Influences of ischemia and reperfusion on the feline small-intestinal mucosa

The alterations of several small-intestinal mucosal enzymes have been examined in cats that underwent different periods (1-4 hr) of occlusion of the superior mesenteric artery, followed by 4 hr of reperfusion. The damage progressed during ischemia and reperfusion from the villus tips to the crypts: first, there was a rapid decrease in the activity of maltase, a brush-border enzyme; a slower decline occurred in two cytoplasmic enzymes, aldolase A (with preferential location in feline villus cells) and lactate dehydrogenase (with an ubiquitous distribution); a lag preceded the decrease in aldolase B (a cytoplasmic enzyme shown to occur mainly in feline crypt cells). For all these enzymes, the initial period of reperfusion was associated with a greater decrease in enzyme activity than persisting ischemia. By determination of the unsedimentable proportion of glutamate dehydrogenase (a mitochondrial matrix enzyme) and of acid phosphatase (a lysosomal enzyme) it was demonstrated that ischemia caused important mitochondrial damage before the cells were lost, whereas no lysosomal damage was observed in any condition. These sensitive parameters of cell damage can serve as a criterion for an adequate evaluation of potential cytoprotective agents.     

In vitro metabolism of ferroquine (SSR97193) in animal and human hepatic models and antimalarial activity of major metabolites on Plasmodium falciparum.

Ferroquine (SSR97193) has been shown to be a promising antimalarial, both on laboratory clones and on field isolates. So far, no resistance was documented in Plasmodium falciparum. In the present work, the metabolic pathway of ferroquine, based on experiments using animal and human hepatic models, is proposed. Ferroquine is metabolized mainly via an oxidative pathway into the major metabolite mono-N-demethyl ferroquine and then into di-N,N-demethyl ferroquine. Some other minor metabolic pathways were also identified. Cytochrome P450 isoforms 2C9, 2C19, and 3A4 and, possibly in some patients, isoform 2D6, are mainly involved in ferroquine oxidation. The metabolites were synthesized and tested against the 3D7 (chloroquine-sensitive) and W2 (chloroquine-resistant) P. falciparum strains. According to the results, the activity of the two main metabolites decreased compared with that of ferroquine; however, the activity of the mono-N-demethyl derivative is significantly higher than that of chloroquine on both strains, and the di-N-demethyl derivative remains more active than chloroquine on the chloroquine-resistant strain. These results further support the potential use of ferroquine against human malaria.     

Study on the Tongue and Groove Effect of the Elekta Multileaf Collimator Using Monte Carlo Simulation and Film Dosimetry

BACKGROUND: Nowadays, multileaf collimation of the treatment fields from medical linear accelerators is a common option. Due to the design of the leaf sides, the tongue and groove effect occurs for certain multileaf collimator applications such as the abutment of fields where the beam edges are defined by the sides of the leaves. MATERIAL AND METHODS: In this study, the tongue and groove effect was measured for two pairs of irregular multileaf collimator fields that were matched along leaf sides in two steps. Measurements were made at 10 cm depth in a polystyrene phantom using Kodak EDR2 films for a photon beam energy of 6 MV on an Elekta Sli-plus accelerator. To verify the measurements, full Monte Carlo simulations were done. In the simulations, the design of the leaf sides was taken into account and one component module of BEAM code was modified to correctly simulate the Elekta multileaf collimator. RESULTS AND CONCLUSION: The results of measurements and simulations are in good agreement and within the tolerance of film dosimetry.     

Assessment of virulence of pigeon isolates of Salmonella enterica subsp. enterica serovar typhimurium variant copenhagen for humans

Salmonella enterica serovar Typhimurium variant Copenhagen was isolated from 5 of 152 (3.3%) feral pigeons from the city of Ghent (Belgium) and from 26 pooled fecal samples from 114 pigeon lofts (22.8%). These isolates belonged to phage type (PT) 99. Seven of the pigeon isolates were further compared in vitro to five human variant Copenhagen isolates, 2 isolates of PT 208, 1 isolate each of PT 120 and U302, and a nontypeable isolate. No differences in invasiveness in human intestinal epithelial Caco-2 cells were found. The human strains, however, were able to multiply significantly more inside human THP-1 macrophages than the pigeon strains. After inoculation of mice with a pigeon PT 99 strain, high numbers of Salmonella bacteria were shed with the feces, the internal organs were heavily colonized, and the animals showed severe clinical symptoms resulting in death. In conclusion, the less-pronounced ability of the pigeon variant Copenhagen strains to multiply inside human macrophages than human strains as well as the lack of human PT 99 isolates during 2002, despite the relatively high frequency of this PT in the pigeon population, suggest these strains to be of low virulence to humans. However, the high virulence for mice of the tested strain implies that rodents may act as reservoirs.     

Inactivation of Notch1 impairs VDJbeta rearrangement and allows pre-TCR-independent survival of early alpha beta Lineage Thymocytes

Notch proteins influence cell fate decisions in many developmental systems. During lymphoid development, Notch1 signaling is essential to direct a bipotent T/B precursor toward the T cell fate, but the role of Notch1 at later stages of T cell development remains controversial. We have recently reported that tissue-specific inactivation of Notch1 in immature (CD44(-) CD25(+)) thymocytes does not affect subsequent T cell development. Here, we demonstrate that loss of Notch1 signaling at an earlier (CD44(+)CD25(+)) developmental stage results in severe perturbation of alpha beta but not gamma delta lineage development. Immature Notch1(-/-) thymocytes show impaired VDJ beta rearrangement and aberrant pre-TCR-independent survival. Collectively, our data demonstrate that Notch1 controls several nonredundant functions necessary for alpha beta lineage development.     

Communication on end-of-life decisions with patients wishing to die at home: the making of a guideline for GPs in Flanders, Belgium

BACKGROUND: Communication with patients on end-of-life decisions is a delicate topic for which there is little guidance.AIM: To describe the development of a guideline for GPs on end-of-life communication with patients who wish to die at home, in a context where patient autonomy and euthanasia are legally regulated. DESIGN OF STUDY: A three-phase process (generation, elaboration and validation). In the generation phase, literature findings were structured and then prioritised in a focus group with GPs of a palliative care consultation network. In the elaboration phase, qualitative data on patients' and caregivers' perspectives were gathered through a focus group with next-of-kin, in-depth interviews with terminal patients, and four quality circle sessions with representatives of all constituencies. In the validation phase, the acceptability of the draft guideline was reviewed in bipolar focus groups (GPs-nurses and GPs-specialists). Finally, comments were solicited from experts by mail. SETTING: Primary home care in Belgium. SUBJECTS: Participants in this study were terminal patients (n = 17), next-of-kin of terminal patients (n = 17), GPs (n = 25), specialists (n = 3), nurses (n = 8), other caregivers (n = 2) and experts (n = 41). RESULTS: Caregivers and patients expressed a need for a comprehensive guideline on communication in end-of-life decisions. Four major communication themes were prioritised: truth telling; exploration of the patient's wishes regarding the end of life; dealing with disproportionate interventions; and dealing with requests for euthanasia in the terminal phase of life. Additional themes required special attention in the guideline: continuity of care by the GP; communication on foregoing food and fluid; and technical aspects of euthanasia. CONCLUSION: It was feasible to develop a guideline by combining the three cornerstones of evidence-based medicine: literature search, patient values and professional experience.     

Effects of Different Test Conditions on MICs of Food Animal Growth-Promoting Antibacterial Agents for Enterococci

The influence of the addition of sheep blood to Mueller-Hinton II agar and the effects of aerobic incubation with or without CO₂ and of anaerobic incubation were tested with bacitracin, tylosin, avoparcin, virginiamycin, avilamycin, narasin, and flavomycin on enterococci. The antibacterial activity of bambermycin (Flavomycin) was strongly inhibited by the addition of blood, except with the species Enterococcus faecium, Enterococcus mundtii, Enterococcus hirae, Enterococcus casseliflavus, and Enterococcus gallinarum, which were not susceptible to this antibiotic on blood-free medium. With all other antimicrobials except avoparcin and tylosin, the presence of blood resulted in MIC increases of 1 to 3 log₂ differences. Incubation in aerobic or anaerobic atmospheres enriched with CO₂ lowered the susceptibility of enterococci to tylosin and increased their susceptibility to avilamycin, narasin, and avoparcin. This effect was most pronounced in tests on blood-free media. Results of susceptibility tests incubated under anaerobiosis and in a CO₂-enriched atmosphere did not differ. For all enterococcal species, the preferred conditions for testing the susceptibility are Mueller-Hinton II medium supplemented with blood and incubation in a CO₂-enriched atmosphere. However, when only E. faecium and Enterococcus faecalis are being tested, Mueller-Hinton II medium without blood incubated aerobically gives satisfactory results.     

Presence and mechanism of macrolide-lincosamide resistance in Enterococcus columbae strains belonging to the intestinal flora of pigeons.

Faecal samples from 50 pigeons all originating from different lofts were screened for the presence of macrolide and lincosamide (ML)-resistant isolates of Streptococcus gallolyticus and Enterococcus columbae by plating the samples onto selective media. Sixty-eight ML-resistant E. columbae strains were recovered from the faecal samples of 29 animals. Two of these samples also harboured ML-resistant S. gallolyticus strains. The erm(B) gene was detected in 58 E. columbae and in five S. gallolyticus isolates. Four of these E. columbae isolates also carried the mef(A) gene. Five E. columbae strains possessed the mef(A) gene in the absence of erm(B). On the basis of the sequence of the complete erm(B) gene, 10 E. columbae isolates clustered together in six groups. In two of these isolates, the erm(B) gene sequence was identical to that of S. gallolyticus strains, indicating that exchange of resistance genes might occur between pathogenic and non-pathogenic bacterial species belonging to the pigeon's intestinal flora.     

Involvement of interleukin 18 in Crohn's disease: evidence from in vitro analysis of human gut inflammatory cells and from experimental colitis models

An imbalance of immunoregulatory factors and/or cells contributes to uncontrolled mucosal T cell activation and inflammation in Crohn's disease (CD). Bioactive interleukin (IL)-18 has been shown to be produced by macrophages in CD lesions. We report here that T cells freshly isolated from inflamed tissue of CD patients (and not T cells from control intestinal tissue) were responsive to IL-18. In the presence of IL-18, these T cells produced more interferon (IFN)-gamma and less IL-10. To analyse further the role of IL-18 in this disease, an acute and a chronic model of murine colitis were used. IL-18 mRNA was significantly enhanced in trinitrobenzene sulphonic acid (TNBS) induced colitis, and treatment with IL-18 binding protein (IL-18BPa), which neutralizes IL-18 bioactivity, significantly reduced the severity of colitis. However, IL-18BPa did not affect the course of chronic colitis in CD45RBhighCD4+ T cell reconstituted SCID mice. Production of IFN-gamma in lamina propria mononuclear cell cultures from IL-18BPa-treated SCID mice was decreased, but at the same time fewer lamina propria CD4+ T cells harvested from IL-18BPa-treated mice compared to non-treated mice were in apoptosis. We conclude that IL-18 clearly has a modulatory role in the inflammatory cascade of CD and experimental colitis by affecting IFN-gamma and IL-10 production, and apoptosis. In view of the divergent effects of IL-18 neutralization in the two different murine colitis models, it is unlikely that IL-18 is at the top of this cascade.     

Variability in acquired resistance of Pasteurella and Mannheimia isolates from the nasopharynx of calves, with particular reference to different herd types

To measure the level of antimicrobial resistance in potential bovine respiratory pathogens at different production types, nasal swabs were collected from 57 calves of 13 dairy herds, 150 calves of 9 beef cattle herds, and 289 calves of 5 high-density veal calf herds and investigated for the presence of Pasteurellaceae. All calves were less than 6 months old. Susceptibilities of the Pasteurella and Mannheimia isolates to eight antimicrobials were determined using an agar dilution method. P. multocida (37.3%) and hemolytic Mannheimia organisms (M. haemolytica sensu lato) (6.3%) were the most frequently detected organisms. The overall prevalence of isolates resistant to at least one antimicrobial from the dairy, beef, and veal calves were 17.6% (6/34), 21.9% (14/64), and 71.9% (64/89), respectively. In isolates obtained on the veal calf herds, acquired resistance to ampicillin, oxytetracycline, potentiated sulfonamides, gentamicin, tilmicosin, and enrofloxacin was frequently present, and 32.6% of these isolates were resistant to more than two of the tested antimicrobials. Resistance to ceftiofur and florfenicol was not detected. A substantial within-herd variability of species diversity and resistance profiles among isolates belonging to the genera Pasteurella and Mannheimia was found among the isolates of the veal calf farms.