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At least 181 records · Page 10Linked to original sources
PubMed2005

Development of a total colonoscopy rat model with endoscopic submucosal injection of the cecal wall.

BACKGROUND: Experimental models of colorectal tumor require either laparotomy for induction or anastomosis following resection. The long murine cecum avoids the need for an anastomosis, making the cecum the preferred site for induction. This study aimed to evaluate total colonoscopy with submucosal injection of cecal wall (TCWI) in rats in terms of failure rate (FR), complication rate (CR), and reproducibility (R). METHODS: A bolus of bowel prep was given. Anesthesia was injected intraperitoneally. A video fiberscope (5.9 mm outer diameter, 180/90 degrees up/down bending, 100/100 degrees right/left bending, 103 cm working length, 120 degrees view field, and 2.0 mm channel) allowed for irrigation and suction. Saline 1 ml was injected in the cecal wall through a 4-mm-long, 23-gauge needle placed on a 3-mm wire, resulting in a blister. FR was a failure to reach and inject the cecum. Rats were allowed to recover. CR was measured at necropsy. R was assessed by comparing TCWI time, FR, and CR for three investigators. Sample size of 120 (type I error, 0.05; power, 80%) was based on a pilot study. Data are presented as median (range). RESULTS: A total of two of 122 rats (1.6%) died after prep or anesthesia. Bowel prep resulted in 99.1% evacuation of solid feces. A total of 120 male Sprague-Dawley retired breeders weighing 592 g (range, 349-780) underwent TCWI. Scope depth was 28 cm (range, 20-36). Irrigating fluid was 290 ml (range, 100-600). TCWI time was 7 min (range, 4-28). FR was 4%. In three failed cases, the scope reached the ascending colon. CR was 2%. There were two perforations in the ascending colon. All three operators had similar TCWI time (p = 0.673), FR (p > 0.1), and CR (p > 0.1). A total of 98.3% of rats survived to planned sacrifice. At 48-h necropsy, the injection site was macroscopically identified in 118 rats. CONCLUSIONS: A safe and reproducible TCWI rat model has been achieved, which may provide a valuable tool in the future for studies of solid colorectal tumors.

Animals↗
PubMed2001

The FAIR-INNOVATION dissemination project.

The goal of the FAIR-INNOVATION dissemination project (FLAIR-FLOW 3) (1997-2000) was to disseminate R&D results from the EU FAIR programme to small and medium-sized food enterprises (SMEs), health professionals (HPs) and consumer groups (CGs) in 19 European countries. The dissemination routes were: (i) one-page technical documents on research results; (ii) their reproduction on the internet; (iii) their reproduction in journals Europe-wide; (iv) workshops on results from EU-supported food research programmes; and (v) lectures and poster presentations by FLAIR-FLOW network personnel. Of the 135 one-pagers produced, 62% were targeted at SMEs, 18% at HPs and 5% at CGs. The remaining 15% were on food safety and were common to the three target groups. There were 1047 publications arising from one-pages in trade journals, and over 8000 requests (paper route) were received for follow-up information. These were in addition to 240 k downloads from the FLAIR-FLOW 3 web site (www.flair-flow.com). Initiatives for HPs included specially collated versions of the one-pagers for major conferences, 20 focused workshops, and interaction with the European Federation of Associations of Dieticians. Currently, dissemination is continuing through FLAIR-FLOW 4 (2001-2003) in 24 countries. FLAIR-FLOW 4 is co-ordinated by M. Jean François Quillien from INRA-CRIAA (FR) at criaa@rennes.inra.fr.

Communication↗
PubMed2003

Mechanism of Cph1 phytochrome assembly from stopped-flow kinetics and circular dichroism.

The kinetics and mechanism of the autocatalytic assembly of holo-Cph1 phytochrome (from Synechocystis) from the apoprotein and the bilin chromophores phycocyanobilin (PCB) and phycoerythrobilin (PEB) were investigated by stopped flow and circular dichroism. At 1:1 stoichiometry, pH 7.9, and 10 degrees C, SVD analysis of the kinetic data for PCB revealed three spectral components involving three transitions with time constants tau(1) approximately 150 ms, tau(2) approximately 2.5 s, and tau(3) approximately 50 s. Tau(1) was associated with a major red shift and transfer of oscillator strength from the Soret region to the 680 nm region. When the sulfhydryl group of cysteine 259 was blocked with iodoacetamide, preventing the formation of a covalent adduct, a noncovalent red-shifted complex (680 nm) was formed with a time constant of 200 ms. Tau(1) could thus be assigned to the formation of a noncovalent complex. The absorption changes during tau(1) are due to the formation of the extended conformation of the linear tetrapyrrole and to its protonation in the binding pocket. From the concentration and pH dependence of the kinetics we obtained a value of 1.5 microM for the K(D) of this noncovalent complex and a value of 8.4 for the pK(a) of the proton donor. The tau(2) component was associated with a blue shift of about 25 nm and was attributed to the formation of the covalent bond (P(r)), accompanied with the loss of the 3-3' double bond to ring A. Tau(3) was due to photoconversion to P(fr). For PEB, which is not photochromic, the formation of the noncovalent complex is faster (tau(1) = 70 ms), but the covalent bond formation is about 80 times slower (tau(2) = 200 s) than with the natural chromophore PCB. The CD spectra of the PCB adduct in the 250-800 nm range show that the chromophore geometries in P(r) and P(fr) are similar to those in plant phytochrome. The opposite rotational strengths of P(r) and P(fr) in the longest wavelength band suggest that the photoisomerization induces a reversal of the chirality. The Cph1 complex with noncovalently bound PCB was still photochromic when cysteine 259 was blocked with IAA or with the bulkier IAF. The covalent linkage to cysteine 259 is thus not required for photoconversion. The CD spectra of the noncovalently bound PCB in P(r)- and P(fr)-like states are qualitatively similar to those of the covalent adducts, suggesting analogous structures in the binding pocket. The noncovalent interactions with the binding pocket are apparently sufficient to hold the chromophore in the appropriate geometry for photoisomerization.

Apoproteins↗
PubMed1997

Mechanism and echo time dependence of the fast response in fMR.

The fast response (FR) is an early reduction in the amplitude of the fMR signal occurring shortly after the onset of stimulation. Owing to its potential advantages in terms of temporal and spatial resolution, it may be of considerable significance in functional experiments. A model for the mechanism of the FR was developed which accounts for the fMRS finding that the amplitude of the dip decreases with increasing echo time. Two computer simulations that confirmed the predictions of the model and showed that it is possible to select optimal echo times for the detection of the FR were performed.

Computer Simulation↗
PubMed1980

Effect of sodium fluoride on the viability and growth of Streptococcus mutans.

A fluoride-sensitive (FS) strain of Streptococcus mutans and a laboratory-induced fluoride-resistant (FR) offspring were compared for the effects of sodium fluoride on viability and growth. There was a significant fluoride-related loss of viability in resting cell suspensions of the FS strain during a 47-hour exposure to fluoride levels above 75 ppm that was not encountered with the FR strain. The addition of 300 ppmF to actively growing six-hour broth cultures almost totally arrested the growth of the FS strain, while only slightly reducing that of the FR culture. The addition of 600 ppmF immediately terminated FS growth, and greatly reduced the rate and maximum growth of FR cultures.

Cell Division↗
PubMed2001

Hydrolyzable carbohydrates in pasture, hay, and horse feeds: direct assay and seasonal variation.

Carbohydrates may be hydrolyzed or fermented in the digestive tract, and this distinction is important for the evaluation of the diet of herbivores. Both hydrolyzable and fermentable carbohydrates are included in the nonstructural carbohydrate (NSC) fraction as estimated by difference using proximate analysis. Our objectives were to measure hydrolyzable carbohydrates in forages and concentrates, to compare these values with nonstructural carbohydrate, to test for prediction of hydrolyzable carbohydrate concentration in forages from its near-infrared spectrum, and to examine seasonal variation of carbohydrates in pasture. Samples of forages (107) and concentrates (25) were collected, dried, ground, and analyzed for NSC (calculated as 100 - water - CP - fat - ash - NDF), hydrolyzable carbohydrate (CHO-H, direct analysis), and rapidly fermentable carbohydrate (NSC minus CHO-H). Hydrolyzable carbohydrate accounted for 97% or more of the NSC in the concentrates but only 33% in pasture and hay. A two-term polynomial equation fit all the data: CHO-H = 0.154 x NSC + 0.00136 x NSC2, R2 = 0.98, P < 0.0001, n = 132. In 83 pasture samples, CHO-H concentrations were predicted by near-infrared spectra with a calibration R2 of 0.97, a mean of 48 g/kg, and a SE of calibration of 3.5 g/kg DM. In pasture samples collected between September 1995 and November 1996, the coefficient of variation was 31% for both CHO-H and rapidly fermentable carbohydrate (CHO-FR); the largest increments were 31 g/kg of CHO-H from September to October and 41 g/kg of CHO-FR from February to March. The increased risk of certain diseases, such as laminitis and colic, that have been previously associated with an abrupt overload of NSC may be more precisely attributed to CHO-H in grain concentrates, and to CHO-H as well as CHO-FR in pastures.

Animal Feed↗
PubMed2001

Early ambulation after diagnostic cardiac catheterization: a 4 French study.

This study is intended to test whether the use of new 4 French (Fr) catheters can safely eliminate the need for supine bed rest and allow earlier ambulation while decreasing groin site complications and patient discomfort. Diagnostic left heart catheterization was performed using 4 Fr catheters via the femoral approach in 100 consecutive patients. After femoral sheath removal, the mean compression time with a mechanical compression device was 16.07 +/- 3.19 minutes. Mean manual compression time was 18.3 +/- 5.7 minutes. Ninety-eight patients were able to sit up 30 degrees immediately after hemostasis was achieved. The mean ambulation time was 2.18 +/- 0.71 hours. There were no major vascular complications. Four patients developed a small area (2.5-5 cm) of ecchymosis at the femoral arterial puncture site. The study demonstrated that upper body elevation and early ambulation are safe as soon as hemostasis is achieved after 4 Fr cardiac catheterization.

Adult↗
PubMed2004

Randomized comparison of rapid ambulation using radial, 4 French femoral access, or femoral access with AngioSeal closure.

Radial access and closure devices are associated with improved quality of life (QOL) after cardiac catheterization. Whether this is related to the access site or time to ambulation is unknown. Seventy-five patients undergoing cardiac catheterization were randomized to femoral 6 Fr with AngioSeal closure (F+C), femoral 4 Fr without closure, and radial (R) access. All patients were ambulated at 1 hr. QOL was measured utilizing visual analogue scales and Short Form-36 at baseline, 1 day, and 1 week. Time to ambulation and discharge were equivalent, as was postprocedure QOL. However, angiographic quality was lower in the 4 Fr group (P < 0.0001) and catheterization costs were higher in the F+C group (P < 0.0001). Ambulation 1 hr after catheterization can be accomplished utilizing radial, femoral 6 Fr with closure device, or femoral 4 Fr access with equivalent outcomes and QOL. However, this is achieved at a higher cost with a closure device, or lesser angiographic quality with 4 Fr catheters.

Aged↗
PubMed1997

Expression of heterologous phytochromes A, B or C in transgenic tobacco plants alters vegetative development and flowering time.

In this study, oat phytochrome A (phyA), Arabidopsis phytochrome B (phyB) or Arabidopsis phytochrome C (phyC) were expressed in both day-neutral and photo-period-sensitive (short-day) tobacco (Nicotiana tabacum cv. Hicks). Introgression of the Maryland Mammoth (MM) gene into cv Hicks was used to confer short-day photo-periodic sensitivity. Expression of oat phyA led to characteristic hypersensitivity of hypocotyls to red light (R) and far-red light (FR) and an overall dwarfing of the mature plant. Expression of Arabidopsis phyB enhanced the sensitivity of hypocotyls to R and caused even more marked dwarfing of the mature plant. In contrast, the expression of Arabidopsis phyC had no detectable consequences for the photocontrol of hypocotyl elongation. However, phyC expression did lead to a R-dependent increase in cotyledon expansion in de-etiolating seedlings and to a significant increase in leaf area in mature plants. This provides the first experimental evidence that phyC is biologically active. The flowering time of cv Hicks plants grown under 8 h photoperiods was virtually unaffected by a 30 min white light (W) night break given 8 h into the dark period. In contrast, cv Hicks MM plants responded to a night break with a delay in flowering. Expression of phyA or phyB led to a night break-dependent delay in flowering in cv Hicks plants. For cv Hicks MM plants, the expression of any of phyA, phyB or phyC caused a marked enhancement of the flower-delaying effect of a night break. These observations indicate that transgenic phyA, phyB or phyC can interact with the endogenous mechanisms controlling flowering time in tobacco.

Apoproteins↗
PubMed1996

Phosphorylation/dephosphorylation steps are key events in the phytochrome-mediated enhancement of nitrate reductase mRNA levels and enzyme activity in maize.

We provide evidence to show that the increase in nitrate reductase (NR) transcript level stimulated by red light is mediated via a phosphorylation-dependent step. The light-stimulated enhancement of NR transcript level was significantly inhibited by H-7, a protein kinase inhibitor, whereas okadaic acid (OKA), a phosphatase inhibitor, had no effect. Phorbol myristate acetate (PMA), an activator of protein kinase C (PKC) enhanced the NR transcript level in dark-grown leaves. No correlation between changes in NR transcript level and NR activity (NRA) was observed. Inhibition of NRA by OKA and stimulation by H-7 indicated that NRA is increased by dephosphorylating the enzyme. We have identified a protein kinase (C type) that can phosphorylate the purified NR in vitro without the involvement of other accessory proteins. By in vivo labelling with 32P and immunoprecipitation of NR with NR antibodies it was found that in the presence of OKA most NR protein (NRP) was present in phosphorylated state, while with H-7 the reverse was seen. The red (R) and far-red (FR) light reversible experiments suggested that phytochrome (Pfr, an active form) stimulation of NRA is mediated by dephosphorylation of the enzyme, suggesting that Pfr regulates both NR transcription and NRA via phosphorylation/dephosphorylation steps controlled by separate signal transduction pathways.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2001

A theoretical analysis of the influence of heterogeneity in chlorophyll distribution on leaf reflectance.

Attempts to determine the vitality of vegetation and to detect vegetation stress from remotely sensed data have focused on chlorophyll concentration, because it influences the reflectance of vegetation and tends to correlate with vegetation health and stress. Pollution, pathogens and pests can cause localized regions of chlorosis and necrosis across a leaf surface, but the extent to which these patches influence the overall reflectance and spectral signature of the leaf and canopy has not been tested. A conifer leaf model (LIBERTY), which simulates the influence of leaf biochemical concentrations of chlorophyll, water, lignin, cellulose and protein on the reflectance of leaves from 400 to 2500 nm, was used to determine the effect of patches of chlorosis on leaf reflectance. A fraction of the leaf f is assumed to be chlorotic with a chlorophyll concentration C(1). The remainder of the leaf has chlorophyll concentration C(2) such that mean leaf chlorophyll concentration, C(mean) = fC(1) + (1 - f)C(2), is constant for a range of f and C(1) values. LIBERTY can be used to estimate the reflectance of a leaf with a particular chlorophyll concentration at a particular wavelength R(lambda,C) (assuming other leaf properties remain constant), thus we can estimate the reflectance of the chlorotic leaf as fR(lambda,C(1))+ (1 - f)R(lambda,C(2)). The model indicated that small areas of chlorosis have a disproportionately large influence on overall leaf reflectance. For example, a leaf with 25% of its area chlorotic can have the same reflectance (400-700 nm) as a homogeneous leaf with 60% less chlorophyll. Thus, determination of chlorophyll concentration from remotely sensed data is prone to underestimation when chlorophyll is nonuniformly distributed. Hence, attempts to model leaf and canopy reflectance using radiative transfer models will need to consider how to incorporate nonuniform chlorophyll distribution.

Chlorophyll↗
PubMed2004

Prediction of the clinical performance of adult arterial cannulas.

The choice of an arterial cannula for cardiac surgery is often difficult. The clinician has to rely on the pressure-flow diagrams provided by the manufacturer that are all produced using water. The conversion of these water data to representative clinical conditions is often difficult if not impossible. In this in vivo study the theory of dynamic similarity is applied to scale the manufacturer's data to the clinical situation, in order to predict the pressure drop desired by the cardiac surgeon. Three hundred and forty-seven samples of pressure drop are obtained in 58 patients. Patients are grouped according to cannula size (20, 22, and 24 Fr). Very good correlation is found between measured and predicted values (r = 0.93; 0.86; 0.87 for 20; 22; 24 Fr). As a result, windows of optimal performance are constructed for each cannula diameter. This technique also allows the construction of an online recommendation for signaling abnormal cannula performance during cardiac surgery.

Adult↗
PubMed1968

Stable concentrations of phytochrome in pisum under continuous illumination with red light.

In vivo spectrophotometry showed that the phytochrome concentration in pea epicotyl hooks decreased at a constant rate for 4 hours when the tissue was exposed to continuous red light. Thereafter the rate slowed progressively so that a steady concentration of phytochrome was approached at hour 7. Returning the plants to darkness resulted in an increase in phytochrome due to the apparent synthesis of P(R). A closely similar pattern of changes was found in the amount of phytochrome extracted from the tissue. The establishment of the stable concentration was inhibited by 2,4-dichlorophenoxyacetic acid and did not occur in segments which had been incubated for longer than 24 hours, but was observed when segment growth was inhibited by mannitol. The results may be explained by an equilibrium between P(FR) destruction and apparent P(R) synthesis.

Journal Article↗
PubMed2006

Protein kinase activity in Cucumis sativus cotyledons: effect of calcium and light.

Light signals received by phytochromes in plants may be transduced through protein phosphorylation. Ca(2+) as second messenger was involved in phytochrome-mediated cellular events. Our experiments with Cucumis sativus cotyledons, treated with red (R) and far-red (FR) light, showed a stimulatory effect on in vitro protein phosphorylation of histone, added as exogenous substrate to the cotyledon extracts, and also modified the phosphorylation of endogenous polypeptides. The effect of light treatments was mimicked by the addition of Ca(2+) to the phosphorylation buffer, indicating phytochrome- and Ca(2+)-dependence on activity of some protein kinases (PKs). In-gel kinase assays were performed to characterize the PKs involved at the cotyledon stage of cucumber plants. Three proteins of about 75, 57 and 47kDa with PK activity were detected between M(r) markers of 94 and 45kDa. All three were able to phosphorylate histone and undergo autophosphorylation. However, only the 75 and 57kDa proteins autophosphorylated and phosphorylated the substrate in a Ca(2+)-dependent manner, and were inhibited when calmodulin (CaM) antagonists were added to the incubation buffer. Western-blot analysis with polyclonal antibodies directed against calcium-dependent protein kinase of rice (OsCDPK11) or Arabidopsis (AtCPK2) recognised 57 and 75kDa polypeptides, respectively. These results indicate the presence in cucumber cotyledons of at least two proteins (ca. 75 and 57kDa) with activity of PKs that could be calcium-dependent protein kinases (CDPKs). Both CDPKs could be modulated by phytochromes throughout FR-HIR and VLFR responses.

Calcium↗
PubMed2005

Red and far-red light alter the transcript profile in the cyanobacterium Synechocystis sp. PCC 6803: impact of cyanobacterial phytochromes.

Cyanobacteria possess genes encoding phytochrome-related proteins. We used a DNA microarray approach to evaluate the impact of the phytochromes Cph1 and Cph2 on red light (R)- and far-red light (FR)-dependent gene expression in the unicellular cyanobacterium Synechocystis sp. PCC 6803. In cells of wild-type and phytochrome mutants, one-fourth of all 3165 annotated putative protein encoding genes was light-responsive. R predominantly enhanced the expression of genes involved in transcription, translation, and photosynthesis, whereas FR upregulated the transcript level of genes known to be inducible by stress. The absence of Cph1 and/or Cph2 altered the light-dependent expression of about 20 genes. Hence, receptor(s) different from the two phytochromes are supposed to trigger the global R/FR alterations of the expression profile.

Bacterial Proteins↗