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M D Lee

Publications and source records attributed to M D Lee.

At least 19 recordsLinked to original sources
PubMed2006

Impact of antimicrobial usage on antimicrobial resistance in commensal Escherichia coli strains colonizing broiler chickens.

Escherichia coli strains isolated from commercial broilers and an experimental flock of chickens were screened to determine phenotypic expression of antimicrobial resistance and carriage of drug resistance determinants. The goal of this study was to investigate the influence of oxytetracycline, sarafloxacin, and enrofloxacin administration on the distribution of resistance determinants and strain types among intestinal commensal E. coli strains isolated from broiler chickens. We detected a high prevalence of resistance to drugs such as tetracycline (36 to 97%), sulfonamides (50 to 100%), and streptomycin (53 to 100%) in E. coli isolates from treated and untreated flocks. These isolates also had a high prevalence of class 1 integron carriage, and most of them possessed the streptomycin resistance cassette, aadA1. In order to investigate the contribution of E. coli strain distribution to the prevalence of antimicrobial resistance and the resistance determinants, isolates from each flock were DNA fingerprinted by enterobacterial repetitive intergenic consensus sequence (ERIC) PCR. Although very diverse E. coli strain types were detected, four ERIC strain types were present on all of the commercial broiler farms, and two of the strains were also found in the experimental flocks. Each E. coli strain consisted of both susceptible and antimicrobial agent-resistant isolates. In some instances, isolates of the same E. coli strain expressed the same drug resistance patterns although they harbored different tet determinants or streptomycin resistance genes. Therefore, drug resistance patterns could not be explained solely by strain prevalence, indicating that mobile elements contributed significantly to the prevalence of resistance.

Animals↗
PubMed2006

Serotonin 1B and 2C receptor interactions in the modulation of feeding behaviour in the mouse.

RATIONALE: To examine the functional relationship between 5-HT1B receptors (5-HT1B-R) and 5-HT2C receptors (5-HT2C-R) in the control of food intake. OBJECTIVES: To compare the hypophagic effect of the 5-HT(2C/1B)-R agonist m-chlorophenylpiperazine (mCPP), with that of the selective 5-HT1B-R agonist CP-94,253 in both wildtype (WT) and 5-HT2C knockout (KO) mice. METHODS: The hypophagic effects of mCPP (1, 3 and 5.6 mg/kg) and CP-94,253 (5, 10 and 20 mg/kg) were assessed in WT and 5-HT2C KO mice using the behavioural satiety sequence paradigm. The effects of pre-treatment with the selective 5-HT2C-R antagonist SB 242,084 (0.5 and 1.5 mg/kg) were assessed in two groups of WT mice, with each group given only mCPP or CP-94,253. RESULTS: The 5-HT(2C/1B) receptor agonist mCPP and the selective 5-HT1B receptor agonist CP-94,253 both suppressed food intake in WT mice. 5-HT2C KO mice were insensitive to the hypophagic effects of mCPP but were more sensitive to CP-94,253-induced hypophagia than WT controls. mCPP induced a significant increase in post-prandial activity in 5-HT2C KO mice, but this effect was absent in 5-HT2C KO mice who were given CP-94,253. Data from WT mice, who were pre-treated with the 5-HT2C receptor antagonist SB 242,084 and then challenged with either mCPP or CP-94,253, were similar to those obtained from 5-HT2C KO mice. CONCLUSIONS: 5-HT2C-R and 5-HT1B-R activation are each sufficient to induce a hypophagic response. However, concurrent 5-HT2C-R inactivation can potentiate the hypophagic response to 5-HT1B-R activation, consistent with an inhibitory role for the 5-HT2C-R in behaviour mediated by the activation of other 5-HT receptors. These results also confirm that 5-HT1B-R activation alone cannot account for the hyperactive response of 5-HT2C KO mice to mCPP.

Aminopyridines↗
PubMed2006

Adult living donor liver transplantation using the right lobe.

BACKGROUND: This article reviewed our experience with right lobe donor hepatectomy in living donor liver transplantations (LDLT), particularly in the context of preserving donor safety. MATERIALS AND METHODS: From January 2000 to August 2005, we performed 206 adult LDLT operations using the right lobe. The donor characteristics, operative findings, postoperative results including the peak values of liver enzymes (aspartate transferase [AST], alanine transferase [ALT], and bilirubin) and regeneration volumes, as evaluated by computed tomography volumetry, were reviewed at 1 week, as well as 3 and 6 months after surgery. The effects of three risk factors on donor safety were analyzed: age (<55 years, > or =55 years): fatty change in the donor liver (<10%, > or =10%); and remnant volume (<35%, > or =35%). RESULTS: The liver enzymes and regeneration volumes showed no significant difference according to age, only ALT was significant increased associated with the severity of fatty change (P < .05). There were significant differences in postoperative AST, ALT, and regeneration volume between the group with <35% and the group with > or =35% remnant liver volume (P < .05). Upon further analysis with combinations of two out of three risk factors, the group according to remnant volume and fatty change was meaningful. Follow-up data on donor ALT showed a return normal levels and after postoperative 3 months there was regeneration of the remnant liver to more than 70% of the whole liver preoperatively. There was no donor mortality, but postoperative complications were observed in 39 patients (39/206, 18.9%). Biliary complications were encountered in 24 patients: one bile duct injury, 22 bile leakages, and one bile duct stricture. Other complications consisted of pleural effusion (n = 8), delayed gastric emptying (n = 6), atelectasis (n = 1), and hepatic encephalopathy (n = 1). CONCLUSION: In cases of careful donor selection, a right lobectomy can be performed safely with minimal risks when the remnant liver volume exceeds 35% of the total liver volume and shows less than 10% fatty changes.

Adult↗
PubMed2006

Effect of middle hepatic vein reconstruction in living donor liver transplantation using right lobe.

BACKGROUND: This study reviewed the impact of middle hepatic vein (MHV) reconstruction on right lobe graft with regard to functional recovery and graft regeneration at 1 week after transplantation. MATERIALS AND METHODS: From January 1999 to September 2005. 211 adult living donor liver transplantations were performed using the right lobe. The reconstruction of hepatic venous tributaries from segment 5 or segment 8 or both was performed in every cases of sufficient size. The patency of graft vessels was evaluated with computed tomography (CT) angiography on postoperative day 7. We analyzed liver enzymes (aspartate transferase [AST], alanine transferase [ALT] and bilirubin) at 1 week postoperatively and evaluated regeneration activity by CT volumetry at 1 week postoperatively. RESULTS: Among 211 cases, 182 (86.3%) were reconstructed with interpositional MHV grafts. Among them, 51 cases (51.9%) were patent at 1 week postoperatively. The levels of AST and ALT in patent cases of all patients and small-for-size grafts were lower than among the occlusion cases, albeit not significantly. The mean graft regeneration at 1 week postoperatively among patent cases was 1.75 +/- 0.39 versus 1.64 +/- 0.24 in the occluded cases (P = .111), but among small-for-size grafts, there was a significant difference in graft regeneration between patent versus occluded cases (2.05 +/- 0.50 vs 1.66 +/- 0.17, P = .037). CONCLUSION: Functional recovery and graft regeneration in small-for-size grafts showed a beneficial effect in patent cases, compared with occluded cases. Our selection criteria for MHV reconstruction must include cases of small-for-size grafts not all cases.

Adult↗
PubMed2005

A new venous conduit utilizing the recipient portal vein branches for segment V in adult partial liver transplantation.

Right anterior-medial lobe congestion due to temporary clamping of segment V and/or VIII is common in the operative theater during adult donor right lobe liver transplantation, the most common procedure in our institute. We have used an autogenous saphenous vein conduit to recipient portal vein tributaries in 15 cases, as a "Y-to-I venoplasty" since January 2004. The recipient portal vein is transected 5 mm proximal to its bifurcation and extended to both sides with partial hepatic dissection. The "Y-to-I venoplasty" is made by suture closure of the portal vein transversely to form a tube. The average length is 7.5 cm with a 1.3 cm width. One end of "Y-to-I venoplasty" conduit is anastomosed to the donor segment V branch on the back table. And the other end is anastomosed directly to the IVC via a new window or the middle hepatic vein stump in recipient. The phase distension of the conduit with respiration is noted in the operative field. A 6/15 (40%) patency rate, was observed by CT angiography at the second postoperative week. All-patient conduits showed good flow on serial examinations at the 60th postoperative day. This new venous graft, made of recipient portal vein is a good conduit for segment V decongestion in adult right lobe partial liver transplantation.

Adult↗
PubMed2005

Effects of orally administered tetracycline on the intestinal community structure of chickens and on tet determinant carriage by commensal bacteria and Campylobacter jejuni.

There is a growing concern that antibiotic usage in animal production has selected for resistant food-borne bacteria. Since tetracyclines are common therapeutic antibiotics used in poultry production, we sought to evaluate the effects of oral administration on the resistance of poultry commensal bacteria and the intestinal bacterial community structure. The diversity indices calculated from terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA amplicons did not indicate significant changes in the cecal bacterial community in response to oxytetracycline. To evaluate its effects on cultivable commensals, Enterococcus spp., Escherichia coli, and Campylobacter spp. were isolated from the cecal droppings of broiler chickens. Enterococcus spp. and E. coli expressed tetracycline MICs of >8 microg/ml and harbored a variety of tet resistance determinants regardless of the tetracycline exposure history of the birds. The enterococcal isolates possessed tetM (61%), tetL (25.4%), and tetK (1.3%), as well as tetO (52.5%), the determinant known to confer a tetracycline resistance phenotype in Campylobacter jejuni. E. coli isolates harbored tetA (32.2%) or tetB (30.5%). Tetracycline MICs remained at <2 microg/ml for Campylobacter isolates before and after tetracycline treatment of the chickens, even though isolates expressing MICs of >16 mug/ml were commonly cultured from flocks that did not receive oxytetracycline. The results imply that complex ecological and genetic factors contribute to the prevalence of antibiotic resistance arising from resistance gene transfer in the production environment.

Animals↗
PubMed2004

mCPP-induced hyperactivity in 5-HT2C receptor mutant mice is mediated by activation of multiple 5-HT receptor subtypes.

The serotonin receptor agonist mCPP induces hyperlocomotion in 5-HT2C receptor knockout (KO) mice or in the presence of a 5-HT2C receptor antagonist. In the present group of experiments, we evaluate the role of 5-HT1A, 5-HT1B and 5-HT2A receptors in mCPP-induced hyperactivity in 5-HT2C KO mice. We also assess the ability of agonists at these receptors to induce hyperactivity in wildtype (WT) mice pre-treated with a selective 5-HT2C receptor antagonist. As previously reported, mCPP (3 mg/kg) induced hyperactivity in 5-HT2C KO mice. A combination of the 5-HT1B receptor agonist CP-94,253 (20 mg/kg) and the 5-HT1A receptor agonist 8-OH-DPAT (0.5 mg/kg) induced marked hyperactivity in WT but not in 5-HT2C KO mice, nor in mice treated with the selective 5-HT2C receptor antagonist, SB 242084 (1.5 mg/kg). Neither CP-94,253 nor 8-OH-DPAT had any intrinsic effect on locomotion in WTs. mCPP-induced hyperactivity was attenuated in 5-HT2C KO mice by the 5-HT1B receptor antagonist SB 224289 (2.5 mg/kg), and the 5-HT2A receptor antagonists ketanserin (0.3 mg/kg) and M100907 (0.01 mg/kg) but not by the 5-HT1A receptor antagonist WAY 100635 (1 mg/kg). The 5-HT(2A/2B/2C) receptor agonist, Ro 60-0175 (3 mg/kg), induced a modest increase in locomotor activity in WT mice pre-treated with SB 242084. However, the combination of Ro 60-0175 with CP-94,253 induced a substantial increase in activity in 5-HT2C KO mice, an effect comparable to mCPP-induced hyperactivity. Thus, joint activation of 5-HT1A and 5-HT1B receptors stimulates locomotion in WT mice but this response is dependent on a functional 5-HT2C receptor population and hence is absent in 5-HT2C KO mice. By contrast, mCPP-induced hyperactivity depends on the inactivation of a separate 5-HT2C receptor population and is mediated by 5-HT2A and 5-HT1B receptor activation.

Animals↗
PubMed2001

Stereochemical elucidation and total synthesis of dihydropacidamycin D, a semisynthetic pacidamycin.

Hydrogenation of the C(4') exocyclic olefin of the pacidamycins has been shown to produce a series of semisynthetic compounds, the dihydropacidamycins, with antimicrobial activity similar to that of the natural products. Elucidation of stereochemistry in the pacidamycins has been completed through a campaign of natural product degradation experiments in combination with the total synthesis of the lowest-molecular weight dihydropacidamycin, dihydropacidamycin D. The stereochemical identities of the tryptophan and two alanine residues contained in pacidamycin D have been shown to be of the natural (S) configuration, and the unique 3-methylamino-2-aminobutyric acid contained in this series of antibiotics has been shown to be of the (2S,3S) configuration. Finally, the stereochemistry obtained by hydrogenation of the C(4')-C(5') exocyclic olefin has been shown to be (R) at the C(4') nucleoside site.

Anti-Bacterial Agents↗
PubMed2001

No evidence for latent learning of liking for flavours conditioned by caffeine.

RATIONALE: The ability of caffeine to condition liking for flavours depends on the caffeine deprivation status of subjects; however, it is not known if a latent liking for a flavour can be acquired in an undeprived state, which subsequently emerges when consumers are caffeine deprived. OBJECTIVES: To determine if exposure of undeprived caffeine consumers to a novel drink containing caffeine leads to increased liking for this drink when they are subsequently tested when caffeine-deprived. METHODS: In a double-blind placebo controlled study, four groups of 13 moderate caffeine consumers evaluated a novel flavoured drink on 5 days. The test group consumed this drink with 100 mg caffeine when undeprived on days 1-4, and in a deprived state on day 5. Three control groups had the same conditions on all 5 days, with an undeprived group receiving the caffeinated drink, and two deprived groups receiving the drink with caffeine or placebo. RESULTS: The pleasantness of the drink did not change over the 4 training days in the test group, and did not alter when this group was tested when caffeine-deprived. At no stage did these ratings differ between the test and undeprived control groups. Pleasantness increased significantly over the 5 days in the deprived group who received caffeine, and decreased in the deprived group who received placebo. CONCLUSIONS: These results suggest that repeated pairing of a novel flavour with the effects of caffeine in subjects who are not caffeine deprived does not lead to an emergent liking for that flavour when subsequently tested caffeine-deprived. However, the pleasantness of the same caffeinated drink increased if it was consumed when caffeine deprived.

Adult↗
PubMed2001

The actual, but not labelled, fat content of a soup preload alters short-term appetite in healthy men.

The effects of the actual and labelled fat content of a soup preload on appetite at a test meal 30 min later were assessed in 16 healthy men. Each participant ate lunch on four occasions, combining two levels of fat energy (Low, 265 kJ or High, 1510 kJ) and two types of label (Low-fat or High-fat), presented as fictitious soup brand names. Preliminary work established that the Low-fat labels produced an expectation of reduced fat content and lower anticipated hedonic ratings, whereas the High-fat labels generated expectations of a high-fat content and above average hedonic ratings. These expectancies were confirmed in the main experiment, with the soups labelled as high fat rated as both more pleasant and creamy than those labelled low-fat, independent of actual fat content. However, intake at the test meal was unaffected by the preload label, but instead reflected the actual fat (hence, energy) content of the soup, with significantly lower food intake after the high-fat soup regardless of the food label. Rated hunger was lower, and fullness higher, at the start of the meal after the high-fat preloads regardless of how they were labelled, while the pattern of appetite change during the test meal was unaffected by preload. These results suggest that realistic food labels can modify the immediate experience of a consumed food, but do not alter appetite 30 min later in healthy men.

Adult↗
PubMed2001

Effects of test-meal palatability on compensatory eating following disguised fat and carbohydrate preloads.

OBJECTIVE: To test whether the palatability of a test meal altered compensatory eating following disguised high-energy fat and carbohydrate preloads. DESIGN: Effects of preload energy (low, 265 kJ, or high, 1510 kJ) and test-meal palatability (bland or palatable) were contrasted within-subjects, with a between-subjects contrast of fat and carbohydrate preloads. SUBJECTS: Twenty-four healthy, normal men (age 23.6+/-1.0 y, (body mass index) BMI 21.3+/-0.5). MEASUREMENTS: Microstructural analysis of test meal intake and rated appetite in the four test conditions, plus diary-based weighed intake analysis of energy intake post-lunch. RESULTS: Subjects ate significantly less at lunch after disguised high-energy fat or carbohydrate preloads relative to the low-energy preload, and ate significantly more of the palatable than bland lunch in all conditions. The reduction in eating following the high-energy preload was significantly less in the palatable condition. Intake post-lunch did not differ between conditions, and overall subjects had higher daily energy intake on the days they consumed the high-energy preloads. Rated hunger was significantly less 30 min after the high- than low-energy preloads, but increased on tasting the palatable food in all conditions. The high-energy preloads suppressed appetite immediately post-lunch. No differences between fat and carbohydrate were found on any measure. CONCLUSIONS: Manipulation of the palatability of a test meal modified the ability to respond to disguised high-energy preloads, with over-consumption most evident when disguised high-energy preloads were followed by a palatable food. Subsequent voluntary intake compensated for over-consumption of the palatable lunch, but not the high-energy preload.

Adult↗
PubMed2001

Incidence of class 1 and 2 integrases in clinical and commensal bacteria from livestock, companion animals, and exotics.

Many pathogenic and commensal organisms are multidrug resistant due to exposure to various antibiotics. Often, this antimicrobial resistance is encoded by integrons that occur on plasmids or that are integrated into the bacterial chromosome. Integrons are commonly associated with bacterial genera in the family Enterobacteriaceae. We determined that class 1 integrases were present in approximately 46% of the isolates from the family Enterobacteriaceae; class 2 integrases were present only among Escherichia coli and Salmonella isolates. Seven percent of veterinary isolates were positive for class 3 integrase by DNA-DNA hybridization but could not be confirmed to be positive by PCR. None of the veterinary isolates possessed the class 4 integrase gene. The distribution of these integrase genes was variable within the members of the family Enterobacteriaceae when some or all integrase classes were absent from a particular genus. There was also considerable variability in the distribution of these integrases within a species, depending on the animal host. Unlike the class 1 integrases, the other integrase class, intI2, appears to be more restricted in its distribution among the members of the family Enterobacteriaceae. There is also considerable variability in the distribution of the class 1 integrases within E. coli strains isolated from different food animals. The class 1 integrases are the most widely disseminated of the four classes among the members of the family Enterobacteriaceae from both the clinical and normal flora of animals. This is the first report to closely examine the distribution of class 2 integrases in members of the family Enterobacteriaceae isolated in the United States.

Animals↗
PubMed2001

Multichannel auditory search: toward understanding control processes in polychotic auditory listening.

Two experiments are presented that serve as a framework for exploring auditory information processing. The framework is referred to as polychotic listening or auditory search, and it requires a listener to scan multiple simultaneous auditory streams for the appearance of a target word (the name of a letter such as A or M). Participants' ability to scan between two and six simultaneous auditory streams of letter and digit names for the name of a target letter was examined using six loudspeakers. The main independent variable was auditory load, or the number of active audio streams on a given trial. The primary dependent variables were target localization accuracy and reaction time. Results showed that as load increased, performance decreased. The performance decrease was evident in reaction time, accuracy, and sensitivity measures. The second study required participants to practice the same task for 10 sessions, for a total of 1800 trials. Results indicated that even with extensive practice, performance was still affected by auditory load. The present results are compared with findings in the visual search literature. The implications for the use of multiple auditory displays are discussed. Potential applications include cockpit and automobile warning displays, virtual reality systems, and training systems.

Adult↗
PubMed2001

Epidemiologic features of Campylobacter jejuni isolated from poultry broiler houses and surrounding environments as determined by use of molecular strain typing.

OBJECTIVE: To genetically type Campylobacter jejuni isolates from broiler houses or the external environment to identify the source of Campylobacter organisms in broiler chickens. SAMPLE POPULATION: Environmental samples associated with broiler chickens, in commercial grow-out houses. PROCEDURE: Polymerase chain reaction (PCR) was used to amplify flaB, and the amplicon was digested with Sau3A to create a restriction fragment length polymorphism assay; PCR was also used to detect a transcribed spacer region in the 23S rRNA gene. RESULTS: Isolates possessing a 23S spacer region were more prevalent outside broiler houses than inside. Houses that had previously contained chickens or lacked biosecurity procedures were more likely to contain isolates possessing the 23S spacer. One house contained only isolates possessing the spacer, whereas an adjacent house contained only isolates lacking the spacer. The flaB type detected in broiler houses was different from the type detected in the environment; however, many isolates within the broiler houses contained untypable flaB genotypes. CONCLUSIONS AND CLINICAL RELEVANCE: Most isolates from within houses were genetically distinct from isolates from outside houses that were examined by bacteriologic culture, suggesting an undetected source of C jejuni. Detection of isolates containing the 23S spacer appeared to be an indicator of environmental contamination of the houses. The observation of completely different C jejuni genetic types simultaneously within adjacent houses suggests that some types do not compete successfully during the grow-out period. In addition, the diversity of genotypes identified within broiler houses indicates the complexity of the ecologic features of C jejuni in the chicken environment.

Animals↗
PubMed2000

Lysosomal accumulation of drugs in drug-sensitive MES-SA but not multidrug-resistant MES-SA/Dx5 uterine sarcoma cells.

Sequestration of drugs in intracellular vesicles has been associated with multidrug-resistance (MDR), but it is not clear why vesicular drug accumulation, which depends upon intracellular pH gradients, should be associated with MDR. Using a human uterine sarcoma cell line (MES-SA) and a doxorubicin (DOX)-resistant variant cell line (Dx-5), which expresses p-glycoprotein (PGP), we have addressed the relationship between multidrug resistance, vesicular acidification, and vesicular drug accumulation. Consistent with a pH-dependent mechanism of vesicular drug accumulation, studies of living cells vitally labeled with multiple probes indicate that DOX and daunorubicin (DNR) predominately accumulate in lysosomes, whose lumenal pH was measured at < 4.5, but are not detected in endosomes, whose pH was measured at 5.9. However, vesicular DOX accumulation is more pronounced in the drug-sensitive MES-SA cells and minimal in Dx5 cells even when cellular levels of DOX are increased by verapamil treatment. While lysosomal accumulation of DOX correlated well with pharmacologically induced differences in lysosome pH in MES-SA cells, lysosomal accumulation was minimal in Dx5 cells regardless of lysosomal pH. We found no differences in the pH of either endosomes or lysosomes between MES-SA and Dx5 cells, suggesting that, in contrast to other MDR cell systems, the drug-resistant Dx5 cells are refractory to pH-dependent vesicular drug accumulation. These studies demonstrate that altered endomembrane pH regulation is not a necessary consequence of cell transformation, and that vesicular sequestration of drugs is not a necessary characteristic of MDR.

Animals↗
PubMed2000

Acquisition and extinction of flavour preferences conditioned by caffeine in humans.

Previous research has shown that moderate caffeine users develop a liking for the flavour of a novel caffeinated drink only if they experience this drink in a caffeine-deprived state. This study tested how sensitive these conditioned-flavour preferences are to subsequent changes in deprivation state and the continued presence or absence of caffeine. Thirty-six moderate caffeine consumers were given 4 training days during which they evaluated a novel flavoured caffeinated drink consumed mid-morning after 12 h caffeine deprivation. Subjects were then divided into four groups depending on whether or not they remained caffeine-deprived and whether the test drink continued to contain caffeine. They then re-evaluated the novel drink over a further 4 test days. As expected, liking for the test drink increased across the 4 training days, and this increased liking was maintained across the 4 test days in the group who continued to receive the caffeinated version of the drink in a caffeine-deprived state. Liking decreased in the test phase in the caffeine-deprived group who no longer received caffeine (extinction). It is surprising that both groups who were tested in a non-deprived state showed a marked decrease in liking on all 4 test days relative to the last training day. This implies that conditioned-flavour preferences may not be expressed in the absence of the relevant motivational state (caffeine deprivation). Together, these data suggest that flavour preferences conditioned by caffeine are very sensitive to changes in the contingent relationship between deprivation state and caffeine content of the drink.

Adult↗