Secretin, VIP, and PHI stimulate rat proximal duodenal surface epithelial bicarbonate secretion in vivo

The surface epithelial cells of the stomach and duodenum secrete bicarbonate at rest and in response to a number of agonists including the gastrointestinal hormones, glucagon, and GIP. Since those hormones with structural homology may have similar effects, the purpose of the present study was to examine the effect of graded doses (6, 24, and 96 nmol/kg) of pure porcine secretin, VIP, and PHI on bicarbonate secretion by the proximal duodenum containing Brunner's glands. Experiments were performed in vivo on unanesthetized Sprague-Dawley rats with chronic Thiry-Vella type loops of the proximal 2 cm of duodenum. The order of testing was random and only one hormone was tested on a single day. Compared to the saline control, each dose of VIP produced a significant increase in duodenal bicarbonate secretion in a dose-response manner. The two higher doses of secretin and only the 96 nmol/kg dose of PHI significantly increased bicarbonate output. The responses to 96 nmol/kg dose of secretin and VIP were similar, and each was significantly greater than observed with PHI. It is concluded that secretin and VIP stimulate proximal duodenal bicarbonate secretion and are more potent than PHI.     

Effects of proteolysis of the extending parts of the high-molecular-weight microtubule-associated proteins on interactions between microtubules

Digestion of assembled microtubules with agarose-bound trypsin was performed to obtain microtubules which lack the extending projections, the non-tubulin-binding part of the high-molecular-weight microtubule-associated proteins. The assembly kinetics and the minimum protein concentration for assembly were the same for these trypsinated microtubules as for normal, untreated microtubules. Furthermore, the digested microtubules gave rise to the same change in turbidity per polymer mass as that found for normal microtubules. However, electron microscopy of pelleted microtubules revealed a closer packing after trypsin treatment. A substantially lower increase in specific viscosity was found upon assembly. At concentrations of above approx. 1.5 mg/ml, the viscosity of trypsin-treated microtubules was almost independent of the protein concentration, in contrast to the turbidity, which still increased. Both microtubules and the trypsin-digested microtubules were easily oriented by shear, although the flow linear dichroism signal for the microtubules after trypsin treatment was only half of that found for perfectly oriented normal microtubules. At higher shear force gradients, digested microtubules aggregated side by side as shown by electron microscopy. This was not found for normal microtubules. Even although the extending parts of the high-molecular-weight proteins are not needed for assembly, they were found to play an important role in microtubule orientation and interactions between microtubules, probably by acting as spacers between microtubules.     

Evaluation of genetic variation of attack and resistance in lodgepole pine in the early stages of a mountain pine beetle outbreak

We examined variation of attack by mountain pine beetle (MPB) (Dendroctonus ponderosae) (Coleoptera: Scolytidae) in a 20-year-old lodgepole pine open-pollinated (OP) family trial composed of 165 OP parent-trees originating from local and nonlocal provenances. Trees were assessed in the summer of 2005 for traits relating to attack, survival, gallery formation, and infection from the fungi associated with MPB, Ophiostoma sp. Successful initial attack was determined by the presence of dead (i.e., red or gray foliage) crowns and the presence of entrance holes from MPB. Eighty-seven percent of the trees still had green crowns in the fall of 2005 (GC05), with family mean differences ranging from 46 to 100%. The mean number of pitch tubes per tree (PT#05) (in a sampling area of 225 cm² at breast height) was 1.5 with a range from 0 to 14 per tree. However, for pitch tubes indicating presence or absence (PTP05) of MPB on each tree, 63% of the trees had pitch tubes and family means ranged from 7 to 100%. Significant levels of genetic variation were found for GC05 and PTP05 with narrow-sense heritabilities of 0.20 (SE = 0.11) and 0.26 (SE = 0.07), respectively. Provenance differences were also significant, indicating that some population structure is present for these “resistance” attributes. The family breeding value correlations between 10-year height growth and PTP05 was 0.22, indicating that at the population level faster growing families may be slightly more subject to attack. An intensive survey of a subsample of 442 trees in the test (selected from 50 families with a range of attack levels) was conducted, and trees were reassessed for the presence of attack, presence of blue stain in the wood, and presence of galleries and egg chambers/eggs in the gallery. Family means ranged from 0 to 57% for blue stain, 11 to 63% for galleries, and 0 to 57% for egg chambers/eggs; however, due to the relatively small sample sizes and the nature of the binary data, family differences were not highly statistically significant. Further research is underway to improve the quantitative genetic parameters and determine the actual mechanisms at work; however, it is clear the MPB does react differently to host genotypes in terms of initial attack.     

Interventions aimed at increasing research use in nursing: a systematic review

Background

There has been considerable interest recently in developing and evaluating interventions to increase research use by clinicians. However, most work has focused on medical practices; and nursing is not well represented in existing systematic reviews. The purpose of this article is to report findings from a systematic review of interventions aimed at increasing research use in nursing.

Objective

To assess the evidence on interventions aimed at increasing research use in nursing.

Methods

A systematic review of research use in nursing was conducted using databases (Medline, CINAHL, Healthstar, ERIC, Cochrane Central Register of Controlled Trials, and Psychinfo), grey literature, ancestry searching (Cochrane Database of Systematic Reviews), key informants, and manual searching of journals. Randomized controlled trials and controlled before- and after-studies were included if they included nurses, if the intervention was explicitly aimed at increasing research use or evidence-based practice, and if there was an explicit outcome to research use. Methodological quality was assessed using pre-existing tools. Data on interventions and outcomes were extracted and categorized using a pre-established taxonomy.

Results

Over 8,000 titles were screened. Three randomized controlled trials and one controlled before- and after-study met the inclusion criteria. The methodological quality of included studies was generally low. Three investigators evaluated single interventions. The most common intervention was education. Investigators measured research use using a combination of surveys (three studies) and compliance with guidelines (one study). Researcher-led educational meetings were ineffective in two studies. Educational meetings led by a local opinion leader (one study) and the formation of multidisciplinary committees (one study) were both effective at increasing research use.

Conclusion

Little is known about how to increase research use in nursing, and the evidence to support or refute specific interventions is inconclusive. To advance the field, we recommend that investigators: (1) use theoretically informed interventions to increase research use, (2) measure research use longitudinally using theoretically informed and psychometrically sound measures of research use, as well as, measuring patient outcomes relevant to the intervention, and (3) use more robust and methodologically sound study designs to evaluate interventions. If investigators aim to establish a link between using research and improved patient outcomes they must first identify those interventions that are effective at increasing research use.