Intravenous cyclosporine for severe attacks of ulcerative colitis: a survey of Canadian gastroenterologists

A single randomized trial evaluated the use of intravenous cyclosporine treatment for severe attacks of ulcerative colitis. The perceived efficacy and safety of this intervention were measured through a survey of the membership of the Canadian Association of Gastroenterology (CAG). METHODS: All CAG members were mailed a survey with questions regarding their familiarity with the data supporting the use of cyclosporine, their perception of the efficacy and toxicity of the drug, and whether patients who fail conventional treatment should receive this therapy. The proportion of respondents who had used cyclosporine to treat severe ulcerative colitis was determined. RESULTS: One hundred and sixty-one responses were received (34% response rate). Sixty-four per cent of respondents were academic faculty members and 82% treated patients with severe colitis. Using multivariate analyses, positive associations were found between the respondents' age (P = 0.004) and subspecialty training in gastroenterology (P = 0.001), and whether respondents treat patients with severe ulcerative colitis. Twenty-six per cent of individuals had prescribed cyclosporine for this indication, of whom 88% were in academic practice (P = 0.007). Over 90% of respondents believe that further clinical trials are needed before cyclosporine becomes accepted as standard therapy. CONCLUSIONS: Although the use of cyclosporine is measurable among Canadian gastroenterologists, the majority believe that further clinical trials are necessary before the drug is accepted as a standard therapy.     

Molecular modelling of mammalian CYP2B isoforms and their interaction with substrates, inhibitors and redox partners

1. The construction of three-dimensional models of CYP2B isozymes from rat (CYP2B1), rabbit (CYP2B4) and man (CYP2B6), based on a multiple sequence alignment with CYP102, a unique eukaryotic-like bacterial P450 (in terms of possessing an NADPH-dependent FAD- and FMN-containing oxidoreductase redox partner) of known crystal structure, is reported. 2. The enzyme models described are shown to be consistent with experimental evidence from site-directed mutagenesis studies, antibody recognition sites and amino acid residues identified as being associated with redox partner interactions, together with the location of a key serine residue (Ser-128) likely to be involved in protein kinaseA-mediated phosphorylation. 3. A substantial number of known substrates and inhibitors of CYP2B isozymes are shown to fit the putative active sites of the enzyme models in agreement with their reported position of metabolism or mode of inhibition respectively. In particular, there is complementarity between the characteristic non-planar geometries of CYP2B substrates and key groups in the enzymes' active sites. 4. Molecular modelling of CYP2B isozymes appears to rationalize a number of the reported findings from quantitative structure-activity relationship investigations on series of CYP2B substrates and inhibitors.     

Experimental and model investigations of bleaching and saturation of fluorescence in flow cytometry

We investigated the fluorescence emission from three fluorophores commonly used for labeling cells in flow cytometry. We have demonstrated that the fluorescence emission from cells labeled with fluorescein-isothiocyanate (FITC), phycoerythrin (PE), and allophycocyanin (APC) is considerably saturated and bleached in standard flow cytometric conditions. Therefore, for optimization of fluorescence detection in a flow cytometer, it is important to know the emission kinetics in detail. We made a mathematical model of the optical processes involved: absorption, fluorescence emission, nonradiative decay, photodestruction, and triplet state occupation. The validity of the model was experimentally tested with a set of averaged fluorescence pulses, measured in a large range of intensities and illumination times. The fluorescence of APC could be completely described by the model and produced the following rate constants: photodestruction rate kb1 = 6 x 10(3) s(-1), triplet state population rate k12 = 2 x 10(5) s(-1), and depopulation rate k20 = 5 x 10(4) s(-1). The fluorescence kinetics of FITC- and PE-labeled cells could not be fitted with only three parameters over the entire range, indicating that other optical processes are involved. We used the model to determine the sensitivity of our flow cytometer and to calculate the optimum conditions for the detection of APC. The results show that in principle a single APC molecule on a cell can be detected in the presence of background, i.e., autofluorescence and Raman scattering by water.     

A common substitution (Asn291Ser) in lipoprotein lipase is associated with increased risk of ischemic heart disease

Lipoprotein lipase degrades triglycerides in plasma and as a byproduct produces HDL particles. Genetic variation in lipoprotein lipase may therefore affect cardiovascular risk. We tested 9,214 men and women from a general population sample and 948 patients with ischemic heart disease for the Asn291Ser substitution in lipoprotein lipase. The allele frequency in the general population was 0.024 and 0.026 for women and men, respectively. In comparison with noncarriers, female heterozygous probands had increased plasma triglycerides (delta = 0.23 mmol/liter), while HDL cholesterol was reduced in both female and male carriers (delta = 0.18 mmol/liter and delta = 0.11 mmol/liter, respectively). A similar phenotype was found in six homozygous carriers. On multiple logistic regression analysis, plasma triglycerides and HDL cholesterol were independent predictors of ischemic heart disease in both genders. On univariate analysis, odds ratios for ischemic heart disease in probands were 1.89 in women (95% CI: 1.19-3.01) and 0.90 in men (95% CI: 0.62-1.31), and on multivariate analysis were 1.98 in women (95% CI: 1.11-3.53) and 1.02 in men (95% CI: 0.65-1.60). This study demonstrates that a single common mutation in the lipoprotein lipase gene is associated with elevated plasma triglycerides and reduced HDL cholesterol levels, whereby carriers, in particular women, seem to be predisposed to ischemic heart disease. It cannot be excluded, however, that male carriers of this substitution may represent a subset of low-HDL individuals without raised triglycerides not predisposed to ischemic heart disease.     

An evaluation of transovarian uptake of metabolites using arterio-venous difference methods in dairy cattle

Arterio-venous (A-V) difference techniques were used in cattle to examine ovarian energy metabolism, cholesterol uptake and steroid hormone outputs. Catheters were inserted into the ovarian vein and facial artery, and Transonic flow transducers were placed around the ovarian A-V plexus. Further, in some cows, the effects of a challenge with GnRH were examined. Glucose uptake and lactate output were significant in most individual cows. Nonesterified fatty acids (NEFA) uptake were not significant in any cow in dioestrus. Ovarian uptake of beta-Hydroxy-butyrate (3-OHB) was significant in 4 cows in dioestrus. Cholesterol uptake was significant in only 1 cow. Oxygen uptake was significant in all cows at all stages of the oestrous cycle. All cows had significant output of progesterone and oestradiol-17 beta. These data show that the bovine ovary utilises significant amounts of glucose, and Respiratory quotient (RQ) estimates demonstrated that glucose was the primary fuel used by the ovary. The significant output of lactate suggested that anaerobic pathways were mainly used for glucose oxidation. The observed uptakes of 3-OHB indicated that the ovary utilises 3-OHB as a source of energy. Cholesterol uptake was not a rate-limiting factor for steroid hormone production in the ovary. Despite the high metabolic rate in the luteal ovary, the small difference in PO2 between arterial and ovarian venous blood indicated that the ovary consumes only a small proportion of available oxygen. GnRH had no significant effect on the uptake of metabolites and energy metabolism, but it increased OBF and the output of progesterone and oestradiol-17 beta. The use of A-V methods to determine the metabolic needs of the ovary is useful in understanding the means by which nutrition can influence fertility.     

Retropharyngeal pseudomeningocele after atlanto-occipital dislocation: report of two cases

OBJECTIVE AND IMPORTANCE: We report two cases of retropharyngeal pseudomeningocele after atlanto-occipital dislocation. This is rare, with only one other reported case in the literature. CLINICAL PRESENTATION: We report two patients who presented after blunt cervical and head trauma. Plain films revealed that each patient had atlanto-occipital dislocation. Subsequent magnetic resonance imaging revealed the delayed development of retropharyngeal pseudomeningocele. Concomitant hydrocephalus was noted in both patients. INTERVENTION: The surviving patient showed marked neurological improvement and resolution of his pseudomeningocele after ventriculoperitoneal shunting. CONCLUSION: For patients with closed head injuries who develop posttraumatic pseudomeningocele, we recommend cranial computed tomography to assess for the presence of hydrocephalus. In patients with atlanto-occipital dislocation, delayed neurological deterioration warrants magnetic resonance imaging of the craniocervical junction to rule out posttraumatic pseudomeningocele.