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.

Simplified and efficient labeling of human platelets in plasma using indium-111-2-mercaptopyridine-N-oxide: preparation and evaluation.

The need for a gamma-emitting radioactive agent that will label platelets in plasma efficiently by a procedure that can be used uniformly in each laboratory is well recognized. A water soluble sodium salt of 2-Mercaptopyridine-N-oxide (Merc) was evaluated that quantitatively chelated 111ln at a pH range of 0.7 to 7.4, and allowed greater than 80% incorporation of 111ln in platelets in plasma. This was dependent on pH, Merc concentration, and platelet concentration. Platelets were labeled using either preformed [111ln]Merc or incubating platelets with 2.5 micrograms dry Merc first and then with 111ln. The latter method provided a simple kit procedure that labeled platelets with negligible alteration of in vitro aggregability. In dogs, labeled platelets had normal survival (7.5 days), 66 +/- 6.6% recovery, detected vascular thrombi (thrombi/blood = 59.4), and pulmonary emboli (PE/blood = 46.2) by scintigraphy. In the kit procedure, the use of Merc compared favorably to that of oxine and tropolone.

Evaluation of indium-111-2-mercaptopyridine-N-oxide for labeling leukocytes in plasma: a kit preparation.

Pure neutrophils, lymphocytes, and mixed leukocytes have been labeled in vitro with 111ln chelated to a nontoxic, water soluble agent 2-mercaptopyridine-N-oxide (Merc). Cells were labeled in isotonic salt-balanced medium with preformed [111ln] Merc (yield greater than 95%), or in 0.5 ml autologous plasma by incubation with dry Merc first and then with 111ln (yield 75%). The latter method facilitated a kit procedure that required 2 micrograms dry Merc when acid citrate dextrose was used as anticoagulant or 20 micrograms when heparin was used. Labeling efficiency was dependent on cell concentration and pH. Labeled cells accumulated avidly in experimental abscesses and provided abscess/blood ratios of greater than 75 at 24 hr postinjection. In dogs, the liver uptake of labeled cells was only 18.8 +/- 7.1% compared to that of 48.5% when cells were labeled with [111ln]oxine.

Neutrophil labeling: problems and pitfalls.

The use of neutrophils labeled with gamma-emitting radionuclides has been shown to be acceptable for in vivo kinetic studies as well as for imaging inflammatory foci. Among the gamma-emitting radionuclides, indium-111 appears to be the agent of choice. Labeling neutrophils with 111In, however, is a relatively new technique. Although simple to perform, it involves several stages, none of which could be carried out without problems. These are discussed and the current research aimed at eliminating the problems is outlined. The knowledge of specific chemotactic receptors and surface antigens has stimulated investigations into selective neutrophil labeling that will continue to be challenging and exciting.

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.

Indium 111-mercaptopyridine N-oxide-labeled human leukocytes and platelets: mechanism of labeling and intracellular location of 111In and mercaptopyridine N-oxide.

Human leukocytes and platelets were labeled in plasma with indium 111, by incubating cells first with 2-mercaptopyridine N-oxide (Merc) and then with ionic or weakly chelated 111In citrate. We investigated the mechanism by which this procedure enabled us to label cells in plasma. The interactions of 111In and Merc with cell membrane and cytoplasm were studied by homogenizing labeled cells and analyzing the homogenate by gel filtration. Studies were facilitated by use of sulfur 35-labeled Merc. Although 65% +/- 12.8% of added 111-In was incorporated in cells in presence of extracellular Merc, only 0.8% +/- 0.1% and 5.1% +/- 3.2% 35S-Merc was associated with 10(8) leukocytes and 10(10) platelets, respectively. In the absence of extracellular Merc, only 4.5% +/- 0.3% 111In was taken up by the cells. In each type of cell 83% to 99% of the cell-incorporated 35S Merc was associated with a cytoplasmic component with apparent molecular weight 5200 daltons, independently of the presence or absence of radioactive or stable indium. An approximately equal proportion of 111In was bound to similar cytoplasmic components in both types of cells. On adenosine diphosphate-induced platelet aggregation, less than 3% of platelet-bound 111In or 35S-Merc was released. These results indicate that it is the extracellular Merc that facilitates 111In labeling. It does not bind to cell membrane, but forms a lipid-soluble complex with 111In. This complex passively diffuses through the cell membrane, allows 111In to bind to cytoplasmic components, and provides a stable cell label.

Myelofibrosis following treatment with a nitrosourea for malignant glioma.

Nitrosoureas are alkylating agents that have been associated with the development of a preleukemic syndrome, secondary acute nonlymphocytic leukemia and a variety of acute and delayed toxicities. Nitrosoureas have activity in the treatment of primary malignant brain tumors. The authors report a patient who developed bone marrow myelofibrosis three years following treatment with radiation therapy and oral CCNU. This is the first case of marrow fibrosis associated with the use of a nitrosourea. Bone marrow myelofibrosis may be another delayed treatment effect of this class of drugs.

[A method of feating intermittent divergence strabismus (author's transl)]. / Eine Behandlungs form des intermittierenden Divergenzschielens

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.

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.