Writing Prompts Help Improve Expression of Conceptual Understanding in Chemistry

To improve the writing performance of secondary school students in chemistry assessments, a set of activities was developed. First, through document analysis of written tests, five categories of frequent mistakes in answers were identified: poor punctuation (capital letters, periods), missing key answer components (omitting concepts necessary to answer the question), incomplete reasoning (logical steps are missing), unclear use of antecedents (meanings of pronouns such as "it" are difficult to discern), and poor connectives (words like "because" are lacking or used incorrectly). After this, five strategies were formulated: focus on punctuation, repeat key question components, show complete reasoning, minimize use of references, and check use of connectives. Second, a two-part intervention study was conducted. In Part A, a written prompt (arrow symbol with the word "LANGUAGE") placed in front of context-based questions was implemented to find out if that could help students avoid making any of those mistakes. Following promising effects on the performance of 99 students, the intervention was extended with a Part B to find out if, in addition to the prompt, bonus points (for each prompt question one bonus point was awarded if the answer was formulated correctly in terms of language use) and language support (prompt card listing the five strategies, and supportive assignments) could be of extra help to students. The findings suggest that the writing performance of students can be improved by increasing students' awareness through a simple written prompt, providing language support, and awarding bonus points for properly formulated answers to chemistry test questions.

Collagenase Lot Selection and Purification for Adipose Tissue Digestion

Crude Clostridial collagenase (CCC) remains the most widely used enzyme for the digestion of tissues prior to cell isolation and culture. CCC contains numerous components in addition to specific collagenases and proteases. A chronic problem associated with CCC is significant lot variability which occurs with respect to the ability of different lots of CCC to digest tissue. We have evaluated numerous commercially available samples of CCC for their ability to digest human liposuction-derived SC fat. Digestion capacity was evaluated as the ability to release endothelial cells from fat as well as the ability of isolated cells to adhere to tissue culture plastic. A significant variation in digestion efficacy between lots of collagenase was observed. We subsequently purified CCC using a partial purification method with dialysis and centrifugation as well as a complete purification, using liquid chromatography, to remove all nonspecific proteases. While partially purified collagenase retained digestion capacity, pure collagenase exhibited reduced digestion capacity. Maximum digestion was achieved with pure collagenase when trypsin was added. The use of completely purified collagenase with trypsin is advantageous where all components in the enzyme digestion mixture must be known.

Modulation of gastrointestinal function by MuDelta, a mixed µ opioid receptor agonist/ µ opioid receptor antagonist

BACKGROUND & PURPOSE

Loperamide is a selective µ opioid receptor agonist acting locally in the gastrointestinal (GI) tract as an effective anti-diarrhoeal but can cause constipation. We tested whether modulating µ opioid receptor agonism with δ opioid receptor antagonism, by combining reference compounds or using a novel compound ('MuDelta'), could normalize GI motility without constipation.

EXPERIMENTAL APPROACH

MuDelta was characterized in vitro as a potent µ opioid receptor agonist and high-affinity δ opioid receptor antagonist. Reference compounds, MuDelta and loperamide were assessed in the following ex vivo and in vivo experiments: guinea pig intestinal smooth muscle contractility, mouse intestinal epithelial ion transport and upper GI tract transit, entire GI transit or faecal output in novel environment stressed mice, or four weeks after intracolonic mustard oil (post-inflammatory). Colonic δ opioid receptor immunoreactivity was quantified.

KEY RESULTS

δ Opioid receptor antagonism opposed µ opioid receptor agonist inhibition of intestinal contractility and motility. MuDelta reduced intestinal contractility and inhibited neurogenically-mediated secretion. Very low plasma levels of MuDelta were detected after oral administration. Stress up-regulated δ opioid receptor expression in colonic epithelial cells. In stressed mice, MuDelta normalized GI transit and faecal output to control levels over a wide dose range, whereas loperamide had a narrow dose range. MuDelta and loperamide reduced upper GI transit in the post-inflammatory model.

CONCLUSIONS AND IMPLICATIONS

MuDelta normalizes, but does not prevent, perturbed GI transit over a wide dose-range in mice. These data support the subsequent assessment of MuDelta in a clinical phase II trial in patients with diarrhoea-predominant irritable bowel syndrome.

Prokineticin-1 evokes secretory and contractile activity in rat small intestine

BACKGROUND

Prokineticins 1 and 2 (PROK1 and PROK2) are so named because they contract gastrointestinal smooth muscle, yet little else is known about their role in gastrointestinal function. Therefore, we used a combination of approaches to elucidate the mechanisms by which PROK1 alters ileal contractility and secretion in rats.

METHODS

RT-PCR and immunofluorescence were used to determine PROK and receptor (PK-R) mRNA levels and PK-R1 localization, respectively. Upper GI transit and fluid secretion were determined in vivo. Contractility and intestinal epithelial ion transport were assessed in isolated ileal segments.

KEY RESULTS

In the gastric fundus, PROK1 mRNA is highly expressed (70-fold >PROK2 mRNA) whereas the ileum has the highest mRNA expression of its receptor. PK-R1 immunoreactivity is visualized in ileal crypt cells, and in submucosal and myenteric neurons. In ileal segments, PROK1 evokes biphasic contractile responses consisting of an early, TTX-sensitive response (EC(50) = 87.8 nmol L(-1)) followed by a late, TTX-insensitive (EC(50) = 72.4 nmol L(-1)) component that is abolished in mucosa-free preparations. Oral administration of PROK1 enhances small bowel transit (111 +/- 3% of control) and fluid secretion (340 +/- 90% of control) and in muscle-stripped ileal preparations increases short-circuit current (EC(50) = 8.2 nmol L(-1)) in a TTX-insensitive manner. The PROK1-evoked Cl- secretion is reduced by piroxicam (non-selective cyclooxygenase inhibitor), and a prostaglandin EP(4) receptor antagonist (AH23848), but not a thromboxane receptor antagonist (GR32191B).

CONCLUSIONS & INFERENCES

These results demonstrate that PROK1 has oral prokinetic and secretogogue activity and that it acts on the intestinal mucosa via PK-R1 and prostaglandin receptors to mediate these effects.

Origin of endothelial cells that line expanded polytetrafluorethylene vascular grafts sodded with cells from microvascularized fat

PURPOSE

Cell transplantation onto prosthetic vascular grafts remains an attractive technique to reduce the thrombogenicity of polymeric materials. In this study we evaluated whether autologous cells isolated from falciform ligament fat and transplanted onto the lumenal surface of 4 mm expanded polytetrafluorethylene grafts were the same cells present on the surface of these grafts when they were explanted from canine carotid arteries 3 weeks after their implantation.

METHODS

The fluorescent dye PKH-26 was used to label transplanted cells to evaluate their fate after implantation of grafts as carotid artery replacements. This fluorescent dye homogeneously labeled all cells in the primary cell isolate.

RESULTS

In vitro studies indicated that dye labeling was nontoxic, as evidenced by the normal growth characteristics of fluorescently labeled cells compared with nonlabeled cells. Immunocytochemical analysis of microvascularized fat before cell isolation determined that approximately 90% of the cells stained positive for von Willebrand factor2. At the time of explant, seeded grafts exhibited a nonthrombogenic lumenal cell lining as evidenced by the lack of adherent platelets or fibrin. Cells on the lumenal surface of grafts exhibited PKH-26 fluorescence emission. In addition, these cells expressed von Willebrand factor and actively sequestered DiI-acetylated low-density lipoprotein.

CONCLUSIONS

We conclude that sodding of prosthetic grafts with autologous microvascularized fat-derived cells results in the formation of an endothelial cell lining on the lumenal flow surface. These endothelial cells are the same cells placed on the lumenal surface of the graft at the time of initial cell transplantation. Finally, a confluent monolayer forms after high-density cell sodding by the process of cell adherence and spreading, without the need for cell proliferation.

[A method of feating intermittent divergence strabismus (author's transl)]

Patching appears to have sensory and motor effects on intermittent exotropia. The sensory effects we have observed are reduction in the size of the scotoma as measured on haploscopic devices and improvement in fusional amplitudes. The motor effects has been increased control of the deviation. A series of patients was studied to document these effects, and their significance in management was discussed.