Spectrum of clinical and histopathologic responses to intracranial electrodes: from multifocal aseptic meningitis to multifocal hypersensitivity-type meningovasculitis.

PURPOSE: We sought to characterize and compare the histopathologic and clinical changes elicited by subdural and depth electrodes in subjects undergoing epilepsy surgery evaluation. METHODS: A retrospective review of clinical records, imaging and histopathologic studies of epilepsy surgery cases requiring subdural strips and depth electrodes for localization of epileptogenic tissue was performed between 1993 and 1999. Forty-nine subjects had a combination of subdural and depth, whereas 10 had depth electrodes only. Histopathologic changes were classified as mild, moderate, or severe based on the density, extent, and composition of the inflammatory infiltrate. RESULTS: Subdural electrodes induced a clinical picture of transient aseptic meningitis; histopathologically, the infiltrates were moderate in degree in the majority (73%) and severe in the remainder (27%), with T cells and eosinophils infiltrating the cortex and arteriolar walls (hypersensitivity-type response). Depth electrodes alone caused minimal or no symptoms of meningeal irritation; the cellular response elicited by these electrodes was mild in five and moderate in the remaining five cases; severe inflammation was not observed in this group. Although the proportion of small clinically silent hematomas was larger in cases with depth (five of 59) compared with subdural electrodes (one of 49), microhemorrhages were considerably more numerous with subdural than with depth electrodes. CONCLUSIONS: These results suggest that the spectrum of brain responses to foreign bodies is wide, ranging from self-limited physiologic to hypersensitivity-type reactions of varying severity. Subdural strips elicited more intense inflammation than did depth electrodes. The histopathologic extent of the reaction to either type of electrodes could not be precisely defined because of the retrospective nature of this study. History of allergy to latex or previous craniotomies are probable risk factors for the hypersensitivity-type reaction. Surgical outcome, excellent in the majority, was independent of the severity or type of inflammation, and there have not been neurologic or systemic sequelae.

Experimental simulations of sulfide formation in the solar nebula.

Sulfurization of meteoritic metal in H2S-H2 gas produced three different sulfides: monosulfide solid solution [(Fe,Ni)1-xS], pentlandite [(Fe,Ni)9-xS8], and a phosphorus-rich sulfide. The composition of the remnant metal was unchanged. These results are contrary to theoretical predictions that sulfide formation in the solar nebula produced troilite (FeS) and enriched the remaining metal in nickel. The experimental sulfides are chemically and morphologically similar to sulfide grains in the matrix of the Alais (class CI) carbonaceous chondrite, suggesting that these meteoritic sulfides may be condensates from the solar nebula.

Preparing children for radiologic procedures: contingent versus noncontingent instruction.

The purpose of this study was to examine the effects of choice of information in preprocedural instruction on children's responses to select radiologic procedures. Sixty-one children were randomly assigned to either the contingent (n = 31) or noncontingent (n = 30) instruction group. Contingent instruction provided information in response to children's questions and requests. Noncontingent instruction provided children information based on recommendations from the literature and clinical practice. Dependent variables were measured using the Manifest Upset Scale, Cooperation Scale, search for information protocol, and self-report of distress. Contingent instruction was associated with less search for information. Prior to painful instrusive radiologic procedures, a choice of information may not support information-seeking, a strategy for adaptation.

Chemical effects of large impacts on the Earth's primitive atmosphere.

Intense bombardment of the moon and terrestrial planets approximately 3.9-4.0 x 10(9) years ago could have caused the chemical reprocessing of the Earth's primitive atmosphere. In particular, the shock heating and rapid quenching caused by the impact of large bodies into the atmosphere could produce molecules such as HCN and H2CO4 which are important precursors for the abiotic synthesis of complex organic molecules. Here we model the production of HCN and H2CO by thermochemical equilibrium and chemical kinetic calculations of the composition of shocked air parcels for a wide range of temperatures, pressures and initial compositions. For atmospheres with C/O > or = 1, our results suggest that bolide impacts cause HCN volume mixing ratios of approximately 10(-3) to 10(-5) in the impact region and global average ratios of 10(-5) to 10(-12). The corresponding H2CO mixing ratios in the impact region are 10(-7) to 10(-9); no-global mixing can occur, however, as H2CO is rapidly destroyed or rained out of the atmosphere within days to hours. Rainout to the oceans of 3-15% of the HCN produced can provide approximately (3-14) x 10(11) mol HCN per year. This is somewhat larger than other predicted sources of HCN and H2CO on the primitive Earth.

X-ray microanalysis of chloride in nails from cystic fibrosis and control patients.

Nail clippings from 60 individuals were examined. There were 34 "old" (greater than 16 years) controls, 16 "young" controls and 10 CF patients. In regard to elements found, Si and Al were considered as exogenous contamination. Other elements examined were variable in both control and CF. Examination of the Cl levels among the 3 groups showed a highly significant difference between the mean Cl integral values of the young controls (619 integral) and the CF patients (2956 integral). The results of the older control population ranged from 0-905 integral with a mean of 269 integral. We found no age or sex difference in the amount of Cl or any other element from either the CF or control population. Results show that the x-ray energy dispersive system (EDS) is very useful in studying the Cl in nails. We found that examination of nails frozen in liquid nitrogen followed by fracturing without prior washing was the preferred method. Although the results of this study clearly show statistically the value of EDS analysis of Cl in the diagnosis of CF, we must await further study of a larger group of patients to determine its usefulness in evaluating individual patients, particularly newborns.

Venus: halide cloud condensation and volatile element inventories.

Several recently suggested Venus cloud condensates, including aluminum chloride and halides, oxides, and sulfides of arsenic and antimony, are assessed for their thermodynamic and geochemical plausibility. Aluminum chloride can confidently be ruled out, and condensation of arsenic sulfides on the surface will cause arsenic compounds to be too rare to produce the observed clouds. Antimony may be sufficiently volatile, but the expected molecular form is gaseous antimony sulfide, not the chloride. Arsenic and antimony compounds in the atmosphere will be regulated at very low levels by sulfide precipitation, irrespective of the planetary inventory of arsenic and antimony. Thus arguments for a volatile-deficient origin for Venus based on depletion of water and mercury (relative to the earth) cannot be tested by a search for atmospheric arsenic or antimony.