Novel pore mutation in SCN5A manifests as a spectrum of phenotypes ranging from atrial flutter, conduction disease, and Brugada syndrome to sudden cardiac death

OBJECTIVES: The purpose of this study was to determine the clinical and biophysical characteristics of a novel SCN5A mutation. BACKGROUND: Brugada syndrome and isolated cardiac conduction defect have been linked to SCN5A mutations. METHODS: Eleven members of a western European family underwent electrophysiologic investigations and mutation analysis of the SCN5A gene. Wild-type and mutant SCN5A channels were expressed in HEK293 cells, and whole cell currents were studied using patch clamp procedures. RESULTS: A novel mutation, R376H, in the first pore segment of SCN5A variably causes Brugada syndrome and/or conduction disease in a single family. Biophysical analysis demonstrated a significant current reduction for the mutant, a pathophysiologic profile consistent with Brugada syndrome and isolated cardiac conduction defect. Among 11 family members, 9 were carriers of the mutation. The proband's initial presentation was a saddleback Brugada ECG, atrial flutter, and diffuse conduction disturbances. He had no inducible ventricular arrhythmias but experienced sudden cardiac death. His brother was affected by atrial flutter and had a clear conduction disorder, but he did not display baseline or evocable ECG signs of Brugada syndrome. He received an implantable cardioverter-defibrillator that delivered one appropriate shock after 1 year of follow-up. The phenotype in the family members was highly variable and ranged from noninducible and inducible asymptomatic carriers of the mutations to isolated conduction disease and to symptomatic Brugada syndrome. CONCLUSIONS: We describe the functional characterization of a novel SCN5A pore mutation, R376H, with variable clinical expression in the same family. Differentiating between electrophysiologic entities (Brugada syndrome-isolated cardiac conduction defect) is more challenging. Recognition of factors modifying the clinical presentation may be important for clinical decision making.     

Dopamine transporter imaging with novel, selective cocaine analogs.

RTI-121 and RTI-122 are 3 beta-substituted phenyltropane analogs of cocaine that have high, selective binding affinity for dopamine transporters. [123I]RTI-121 and [123I]RTI-122 bind to dopamine transporters in vivo after intravenous administration and permit imaging of the transporters.     

Pharmacokinetics of indium-111-labeled B72.3 monoclonal antibody in colorectal cancer patients.

Mean time parameters provide a new approach to plasma pharmacokinetics of radiolabeled Mabs that may show important patient differences affecting diagnosis or treatment. We determined mean time pharmacokinetic parameters for 11 patients entered in a Phase I/II clinical trial for detection of colorectal cancer. Patients were administered 0.5-2 mg of B72.3 anti-TAG-72 radiolabeled with 3.5-5 mCi of 111In, plasma activity was measured over time. Mean time pharmacokinetic parameters were (mean +/- s.e.m.): mean residence time; body (MRTB) 88.9 +/- 7.2 hr, central (MRTC) 73.8 +/- 6.0 hr; mean transit time, central (MTTC) 41.1 +/- 9.0 hr; mean residence time, periphery (MRTP) 15.1 +/- 3.4 hr; intrinsic mean residence time, periphery (IMPTP) 39.0 +/- 7.6 hr; mean transit time, periphery (MTTP) 24.0 +/- 6.7 hr; probability of distribution (PRD) 50% +/- 10%; and n compartmental cycles of 4.54 +/- 2.3 times. In patients with increased circulating specific TAG-72 antigen, MRTC greater than MTTC and n much greater than 1. In patients without specific antigen, MRTC approximately equal to MTTC and n much less than 1. Pharmacokinetic studies may identify patients who do not have the tumor produced target antigen for the specific Mab and may provide an opportunity to select another specific Mab with an increased chance for successful diagnosis or treatment.     

Decreased serum levels of nutritional biochemical indices in healthy children with marginally delayed physical growth

Biochemical markers of nutritional status (albumin, transthyretin, insulin-like growth factor-I and zinc) were measured in slowly growing two- to five-year-old, low-income Parisian children whose weight-for-height or height-for-age z scores (WHZ or HAZ) were between — 1 and — 2 SD of the NCHS median. The results were compared to controls who were matched for age, sex, and ethnic origin with WHZ and HAZ between — 1 and + 2 SD. Mean serum levels of transthyretin, albumin and insulin-like growth factor-I and mean plasma zinc concentrations were significantly lower in the growth-impaired children than in the controls ( p = 0.002, p = 0.006, p = 0.015, and p = 0.035, respectively). While the height-retarded children had low mean serum insulin-like growth factor-I values, the weight-retarded subjects had decreased levels of albumin, transthyretin and zinc when compared to controls. Lower mean levels of nutritional markers in healthy, slowly growing children suggest that inadequate dietary intakes of zinc, protein and/or energy may result in marginal delays in weight and height gains.