KCNJ2 mutations in arrhythmia patients referred for LQT testing: A mutation T305A with novel effect on rectification properties

BACKGROUND: Loss-of-function mutations in the KCNJ2 cause approximately 50% of Andersen-Tawil Syndrome (ATS) characterized by a classic triad of periodic paralysis, ventricular arrhythmia, and dysmorphic features. Do KCNJ2 mutations occur in patients lacking this triad and lacking a family history of ATS? OBJECTIVES: The purpose of this study was to identify and characterize mutations in the KCNJ2-encoded inward rectifier potassium channel Kir2.1 from patients referred for genetic arrhythmia testing. METHODS: Mutational analysis of KCNJ2 was performed for 541 unrelated patients. The mutations were made in wild type (WT) and expressed in COS-1 cells and voltage clamped for ion currents. RESULTS: Three novel missense mutations (R67Q, R85W, and T305A) and one known mutation (T75M) were identified in 4/249 (1.6%) patients genotype-negative for other known arrhythmia genes with overall incidence 4/541 (0.74%). They had prominent U-waves, marked ventricular ectopy, and polymorphic ventricular tachycardia but no facial/skeletal abnormalities. Periodic paralysis was present in only one case. Outward current was decreased to less than 5% of WT for all mutants expressed alone. Co-expression with WT (simulating heterozygosity) caused a marked dominant negative effect for T75M and R82W, no dominant negative effect for R67Q, and a novel selective enhancement of inward rectification for T305A. CONCLUSIONS: KCNJ2 loss of function mutations were found in approximately 1% of patients referred for genetic arrhythmia testing that lacked criteria for ATS. Characterization of three new mutations identified a novel dominant negative effect selectively reducing outward current for T305A. These results extend the range of clinical phenotype and molecular phenotype associated with KCNJ2 mutations.     

Evaluation of a new generation of plastic evacuated blood-collection tubes in clinical chemistry, therapeutic drug monitoring, hormone and trace metal analysis.

Polyethylene terephthalate (PET) tubes have several advantages over glass tubes: they are unbreakable, lighter and more easily disposed of. Despite a steady increase in their use and an expansion of the range of available tubes, few studies validating their use have been published in the literature. This paper describes the various studies that have been performed to compare VENOJECT glass, VENOSAFE PET and VENOSAFE PET/heparin tubes for the assay of a panel of analytes in routine clinical chemistry, immunochemistry, hormone and tumor marker analysis and trace metal determination. These studies demonstrate that VENOSAFE PET tubes are a suitable alternative to glass tubes.     

Salvage robot-assisted radical prostatectomy with pelvic lymph node dissection after cryotherapy failure

We report the first case of post-cryotherapy salvage radical prostatectomy for local recurrence performed laparoscopically with the da Vinci robot. Total operative time was 210 minutes and blood loss was 50ml. There were no intraoperative or postoperative complications. The hospital stay was 24 hours and the Foley catheter was removed on postoperative day 7. The patient achieved a pad free status 4 weeks postoperatively. Pathology showed extensive disease, pT3bN0, Gleason score of 5+3 and positive margins. The patient continued on complete androgen deprivation therapy and his follow up PSA at 10 months was <0.1. Further studies are needed to evaluate both functional and oncological results with this approach.     

Differential generation of class I H-2D- versus H-2K-restricted cytotoxicity against a demyelinating virus following central nervous system infection

Despite the fact that both H-2K and D molecules are up-regulated in the central nervous system (CNS) following Theiler's murine encephalomyelitis virus (TMEV) infection, resistance in this virus model of multiple sclerosis maps exclusively to D. To address this paradox, we examined the ability of the K and D molecules to present viral antigens to cytotoxic T lymphocytes (CTL). Whereas no virus-specific CTL were detected in the CNS of susceptible B10.Q and B10.S mice 7 days post-infection, D-restricted CTL were identified readily in the CNS of resistant B10 animals. There was no evidence of K-restricted CTL in the CNS of B10 mice at day 7 post-infection. The presence of both K- and D-restricted virus-specific CTL in the spleen of immunized B10 mice demonstrates that the exclusive use of D molecules by CTL in the CNS of mice 7 days post-infection is not due to the inability of the K molecules to present viral peptides to lymphocytes. We conclude that the prominent role of the D locus in determining resistance or susceptibility to TMEV-induced demyelination is determined by factors governing the regulation of the immune response, and not by the presence or absence of CTL precursors capable of recognizing viral peptides presented by the K and D antigen-presenting molecules, or by differences in the ability of the K and D molecules to present viral peptides.     

Histologic, morphometric, and biochemical evolution of vein bypass grafts in a nonhuman primate model. II. Modification of early changes by platelet inhibition with aspirin and dipyridamole

The objective of this study was to determine the early influence of platelet inhibition on the histologic, morphometric, and biochemical evolution of vein bypass grafts in a nonhuman primate model. Cephalic vein grafts were interposed bilaterally in the femoral arteries of 15 stump-tailed macaque monkeys fed a diet that sustains plasma cholesterol levels of approximately 225 mg/dl. All animals received in combination aspirin, 80 mg/day, and dipyridamole, 50 mg/day. Grafts were excised from five animals for analysis on each of postoperative days 3, 7, 14, 30, 60, and 90. In animals subjected to platelet inhibition, cholesterol content in the graft was 170 +/- 52 micrograms/100 mg at 90 days, 205% of the level in ungrafted vein (p less than 0.01). This change was small in comparison with the increase to 686% of ungrafted vein observed in our study of control animals. In stepwise regression analysis, cholesterol content of grafts was best predicted by prevalence of foam cells (r2 = 0.82), and the proportion of intima as a fraction of total wall area was best predicted by the presence of macrophages (r2 = 0.69). Platelet inhibition did not decrease the extent of intimal hyperplasia. The prevalence of adherent platelets (r = -0.72) and the amount of fibrin (r = -0.78) correlated inversely with the amount of endothelium present during the first 14 days. The strength of these correlations declined with time, despite persistent lack of endothelium in some areas. Medial fibrosis occurred to the same extent as in control grafts, as did the early appearance of platelet factor VIII and fibronectin and the lack of vasa vasorum at 3 days followed by reappearance at 7 days. These data demonstrate that platelet inhibition dramatically reduces lipid uptake by grafts in the first 90 days but has less influence over histologic or morphometric changes.     

Mammaplasty on breast implants (or cutaneous expansion in treating distended skin)]

The authors present their experience of the use of skin expansion in secondary surgery to previously implanted breasts. This technique constituted a relatively simple solution with minimal scarring for certain cases in which the residual breast volume was insufficient or non-existent and in which it was impossible to reconstruct a breast with acceptable shape and volume after removal of the implant.     

Reflex myoclonus in olivopontocerebellar atrophy.

The presence of reflex myoclonus in response to touching and pin-pricking the wrist or stretching the fingers and to photic stimulation was assessed in 24 patients with a presumed diagnosis of olivopontocerebellar atrophy (OPCA) and in 30 age matched control subjects. Reflex myoclonus to soma-esthetic stimulation was found in 23 patients and in none of the controls. Photic myoclonus was present in 12 patients and in none of the controls. Electrophysiological study of the reflex myoclonus showed enhanced (> 10 microV) somatosensory evoked potentials and an associated reflex electromyographic discharge (C-wave) in 15 patients. These findings indicate that reflex myoclonus is common in OPCA and probably of cortical origin.     

A phase I clinical and pharmacokinetic study of the topoisomerase I inhibitor topotecan (SK&F 104864) given as an intravenous bolus every 21 days.

Topotecan (SK&F 104864) is a novel antitumor agent whose mechanism of action is inhibition of the DNA unwinding protein topoisomerase I. An analog of camptothecin, topotecan was designed to be more water soluble in an effort to decrease the severe and sporadic toxicities experienced during phase I/II trials of the parent compound. In this phase I clinical and pharmacological trial, topotecan was given as a bolus intravenous (i.v.) infusion over 30 min every 21 days. A total of 42 patients entered the study, receiving doses ranging from 2.5 to 22.5 mg/m2. The maximum tolerated dose (MTD) of topotecan given in this schedule was 22.5 mg/m2. Myelosuppression, primarily neutropenia, was dose-limiting. The extent of prior therapy did not predict for more severe neutropenia. Non-hematologic toxicities were mild and included low-grade to moderate fever, nausea, vomiting, alopecia, diarrhea and skin rashes. There were no objective partial or complete responses, although there was a suggestion of antitumor activity in three patients. Topotecan undergoes pH-dependent hydrolysis of the lactone ring; only the closed, lactone form is active. The lactone form predominated during infusion, with hydrolysis occurring rapidly following the end of infusion. There were linear relationships between dose administered and peak plasma lactone concentrations as well as AUC lactone to AUC total. The lactone was rapidly cleared from plasma with a total body clearance of 25.7 (+/- 6.7) l/h/m2. The plasma lactone concentration declined rapidly with a harmonic mean terminal half-life of 3.4 (+/- 1.1)h. Lactone hydrolysis and renal excretion were the major routes of elimination.(ABSTRACT TRUNCATED AT 250 WORDS)