Reduced COX-2 protein in colorectal cancer with defective mismatch repair

Most colorectal adenomas and carcinomas arise in the setting of chromosomal instability characterized by progressive loss of heterozygosity. In contrast, approximately 15-20% of colorectal neoplasms arise through a distinct genetic pathway characterized by microsatellite instability (MSI) associated with frequent loss of expression of one of the DNA mismatch repair enzymes, most often hMLH1 or hMSH2. These distinct genetic pathways are reflected by differences in tumor histopathology, distribution in the colon, prognosis, and dwell time required for progression from adenoma to carcinoma. To determine whether these two groups of tumors differ in their expression of cyclooxygenase-2 (COX-2), a putative chemopreventative target, immunostaining for this protein was performed in colorectal cancers categorized by the presence (n = 41) and absence (n = 66) of defective mismatch repair. Defective mismatch repair was defined by the presence of tumor microsatellite instability (MSI-H, > or =40% of markers demonstrating instability) and by the absence of protein expression for either hMLH1 or hMSH2. Overall, our results showed that low or absent COX-2 staining was significantly more common among tumors with defective mismatch repair (P = 0.001). Other features predictive of low COX-2 staining included marked tumor infiltrating lymphocytosis, and solid/cribiform or signet ring histological patterns. These observations indicate that colorectal cancers with molecular and phenotypic characteristics of defective DNA mismatch repair express lower levels of COX-2. The clinical implications of this biological distinction remain unknown but should be considered when assessing the efficacy of COX-2 inhibitors for chemoprevention in patients whose tumors may arise in the setting of defective DNA mismatch repair.     

Issues in the design and interpretation of studies to evaluate the impact of community-based interventions

Increasingly, epidemiologists are faced with the need to evaluate the impact of an intervention that is delivered at the level of a community or cluster of individuals, rather than at the individual level. This has profound implications for the design and interpretation of a study to evaluate its impact. We start by discussing the issues arising in the extension of the randomized double-blind controlled trial methodology to the evaluation of interventions delivered to clusters of individuals, or to whole communities, where the unit of randomization is a cluster of individuals rather than an individual. We then consider alternative approaches to design, discuss their relative strengths and weaknesses and present a framework of design options. Finally we propose a pragmatic approach to evaluation design in this setting. We believe that the answer lies in the judicious selection of different design elements, combined in such a way that when the evidence from each is presented together, a clear picture of the impact of the intervention emerges. We illustrate this using an example from the recent literature.     

Aggressiveness, hypoalgesia and high blood pressure in mice lacking the adenosine A2a receptor

Adenosine is released from metabolically active cells by facilitated diffusion, and is generated extracellularly by degradation of released ATP. It is a potent biological mediator that modulates the activity of numerous cell types, including various neuronal populations, platelets, neutrophils and mast cells, and smooth muscle cells in bronchi and vasculature. Most of these effects help to protect cells and tissues during stress conditions such as ischaemia. Adenosine mediates its effects through four receptor subtypes: the A1, A2a, A2b and A3 receptors. The A2a receptor (A2aR) is abundant in basal ganglia, vasculature and platelets, and stimulates adenylyl cyclase. It is a major target of caffeine, the most widely used psychoactive drug. Here we investigate the role of the A2a receptor by disrupting the gene in mice. We found that A2aR-knockout (A2aR-/-) mice were viable and bred normally. Their exploratory activity was reduced, whereas caffeine, which normally stimulates exploratory behaviour, became a depressant of exploratory activity. Knockout animals scored higher in anxiety tests, and male mice were much more aggressive towards intruders. The response of A2aR-/- mice to acute pain stimuli was slower. Blood pressure and heart rate were increased, as well as platelet aggregation. The specific A2a agonist CGS 21680 lost its biological activity in all systems tested.     

The impact of a required college health and physical education course on the health status of alumni

Social interactions between mothers that were holding their infants and other group members were studied in a wild group of moor macaques (Macaca maurus). Affiliative approaches to infants (AAI) by group members that were accompanied with particular behaviours, such as mouthing and touching or affiliative grunts, were observed frequently. Females approached mothers with infants more frequently than did males in all age classes. Female reproductive status, parity and dominance relationships between interactants had little effect on the frequency of approaches. Mothers received more grooming and performed less grooming when they were holding their infants than when they were not. A high level of social tolerance in macaque species with relaxed dominance styles might allow the free expression of AAI. Dominance styles among females and AAI could be linked via a positive feedback relationship since AAI might play a role in relaxing the dominance style among females.     

Localization of a domain in the FimH adhesin of Escherichia coli type 1 fimbriae capable of receptor recognition and use of a domain-specific antibody to confer protection against experimental urinary tract infection

The FimH subunit of type 1-fimbriated Escherichia coli has been implicated as an important determinant of bacterial adherence and colonization of the urinary tract. Here, we sought to localize the functionally important domain(s) within the FimH molecule and to determine if antibodies against this domain would block adherence of type 1-fimbriated E. coli to the bladder mucosa in situ and in vivo in an established mouse model of cystitis. We generated translational fusion proteins of disparate regions of the FimH molecule with an affinity tag MalE, and tested each of the fusion products in vitro for functional activity. The minimum region responsible for binding mouse bladder epithelial cells and a soluble mannoprotein, horseradish peroxidase, was contained within residues 1-100 of the FimH molecule. We validated and extended these findings by demonstrating that antibodies directed at the putative binding region of FimH or at synthetic peptides corresponding to epitopes within the binding domain could specifically block type 1 fimbriae-mediated bacterial adherence to bladder epithelial cells in situ and yeast cells in vitro. Next, we compared the ability of mice passively immunized intraperitoneally with antisera raised against residues 1-25 and 253-264 of FimH or 1-13 of FimA to resist bladder colonization in vivo after intravesicular challenge with type 1-fimbriated E. coli. Only the antibody directed at the putative binding region of FimH (anti- s-FimH1-25) significantly reduced E. coli bladder infections in the experimental mouse model of urinary tract infections. Similar results were obtained when the mice were actively immunized with synthetic peptides corresponding to residues 1-25 and 253-264 of FimH or 1-13 of FimA. The mechanism of protection was attributed, at least in part, to inhibition of bacterial adherence to the bladder surface by s-FimH1-25-specific antibody molecules that had filtered through the kidneys into the urine. The level of FimH antibodies entering the bladder from the circulatory system of the immunized mice was found to be markedly enhanced upon bacterial challenge. The potential broad spectrum activity of the protective FimH antibody was indicated from its serologic cross-reactivity with various urinary tract bacterial isolates bearing type 1 fimbriae. These findings could be relevant in the design of an efficacious and broadly reactive FimH vaccine against urinary tract infections.     

The effect of priming with vecuronium and rocuronium on young and elderly patients

The priming principle consists of administering a subparalyzing dose of nondepolarizing neuromuscular blocking drug 3-6 min before giving a second dose for tracheal intubation. This study was performed to observe the effects of priming doses of vecuronium and rocuronium on pulmonary function tests and muscular weaknesses in young (25-35 yr of age) and elderly (65-73 yr of age) patients. Ten young and 10 elderly patients were each placed in vecuronium and rocuronium groups. Oxygen saturation and train-of-four (TOF) ratio were determined, and pulmonary function tests were performed. Then 20% of the 95% effective dose (ED95) of the muscle relaxants was given intravenously. All tests were performed again 4 min after vecuronium and 3 min after rocuronium. Other signs of muscular weaknesses were also recorded. Elderly patients showed more signs of muscle weakness in both groups. The TOF ratio was 0.77 and 0.79 in the elderly rocuronium and vecuronium groups, respectively, and 0.89 and 0.90 in the young rocuronium and vecuronium groups, respectively. Dynamic spirometry revealed decreases in forced expiratory volume in 1 s and forced vital capacity in both groups, and no significant changes in peak expiratory flow rate. The expiratory reserve volume was reduced more in the elderly groups. Oxygen saturation decreased in both groups. We conclude that oxygen saturation, pulmonary function, and muscle strength decrease more in the elderly than in their younger counterparts from priming doses of vecuronium or rocuronium. IMPLICATIONS: The priming principle consists of giving a subparalyzing dose of muscle relaxant 3-6 min before giving a second dose for tracheal intubation. We found that priming doses of vecuronium and rocuronium produced greater decreases in oxygen saturation and pulmonary function in the elderly (aged 65-73 yr) than their younger (aged 25-35 yr) counterparts. Priming may not be a safe approach in elderly patients.     

Prospective study of human herpesvirus 6, human herpesvirus 7, and cytomegalovirus infections in human immunodeficiency virus-positive patients

Blood samples from human immunodeficiency virus (HIV)-positive patients were monitored for cytomegalovirus (CMV), human herpesvirus 6 (HHV-6), and HHV-7 by PCR. We detected CMV in 17% of the patients, HHV-6 in 6%, and HHV-7 in 3%. The viral loads of CMV were significantly higher than those of HHV-6 (P = 0.007) or HHV-7 (P = 0.01). Detection of CMV and HHV-6 was associated with low and high CD4 counts, respectively.     

Comparative aging and life histories in mammals

A comparative assessment of aging and longevity in mammals has four uses in aging research. These are: (1) hypothesis formulation and evaluation, (2) investigating the generality of putative aging mechanisms, (3) isolating key physiological factors influencing aging rate, and (4) allowing the most appropriate choice of animal models for particular research questions. The first use requires detailed information on a wide variety of species, and I will examine general patterns of aging in a sample of over 600 species of mammals. The second use requires the selection of several models as distantly related to one another as feasible. The third use is best served by evaluating species or populations as closely related to one another as possible, assuming that they differ substantially in aging rate. The fourth use requires a logic of animal model selection, as well detailed information about a wide range of species. Specific examples of each use will be given.