors but an acceptable number of minor errors.