Deuterium NMR tissue perfusion measurements using the tracer uptake approach: I. Optimization of methods.

This paper considers potential problems encountered when using the Kety approach to measure perfusion in small laboratory animals with nuclear magnetic resonance (NMR) tracer uptake methods: a) the need to measure the arterial input function (AIF) in each animal; b) sensitivity to perfusion heterogeneity; c) sensitivity to low signal-to-noise ratio (SNR); and d) influence of changes in the AIF. A method to estimate the AIF in rats is presented that derives an AIF from the time course of a tracer passing through a carotid chamber. The results of computer simulations indicate that a common AIF obtained in one set of animals can be used for perfusion estimations in another set of animals if the tracer is delivered as a dose and that optimal data analysis (fitting data vs. integration approach) is dictated by SNR and perfusion heterogeneity. Experimental strategies are suggested to minimize the effects of changes in the individual AIF that could distort perfusion estimates.     

Desensitization to co-trimoxazole (trimethoprim-sulphamethoxazole) in HIV-infected patients: is patch testing a useful predictor of reaction?

OBJECTIVE: To establish the safety and efficacy of desensitization to co-trimoxazole in hypersensitive HIV-infected subjects. To assess if delayed hypersensitivity (type IV) to co-trimoxazole predicts those unable to be desensitized. METHOD: desensitization to co-trimoxazole, comprising trimethoprim (T) 0.4 mg and sulphamethoxazole (S) 2 mg initially with doubling dose daily, full strength co-trimoxazole (T/S 160 mg/800 mg) at 10 days. Patch testing with 4.5% and 9% co-trimoxazole in yellow soft paraffin, CMI Multitest. RESULTS: nineteen patients, 18 male and one female, were recruited and completed the desensitization regime. Of these 80%(15) achieved successful desensitization. Three of those who reacted did so within 18 days. All patients were successfully managed in an outpatient setting. There were no major adverse reactions. Of those reacting none gave a positive patch test to co-trimoxazole and all showed absent delayed type hypersensitivity reactions to recall antigens. CONCLUSIONS: co-trimoxazole desensitization is a safe and efficacious procedure, with a success rate of 80% using the above regime. Patch testing with co-trimoxazole gives no useful information about those that reacted.     

Absolute activity of (133)Ba by liquid scintillation coincidence counting using the 4pi(e,X)-gamma extrapolation technique.

The Technical Committee for Ionizing Radiation (TCRI) of the Asia Pacific Metrology Programme (APMP) recently organized a regional key comparison of activity measurements of the radionuclide ¹³³Ba. This paper reports on absolute measurements made at the National Metrology Institute of South Africa (NMISA) by the coincidence extrapolation technique, with liquid scintillation counting (LSC) comprising the 4π channel. A detection efficiency analysis was undertaken to predict the maximum efficiency likely to be achieved and to confirm that the method does indeed provide the source disintegration rate for ¹³³Ba. Various experimental and data analysis difficulties to be aware of are discussed in the paper.     

Persistent pulmonary hypertension of the newborn associated with pulmonary atresia and intact interventricular septum

Neonates with pulmonary atresia and intact interventricular septum (PAIVS) do not have pulmonary vascular disease secondary to their heart abnormality. Persistent pulmonary hypertension of the newborn has not been described in association with this condition. The case is reported of a female neonate born with PAIVS, who preoperatively had no clinical evidence or any risk factors for persistent pulmonary hypertension of the newborn, but whose postoperative course was highly suggestive of persistent pulmonary hypertension; necropsy confirmed the features of pulmonary vascular disease.


Keywords: persistent pulmonary hypertension; pulmonary atresia and intact ventricular septum; pulmonary vascular disease; surgery; congenital heart defects