A sequential native chemical ligation – thiol-Michael addition strategy for polymer–polymer ligation

Native Chemical Ligation (NCL) between cysteine-terminated polymers and functional thioesters has been employed to prepare functional (co)polymers. The retained thiol functionality at the NCL junction can be exploited for thiol-Michael addition

Software modules to further assist the rapid production of optimised electrical reticulation schemes

To assist with them ass rural electrification drive being undertaken in South Africa, special CAD based softw are is being developed by the Software for Electrical Distribution (SED) Group a t the University of the Witwatersrand. Various optimisation modules have been previously developed by the SED group that relieve the designer of many routine tasks, thus facilitating more creative decisions. This dissertation describes a research project in which two further aspcts were investigated. 1. In order to use many advanced optimisation techniques, a specific form of "intelligent" map is required that will enable the software to identify relevant features on the map of th e township. A software module that can create an "intelligent" map with minimal operator intervention from conventional CAD sources is presented. Only the conceptual overview and the high level design of this softw are module is discussed. 2. Determining optimum distribution transform er locations and their service areas (transform er zones) is still a time consuming activity. Delineation of optimum transform er zones minimises conductor lengths and improves transform er utilisation. The software described in this dissertation, delineates suitable transform er zones rapidly thus permitting various alternative strategies to be speedily investigated. T he program w as implemented and has been tested on maps of actual townships. Although the proposed algorithm performed well it was found that, the final layouts required minor manual adjustment. Reasons for this are discussed. Recommendations regarding the further development of certain aspects of the software are provided

The effect of side chain spacer length on the thermoresponsive behaviour of poly(methylamide acrylate)s

We report the synthesis of three methylamide acrylate monomers with varying spacer length between the polymerizable acrylate and pendant amide functionalities; methylamide ethyl acrylate (MAmEA), methylamide propyl acrylate (MAmPA) and methylamide butyl acrylate (MAmBA). Each monomer was subsequently polymerised via redox-initiated reversible addittion-fragmentation chain transfer (RRAFT) to yield well-defined homopolymers with differing physicochemical properties. All homopolymers were found to be amorphous, and thermally degrade via a two-step decomposition process. Whilst P(MAmEA) and P(MAmPA) were found to be soluble in aqueous solution between 30–80 °C, P(MAmBA) showed a lower critical solution temperature (LCST) behaviour. Detailed aqueous solubilty studies performed on P(MAmBA) revealed that the cloud point temperature (Tcp) could be tuned based on the degree of polymerisation (DPn), concentration and nature of the aqueous media, highlighting its potential use as a water-soluble, thermoresponsive polymer in a range of applications

Anti-digoxin Fab fragments in cardiotoxicity induced by ingestion of yellow oleander: a randomised controlled trial.

BACKGROUND: Severe cardiac glycoside cardiotoxicity after ingestion of yellow oleander seeds is an important problem in rural areas of Sri Lanka. Currently, patients must be transferred to the capital for temporary cardiac pacing. We did a randomised controlled trial to investigate whether anti-digoxin Fab could reverse serious oleander-induced arrhythmias. METHODS: After a preliminary dose-finding study, 66 patients who presented to hospital with a serious cardiac arrhythmia were randomised to receive either 1200 mg of anti-digoxin Fab or a saline placebo. A 12-lead electrocardiogram, 3 min rhythm strip, and blood sample for measurement of electrolytes and cardiac glycosides were taken before treatment and at 12 timepoints thereafter. FINDINGS: 34 patients received anti-digoxin Fab and 32 received placebo. The presenting arrhythmia had resolved completely after 2 h in 15 antibody-treated patients and two controls (p<0.001); 24 and five patients, respectively, were in sinus rhythm at 8 h (p<0.001). Kaplan-Meier analysis of time to first reversal showed a significant response to anti-digoxin Fab. The heart rate increased in cases, from 49.1 per min at baseline to 66.8 at 2 h, but not in controls (50.6 per min at baseline to 51.5; p<0.001). Mean serum potassium concentrations decreased from 4.9 mmol/L to 4.1 mmol/L at 2 h in cases; no such decrease occurred in controls. INTERPRETATION: Anti-digoxin Fab fragments are a safe and effective treatment for serious cardiac arrhythmias induced by yellow oleander. Their use in small rural hospitals in Sri Lanka should minimise costly transfer of patients and reduce the numbers of deaths; however, further study will be required to confirm this reduction

Deaths due to absence of an affordable antitoxin for plant poisoning

There is a severe shortage of affordable antivenoms and antitoxins in the developing world. An anti-digoxin antitoxin for oleander poisoning was introduced in Sri Lanka in July, 2001, but because of its cost, stocks ran out in July, 2002. We looked at the effect of its introduction and withdrawal on case fatality, and determined its cost-effectiveness. The antitoxin strikingly reduced the case fatality; its absence resulted in a three-fold rise in deaths. At the present price of US$2650 per course, every life saved cost$10 209 and every life year cost $248. Reduction of the antitoxin's price to$400 would reduce costs to $1137 per life gained; a further reduction to$103 would save money for every life gained. Treatments for poisoning and envenoming should be included in the present campaign to increase availability of affordable treatments in the developing world

Acute yellow oleander (Thevetia peruviana) poisoning: cardiac arrhythmias, electrolyte disturbances, and serum cardiac glycoside concentrations on presentation to hospital

OBJECTIVE—To describe the cardiac arrhythmias, electrolyte disturbances, and serum cardiac glycoside levels seen in patients presenting to hospital with acute yellow oleander (Thevetia peruviana) poisoning and to compare these with published reports of digitalis poisoning.
DESIGN—Case series.
SETTING—Medical wards of Anuradhapura District General Hospital, Sri Lanka, and coronary care unit of the Institute of Cardiology, National Hospital of Sri Lanka, Colombo, the national tertiary referral centre for cardiology.
PATIENTS—351 patients with a history of oleander ingestion.
MEASUREMENTS—ECG and blood sample analysis on admission.
RESULTS—Most symptomatic patients had conduction defects affecting the sinus node, the atrioventricular (AV) node, or both. Patients showing cardiac arrhythmias that required transfer for specialised management had significantly higher mean serum cardiac glycoside and potassium but not magnesium concentrations. Although there was considerable overlap between groups, those with conduction defects affecting both sinus and AV nodes had significantly higher mean serum cardiac glycoside levels.
CONCLUSIONS—Most of these young previously healthy patients had conduction defects affecting the sinus or AV nodes. Relatively few had the atrial or ventricular tachyarrhythmias or ventricular ectopic beats that are typical of digoxin poisoning. Serious yellow oleander induced arrhythmias were associated with higher serum cardiac glycoside concentrations and hyperkalaemia but not with disturbances of magnesium.


Keywords: oleander poisoning; arrhythmias; cardiac glycoside