Topiramate selectively attenuates nicotine-induced increases in monoamine release.
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Animals↗
Biomedical subjects
C Barnett
Publications and source records attributed to C Barnett.
Cloning and expression of an endocellulase gene from a novel streptomycete isolated from an East African soda lake.
Alkaline cellulase-producing actinomycete strains were isolated from mud samples collected from East African soda lakes. The strains were identified as novel Streptomyces spp. by 16S rDNA sequence analysis. A cellulase gene (cel12A) from Streptomyces sp. strain 11AG8 was cloned by expression screening of a genomic DNA library in Escherichia coli. From the nucleotide sequence of a 1.5-kb DNA fragment, an open reading frame of 1,113 nucleotides was identified encoding a protein of 371 amino acids. From computer analysis of the sequence, it was deduced that the Cel12A mature enzyme is a protein of 340 amino acids. The protein contained a catalytic domain, a glycine-rich linker region, and a cellulose-binding domain of 221, 12, and 107 amino acids, respectively. FASTA analysis of the catalytic domain of Cel12A classified the enzyme as a family 12 endoglucanase and the cellulose-binding domain as a family IIa CBD. Streptomyces rochei EglS was determined as nearest neighbor with a similarity of 75.2% and 61.0% to the catalytic domain and the cellulose-binding domain, respectively. The cell2A gene was subcloned in a Bacillus high-expression vector carrying the Bacillus amyloliquefaciens amylase regulatory sequences, and the construct was transformed to a Bacillus subtilis host strain. Crude enzyme preparations were obtained by ultrafiltration of cultures of the Bacillus subtilis recombinant strain containing the 11AG8 cell2A gene. The enzyme showed carboxymethylcellulase (CMCase) activities over a broad pH range (5-10) with an optimum activity at pH 8 and 50 degrees C. The enzyme retained more than 95% of its activity after incubation for 30 min under these conditions.
Africa, Eastern↗
Age-related accumulation of oxidative DNA damage and alterations in levels of p16(INK4a/CDKN2a), p21(WAF1/CIP1/SDI1) and p27(KIP1) in human CD4+ T cell clones in vitro.
T cells in vivo have been shown to accumulate DNA damage with age. To investigate the effects of DNA damage on T cell biology we have utilised an in vitro human CD4+ T cell clone model. Levels and types of DNA damage were determined in 11 independent T cell clones as a function of their in vitro lifespan. Increased levels of reactive oxygen species (ROS) induced DNA damage with increasing age were found in all clones analysed using a modified alkaline comet assay. T cell clones underwent apoptosis at the end of their lifespans. There were no consistent changes in the mRNA levels for the cyclin-dependent kinase inhibitors (CKI) p16, p21, and p27 during the clones' lifespans. It appears that the increased levels of ROS induced DNA damage in the T cells is not the major trigger of apoptosis, via the p53/p21 pathway. In addition, at the end of their lifespans, the T cell clones did not display the CKI phenotype reported for senescent cells (an increase in p16 and p21 levels). Thus, while the T cell clones appear sensitive to ROS-induced DNA damage, the molecular mechanisms through which this influences T cell dysfunction with age remains to be elucidated.
Adult↗
The effects of carnosine on oxidative DNA damage levels and in vitro lifespan in human peripheral blood derived CD4+T cell clones.
Carnosine (beta-alanyl-L-histidine), an abundant naturally-occurring dipeptide has been shown to exhibit anti-ageing properties towards cultured cells, possibly due in part to its antioxidant/free radical scavenging abilities. In this paper the results of an investigation on the effects of carnosine, at the physiological concentration of 20 mM, on oxidative DNA damage levels and in vitro lifespan in peripheral blood derived human CD4+ T cell clones are reported. Under the culture conditions used (20% O(2)) long term culture with carnosine resulted in a significant increase in the lifespan of a clone derived from a healthy young subject. No such extension was observed when a T cell clone from a healthy old SENIEUR donor was similarly cultured. Culture with carnosine from the midpoint of each clone's lifespan did not have any effect on longevity, independent of donor age. Oxidative DNA damage levels were measured in the clones at various points in their lifespans. Carnosine acted as a weak antioxidant, with levels of oxidative DNA damage being lower in T cells grown long term in the presence of carnosine. The possibility that carnosine might confer anti-ageing effects to T cells under physiological oxygen tensions would appear to be worthy of further investigation.
Carnosine↗
Acute gastritis with hypochlorhydria: report of 35 cases with long term follow up.
BACKGROUND: Between 1976 and 1987, 35 cases of acute gastritis with hypochlorhydria (AGH) were seen in our research laboratory. The aims of this study were to determine the natural history of AGH and the role of Helicobacter pylori in its pathogenesis. METHODS: Archived serum and gastric biopsy samples obtained from AGH subjects were examined for evidence of H pylori colonisation. Twenty eight of 33 (85%) surviving AGH subjects returned a mean of 12 years after AGH for follow up studies, including determination of H pylori antibodies, basal and peak acid output, endoscopy, and gastric biopsies. A matched control group underwent the same studies. RESULTS: Archived material provided strong evidence of new H pylori acquisition in a total of 14 subjects within two months, in 18 within four months, and in 22 within 12 months of recognition of AGH. Prevalence of H pylori colonisation at follow up was 82% (23 of 28) in AGH subjects, significantly (p<0.05) higher than in matched controls (29%). Basal and peak acid output returned to pre-AGH levels in all but two subjects. CONCLUSIONS: One of several possible initial manifestations of H pylori acquisition in adults may be AGH. While H pylori colonisation usually persists, hypochlorhydria resolves in most subjects.
Achlorhydria↗
Realigning the service. Evaluating maternity day care in Ninewells Hospital, Dundee.
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Day Care, Medical↗
Mechanism of gastroesophageal reflux in premature infants with chronic lung disease.
BACKGROUND/PURPOSE: The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of preterm infants with chronic lung disease (CLD). METHODS: Esophageal motility was recorded for 2 to 3 hours postprandially in 14 preterm infants with mild-moderate or moderate-severe CLD at 33 to 39 weeks postmenstrual age using a sleeve-side hole micromanometric assembly into which a pH probe had been installed. RESULTS: Twenty-six acid GER episodes were recorded by pH probe. Of these, 22 (85%) were associated with transient lower esophageal sphincter (LES) relaxation. Transient LES relaxations were significantly longer in duration than single swallows (13.7 seconds v 4.6 seconds, P < .001) and had lower nadir pressures (1.1 mm Hg v 2.5 mm Hg, P < .001). During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences. CONCLUSIONS: In preterm infants with CLD, transient LES relaxations are the predominant mechanism underlying GER, and esophageal clearance mechanisms are fully functional, which is similar to that seen in healthy preterm infants.
Chronic Disease↗
Reproducibility of the 13C-octanoic acid breath test for assessment of gastric emptying in healthy preterm infants.
BACKGROUND: The 13C-octanoic acid breath test has been used to measure gastric emptying in preterm infants, but the reproducibility of the test has not been evaluated in this population. METHODS: Fifty-six paired breath test analyses were performed on 28 healthy preterm infants 1 to 5 days apart using the same food type, volume, and energy content for each paired sample. Breath samples were taken before the feeding, at 5-minute intervals after feeding for 30 minutes, then each 15 minutes for 4 hours. Samples were analyzed using an isotope-ratio mass spectrometer, and 3C recovery was used to calculate values for gastric-emptying coefficient and gastric half-emptying time. RESULTS: There was no significant difference between test results on different days in the paired samples studied. gastric-emptying coefficients for the first and subsequent samples were 2.6+/-0.1 (mean+/-SEM) and 2.7+/-0.1, respectively, and half-emptying times were 44.5+/-3.7 minutes and 41.4+/-3.2 minutes. CONCLUSION: The 13C-octanoic acid breath test is a reliable, noninvasive, and reproducible measure of gastric emptying in preterm infants that should have wide application for use in this population.
Breath Tests↗
Arteriovenous fistula presenting as airway hemorrhage after percutaneous tracheostomy.
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Adult↗
Measurement of upper esophageal sphincter tone and relaxation during swallowing in premature infants.
Upper esophageal sphincter (UES) motor function has not been previously evaluated in premature infants. The motor patterns associated with tonic activity and swallow-related relaxation of the UES were recorded for 1 h after completion of gavage feeding in 11 healthy preterm neonates (postmenstrual age 33-37 wk) with a micromanometric assembly, which included a sleeve sensor specifically adapted for UES recordings. A clearly defined UES high-pressure zone was observed in all premature infants studied. Resting UES pressure ranged from 2.3 to 26.2 mmHg and was higher during periods of irritability and apparent discomfort. During dry swallows, UES pressure relaxed from a resting pressure of 28.2 +/- 4.0 mmHg to a nadir of 1.1 +/- 3.3 mmHg. The mean UES relaxation interval (the time from relaxation onset to relaxation offset) was 0. 31 +/- 0.11 s. We conclude that in premature infants >/=33 wk postmenstrual age the motor mechanisms regulating UES resting pressure and the onset of UES relaxation are well developed.
Deglutition↗
Mechanisms of gastroesophageal reflux in healthy premature infants.
OBJECTIVES: The aim of this study was to characterize the motor events responsible for gastroesophageal reflux (GER) and esophageal acid clearance in a cohort of healthy preterm infants. STUDY DESIGN: Esophageal motility was recorded for 2 to 3 hours after a feeding in 24 preterm infants, 31 to 38 weeks' postmenstrual age, by using a sleeveside hole micromanometric assembly incorporating a pH probe. RESULTS: Sixty acid GER episodes were recorded by pH probe, and 133 non-acid GER episodes were recorded manometrically by the presence of esophageal common cavities. Of the 193 GER episodes, 159 (82%) were associated with transient lower esophageal sphincter relaxation (TLESR). TLESRs were significantly longer in duration than single swallows (15.1 seconds vs 5.6 seconds, P < .001) and had lower nadir pressures (0.8 mm Hg vs 2.3 mm Hg, P < .001). A total of 3216 esophageal body pressure waves were analyzed; 70% of swallow-induced pressure waves were peristaltic in sequence compared with 5% of swallow-unrelated pressure waves. During periods of esophageal acidification (pH below 4), peristaltic esophageal body pressure wave sequences cleared acid refluxate more effectively than nonperistaltic pressure wave sequences. CONCLUSIONS: In healthy preterm infants, TLESRs are the predominant mechanism underlying GER, and esophageal clearance mechanisms are well developed by at least 31 weeks' postmenstrual age.
Cohort Studies↗
The relationship between plasma potassium concentration and muscle torque during recovery following intense exercise.
The present study investigated the relationship between plasma potassium ion concentration ([K+]) and skeletal muscle torque during three different 15-min recovery periods after fatigue induced by four 30-s sprints. Four males and one female completed the multiple sprint exercise on three separate days; recovery was passive, i.e. no cycling exercise (PRec), active cycling at 30% peak oxygen consumption. VO2peak (30% Rec) and active cycling at 60% VO2peak (60% Rec). Plasma [K+] was measured from blood sampled from an antecubital vein of subjects at rest and at 0, 3, 5, 10 and 15 min into each recovery. Isokinetic leg strength was measured at rest and at 1, 6, 11 and 16 min during each recovery. Following the exhaustive sprints, [K+] increased significantly from an average mean (SEM) resting value of 3.81 (0.07) mmol.l-1 to 4.48 (0.19) mmol.l-1 (P < 0.01). In all recovery conditions, plasma [K+] returned to resting levels within 3 min following the fourth sprint. However, in the two active recovery conditions plasma [K+] increased over the remainder of the recovery periods to 4.36 (0.12) mmol.l-1 in the 30% Rec condition and 4.62 (0.12) mmol.l-1 in the 60% Rec condition, the latter being significantly higher than the former (P < 0.01). The maximum torque measured following the sprints decreased significantly, on average, to 61.1 (8.36)% of peak levels (P < 0.01). After 15 min of recovery, maximum torque was highest in the 30% Rec condition at 92.13 (3.06)% of peak levels (P < 0.01), compared to 85.23 (3.64)% and 85.71 (0.82)% for the PRec and 60% Rec conditions, respectively. In contrast to the significant differences in plasma [K+] across all three recovery conditions, muscle torque recovery was significantly different in only the 30% Rec condition. In summary, recovery of peak levels of muscle torque following fatiguing exercise does not appear to follow changes in plasma [K+].
Adult↗
Nitric oxide reduces endothelial expression of intercellular adhesion molecule (ICAM)-1.
Nitric oxide (NO.) has proven effective in improving oxygenation and reducing pulmonary hypertension in the acute respiratory distress syndrome (ARDS), but the precise mechanism remains unclear. NO. has been shown to reduce leukocyte-endothelial adhesion, attenuate neutrophil (PMN) sequestration, and protect endothelium from an inflammatory insult. Intercellular adhesion molecule (ICAM)-1 is a pivotal regulator of PMN-endothelial adhesion and, thus, a critical mediator of PMN cytotoxicity. Consequently, we hypothesized that NO. suppresses ICAM-1 expression on endothelium. Human umbilical vein endothelial cells (HUVEC) were cultured. The NO. donor 3-morpholinosidnonimine (SIN-1) (0.1-10 microM) was incubated with HUVEC for 4 hr. In separate experiments, HUVEC were incubated with bacterial lipopolysaccharide (LPS) (100 ng/ml) alone or following SIN-1 pretreatment. ICAM-1 expression on HUVEC was measured by flow cytometric analysis. SIN-1 (1 and 10 microM) reduced the expression of ICAM-1 on resting HUVEC by 58 and 47%, respectively. LPS upregulated ICAM-1 expression; however, this was not affected by SIN-1 pretreatment. We conclude that NO. reduces constitutive endothelial expression of ICAM-1, but does not prevent LPS-stimulated upregulation of ICAM-1 expression. Downregulation of ICAM-1 may be a mechanism whereby NO. protects resting endothelium (distant organ bed) from circulating primed or activated PMNs, but may not be as effective at a primary inflammatory site.
Analysis of Variance↗
Relationship between gear ratio and 10-s sprint cycling on an air-braked ergometer.
This investigation examined the relationship between gear ratio and peak and mean power outputs (PPO and MPO) and peak cadence (PC) during a 10-s all-out sprint on a multi-geared air-braked cycle ergometer. Ten physically active men [mean age 21.0 years (SEM 0.7)] performed in random order six 10-s sprints (15-min rest between each sprint) on two occasions (48 h apart) in six different gear ratios; flywheel revolutions per pedal crank revolution (FR/PCR) ranged between 5.22 and 11.61. The PPO, MPO, and PC were recorded from each sprint. Of the six gear ratios tested, a gear ratio eliciting 8.87 FR/PCR elicited the highest PPO for the initial test session; the PPO output of 1274 W was significantly greater (P < 0.01) than that produced in the other five gears. Analysis of data from the second test session revealed no statistically significant difference in PPO between gear ratios eliciting 8.00, 8.87, and 10.06 FR/PCR. The PPO from these three ratios were significantly greater (P < 0.05) than those produced using the ratios resulting in 6.32, 7.06, and 10.78 FR/PCR. The PC in the gear ratio maximising PPO was 120 rpm. Analysis of PC data revealed a significant decrease (P < 0.05) as the number of FR/PCR increased.
Adult↗
Would reading an account of an event refresh your memory?
Witnesses to an event who have prepared an account of it may be given an opportunity to review this account or to read another account before testifying. The authors investigated the effects of this procedure by using participant accounts and both accurate and misleading experimenter-prepared accounts. Another experimental group did not review any account. Participants given no opportunity to refresh memory were less accurate in free recall than participants who refreshed memory, but they were equally accurate in answering direct questions. Measures of consistency between performance on testing sessions showed that the opportunity to review a self-produced account resulted in more consistent performance than nonreview. Results of this study have important implications in pretrial witness preparation.
Adolescent↗
A new method for the calculation of constant supra-VO2peak power outputs.
This investigation compared the variance in times to exhaustion among four different methods of supra-VO2peak power output calculation. Ten male subjects cycled to exhaustion at power outputs equivalent to 1) 120% VO2peak, 2) 6 W.kg-1, 3) 100% VO2peak + 10% of the peak anaerobic scope (PAS), and 4) 100% VO2peak + 20% of the mean anaerobic scope (MAS). PAS was defined as the difference between the peak power output (PPO) during a 30-s all-out cycle sprint and the power output at VO2peak MAS was defined as the difference between the mean power output (MPO) during a 30-s all-out cycle sprint and the power output at VO2peak. While the mean times to exhaustion for the four methods were not significantly different, the supra-VO2peak power output calculated as 120% VO2peak resulted in significantly more variance (P = 0.0173) in the times to exhaustion than did the power output equivalent to 20% MAS + 100% VO2peak (SE 16.2 s vs 6.9 s). The variance in time to exhaustion was significantly higher with the power output of 6 W.kg-1 than for the remaining three methods, while the variance in times to exhaustion at a power output of 10% PAS + 100% VO2peak was not significantly different from either 120% VO2peak or 20% MAS + 100% VO2peak. These results indicate that a supra-VO2peak power output that accounts for both aerobic ability and anaerobic work capacity (20% MAS + 100% VO2peak) results in less variance in time to exhaustion than a method which extrapolates the submaximal power output-VO2 relationship to a supramaximal intensity (120% VO2peak).
Adolescent↗
Effects of oral creatine supplementation on multiple sprint cycle performance.
This study examined the influence of oral creatine monohydrate supplementation on repeated 10 s cycle ergometer sprint performance. Seventeen recreationally active males (mean +/- SD age, body mass, height, and peak oxygen uptake = 20.5 +/- 1.2 yr, 72.1 +/- 10.3 kg, 176.8 +/- 6.6 cm and 3.87 +/- 0.91 l.min-1, respectively) participated in the 16 day experiment. All subjects initially completed a VO2peak test and were then administered glucose (4 x 10 g per day) in a single blind fashion for four days, after which they completed the first series of multiple sprints (7 x 10 s). Following the sprints, subjects were matched on sprint performance and divided into two groups (n = 8, placebo (Pl); and n = 9, creatine (Cr)). For the following four days, diets were supplemented with either Cr (4 x 70 mg.kg-1 body mass per day mixed with 5 g glucose) or glucose (4 x 10 g per day); supplementation during this phase was double-blind. Subjects then repeated the multiple sprint and VO2peak tests. Measures of peak power output (PPO), mean power output (MPO), end-power output (EPO), and percent power decline were recorded during the sprints. Each 10 s sprint was separated by 30 s of passive recovery except for sprints five and six which were separated by five minutes. Venous blood was sampled at rest, immediately after sprint five, before sprint six, and following sprint seven for the analysis of plasma lactate and blood pH. Expired air was sampled for five minutes following sprint seven for the calculation of post-exercise VO2. Analysis of variance revealed that four days of Cr supplementation did not influence multiple sprint performance, plasma lactate, blood pH and excess post-sprint oxygen consumption. Furthermore, VO2peak was unchanged following Cr supplementation. The data suggest that either the four day period of Cr supplementation failed to significantly raise resting muscle [Cr], or that multiple sprint performance was not enhanced by increases in resting muscle [Cr].
Adult↗
Relationships between the acidity and osmolality of popular beverages and reported postprandial heartburn.
BACKGROUND/AIMS: Although many beverages produce heartburn, the relationship between the acidity and osmolality of beverages and heartburn is unclear. The aim of this study was to relate the acidity and osmolality of beverages with their ability to cause heartburn. METHODS: We measured pH, total titratable acidity, and osmolality of 38 beverages in vitro and then correlated acidity and osmolality with the amount of heartburn reported by questionnaire in 394 people with heartburn. RESULTS: Among 17 citrus drinks and juices, titratable acidity correlated with reported heartburn scores (r = 0.65; P = 0.004). Soft drinks had the lowest pH readings of any beverages studied, and decreasing pH among soft drinks was correlated with reported heartburn scores (r = 0.82; P < 0.001). Alcoholic beverages (wines and beer), coffee, and (to a lesser extent) tea were associated with significant amounts of reported heartburn when compared with water. Milk was also associated with a modest amount of reported heartburn that was related to its fat content. Osmolality of beverages was unrelated to reported heartburn. CONCLUSIONS: High titratable acidity of citrus drinks and juices and low pH of soft drinks are associated with more reported heartburn. Our findings provide a foundation for dietary advice in patients with heartburn and reflux esophagitis.
Acids↗