Bladder dysfunction in Duchenne muscular dystrophy.

Although bladder function is thought to be unaffected in Duchenne muscular dystrophy, 46/88 boys interviewed had urinary problems. Nine underwent video urodynamics, showing in eight a small capacity, hyperreflexic bladder, and in the ninth (post spinal surgery) hyperreflexia and detrusor sphincter dyssynergia. Urinary dysfunction is a treatable feature of DMD.     

JAK2 V617F tyrosine kinase mutation in cell lines derived from myeloproliferative disorders.

A mutation in the JH2 pseudokinase domain of the Janus kinase 2 gene (JAK2 V617F) has been described in chronic myeloproliferative disorders (MPD). We screened 79 acute myeloid leukemia (AML) cell lines and found five positive for JAK2 V617F (HEL, MB-02, MUTZ-8, SET-2, UKE-1), 4/5 with histories of MPD/MDS. While SET-2 expressed both mutant (mu) and wild-type (wt) JAK2, remaining positives carried homo-/hemizygous JAK2 mutations. Microsatellite analysis confirmed losses of heterozygosity (LOH) affecting the JAK2 region on chromosome 9p in MB-02, MUTZ-8 and UKE-1, but also in HEL, the only JAK2mu cell line lacking any reported MPD/MDS history. All five JAK2mu cell lines displayed cytogenetic hallmarks of MDS, namely losses of 5q or 7q, remarkably in 4/5 cases affecting both chromosomes. Our combined FISH and microsatellite analysis uncovered a novel mechanism to supplement mitotic recombination previously proposed to explain JAK2 LOH, namely chromosome deletion with/without selective JAK2mu amplification. Confirming the importance of the mutated JAK2 protein for growth and prevention of apoptosis, JAK2mu cell lines displayed higher sensitivities to JAK2 inhibition than JAK2wt cell lines. In summary, JAK2 V617F cell lines, derived from patients with history of MPD/MDS, represent novel research tools for elucidating the pathobiology of this JAK2 mutation.     

Reconstruction of mandibular defects with metallic prostheses and microvascular jejunal autografts: an experimental study

A study was undertaken to determine the adequacy of vascularised jejunum to provide stable mucosal cover over a non-biological mandibular substitute. Employing a canine model, composite intra-oral bone-mucosal defects were created and reconstructed with a metal plate covered by a microvascular jejunal patch. These were followed for six months and were assessed clinically, histologically and radiologically. Rapid mucosal healing occurred in all cases. The autografts conformed to the contour of the prosthesis and adequate tongue mobility was preserved. All mandibles remained stable throughout the follow-up period. Histologically, short villi covered the jejunal grafts to three months whilst at six months both normal and abnormal jejunal mucosal morphology was evident.     

Effects of halothane on arrhythmias induced by myocardial ischaemia

The effect of halothane on arrhythmias induced by ischaemia was investigated in rats, isolated perfused rat hearts, and pigs. Responses to the occlusion of the left anterior descending coronary artery were determined in groups (n = 9) of chronically prepared rats treated with no halothane, 0.5, or 1.0 per cent halothane immediately after occlusion; in isolated rat hearts (n = 10) treated with no halothane, 0.5, 1.0, 2.0, or 4.0 per cent halothane for 15 min before and after occlusion; and 20–25 kg pigs (n = 11) anaesthetised with halothane or pentobarbital. The ECG, arrhythmias, blood pressure (BP), heart rate (HR) and extent of infarction were determined in each model. In pigs, left ventricular pressure, dp/dt_max and cardiac output were also measured. In chronically prepared rats, halothane anaesthesia started after occlusion was antiarrhythmic and decreased the incidence of ventricular fibrillation and resulting mortality. In isolated rat hearts, 0.5 or 1.0 per cent halothane had little effect on occlusion-induced arrhythmias. The highest concentration of halothane increased the incidence of ventricular fibrillation both before and after occlusion. Halothane decreased developed ventricular pressure in a dose-dependent manner. In acutely prepared pigs, halothane pre-treatment had no appreciable effect upon occlusion-induced arrhythmias when compared with pentobarbital anaesthesia. Thus, halothane is antiarrhythmic when treatment is initiated after occlusion in the rat but this action is not seen in isolated hearts or intact pigs. The antiarrhythmic action of halothane is, therefore, species and model dependent.     

Effect of inhaled corticosteroids on symptom severity and sputum mediator levels in chronic persistent cough

BACKGROUND: Chronic cough often lasts for more than 1 year and is associated with airway inflammation. The effect of inhaled corticosteroids on symptom severity and inflammatory mediator levels in these patients is unknown. OBJECTIVE: We sought to determine whether inhaled corticosteroids reduce cough severity and sputum mediator concentrations in patients with chronic persistent cough. METHODS: We performed a double-blind, randomized, placebo-controlled crossover study with inhaled fluticasone, 500 microg twice daily, and placebo for 14 days in 88 patients with cough for more than 1 year, with normal chest radiography and spirometry results. Outcome measures were a daily cough visual analogue scale and induced sputum concentrations of eosinophilic cationic protein (ECP), myeloperoxidase, leukotriene B(4) (LTB(4)), leukotrienes C(4)/D(4)/E(4) (cysteinyl leukotrienes [Cys-LTs]), prostaglandin E(2) (PGE(2)), IL-8, and TNF-alpha. Sputum cell counts, exhaled nitric oxide levels, and carbon monoxide levels were also measured. RESULTS: There was a significant improvement in the cough visual analogue scale after inhaled fluticasone compared with placebo (mean difference, 1.0; 95% CI, 0.4-1.5; P <.001). LTB(4), Cys-LT, and PGE(2) levels were increased in all causes of cough. Sputum ECP counts, exhaled nitric oxide levels, and carbon monoxide levels decreased significantly after inhaled fluticasone. There was no change in sputum cell counts and other mediator concentrations. CONCLUSION: Cough severity and sputum ECP levels are modestly reduced by inhaled corticosteroids in patients with chronic cough persisting for more than 1 year. LTB(4), Cys-LT, PGE(2), IL-8, myeloperoxidase, and TNF-alpha levels are unaltered by this therapy. This raises the possibility that drugs targeted to reduce the effects of these mediators might be of benefit in chronic persistent cough.     

Metabolic depression and myocardial potassium

Summary The action potential duration (APD) of guinea pig atrial muscle responded qualitatively to metabolic depression and altered glucose concentration as shown previously for papillary muscle. Both preparations lost potassium and gained sodium during 8 h anoxic incubations and these changes were partially prevented by 50 mM glucose. Experiments with potassium⁴² indicated that anoxia-induced loss of potassium was not primarily due to an increased efflux but to a decreased influx. Stimulation did not increase potassium⁴² efflux from atria but caused some increase in potassium loss. The ATP content of atria and ventricular muscle decreased rapidly during anoxic incubation but was maintained at a significantly higher level in the presence of 50 mM glucose. Since muscle potassium levels following 8 h of anoxic incubation were incompatible with observed resting potentials, the results support the concept of either an electrogenic sodium pump or the intracellular compartmentalization of potassium. In addition, the anoxia-induced reduction of action potential duration does not appear to be associated with an increase in potassium⁴² efflux.This work was supported by grants from the Medical Research Council of Canada and the Canadian Heart Foundation.