Quantitative relationship between phenylalanine ammonia-lyase levels and phenylpropanoid accumulation in transgenic tobacco identifies a rate-determining step in natural product synthesis

Phenylalanine ammonia-lyase (PAL) catalyzes the first step in phenylpropanoid synthesis. The role of PAL in pathway regulation was investigated by measurement of product accumulation as a function of enzyme activity in a collection of near-isogenic transgenic tobacco plants exhibiting a range of PAL levels from wild type to 0.2% of wild type. In leaf tissue, PAL level is the dominant factor regulating accumulation of the major product chlorogenic acid and overall flux into the pathway. In stems, PAL at wild-type levels contributes, together with downstream steps, in the regulation of lignin deposition and becomes the dominant, rate-determining step at levels 3- to 4-fold below wild type. The metabolic impact of elevated PAL levels was investigated in transgenic leaf callus that overexpressed PAL. Accumulation of the flavonoid rutin, the major product in wild-type callus, was not increased, but several other products accumulated to similarly high levels. These data indicate that PAL is a key step in the regulation of overall flux into the pathway and, hence, accumulation of major phenylpropanoid products, with the regulatory architecture of the pathway poised so that downstream steps control partitioning into different branch pathways.

[Mediastinitis secondary to esophageal ulceration after doxycillin]

Doxycillin is a tetracycline antibiotic widely used in outpatients, particularly for treating pelvic inflammatory disease, acne, and Rickettsial infections. Among the more common side effects is acute esophageal inflammation leading to ulceration and occasionally to perforation. We describe the clinical course of a 35-year-old woman with esophageal perforation secondary to the use of Doxycillin.

Characterization of Caramel Colours I, II and III

Groups of representative samples of Caramel Colours I, II, and III were characterized in order to assess the compositional uniformity within each class and to determine differences between each class. Compositional uniformity within each class was demonstrated by fractionation of the caramel samples and analysis by UV and visible absorbance, HPLC and chemical analysis. Although there was overlap between certain parameters of one or more caramel colour classes, the overall 'fingerprint' for each class, based on several different parameters, was distinctly unique. Such parameters included net ionic charge, absorbance properties, nitrogen and sulphur content, specific low molecular weight compounds and HPLC profiles. HPLC analysis revealed unique profiles within each class and distinct differences between classes. The data presented here for Caramel Colours I, II, and III, and elsewhere for Caramel Colour IV, indicate that each of the four classes can be considered as separate and that, throughout each class, the samples characterized constitute a homologous series of mixtures in terms of chemical composition.

Characterization of Caramel Colour IV

A large number of commercial Caramel Colour IV samples were characterized in order to assess the uniformity of the class and to provide data to be used in specifications development. Owing to the chemical and physical complexity of caramel colour it was not feasible to perform detailed analysis of all constituents for assessment of uniformity. Instead, selected parameters were evaluated and judgements were made with respect to compositional uniformity based on the similarities of these parameters among the various samples. As Caramel Colour IV is required by the food industry in a range of colour intensities, there must be a range of properties that differ from sample to sample, but that are sufficiently similar for the material to still be considered as part of the Caramel Colour IV class. Fractions as well as whole caramel were analysed using selected spectrophotometric, chromatographic and chemical techniques. Samples were fractionated based on molecular weight and polarity. The data presented here provide evidence for the uniformity in composition of Caramel Colour IV with respect to molecular weight distribution, to nitrogen and sulphur content and their distribution throughout the fractions, to absorbance properties and to specific low molecular weight compounds. Thus, it can be concluded that Caramel Colour IV exhibits compositional uniformity within the range of colour intensity required by the food industry worldwide.

Development of specifications for caramel colours

Specifications have been developed to define each of the four classes of caramel colour. The specifications were based on analysis of a large database generated during the course of characterization studies of each of the classes. A series of simple and practical tests was developed for the analysis of caramel colour samples to ensure conformity to the specifications.

Systematic pain records and their impact on pain control. A pilot study

This study examined the impact of a systematic nursing pain assessment tool (PAT) and pain flow sheet (PFS) on pain management. A control group (N = 23) was compared with a treatment group (N = 20) of hospitalized patients on a medical oncology unit. In the control group, "routine" charting of pain was done in the nurses' narrative notes. Patients in the treatment group underwent standardized pain assessment and documentation using a PAT and PFS. The treatment group reported significantly lower average pain intensity ratings (chi 2 = 5.019, p = 0.02) on day three of follow-up. In addition, a greater number of patients in the treatment group (85%) reported decreased pain intensity from day one to day three as compared with the control group (57%). This study supports other research and recommendations in the literature that use of systematic pain records can improve pain management.

Piaget's theory of cognitive development may be useful in deciding what to teach and how to teach it

The author outlines the relevant aspects of Piaget's theory of cognitive development and argues that, far from being restricted to childhood development, the theory has relevance for adult learners. An attempt is made to demonstrate the importance of practice within the educational framework of the student who is learning to become a nurse. It is argued that emphasis should be placed upon the provision of environments which allow the student to practise the schemas which he already possesses in order to provide opportunities for the elaboration of these schemas. Piaget's view that the existence of 'schema is motivation in itself' and the environment is important insofar as it should be geared to 'match' the classroom experiences of the student with the student's ability to respond to them, is outlined; with the contention that the most important means of growth is through action and through operations that the student himself performs on the environment. The author concludes with a note of caution for curriculum planners in a Project 2000 scenario who may promote theory at the expense of practice.