Community ecology and functional potential of bacteria, archaea, eukarya and viruses in Guerrero Negro microbial mat

In this study, the microbial ecology, potential environmental adaptive mechanisms, and the potential evolutionary interlinking of genes between bacterial, archaeal and viral lineages in Guerrero Negro (GN) microbial mat were investigated using metagenomic sequencing across a vertical transect at millimeter scale. The community composition based on unique genes comprised bacteria (98.01%), archaea (1.81%), eukarya (0.07%) and viruses (0.11%). A gene-focused analysis of bacteria archaea, eukarya and viruses showed a vertical partition of the community. The greatest coverages of genes of bacteria and eukarya were detected in first layers, while the highest coverages of genes of archaea and viruses were found in deeper layers. Many genes potentially related to adaptation to the local environment were detected, such as UV radiation, multidrug resistance, oxidative stress, heavy metals, salinity and desiccation. Those genes were found in bacterial, archaeal and viral lineages with 6477, 44, and 1 genes, respectively. The evolutionary histories of those genes were studied using phylogenetic analysis, showing an interlinking between domains in GN mat.

Application of Digital Cognitive Biomarkers for Alzheimer's Disease: Identifying Cognitive Process Changes and Impending Cognitive Decline

BACKGROUND

Recent Alzheimer's disease (AD) trials have faced significant challenges to enroll pre-symptomatic or early stage AD subjects with biomarker positivity, minimal or no cognitive impairment, and likelihood to decline cognitively during a short trial period. Our previous study showed that digital cognitive biomarkers (DCB), generated by a hierarchical Bayesian cognitive process (HBCP) model, were able to distinguish groups of cognitively normal individuals with impending cognitive decline from those without. We generated DCBs using only baseline Auditory Verbal Learning Test's wordlist memory (WLM) item response data from the Mayo Clinic Alzheimer's Disease Patient Registry.

OBJECTIVES

To replicate our previous findings, using baseline ADAS-Cog WLM item response data from the Alzheimer's Disease Neuroimaging Initiative, and compare DCBs to traditional approaches for scoring word-list memory tests.

DESIGN

Classified decliner subjects (n = 61) as those who developed amnestic MCI or AD dementia within 3 years of normal baseline assessment and non-decliner (n = 442) as those who did not.

MEASURES

Evaluated the relative value of DCBs compared to traditional measures, using three analytic approaches to group differences: 1) logistic regression of summary scores per ADAS-Cog WLM task; 2) Bayesian modeling of summary scores; and 3) HBCP modeling to generate DCBs from item-level responses.

RESULTS

The HBCP model produced posterior distributions of group differences, of which Bayes factor assessment identified three DCBs with notable group differences: Immediate Retrieval from Durable Storage, (BFds = 11.8, strong evidence); One-Shot Learning, (BFds = 4.5, moderate evidence); and Partial Learning (BFds = 2.9, weak evidence). In contrast, logistic regression of summary scores did not significantly discriminate between groups, and the Bayes factor assessment of modeled summary scores provided moderate evidence that the groups were equivalent (BFsd = 3.4, 3.1, 2.9, and 1.4, respectively).

CONCLUSIONS

This study demonstrated DCBs' ability to distinguish , at baseline, between impending cognitive decline and non-decline groups where individuals in both groups were classified as cognitively normal. This validated findings from our previous study, demonstrating DCBs' advantages over traditional approaches. This study warrants further refinement of the HBCP DCBs to predict impending cognitive decline in individuals and other factors associated with AD, such as physical biomarker load.

Utility of Percentage Signal Recovery and Baseline Signal in DSC-MRI Optimized for Relative CBV Measurement for Differentiating Glioblastoma, Lymphoma, Metastasis, and Meningioma

BACKGROUND AND PURPOSE

The percentage signal recovery in non-leakage-corrected (no preload, high flip angle, intermediate TE) DSC-MR imaging is known to differ significantly for glioblastoma, metastasis, and primary CNS lymphoma. Because the percentage signal recovery is influenced by preload and pulse sequence parameters, we investigated whether the percentage signal recovery can still differentiate these common contrast-enhancing neoplasms using a DSC-MR imaging protocol designed for relative CBV accuracy (preload, intermediate flip angle, low TE).

MATERIALS AND METHODS

We retrospectively analyzed DSC-MR imaging of treatment-naïve, pathology-proved glioblastomas (n = 14), primary central nervous system lymphomas (n = 7), metastases (n = 20), and meningiomas (n = 13) using a protocol designed for relative CBV accuracy (a one-quarter-dose preload and single-dose bolus of gadobutrol, TR/TE = 1290/40 ms, flip angle = 60° at 1.5T). Mean percentage signal recovery, relative CBV, and normalized baseline signal intensity were compared within contrast-enhancing lesion volumes. Classification accuracy was determined by receiver operating characteristic analysis.

RESULTS

Relative CBV best differentiated meningioma from glioblastoma and from metastasis with areas under the curve of 0.84 and 0.82, respectively. The percentage signal recovery best differentiated primary central nervous system lymphoma from metastasis with an area under the curve of 0.81. Relative CBV and percentage signal recovery were similar in differentiating primary central nervous system lymphoma from glioblastoma and from meningioma. Although neither relative CBV nor percentage signal recovery differentiated glioblastoma from metastasis, mean normalized baseline signal intensity achieved 86% sensitivity and 50% specificity.

CONCLUSIONS

Similar to results for non-preload-based DSC-MR imaging, percentage signal recovery for one-quarter-dose preload-based, intermediate flip angle DSC-MR imaging differentiates most pair-wise comparisons of glioblastoma, metastasis, primary central nervous system lymphoma, and meningioma, except for glioblastoma versus metastasis. Differences in normalized post-preload baseline signal for glioblastoma and metastasis, reflecting a snapshot of dynamic contrast enhancement, may motivate the use of single-dose multiecho protocols permitting simultaneous quantification of DSC-MR imaging and dynamic contrast-enhanced MR imaging parameters.

Experiences of Living Donors for Small Bowel Transplantation

INTRODUCTION

Along with developments in surgical and immunosuppression techniques, the success rate of small bowel transplantation has increased. In Korea, the incidence of small bowel transplantations has increased, and the longest surviving living donor recipient has now survived for over 12 years postsurgery. The purpose of this study was to assess the experiences of living donors for small bowel transplantation before, during, and after the transplantation.

METHODS

In one hospital, we conducted interviews, based on open-ended questions, with three small bowel donors. We asked them about experiences during small bowel donation. The living donor's statements were analyzed using interpretive phenomenological analysis.

RESULTS

Donors decided to donate because they felt "sorry for the suffering of a family member" and they had "faith in the medical staff." In the early phase after donation, living donors experienced physical changes in their body, including pain, fatigue, altered bowel habits, and abdominal discomfort. Despite temporary limitations in daily and social activities, support from family members allowed the donors to fully recover and return to normal physical, social, and psychological status. The donors mentioned they experienced love and support from their family, as well as satisfaction and pride from donation, during the entire process.

CONCLUSION

We hope that the physical, psychological, and social experience of living donors during small bowel transplantation deduced in this study will serve as a foundation for the establishment of an intervention method to provide education before donation and help recovery after donation.

Ten-Year Experience With Bowel Transplantation at Seoul St. Mary's Hospital

A retrospective review of intestinal transplantation (ITx) at Seoul St. Mary's Hospital was made by collecting clinical data over the past 10 years. Fifteen consecutive cases from 2004 were analyzed. Five children and 10 adults (6 months to 69 years of age) were included. Primary diseases in adults included 4 mesenteric vessel thromboses, 2 strangulations, and 1 each of visceral myopathy, malignant gastrointestinal stromal tumor (GIST), mesenteric lymphangiectasis, and injury. Pediatric cases involved 2 Hirschsprung disease, 2 visceral myopathy, and 1 necrotizing enterocolitis. Three of 7 stomas were closed using a serial transverse enteroplasty procedure before transplantation. The ITx were performed using 3 living-donor Itx, 12 deceased-donor ITx, 14 isolated Itx, and 1 modified multivisceral transplantation. Daclizumab, basiliximab, alemtusumab, or basiliximab with rabbit antithymocyte globulin (rATG) was used for the induction; tacrolimus monotherapy was used as the basic maintenance immunosuppressant; and m-TOR inhibitor was used for renal dysfunction patients. Seven cases of acute cellular rejection were treated with rATG. Three cases of antibody-mediated rejection were treated with rituximab alone or with rituximab and bortezomib combination. There were 4 cases of early mortality within 6 months after Itx. Causes of death were declamping shock, cardiac tamponade with acute cellular rejection, dysmotility, and sepsis. Surgical complications consisted of 1 feeding jejunostomy displacement, and a minor leakage at a colo-colostomy site. One-year survival of the patient and graft was 73.33% (Kaplan-Meier survival curve). Although the total number of ITx is small, its social impact has been remarkable in changing the related laws and reimbursement policy in Korea.

Can Bacteriotherapy Using Commercially Available Probiotics, Prebiotics, and Organic Acids Ameliorate the Symptoms Associated With Runting-Stunting Syndrome in Broiler Chickens?

Runting-stunting syndrome (RSS) in poultry has been known for more than 40 years, but the precise etiology remains unknown and a licensed vaccine is consequently not currently available. In order to mitigate the symptoms associated with RSS, a series of experiments was performed to investigate whether a combined bacteriotherapeutic treatment consisting of probiotics, prebiotics, and organic acids could influence the outcome of this disease. Initially two groups of commercial broiler chickens were either left uninoculated or inoculated with filtrate from homogenized intestines of RSS-affected broiler chickens. One group from each of these two challenge groups was treated, with a bacteriotherapeutic regimen. After 12 days chickens were euthanatized, the body weight was measured, and duodenal lesions were enumerated. Five consecutive broiler chicken flocks were then raised either on litter from RSS-affected birds or on fresh wood shavings. Treatment had no beneficial effect on the number and severity of intestinal lesions. There appeared to be a significant build-up of RSS agent(s) in poultry litter, with each consecutive flock placement, independent of bacteriotherapeutic treatment, as more individuals exhibited intestinal lesions on built-up litter in RSS-affected houses (28.9% vs. 44%). While treatment did not appear to consistently reduce intestinal lesions, it did significantly improve the mean body weights (P<0.05) and uniformity of 12-day-old chickens placed on reused litter in houses in which RSS-infected birds were previously raised. A combination of litter management and bacteriotherapy may be needed to ameliorate the adverse effects of RSS on intestinal health and body weight in broiler chickens.

Compact, hydrophilic, lanthanide-binding tags for paramagnetic NMR spectroscopy

The design, synthesis and evaluation of four novel lanthanide-binding tags for paramagnetic NMR spectroscopy are reported.

The design, synthesis and evaluation of four novel lanthanide-binding tags for paramagnetic NMR spectroscopy are reported. Each tag is based on the ((2S,2′S,2′′S,2′′′S)-1,1′,1′′,1′′′-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetrakis(propan-2-ol)) scaffold, featuring small chiral alcohol coordinating pendants to minimise the size and hydrophobic character of each tag. The tags feature different linkers of variable length for conjugation to protein via a single cysteine residue. Each tag's ability to induce pseudocontact shifts (PCS) was assessed on a ubiquitin A28C mutant. Two enantiomeric tags of particular note, C7 and C8, produced significantly larger Δχ-tensors compared to a previously developed tag, C1, attributed to the extremely short linker utilised, limiting the mobility of the bound lanthanide ion. The C7 and C8 tags' capacity to induce PCSs was further demonstrated on GB1 Q32C and 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) S112C/C80A mutants. Whilst factors such as the choice of lanthanide ion, pH and site of conjugation influence the size of the PCSs obtained, the tags represent a significant advance in the field.

Early influences on child satiety-responsiveness: the role of weaning style

BACKGROUND

Nutrition during infancy may have a long-term impact upon weight gain and eating style. How infants are introduced to solid foods may be important. Traditionally, infants are introduced to solid foods via spoon-feeding of purees. However, baby-led weaning advocates allowing infants to self-feed foods in their whole form. Advocates suggest this may promote healthy eating styles, but evidence is sparse. The aim of the current study was to compare child eating behaviour at 18-24 months between infants weaned using a traditional weaning approach and those weaned using a baby-led weaning style.

METHODS

Two hundred ninety-eight mothers with an infant aged 18-24 months completed a longitudinal, self-report questionnaire. In Phase One, mothers with an infant aged 6-12 months reported breastfeeding duration, timing of solid foods, weaning style (baby-led or standard) and maternal control, measured using the Child Feeding Questionnaire. At 18-24 months, post-partum mothers completed a follow-up questionnaire examining child eating style (satiety-responsiveness, food-responsiveness, fussiness, enjoyment of food) and reported child weight.

RESULTS

Infants weaned using a baby-led approach were significantly more satiety-responsive and less likely to be overweight compared with those weaned using a standard approach. This was independent of breastfeeding duration, timing of introduction to complementary foods and maternal control.

CONCLUSIONS

A baby-led weaning approach may encourage greater satiety-responsiveness and healthy weight-gain trajectories in infants. However, the limitations of a self-report correlational study are noted. Further research using randomized controlled trial is needed.

Evidence for horizontal and vertical transmission in Campylobacter passage from hen to her progeny

Campylobacter is an important human pathogen, and consumption of undercooked poultry has been linked to significant human illnesses. To reduce human illness, intervention strategies targeting Campylobacter reduction in poultry are in development. For more than a decade, there has been an ongoing national and international controversy about whether Campylobacter can pass from one generation of poultry to the next via the fertile egg. We recognize that there are numerous sources of Campylobacter entry into flocks of commercial poultry (including egg transmission), yet the environment is often cited as the only source. There has been an abundance of published research globally that refutes this contention, and this article lists and discusses many of them, along with other studies that support environment as the sole or primary source. One must remember that egg passage can mean more than vertical, transovarian transmission. Fecal bacteria, including Campylobacter, can contaminate the shell, shell membranes, and albumen of freshly laid fertile eggs. This contamination is drawn through the shell by temperature differential, aided by the presence of moisture (the "sweating" of the egg); then, when the chick emerges from the egg, it can ingest bacteria such as Campylobacter, become colonized, and spread this contamination to flock mates in the grow house. Improvements in cultural laboratory methods continue to advance our knowledge of the ecology of Campylobacter, and in the not-so-distant future, egg passage will not be a subject continuously debated but will be embraced, thus allowing the development and implementation of more effective intervention strategies.

Multilevel analysis of environmental Salmonella prevalences and management practices on 49 broiler breeder farms in four south-eastern States, USA

A two-part serial survey of 49 broiler breeder farms was conducted in four south-eastern states: Arkansas, Alabama, Georgia and North Carolina. Broiler breeder farms from three to five broiler company complexes in each state were visited on two separate occasions to document management practices and perform environmental sampling for Salmonella prevalence estimation. Salmonella was detected in 88% of the broiler breeder houses that were sampled and was identified on all 49 farms enrolled. Many management characteristics were consistent across the different states and companies. Multilevel analysis was used to evaluate management characteristics as risk factors for Salmonella prevalence and to estimate the proportion of variance residing at the different hierarchical sampling levels. Management characteristics associated with increased Salmonella prevalence included treatment of the flock for any disease, having dusty conditions in the house, having dry conditions under the slats and walking through the house more than one time per day to pick-up dead birds. After adjusting for state as a fixed effect, the percentages of variance in Salmonella prevalence occurring at the complex, farm, visit, house and individual sample levels were 5.2%, 6.8%, 11.8%, 2.8% and 73.4%, respectively. The intraclass correlations for samples collected from the same house; for samples from different houses during the same visit; for samples from different visits to the same farm; and for samples from different farms in the same complex were as follows: 0.27, 0.24, 0.12 and 0.05, respectively.

High mortality associated with Acinetobacter species infection in liver transplant patients

BACKGROUND

Acinetobacter species have become increasingly important nosocomial pathogens worldwide and can result in a wide range of infections, including bacteremia, pneumonia, urinary tract infection, peritonitis, among others. The aim of this study was to investigate clinical characteristics, mortality, and outcomes among liver transplant recipients with Acinetobacter species infections.

METHODS

We retrospectively analyzed 451 subjects who had undergone living donor liver transplantations between January 2001 and May 2010. Pandrug-resistant (PDR) Acinetobacter species were defined as resistant to all commercially available antibiotics except colistin.

RESULTS

Infectious complications due to Acinetobacter species appeared in 26 patients (5.8%) with a total of 37 episodes. Of the species identified, 34 were Acinetobacter baumannii and 3 Acinetobacter Iwoffiii. The presumed sources of infection were the biliary tract (n = 21, 56.8%), lung (n = 7, 18.9%), intra-abdomen (n = 6, 16.2%), catheter (n = 2, 5.4%), and urinary tract (n = 1, 3.6%). Among the 37 Acinetobacter species, 75.7% (28/37) were PDR species. Age, duration of intensive care unit stay, Child-Pugh score, and Model for End-stage Liver Disease score were not significant risk factors for Acinetobacter species infection. However, the overall mortality among patients with Acinetobacter species infections was 50% (13/26), which was significantly higher than that among those free of infection (50% vs 11.5%, P < .05). Multivariate analysis using a Cox regression model showed that inappropriate antimicrobial treatment was a significant independent risk factor for mortality among patients with Acinetobacter species infections (hazard Ratio = 4.19, 95% confidence interval 1.1-18.7; P = .06).

CONCLUSION

Patients with Acinetobacter species infections after liver transplantation show a significantly worse prognosis. PDR Acinetobacter species have been a major problem in our center.

Using bacteriophages to modulate Salmonella colonization of the chicken's gastrointestinal tract: lessons learned from in silico and in vivo modeling

An increasing prevalence of antibiotic-resistant foodborne infections has resulted in considerable concern about how antimicrobials are used in meat and poultry production. Because many foodborne bacterial pathogens are commonly found among the intestinal bacterial community of poultry, new methods of prevention are being considered. Bacteriophage therapy is one such alternative method that has not been well developed in the United States; however, bacteriophages have been shown to be effective in modulating bacterial numbers in acute infection models. In this study we evaluated whether bacteriophages could theoretically reduce Salmonella colonization of the gastrointestinal tract of chickens. Using computer simulations, we studied bacteriophage and bacterial replication dynamics in a mathematical model based on parameters expected to occur in the intestinal environment. In addition, we performed in vivo experiments by administering SP6 bacteriophage and Salmonella orally to young chickens and compared the levels of phage and Salmonella shed in the feces to the models of replication dynamics. SP6 is an ideal candidate bacteriophage because its genome and target receptor are known. Although SP6 did not reduce the levels of Salmonella shed by treated birds, most of the isolates recovered from treated birds were not resistant to the bacteriophage. These results suggest that phage resistance may not be the primary limiting parameter of phage prophylaxis for modulating colonization of the intestine. Our findings that this phage could be replicated in vivo supports the attractiveness of phage use, because unlike antibiotics they may be amplified in vivo if given a suitable host on which to replicate. If successful, this approach to modulating bacterial colonization of the intestinal tract could have a tremendous effect on the meat and poultry industry by reducing the use of antimicrobial drugs and increasing the use of biological therapeutics.

Surgical techniques according to anatomic variations in living donor liver transplantation using the right lobe

OBJECTIVES

In living donor liver transplantation, the right lobe has many anatomic variations in the vascular tree, which could lead to surgical complications. We need to define surgical technique according to anatomy.

METHODS

From January 2000 to September 2007, 310 living donor liver transplantations using the right lobe were performed in patients with end-stage liver disease. The vascular trees were evaluated preoperatively with computed tomography and magnetic resonance angiography. We classified anatomic points for safe harvest in the hepatic artery, portal vein, and hepatic vein and described technical points based on anatomic variations.

RESULT

There were many anatomic variations in the hepatic vasculature. Hepatic artery variations were observed in 16.8% of cases. Double hepatic artery was observed in 14 cases (4.5%). Of these 14 cases, reconstruction as a single artery was performed in 6 and dual reconstruction was performed in 8 cases. Portal vein variation was observed in 45 cases (14.5%): Dual anastomosis to right and left portal vein was performed in type III (n = 20; 6.4%) and type IV (n = 3; 1.0%) variations. There were 70 cases of portal vein thrombosis. In 8 of the 70, a jump or interposition graft with iliac vein was utilized. Of the middle hepatic vein variant, segment V vein only was reconstructed in 188 (60.6%) cases. In 21 (6.8%) cases, segment VIII vein only was reconstructed, and in 43 (13.9%) cases, both segment V and segment VIII veins were reconstructed using the recipient's portal vein, a cryopreserved iliac vein, or a prosthetic graft. The most common variation of right inferior hepatic vein was type II (n = 141; 45.5%), which has 1 right inferior hepatic vein.

CONCLUSION

Living donor liver transplantation using the right lobe can be performed safely, but there is a potential operative risk because of various anatomic variations. To minimize operative complications, anatomic variations should be kept in mind to ensure a safe and successful operation.

Reconstruction of three right hepatic veins using cadaveric iliac vein in right lobe living donor liver transplantation: case report

In various right hepatic vein anatomies, reconstruction is a surgically challenging technique in right lobe living donor liver transplantation. The right inferior hepatic vein is the most common hepatic vein abnormality in right lobe living-donor liver transplantation. Three accessory right hepatic veins is a rare right hepatic vein variation. We experienced one case of three right hepatic vein reconstruction among 300 partial liver transplantations using the right lobe in our center over 10 years. The donor right lobe had one main right hepatic vein and three accessory hepatic veins at the lower border of the liver. Restoration of accessory hepatic veins to the inferior vena cava was performed after construction of one conduit from the three accessory hepatic veins using a cadaveric donor iliac vein.

Infectious complications in living-donor liver transplant recipients: a 9-year single-center experience

BACKGROUND

Infectious complications following living-donor liver transplantation (LDLT) remain a major cause of morbidity and mortality. We analyzed the frequency and type of infectious complications according to the post-transplantation period, and their risk factors with regard to morbidity and mortality.

METHODS

We retrospectively analyzed 208 subjects who had undergone LDLT during a 9-year period.

RESULTS

The rate of infection was 1.69 per patient during the study period. The predominant infections were intra-abdominal infections (37.6%), primary bacteremia (17.4%), and pneumonia (14.5%). Within the first post-transplant month, 140 (39.9%) infections were detected, and catheter-related coagulase-negative staphylococci (44) were the most common infectious agents. During the 2-6-month post-transplant period, 109 infectious episodes occurred (31.1%), and Enterococcus sp. (n=16) related to biliary infection was the most frequent isolate. After the sixth month, 96 infectious episodes (29%) occurred, and biliary tract-related Escherichia coli (n=19) was the major causative organism. The overall mortality was 24.5% (51/208); 1-year survival rate was 88% (196/208). Post-transplant infection-related mortality was 52.9% (27/51). Biliary tract complications, such as biliary stenosis or leakage, significantly increased the mortality (P=0.01); however, reoperation (retransplantation or resurgery for biliary tract obstruction/leakage or to control bleeding) significantly reduced the mortality (P=0.01).

CONCLUSIONS

Our data showed that early catheter removal would mainly aid in reducing infectious complications in the 1-month post-transplantation period. Aggressive management, including reoperation, would lower the mortality in the LDLT recipients.

Drug-induced changes in P450 enzyme expression at the gene expression level: a new dimension to the analysis of drug-drug interactions

Drug-drug interactions (DDIs) caused by direct chemical inhibition of key drug-metabolizing cytochrome P450 enzymes by a co-administered drug have been well documented and well understood. However, many other well-documented DDIs cannot be so readily explained. Recent investigations into drug and other xenobiotic-mediated expression changes of P450 genes have broadened our understanding of drug metabolism and DDI. In order to gain additional information on DDI, we have integrated existing information on drugs that are substrates, inhibitors, or inducers of important drug-metabolizing P450s with new data on drug-mediated expression changes of the same set of cytochrome P450s from a large-scale microarray gene expression database of drug-treated rat tissues. Existing information on substrates and inhibitors has been updated and reorganized into drug-cytochrome P450 matrices in order to facilitate comparative analysis of new information on inducers and suppressors. When examined at the gene expression level, a total of 119 currently marketed drugs from 265 examined were found to be cytochrome P450 inducers, and 83 were found to be suppressors. The value of this new information is illustrated with a more detailed examination of the DDI between PPARalpha agonists and HMG-CoA reductase inhibitors. This paper proposes that the well-documented, but poorly understood, increase in incidence of rhabdomyolysis when a PPARalpha agonist is co-administered with a HMG-CoA reductase inhibitor is at least in part the result of PPARalpha-induced general suppression of drug metabolism enzymes in liver. The authors believe this type of information will provide insights to other poorly understood DDI questions and stimulate further laboratory and clinical investigations on xenobiotic-mediated induction and suppression of drug metabolism.

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.

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.

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.

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.

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.

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.

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.

Effect of spaceflight on oxidative and antioxidant enzyme activity in rat diaphragm and intercostal muscles

There are limited data regarding changes in oxidative and antioxidant enzymes induced by simulated or actual weightlessness, and any additional information would provide insight into potential mechanisms involving other changes observed in muscles from animals previously flown in space. Thus, the NASA Biospecimen Sharing Program was an opportunity to collect valuable information. Oxidative and antioxidant enzyme levels, as well as lipid perioxidation, were measured in respiratory muscles from rats flown on board Space Shuttle mission STS-54. The results indicated that there was an increasing trend in citrate synthase activity in the flight diaphragm when compared to ground based controls, and there were no significant changes observed in the intercostal muscles for any of the parameters. However, lipid peroxidation was significantly (p<0.05) decreased in the flight diaphragm. These results indicate that 6 day exposure to microgravity may have a different effect on oxidative and antioxidant activity in rat respiratory muscles when compared to data from previous 14 day hindlimb suspension studies.

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.

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.

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.

New perspectives on microbial dehalogenation of chlorinated solvents: insights from the field

A variety of microbial dechlorination mechanisms have been demonstrated in laboratory microcosms, pure cultures, and in situ sedimentary environments. New perspectives on in situ processes from these efforts allow the design of more realistic bioremediation strategies that complement natural processes regardless of whether the strategy used is one of engineered accelerated bioremediation or natural attenuation. Since 1994 the scientific community has acquired considerable knowledge regarding natural attenuation of organochlorine compounds. Natural attenuation of chlorinated solvents has been documented at a number of field sites. Reductive dechlorination driven by co-contaminants or naturally occurring organics as substrates in combination with aerobic or co-metabolic degradation contains certain chlorinated solvent plumes. Although natural attenuation is not a panacea, at sites where it is applicable, it offers a scientifically sound, cost-effective method to remediate groundwater contaminated with chlorinated solvents.

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.

Microbial fermentation-derived inhibitors of efflux-pump-mediated drug resistance

A library of 85000 microbial fermentation extracts was screened for inhibitors of multidrug resistance efflux pumps in Pseudomonas aeruginosa and Candida albicans. New compounds EA-371alpha and EA-371delta were isolated and demonstrated to be potent and specific inhibitors of the MexAB-OprM pump in P. aeruginosa. Two series of fungal metabolites, enniatins and beauvericins, were found to be ubiquitous and potent inhibitors of ABC transporters. Milbemycins were rediscovered as potent inhibitors of the CDRI pump in C. albicans, and demonstrated to potentiate effectively the antifungal activity of fluconazole and SCH-56592 against a wide variety of Candida clinical isolates.

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.

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.

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.

Characterization of chloramphenicol and florfenicol resistance in Escherichia coli associated with bovine diarrhea

Florfenicol, a veterinary fluorinated analog of thiamphenicol, is approved for treatment of bovine respiratory pathogens in the United States. However, florfenicol resistance has recently emerged among veterinary Escherichia coli isolates incriminated in bovine diarrhea. The flo gene, which confers resistance to florfenicol and chloramphenicol, has previously been identified in Photobacterium piscicida and Salmonella enterica serovar Typhimurium DT104. The flo gene product is closely related to the CmlA protein identified in Pseudomonas aeruginosa. The cmlA gene confers nonenzymatic chloramphenicol resistance via an efflux mechanism. Forty-eight E. coli isolates recovered from calves with diarrhea, including 41 that were both chloramphenicol and florfenicol resistant, were assayed for the presence of both flo and cmlA genes. Forty-two of the 44 isolates for which florfenicol MICs were > or =16 microg/ml were positive via PCR for the flo gene. All E. coli isolates for which florfenicol MICs were < or =8 microg/ml were negative for the flo gene (n = 4) Twelve E. coli isolates were positive for cmlA, and chloramphenicol MICs for all 12 were > or =32 microg/ml. Additionally, eight isolates were positive for both flo and cmlA, and both florfenicol and chloramphenicol MICs for these isolates were > or =64 microg/ml. DNA sequence analysis of the E. coli flo gene demonstrated 98% identity to the published GenBank sequences of both serovar Typhimurium flo(St) and P. piscicida pp-flo. The flo gene was identified on high-molecular-weight plasmids of approximately 225 kb among the majority of florfenicol-resistant E. coli isolates. However, not all of the florfenicol-resistant E. coli isolates tested contained the large flo-positive plasmids. This suggests that several of the E. coli isolates may possess a chromosomal flo gene. The E. coli flo gene specifies nonenzymatic cross-resistance to both florfenicol and chloramphenicol, and its presence among bovine E. coli isolates of diverse genetic backgrounds indicates a distribution much wider than previously thought.

Cloning and characterization of sialidases with 2-6' and 2-3' sialyl lactose specificity from Pasteurella multocida

Pasteurella multocida is a mucosal pathogen that colonizes the respiratory system of susceptible hosts. Most isolates of P. multocida produce sialidase activity, which may contribute to colonization of the respiratory tract or the production of lesions in an active infection. We have cloned and sequenced a sialidase gene, nanH, from a fowl cholera isolate of P. multocida. Sequence analysis of NanH revealed that it exhibited significant amino acid sequence homology with many microbial sialidases. Insertional inactivation of nanH resulted in a mutant strain that was not deficient in sialidase production. However, this mutant exhibited reduced enzyme activity and growth rate on 2-3' sialyl lactose compared to the wild type. Subsequently, we demonstrated the presence of two sialidases by cloning another sialidase gene that differed from nanH in DNA sequence and substrate specificity. NanB demonstrated activity on both 2-3' and 2-6' sialyl lactose, while NanH demonstrated activity only on 2-3' sialyl lactose. Neither enzyme liberated sialic acid from colominic acid (2-8' sialyl lactose). Recombinant E. coli containing the sialidase genes were able to utilize several sialoconjugants when they were provided as sole carbon sources in minimal medium. These data suggest that sialidases have a nutritional function and may contribute to the ability of P. multocida to colonize and persist on vertebrate mucosal surfaces.

Emerging perspectives on glaucoma: highlights of a roundtable discussion

PURPOSE

To present emerging perspectives on open-angle glaucoma related to patient compliance, current drug therapy, and treatment options.

METHODS

Roundtable discussion.

RESULTS

The panel discussion identified the following issues about patient compliance:1. It is a common problem in clinical practice and is often underappreciated by physicians.2. It is difficult for clinicians to detect.3. There are several risk factors that increase the probability of noncompliance. 4. Compliance can be improved through education, communication, improvement of the doctor-patient relationship, compliance aids, and simplifying the treatment regimen.

CONCLUSION

Patients' compliance with the therapeutic regimen for open-angle glaucoma is very important to the eventual outcome of their disease treatment. Physicians can improve their patients' compliance by a few simple, cost-effective interventions in the clinical setting. When considering different agents as first-line therapies, once-a-day dosing would be optimal for enhancing compliance.

Similarities in the action of Ro 60-0175, a 5-HT2C receptor agonist and d-fenfluramine on feeding patterns in the rat

RATIONALE

Activation of 5-HT2C receptors is thought to enhance satiety and to mediate the action of the prototypical anorectic drug d-fenfluramine.

OBJECTIVE

Four experiments investigated the role of the 5-HT2C receptor in the modulation of feeding by comparison of the effects of the putative selective 5-HT2C receptor agonist Ro 60-0175 and d-fenfluramine on feeding behaviour.

METHODS

Microstructural analyses of meal patterning and drinking of a palatable solution were made over a range of drug doses administered to male Lister hooded rats.

RESULTS

Ro 60-0175 increased the latency to the first meal (3 mg/kg) and reduced meal size (1 mg/kg). d-Fenfluramine (1 mg/kg) produced a similar behavioural pattern, but 3 mg/kg produced a more profound hypophagia that persisted for 10-12 h. Ro 60-0175 (1, 3 mg/kg) and d-fenfluramine (1.5 mg/kg) reduced ingestion of a palatable glucose/saccharin solution, by a reduction in the number of bouts of licking, with little effect on the size of individual bouts. d-Fenfluramine-induced hypophagia (2.1 mg/kg) was challenged by the administration of the selective 5-HT2C receptor antagonist SB 242084 (1, 3 mg/kg) in the meal patterning paradigm. SB 242084 significantly attenuated the decrease in feeding rate and increase in latency to feed produced by d-fenfluramine, but had no effect on the fenfluramine-induced reduction in meal size. A similar pattern of results was obtained when Ro 60-0175-induced hypophagia (3 mg/kg) was challenged by SB 242084 (1, 3 mg/kg).

CONCLUSIONS

These results demonstrate that Ro 60-0175 is a useful probe of the importance of 5-HT2C activation in the control of food intake and support the hypothesis that activation of 5-HT2C receptors is a critical aspect of the hypophagic action of d-fenfluramine. The 5-HT2C receptor may prove to be a useful target in the development of clinically effective drugs for the treatment of obesity.

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.

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.

Adherence of Lactobacillus to intestinal 407 cells in culture correlates with fibronectin binding

Lactobacilli are members of the normal mucosal microflora of most animals. Many isolates of Lactobacillus spp. are adherent to epithelial cells. In this study, using Lactobacillus acidophilus and L. agilis, we detected adherence in a pattern that suggested that the bacteria were binding to extracellular matrix proteins. Fluorescent microscopy, by using anti-fibronectin antibody, demonstrated that the isolates localize in those areas where fibronectin was detected. In addition, fibronectin pretreatment of the bacterial cells decreased adherence to Intestinal 407 epithelial cell monolayers. Cellular binding to fibronectin was detected by enzyme-linked immunosorbent assay and affinity binding to radio-labeled fibronectin. Fibronectin may be one of the eukaryotic receptors mediating attachment of Lactobacillus to mucosal surfaces.

Expression of flavour preferences conditioned by caffeine is dependent on caffeine deprivation state

RATIONALE

The acquisition of a caffeine conditioned flavour preference depends on the caffeine deprivation status of subjects during conditioning. It is not known if the expression of an established flavour preference is also state-dependent.

OBJECTIVES

To determine if the expression of a flavour preference conditioned by caffeine is dependent on the level of deprivation at the time of testing.

METHODS

In a double-blind placebo controlled study, 44 subjects were given 4 days exposure to a novel flavoured drink following overnight abstinence from caffeine. Half the subjects received caffeine (100 mg) in the drink, while the remainder had placebo (maltodextrin, 100 mg). Subjects rated the pleasantness of the drink each time. On a fifth (test) day, the subjects were given additional caffeine (100 mg) or placebo 2 h before consuming and rating the pleasantness of the drink.

RESULTS

Pleasantness ratings for the novel drink increased over the 4 conditioning days in subjects receiving caffeine, but decreased in those given placebo. On day 5, subjects who were trained and tested in the same caffeine deprivation state expressed pleasantness ratings similar to those for the final training day. In contrast, subjects who were trained and tested in different states expressed pleasantness ratings that were significantly different from those of the final training day.

CONCLUSIONS

These results suggest that the expression of caffeine conditioned flavour preferences are acutely sensitive to current motivational state, and a number of possible explanations are discussed.

Genetic relatedness of Salmonella isolates from nondomestic birds in Southeastern United States

Salmonella infections have been implicated in large-scale die-offs of wild birds in the United States. Although we know quite a bit about the epidemiology of Salmonella infection among domestic fowl, we know little about the incidence, epidemiology, and genetic relatedness of salmonellae in nondomestic birds. To gain further insight into salmonellae in these hosts, 22 Salmonella isolates from diseased nondomestic birds were screened for the presence of virulence and antibiotic resistance-associated genes and compared genetically using pulsed-field gel electrophoresis (PFGE) and random amplified polymorphic DNA analysis. Of the 22 Salmonella isolates examined, 15 were positive for the invasion gene invA and the virulence plasmid-associated genes spvC and pef. Most (15 of 22) were generally sensitive to antibiotics. However, two Salmonella isolates from pet birds were identified as Salmonella enterica serovar Typhimurium DT104. Despite the general susceptibility of these Salmonella isolates to most antimicrobial agents, antibiotic resistance-associated genes intI1, merA, and aadA1 were identified in a number of these isolates. Five distinct XbaI and nine distinct BlnI DNA patterns were observed for the 22 Salmonella isolates typed by PFGE. PFGE analysis determined that Salmonella isolates from passerines in Georgia and Wyoming were genetically related.

HMG-CoA reductase inhibitors increase BMD in type 2 diabetes mellitus patients

Recently, it was reported that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors increased bone mineral density (BMD) in mice. We studied the effect of HMG-CoA reductase inhibitors on BMD of type 2 diabetes mellitus by a retrospective review of medical records. Sixty-nine type 2 diabetic patients were included. The control group (n = 33) did not take HMG-CoA reductase inhibitors. The treatment group (n = 36) was administered either lovastatin, pravastatin, or simvastatin. BMD of the spine, femoral neck, femoral trochanter, and total hip were measured by dual-energy X-ray absorptiometry. There were no significant differences between control and treatment groups in age, sex, body mass index, glycemic control, and serum insulin levels. In the control group, BMD of the spine significantly decreased (from 1.116 +/- 0.165 to 1.081 +/- 0.178 g/cm2) after 14 months. In the treatment group, BMD of the femoral neck significantly increased (from 0.853 +/- 0.139 to 0.878 +/- 0.147 g/cm2) after 15 months. In male subjects treated with HMG-CoA reductase inhibitors, there was a significant increase in BMD of the femoral neck and femoral trochanter (from 0.899 +/- 0.139 to 0.934 +/- 0.139 and from 0.801 +/- 0.145 to 0.833 +/- 0.167 g/cm2, respectively), but in female subjects, only BMD of the femoral neck increased (from 0.819 +/- 0.132 to 0.834 +/- 0.143 g/cm2). Percentage increments of BMD of the femoral neck, femoral wards triangle, femoral trochanter, and total hip in the treatment group were significantly higher than in the control group (2.32% vs. -0.99, 1.77% vs. -1.25%, 1.40% vs. -1.21%, 0.88% vs. -1.03%, respectively). The proportion of subjects who had an increase in BMD of the spine and total hip more than two percentages was significantly larger in the treatment group than in the control group (30.6% vs. 15.2% and 30.6% vs. 9.1%, respectively). The increased increment in BMD of the treatment group was significantly greater than those in the control group after adjustment for age and body mass index (P < 0.05). These results suggest that HMG-CoA reductase inhibitors may increase BMD of the femur in male patients with type 2 diabetes mellitus.

Detection of florfenicol resistance genes in Escherichia coli isolated from sick chickens

Florfenicol is an antibiotic approved for veterinary use in cattle in the United States in 1996. Although this drug is not used in poultry, we have detected resistance to florfenicol in clinical isolates of avian Escherichia coli. Molecular typing demonstrated that the florfenicol resistance gene, flo, was independently acquired and is plasmid encoded.

The importance of the convex hull for human performance on the traveling salesman problem: a comment on MacGregor and Ormerod (1996)

MacGregor and Ormerod (1996) have presented results purporting to show that human performance on visually presented traveling salesman problems, as indexed by a measure of response uncertainty, is strongly determined by the number of points in the stimulus array falling inside the convex hull, as distinct from the total number of points. It is argued that this conclusion is artifactually determined by their constrained procedure for stimulus construction, and, even if true, would be limited to arrays with fewer than around 50 points.