Inverting a Laplacian topography map

Summary There are some occasions when it is better to use the Laplacian of the scalp voltages (e.g., for topographic displays and dipole source localization) and other occasions when it is better to use the original voltages (e.g., for comparison to non-Laplacian topography maps). This paper presents a simple algorithm for going between these two representations of the data. The inverse Laplacian involves iterative feedback. An Excel spreadsheet implementation of the algorithm is presented.This research was supported by grant AFOSR 89-0238 from the Air Force Office of Sponsored Research.     

Potential interference of agents on radioiodide thyroid uptake in the euthyroid rat.

The objective of this research was to investigate the merits of controlled studies with euthyroid rats as a means of determining the influence of dose and time after administration of agents that may interfere with radioiodide uptake in the thyroid. METHODS: Potassium iodide (KI), propylthiouracil (PTU), diatrizoate meglumine, and iohexol were selected to represent interfering agents. Two dose levels per agent were investigated. Doses used were 1 and 2 mg/kg of body weight for KI, 3.5 and 7 mg/kg of body weight for PTU, 1 mL/kg (282 mg I/kg) and 2 mL/kg (564 mg I/kg) of body weight for diatrizoate meglumine, and 1 mL/kg (300 mg I/kg) and 2 mL/kg (600 mg I/kg) of body weight for iohexol. The 24-h radioiodide thyroid uptake was determined after (131)I was given at 1, 8, 15, and 22 d after administration of interfering agents. RESULTS: The percentage radioiodide uptake value for the thyroid decreased significantly compared with controls for all agents and both doses on day 1 but returned to control levels by day 22 for all agents and both doses The time to return to normal varied between agents and doses. CONCLUSION: We conclude that the interfering agent, the dose given, and the length of time after administration influence the potential for an agent to affect radioiodide uptake in the thyroid. Further studies with the rat, preferably hyperthyroid, would be beneficial in generating data to reduce confusing contradictory information on the length and severity of interference of agents in radioiodide thyroid studies.     

From the Editor

Sexuality and Disability -     

Iatrogenic injection injuries of the hand and upper limb.

30 cases of iatrogenic injection injuries to the hand and upper limb are reported. 16 followed therapeutic injections (steroids--11 cases, infusions--five cases) and 14 occurred during anaesthetics procedures (local blocks--ten cases, general anaesthetics--four cases). Guidelines for minimizing the risk of injection injury are outlined.     

Clinical Acumen: Brief Report: Therapeutic Manipulations in Severe Nocturnal Asthma. A Nonconventional Approach in a Severe High-Risk Asthmatic

A patient with severe nocturnal asthma of multifactorial pathogenesis with high-risk features leading to several episodes of nocturnal respiratory arrests is described. Despite aggressive conventional therapy with broncho-dilators and glucocorticoid agents, the patient had progressive worsening within the year prior to admission. After a nonconventional approach consisting of: high-dose inhaled steroids, afternoon dose of prednisone, addition of troleandomycin therapy, high-dose inhaled ipratropium at bedtime, maximizing serum theophylline concentrations in the early morning, and nasal CPAP through the night; the patient's pulmonary functions were optimized with minimal or no reduction in morning FEV₁, and decreased airways hyperresponsiveness to methacholine.