Microarray gene expression profiling of a human glioblastoma cell line exposed in vitro to a 1.9 GHz pulse-modulated radiofrequency field.

The widespread use of mobile phones has led to public concerns about the health effects associated with exposure to radiofrequency (RF) fields. The paramount concern of most persons relates to the potential of these fields to cause cancer. Unlike ionizing radiation, RF fields used for mobile telecommunications (800-1900 MHz) do not possess sufficient energy to directly damage DNA. Most rodent bioassay and in vitro genotoxicity/mutation studies have reported that RF fields at non-thermal levels have no direct mutagenic, genotoxic or carcinogenic effects. However, some evidence has suggested that RF fields may cause detectable postexposure changes in gene expression. Therefore, the purpose of this study was to assess the ability of exposure to a 1.9 GHz pulse-modulated RF field for 4 h at specific absorption rates (SARs) of 0.1, 1.0 and 10.0 W/kg to affect global gene expression in U87MG glioblastoma cells. We found no evidence that non-thermal RF fields can affect gene expression in cultured U87MG cells relative to the nonirradiated control groups, whereas exposure to heat shock at 43 degrees C for 1 h up-regulated a number of typical stress-responsive genes in the positive control group. Future studies will assess the effect of RF fields on other cell lines and on gene expression in the mouse brain after in vivo exposure.

Mutagenic activity of rhodamine dyes and their impurities as detected by mutation induction in Salmonella and DNA damage in Chinese hamster ovary cells.

Commercial rhodamine dyes 6G and B induce His+ reversion mutations in Salmonella and single-strand breaks in Chinese hamster ovary cells, as detected by alkaline sucrose sedimentation. Aroclor 1254-induced rat liver homogenate (S9) is required for production of genetic activity by these dyes. Rhodamine 6G induces both frameshift and base substitution mutations, whereas rhodamine B induces only frameshift mutations. Rhodamine 6G is genetically more active and more toxic than is rhodamine B in both the bacterial and mammalian assays. Rhodamine 6G and B induce doublings of His+ revertants in Salmonella at the doses of 0.02 and 0.52 mumol/plate and shifts in the molecular weight of Chinese hamster ovary DNA at concentrations of 9 x 10(-5) and 9 x 10(-4) M, respectively. All genetic effects assayed demonstrate dose-related increases. Further testing of the pure dyes in Salmonella revealed that rhodamine B loses most of its mutagenicity with purification, whereas rhodamine 6G does not. Impurities from commercial rhodamine B demonstrate the same extent of mutagenicity as the commercial dye.

The retinal nerve fiber layer, neuroretinal rim area, and visual evoked potentials in MS.

In a prospective study of 57 patients with clinically definite, probable, or possible multiple sclerosis (MS), one-half of whom had a history of optic neuritis, retinal nerve fiber layer (RNFL) defects and the neuroretinal rim (NRR) area were quantitatively determined and compared with the visual evoked potential (VEP). There were abnormal VEP latencies in 63% of all patients (definite and probable = 68%, possible = 50%); local or diffuse RNFL defects in 54%, (definite and probable = 54%, possible = 50%); and an abnormally small NRR area in 30% (definite and probable = 32%, possible = 25%). Abnormalities in one or more of the VEP, RNFL, or NRR area occurred in 86% of all patients (definite and probable = 90%, possible = 75%), thus considerably increasing the yield of optic nerve abnormalities over that of the VEP alone. The predominance and extent of the diffuse RNFL defects, which are axonal abnormalities, suggest a more diffuse optic nerve pathology in MS than can be accounted for by a "plaque" pathology and indicate that extensive axonal loss commonly occurs in the optic nerves of MS.

The effect of long-term intraocular pressure reduction on the differential light sensitivity in glaucoma suspects.

This study was undertaken to observe the effect on the differential light sensitivity in glaucoma suspects produced by a long-term reduction in intraocular pressure (IOP) with timolol maleate. The results are taken from an ongoing 6 year follow-up study of glaucoma suspects randomly selected for treatment and nontreatment. We present fine-grid meridional data, recorded every 4 months by automated perimetry, of all 46 patients (24 treated and 22 untreated) who completed the 6 year follow-up without developing localized visual field defects, acquired optic disc changes and whose IOP was not judged clinically dangerous during the follow-up. Methods of analyzing the profile sensitivity, the profile slope and the sensitivity of specific locations over the follow-up are described. The results show that the long-term fluctuation in differential light sensitivity in the two groups was not significantly different (P = 0.395) and that the sensitivity at most of the locations remained stable. The number of stable locations was not significantly different in the two groups (P = 0.412) and there was also no difference in the number of locations where the sensitivity appeared to decrease (P = 0.193) or increase (P = 0.540). Analysis of covariance showed no group difference in the profile sensitivity or the profile slope and that these variables remained stable in both groups over the 6 year period. Although the treated group maintained a consistently lower IOP than the untreated controls, our results showed that long-term pressure reduction with timolol in glaucoma suspects appeared not to influence the differential light sensitivity in the tested meridian.

The use of visual field indices in detecting changes in the visual field in glaucoma.

We present results from 64 glaucoma patients and glaucoma suspects followed up for a median period of 7.4 yr who had a median of seven examinations using Program 31 on the Octopus perimeter. The patients also had manual visual fields recorded on either the Tübinger or Goldmann perimeter during the same period. By examining all manual fields over the follow-up, we classified 37 patients as deteriorating and 27 as nondeteriorating by using predetermined field criteria which we believed to be clinically significant. In a masked fashion, the indices mean defect (MD) and corrected loss variance (CLV), in addition to the three cluster analysis indices SIZ, CLUS, and PCLUS were computed for each patient and regressed on time. When a significant positive index/time slope (P less than 0.05) was defined as indication of deterioration, all indices had remarkably poor sensitivities because their slopes did not reach statistical significance in the great majority of patients. When, regardless of statistical significance, positive slopes were defined as indication of deterioration and negative slopes as nondeterioration, the most sensitive index, PCLUS, still had a sensitivity of less than 65%. The indices were better in detecting the presence or absence of visual field deterioration in fields that were initially normal than in those that were initially abnormal. Since the testing modalities of manual and automated perimetry are different, our study was not designed to compare the sensitivity of one technique over the other. Our study does, however, demonstrate that the indices used currently may not be clinically reliable in the assessment of changes in the visual field.

Comparison of psychophysical and electrophysiological testing in early glaucoma.

PURPOSE: To compare the sensitivity and specificity of a wide range of psychophysical and electrophysiological tests in the detection of early glaucomatous damage. METHODS: Forty-three normals and 43 patients with early glaucoma, some still without field defects, were tested with differential light threshold perimetry, short-wavelength automated perimetry, high-pass resolution perimetry, motion detection, flicker contrast sensitivity, flickering and isoluminantly matched letter tests, and pattern and flash electroretinography, including photopic, scotopic, oscillatory potentials, and 30 Hz flicker. Receiver operating characteristic analysis was applied to continuous variables derived from each of the tests. RESULTS: Most parameters reflected glaucomatous loss to some degree, even though only single variables were analyzed separately in the receiver operating characteristic analysis. The pattern electroretinogram and some of the letter acuity tests had the best sensitivity and specificity, followed by short-wavelength automated perimetry and high-pass resolution-perimetry. Motion detection, flicker contrast, and flash electroretinogram parameters scored poorly. Six patients with normal results on the Humphrey field test had abnormal results on many of the other tests. CONCLUSIONS: Applying different psychophysical and electrophysiological tests may add to our ability to detect early glaucomatous damage.

Contribution of chlorination to the mutagenic activity of drinking water extracts in Salmonella and Chinese hamster ovary cells.

The production of chlorinated by-products through chlorine disinfection of drinking water has been well documented. Natural organic precursors for these chemicals include fulvic and humic acids, the chlorination of which leads to the production of mutagenic compounds. Comparisons of extracts of raw versus treated waters have confirmed that clorination during water treatment produces mutagenic activity in the Salmonella (Ames) test. Present work on XAD-2 extracts of raw and chlorinated water from six municipalities in the Great Lakes region of Canada has involved a battery of mutagenicity assays for various genetic endpoints: the Salmonella test, the sister-chromatid exchange (SCE), and the micronucleus (MN) induction in Chinese hamster ovary (CHO) cells. All extracts of treated (chlorinated), but none of untreated, water were mutagenic in the Salmonella assay. On the other hand, extracts of both treated and untreated water samples showed activity in the SCE and MN assays, but no consistent pattern of response with regard to treatment (chlorination) was evident. These data show that chlorination contributes mutagens to drinking water and suggest that mammalian in vitro assays may be more sensitive for detecting mutagenicity in water samples than the Salmonella test.

Genetic toxicology of phthalate esters: mutagenic and other genotoxic effects.

The effects of DEHP on sperm morphology and on peripheral blood micronuclei were studied for 12 weeks following five subacute IP injections of DEHP at 1/6, 1/12, and 1/60 of the LD50 per day. Sperm morphology was examined in both adult mice and rats, while peripheral blood micronuclei were scored in mice up to 4 weeks after treatment. In mice, DEHP at 1/6 LD50 significantly depressed body weight gain for up to 12 weeks after treatment, and reduced epididymal sperm number by 4 weeks. Numbers of morphologically abnormal sperm did not differ from controls in the 12 weeks following treatment. In addition, DEHP did not increase the numbers of peripheral blood micronuclei. Studies in the rat indicated that exposure to doses of 1/6 and 1/12 of the LD50 per day of DEHP resulted in a reduced gain in body weight compared to controls. Testis weight, sperm number, and numbers of morphologically abnormal sperm were unaffected by DEHP following treatment. In separate experiments, DEHP did not induce sister chromatid exchange (SCE) or DNA damage in Chinese hamster ovary (CHO) cells. Although DEHP is known to cause testicular atrophy in rats and to a lesser extent in mice, it did not cause an increase in abnormal sperm in either species. Together with the CHO and micronucleus data, these findings suggest that DEHP has a low probability of causing genetic damage capable of being transmitted through the male germ line.

Automatic perimetry (COMPETER). Ability to detect early glaucomatous field defects.

The ability of fully automatic computerized perimetry to detect early glaucomatous field damage was compared with that of careful static and kinetic manual perimetry in a clinical study on 104 patients, 51 of whom had early glaucomatous field defects, 20 of whom were glaucoma suspects with no field defects, and 33 of whom were normal. The automatic perimeter used was the COMPETER automatic perimeter employing actual threshold measurements. The interpretation of the automatic fields followed a set of predetermined criteria. Fifty-one eyes had defects in the manual charts, 48 (94%) of which were detected by automatic perimetry using the central test point pattern of the perimeter. Two (4%) fields thought to be normal after manual perimetry were correctly found to be abnormal by the automatic perimeter, which yielded four (8%) false-positives in the normal fields. By using a different set of criteria for the interpretation of the automatic fields, the sensitivity could be increased to 98% of these early defects, but at the cost of 22% false-positives.

Visual field defects in low-tension glaucoma. Comparison of defects in low-tension glaucoma and chronic open angle glaucoma.

In a study of the visual fields of 160 eyes with low-tension glaucoma (LTG) and 154 eyes with chronic open angle glaucoma with the same degree of optic nerve change, no differences in the qualitative or quantitative characteristics were found. The field defects in those eyes with LTG in which a major hemodynamic crisis had occurred were not different from those in which no crisis had been documented.

The early psychophysical disturbances in chronic open-angle glaucoma. A study of visual functions with asymmetric disc cupping.

Fourteen patients with elevated intraocular pressures, normal visual fields, and asymmetry of disc cupping were examined using a number of psychophysical tests. The results suggest that color vision and visually evoked potentials show early disturbances, but a contraction of the visual field is variable.

The visual field and nerve head in angle-closure glaucoma. A comparison of the effects of acute and chronic angle closure.

Eighteen unilaterally affected acute angle-closure glaucoma patients were seen a period of time after the acute episode, and 11 unilateral chronic angle-closure patients were seen while under control. Visual fields, optic nerve heads, and vision were assessed using the normal eye as a control. Nerve fiber bundle defects were seen in seven of the acute and nine of the chronic angle-closure cases. None of the acute, but five of the chronic angle-closure patients, showed asymmetry of cupping, while pallor was seen in seven of the acute and nine of the chronic patients. No significant difference in reduction of vision was seen between the two groups. The duration of pressure is a possible reason for cupping in glaucoma.

Neuroretinal rim area in suspected glaucoma and early chronic open-angle glaucoma. Correlation with parameters of visual function.

The cup-disc ratio is an indirect measure of the amount of neural tissue present at the optic nerve head. A large cup-disc ratio in a large disc may be accompanied by a normal neuroretinal rim. The area of the neuroretinal rim is relatively constant in normal persons and should relate to visual function. In 39 eyes of patients with suspected glaucoma, normal subjects, and patients with early open-angle glaucoma, biometric findings, psychophysical functions, and optic nerve measurements were studied. The area of the neuroretinal rim was determined from stereophotographs and corrected for the magnification by the optical components of the eye. A statistically significant relation between this neuroretinal area and parameters of visual function was found. The cup-disc ratio correlated more weakly with visual function. Covariant analysis showed the neuroretinal area to be the only parameter capable in our sample of discriminating among the three clinical groups.

Acquired color vision changes in glaucoma. Use of 100-hue test and Pickford anomaloscope as predictors of glaucomatous field change.

A five-year follow-up of eyes with elevated intraocular pressures, but without field defects, in which the color vision had been assessed by the 100-Hue test and an anomaloscope was carried out. Field defects developed in eight of 42 eyes with a low 100-Hue score, whereas field defects developed in ten of 13 eyes with a high abnormality in the 100-Hue test score. In the case of the anomaloscope (Pickford Nicholson) scores, field defects developed in four of five eyes with poor yellow-blue scores, whereas similar field defects developed in only nine of 40 years with a normal yellow-blue scores. With regard to blue-green scores, field defects developed in six of 11 eyes with a poor blue-green score, whereas field defects developed in only seven of 40 eyes with a normal blue-green score. These differences are statistically significant, and the probabilities of an abnormal color vision the results in subsequent field defects have been worked out. The red-green scores were not predictive.

Use of discriminant analysis. II. Identification of persons with glaucomatous visual field defects.

Thirty-three ocular, systemic, and laboratory variables were used in a discriminant analysis to separate 219 patients suffering from chronic open-angle glaucoma from 100 people who did not have the disease. The analysis used seven of the variables to separate 93% of the patients correctly. Without intraocular pressure, a 90% separation was obtained.

Multivariate analysis in glaucoma. Use of discriminant analysis in predicting glaucomatous visual field damage.

A discriminant function obtained in 1978 to separate patients with glaucomatous visual field loss from those without visual field loss was shown to have a predictive value in ocular hypertensive persons as to the subsequent development of visual field loss in five years. A prospective discriminant analysis also was carried out to identify those factors that best separate those in whom visual field defects developed from those in whom they did not.

The detection of paracentral scotomas with varying grids in computed perimetry.

The ability to identify the physiologic blind spot was reviewed for programs 31 and 32 on the OCTOPUS 201 perimeter. One eye of 100 randomly selected patients suspected of having glaucoma were used in the study. OCTOPUS program 31 failed to identify the physiologic blind spot in 11 eyes (22%), while program 32 missed the blind spot in three eyes (6%). These findings suggest that a 6 degrees grid may not be adequate for identification of scotomas of the size and depth of the physiologic blind spot in the central field.

Visual field and retinal nerve fiber layer comparisons in glaucoma.

Semiquantitative retinal nerve fiber layer (RNFL) scores given separately to diffuse and localized changes of the RNFL were correlated with the overall mean retinal sensitivity and visual field indexes calculated from 49 thresholds of the OCTOPUS program JO. The indexes have been developed to differentiate between generalized reduction and localized disturbances of the retinal sensitivity. The RNFL scores and visual field functions were highly correlated. Approximately 50% of the variation of the visual field functions could be accounted for by the RNFL loss scores. An adequate fit of visual field data on localized nerve fiber loss score was achieved by linear regression, whereas the diffuse nerve fiber loss score was improved by quadratic regression. This suggests that localized nerve fiber loss may be more directly associated with localized visual field disturbances than generalized fiber loss and that there may be a latency between the appearance of structural changes and generalized reduction of retinal sensitivity.

A comparison of experienced clinical observers and statistical tests in detection of progressive visual field loss in glaucoma using automated perimetry.

The visual fields of 30 patients (subjects) with glaucoma were sent to six experienced clinicians (observers). Each subject had at least four visual field examinations on the OCTOPUS 201 automated perimeter spanning at least one year. Each observer was asked to review the visual field data of each subject and determine whether the visual fields were stable, improved, or worse over time. The visual field data were then analyzed using six different statistical models. In only 15 of the 30 subjects did at least five of the six human observers agree on the behavior of the visual field. Agreement among the statistical models was better, with at least five of the six models agreeing on 22 of the 30 subjects. It was concluded that there is, at present, no validated technique for detecting progressive visual field loss in glaucoma using automated perimetry when relatively few visual fields are available for analysis.

The Auger electron dosimetry of indium-111 in mammalian cells in vitro.

Most of the radionuclides used in the formulation of radiopharmaceuticals emit Auger electrons when they undergo radioactive decay. The release of these low-energy electrons at extracellular sites produces little direct damage to intracellular structures. However, many radiopharmaceuticals, or their metabolites, can be transported into the cell where the Auger electrons have the potential to damage nearby intracellular macromolecules, including DNA. In this preliminary study, chromosome damage, expressed as 60Co equivalent doses, and the effects on cell division following treatment with intracellular and extracellular 111In were measured in Chinese hamster V79 cells. The chromosome aberration yield in cells irradiated by intracellular 111In indicated that damage was induced at a rate of 7.2 X 10(-4) Gy/decay for levels of activity up to 0.075 Bq/cell and 4.5 X 10(4) and 2.9 X 10(4) Gy/decay for intermediate (0.204 Bq/cell) and high (0.389 Bq/cell) levels, respectively. Extracellular 111In-chloride produced damage at a rate of about 6.1 X 10(-12) Gy/decay. As little as 4.4 mBq/cell (about 4.4 X 10(3) Bq/ml of culture) of intracellular 111In was able to affect cell division, whereas extracellular 111In at 1.150 MBq/ml of culture had little effect. These data indicate that the Medical Internal Radiation Dose and International Committee on Radiation Units methods for organ dosimetry may underestimate the potential of intracellular Auger electron emitters to produce radiation damage.