A novel fluorometric assay for aldo-keto reductase 1C3 predicts metabolic activation of the nitrogen mustard prodrug PR-104A in human leukaemia cells

Aldo-keto reductase 1C3 (AKR1C3, EC 1.1.1.188) metabolises steroid hormones, prostaglandins and xenobiotics, and activates the dinitrobenzamide mustard prodrug PR-104A by reducing it to hydroxylamine PR-104H. Here, we describe a functional assay for AKR1C3 in cells using the fluorogenic probe coumberone (a substrate for all AKR1C isoforms) in conjunction with a specific inhibitor of AKR1C3, the morpholylurea SN34037. We use this assay to evaluate AKR1C3 activity and PR-104A sensitivity in human leukaemia cells. SN34037-sensitive reduction of coumberone to fluorescent coumberol correlated with AKR1C3 protein expression by immunoblotting in a panel of seven diverse human leukaemia cell lines, and with SN34037-sensitive reduction of PR-104A to PR-104H. SN34037 inhibited aerobic cytotoxicity of PR-104A in high-AKR1C3 TF1 erythroleukaemia cells, but not in low-AKR1C3 Nalm6 pre-B cell acute lymphocytic leukaemia (B-ALL) cells, although variation in PR-104H sensitivity confounded the relationship between AKR1C3 activity and PR-104A sensitivity across the cell line panel. AKR1C3 mRNA expression showed wide variation between leukaemia patients, with consistently higher levels in T-ALL than B-ALL. In short term cultures from patient-derived paediatric ALL xenografts, PR-104A was more potent in T-ALL than B-ALL lines, and PR-104A cytotoxicity was significantly inhibited by SN34037 in T-ALL but not B-ALL. Overall, the results demonstrate that SN34037-sensitive coumberone reduction provides a rapid and specific assay for AKR1C3 activity in cells, with potential utility for identifying PR-104A-responsive leukaemias. However, variations in PR-104H sensitivity indicate the need for additional biomarkers for patient stratification.     

EDIN-B Promotes the Translocation of Staphylococcus aureus to the Bloodstream in the Course of Pneumonia

It is crucial to define risk factors that contribute to host invasion by Staphylococcus aureus. Here, we demonstrate that the chromosomally encoded EDIN-B isoform from S. aureus contributes to the onset of bacteremia during the course of pneumonia. Deletion of edinB in a European lineage community-acquired methicillin resistant S. aureus (CA-MRSA) strain (ST80-MRSA-IV) dramatically decreased the frequency and magnitude of bacteremia in mice suffering from pneumonia. This deletion had no effect on the bacterial burden in both blood circulation and lung tissues. Re-expression of wild-type EDIN-B, unlike the catalytically inactive mutant EDIN-R185E, restored the invasive characteristics of ST80-MRSA-IV.     

Cardiac monitoring for patients with palpitations

Palpitations are one of the most common reasons for medical consultation. They tend to worry patients and can affect their quality of life. They are often a symptom associated with cardiac rhythm disorders, although there are other etiologies. For diagnosis, it is essential to be able to reliably correlate the symptoms with an electrocardiographic record allowing the identification or ruling out of a possible rhythm disorder. However, reaching a diagnosis is not always simple, given that they tend to be transitory symptoms and the patient is frequently asymptomatic at the time of assessment. In recent years, electrocardiographic monitoring systems have incorporated many technical improvements that solve several of the 24-h Holter monitor limitations. The objective of this review is to provide an update on the different monitoring methods currently available, remarking their indications and limitations, to help healthcare professionals to appropriately select and use them in the work-up of patients with palpitations.     

Rotational ablation of chronic coronary occlusions

Rotational ablation was performed successfully in three chronic coronary occlusions. At 3 months follow-up, two of the three lesions were patent. These cases illustrate the overall advantages and unique technical aspects of this device.     

Catheter ablation of accessory pathways in patients with congenital cardiopathies

The catheter ablation procedure in patients with accessory pathways and congenital heart defects can potentially become complicated because of abnormal anatomy and atypical conduction system. Eight patients ranging in age from 4.5 months to 18 years with accessory pathways and congenital heart defects underwent radiofrequency ablation. The cardiac diseases were diagnosed as Ebstein anomaly (n = 3), cardiac rhabdomyomas (n = 1), double outlet right ventricle (n = 1), endocardial cushion defect, partial form (n = 1), repaired Fallot's tetralogy (n = 1) and interventricular septal defect (n = 1). Six patients had manifest Wolff-Parkinson-White syndrome and 2 had concealed pathways. One patient with Ebstein anomaly had multiple accessory pathways. Radiofrequency ablation was initially successful in eight of the nine accessory pathways (89%). Two procedures were performed in one patient for pathway recurrence. Procedure was unsuccessful in 1 patient with Ebstein anomaly who later had surgical interruption of the accessory pathway. After a mean follow-up of 30.9 +/- 16.4 months, six of the 7 patients in which pathways were successfully ablated are tachycardia-free. One patient had late recurrence of tachycardia and is well controlled by propafenone.     

Molecular characterization of a high A2 beta thalassemia by direct sequencing of single strand enriched amplified genomic DNA

Two families, one of Anglo-Saxon-Dutch descent, and the other, West Indian black, have an atypical beta thalassemia characterized by an unusually high level of Hb A2 in the heterozygous state. Restriction endonuclease mapping showed a deletion of about 1.35 kilobase (kb) in the 5' region of the beta globin gene. Direct sequencing of a specific region of genomic DNA amplified by a new modification of the polymerase chain reaction defined the deletion to be 1,393 base pairs (bp) and to be the same in both families. The deletion extends from 485 bp 5' to the mRNA CAP site to the middle of the second intervening sequence. This deletion, together with three others previously described that remove the 5' end of the beta gene but leave the delta gene intact, are all associated with unusually high levels of Hb A2 in the heterozygous state.     

Coronary stenting with a new ultra-short balloon expandable device: Early and late animal results

The early and late effects of a new balloon-expandable coronary stent (Boneau II) were studied in 16 adult mongrel dogs. Thirty-three balloon-expandable stents were deployed using standard transfemoral coronary angioplasty technique. Single stents were placed in eight dogs and multiple (two to four) stents were placed in eight dogs. Intravenous heparin (3,000 units) was administered at the beginning of the procedure. Aspirin, dipyridamole, dextran, and warfarin were not administered before or after the procedure. All stent deployments were successful. Angiographic or pathologic examinations were performed within 24 hr of deployment on two of the dogs, at 2 weeks on two of the dogs, at 2 months on three of the dogs, at 6 months on six of the dogs, and at 1 year on three of the dogs. All successfully deployed stents were noted to be widely patent. There was no evidence of side-branch vessel occlusion. There was no evidence of acute or late vessel thrombosis. Histologic examination at 2 months showed a mean intimal thickness of 153 μm. The stainless steel Boneau II coronary stent is relatively short and easily deployed. This balloon-expandable coronary stent was successfully deployed in normal canine arteries without the use of anticoagulation or antiplatelet therapy before or after the procedure. The Boneau II intracoronary stent has a very low thrombogenic potential in dogs.