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.     

THE POINT PREVALENCE OF WOUNDS IN A TEACHING HOSPITAL

Background : Wounds are a common problem, particularly in the elderly population. The scale of wound problems in hospital is largely unknown because wounds are widely dispersed. The present study examined the point prevalence of hospital wounds and undertook a pressure ulcer risk assessment of all patients on one day. Methods : All 360 inpatients were surveyed and thoroughly examined. A risk scale for pressure sore development, the Norton score, was applied. When wounds were found, information was collected to determine their aetiology. Results : Forty leg ulcers, 40 pressure sores, 85 surgical wounds and seven other types of wounds were found. Most leg ulcer and pressure sore cases were admitted for other reasons. The Norton score did not predict all cases of pressure ulceration. A total of 52% of wounds did not qualify for additional funding under current funding criteria. Conclusion : The prevalence of non-surgical wounds in Heidelberg Repatriation Hospital was easily underestimated. Wound care management can be optimized by staff education and protocol design, early identification of troublesome wounds and of at-risk patients, and a cross-sectional approach that incorporates wound-management teams.     

Immunocytochemical characterization of large granular lymphocytes in normal cervix and HPV associated disease.

A quantitative immunocytochemical study of large granular lymphocytes (LGLs) in the normal cervix and in human papillomavirus (HPV) associated disease was performed using a panel of monoclonal antibodies which included those for LGL surface markers CD56, CD16, and CD57. Only CD56-positive cells were found within the ectocervical epithelium and these cells increased in number in cervical intraepithelial neoplasia (CIN) in comparison with normal cervix. Examination of serial sections and double labelling suggests that these cells are CD3+, CD8+, CD56+, CD16+. The observed increase in number of this subset was not associated specifically with HPV infection but was related to CIN. Lymphocytes expressing all three LGL markers were found in the stroma and CD16(+)-positive cells clustered around endocervical glands with occasional cells extending into the endocervical epithelium. These results indicate that a small subset of LGLs which express T-cell markers is increased in number in CIN. Cells expressing classical NK markers are restricted to the stroma and are not found within the ectocervical epithelium.