Attention deficit/hyperactivity disorder's effects on individuals' scan paths during a simulated drive

Individuals who have Attention Deficit/Hyperactivity Disorder (ADHD) experience adverse effects relating to driving; additionally, they experience deficits in scanning ability. The present study examined the effects of ADHD on eye tracking while driving. This study consisted of ten participants, of which, five have ADHD. It was hypothesized that individuals who have ADHD will make more saccadic eye movements and thus shorter fixations than individuals without ADHD (Control). Furthermore, it was hypothesized that despite the fact that individuals who have ADHD will make more saccadic eye movements than individuals without ADHD, those individuals with ADHD will commit more traffic violations including collisions compared to the control group. Findings indicated that hypothesis one was not supported by the data, whereas hypothesis two was supported in that ADHD individuals' had more collisions and committed more traffic violations than the control group. Additionally, a significant difference was found in the spatial distributions of the fixations between the ADHD and Control groups. The findings of this study could help better understand the factors involved in ADHD driving and could be used to train individuals with ADHD to become more aware of their surroundings and driving habits and thus become safer drivers.

Determining skill transferability of action games as a method to reduce in-vehicle phone distractions

Distracted driving has been shown to be a safety issue in numerous studies. To combat this problem, in-vehicle technology, legislation, media interventions, and other methods have been proposed and attempted. However research indicates that the drivers themselves may circumvent, ignore, or not be able to react in time for these interventions to be effective. Therefore research into training programs for drivers may improve reaction time under distraction. Research indicates that action game players have faster reaction times and more attentional resources than non-players on paper-based tests. However, transferability to driving has not been studied yet. This paper outlines a study to determine if action game players perform better at a driving task based on frequency of game-play. Participants will be placed into two groups of play (high vs. low) and tested against two levels of distraction (none vs. phone conversation). It is expected that participants who play higher frequency of action games will perform better under distraction than lower frequency players. Driver performance, conversation recall, frequency and durations of eye fixations will be analyzed based on previous research which has validated those variables as a measure of distraction and higher workload.

Ovarian adrenal interactions during the menopausal transition

Observations over the past decade using longitudinal data reveal a gender-specific shift in adrenal steroid production. This shift is represented by an increase in the circulating concentrations of delta 5 steroids in 85% of all women and is initiated only after the menopausal transition has begun. While the associated rise in the major adrenal androgen, dehydroepiandrosterone sulfate (DHEAS), is modest, the parallel rises in dehydroepiandrosteone (DHEA) and androstenediol (Adiol) are much more robust. These increases in circulating steroid concentrations are qualitatively similar on average between ethnicities but quantitatively different between individual women. Both circulating testosterone (T) and androstenedione (Adione) also rise concomitantly but modestly by comparison. This phenomenon presents a new and provocative aspect to the endocrine foundations of the menopausal transition and may provide important clues to understanding the fundamentals of mid-aged women's healthy aging, particularly an explanation for the wide diversity in phenotypes observed during the MT as well as their different responses to hormone replacement therapies. Experimental studies using the nonhuman primate animal model show an acute adrenal response to human chorionic gonadotropin (hCG) challenge as well as the presence of luteinizing hormone receptors (LHR) in their adrenal cortices. These experimental results support the concept that LHRs are recruited to the adrenal cortices of mid-aged women that subsequently function to respond to increasing circulating LH to shunt pregnenolone metabolites towards the delta 5 pathway. Future investigations are required to determine the relationship of these changes in adrenal function to symptoms and health outcomes of mid-aged women.

Adjunctive GnRH-a treatment attenuates depletion of ovarian reserve associated with cyclophosphamide therapy in premenopausal SLE patients

BACKGROUND

We measured antimullerian hormone (AMH), a marker of ovarian reserve, in women with lupus treated with cyclophosphamide (CYC) (group I), CYC plus gonadotropin-releasing hormone agonist (GnRH-a) (group II) or neither (group III). We hypothesized that AMH would be diminished in women exposed to CYC versus women receiving adjunctive GnRH-a treatment or no CYC exposure.

METHODS

Forty-eight premenopausal lupus patients were retrospectively divided into three treatment groups: CYC alone (group I, n = 11), CYC + GnRH-a (group II, n = 10) and neither (group III, n = 27). Serum AMH levels between groups were compared using a nonparametric test (Wilcoxon rank-sum). Multiple linear regression adjusting for age was performed.

RESULTS

AMH (ng/mL) levels at the last collection were significantly lower in group I versus group III (mean ± SD: 0.18 ± 0.20 group I vs 1.33 ± 1.59 group III; p = 0.015), and versus group II (mean ± SD: 0.86 ± 1.06; p = 0.018). When centered on age 30 years, average AMH levels for group I, group II and group III were 0.20, 0.44 and 1.00, respectively. When adjusted for age, AMH between all groups was significantly different (p<0.0001).

CONCLUSION

Posttreatment AMH levels were significantly higher among patients receiving CYC + GnRH-a compared to CYC alone, suggesting that GnRH-a coadministration mitigates CYC-induced ovarian injury.

Commentary on Jacobs and Michaels (2001): calibration and perceptual learning in event perception

Jacobs and Michaels (2001) have argued that increased precision in judgments of the viewing distance to a perceived event should be attributed in part to perceptual learning. They found that observers used feedback to attune to the appropriate information variables gradually. McConnell, Muchisky, and Bingham (1998) had found that observers used feedback to calibrate event-specific scaling coefficients, that the calibration of one type of event generalized to other types, and that calibration occurred suddenly. We argue that Jacobs and Michaels must be partially correct and that, in our experiments, both calibration and perceptual attunement were required for accurate and precise judgments.

Reaching measures of monocular distance perception: forward versus side-to-side head movements and haptic feedback

We investigated whether forward or side-to-side head movements yielded more accurate and precise monocular egocentric distance information, as shown by performance in a reaching task. Observers wore a head-mounted camera and display to isolate the optic flow generated by their head movements and had to reach to align a stylus directly under a target surface. Performance in the two head movement conditions was also tested with normal monocular vision. We tested performance in the two head movement conditions when the observers were given haptic feedback and compared performance when haptic feedback was removed. Performance was both more accurate and more precise in the forward head movement condition than in the side-to-side head movement condition. Performance in the side-to-side condition also deteriorated more after the removal of haptic feedback than did performance in the forward head movement condition. In the normal monocular condition, performance was comparable for the two head movement conditions. The implications for enucleated patients are discussed.

The use of time and trajectory forms as visual information about spatial scale in events

Spatial metrics are lost but temporal metrics are preserved in the mapping from events to optic flow. In inanimate events governed by gravity, temporal scale is linked to spatial scale in ways specific to particular events. We tested whether time can be used as information about spatial scale in visually recognizable events. On average, observers were able to judge object size in event displays that eliminated information other than time and trajectory forms. However, judgment variability was substantial. After feedback on one event, observers judging distance performed better and generalized training to other events. Observers are sensitive to the general form of the scaling relation, but they require feedback to attune event-specific constants.

A two-site chemiluminescent assay for activin-free follistatin reveals that most follistatin circulating in men and normal cycling women is in an activin-bound state

Follistatin (FS) is a monomeric protein that binds and regulates the bioavailability of activin. Previously, we found circulating levels of total FS to be similar in men and cycling women. Because relative amounts of activin-bound and free FS are important considerations in determining activin bioavailability, we asked here whether the relative proportions of these two changed during different physiologic states. For this, we developed a two-site, solid-phase, immunochemiluminescent assay for free FS. The assay recognizes the 288 or 315 amino acid variants of human FS and has a detectable limit of 1 ng/mL. Inhibin, transforming growth factor-beta, or alpha-2-macroglobulin do not cross-react or interfere in this assay. Preincubation of FS with activin results in dose-dependent loss of immunoreactivity, confirming specificity of the assay for free FS. Human follicular fluid, pituitary extract, and serum with added FS dilute parallel with the recombinant human FS-288 standard. Recovery of recombinant human FS-288 from serum is quantitative. Using this assay, we found circulating concentrations of free FS to be at or below the detection limit of the assay throughout the menstrual cycle. Comparison of circulating total and free FS levels in postmenopausal or cycling women and normal men suggested that at least 90% is activin-bound. In contrast, measurable quantities of free FS were found in follicular fluid and pituitary extracts. The results of this study, showing that most circulating FS is normally activin-bound, argue against an endocrine role for FS and suggest that a major role of circulating FS is to bind and neutralize the bioactivity of circulating activin. The roles of FS as a local autocrine or paracrine regulator of activin in target tissues, where FS exists in free form, or as an endocrine regulator in human pathophysiology, warrants further investigation.

Circulating concentrations of dimeric inhibin A and B in the male rhesus monkey (Macaca mulatta)

The purpose of this study was to determine the relative concentrations of inhibin A and B in peripheral serum of the adult male rhesus monkey and to examine the testicular contribution to these circulating forms of inhibin. In addition, inhibin B concentrations were also determined in peripheral sera of neonatal and juvenile males and in spermatic vein blood of adults. Immunoradiometric assays specific for the measurement of inhibin A and B were used. These assays also provided an opportunity to reexamine the physiological significance of a replacement infusion of recombinant human (rh)-inhibin A previously employed to study the role of this hormone in regulating FSH secretion in the monkey. In intact adults, the mean (+/-SE) serum concentration of inhibin B was 1008 +/- 184 pg/mL. In contrast, circulating inhibin A concentrations were very low (< 46 pg/mL). Inhibin B was consistently detected in neonatal monkey serum (275 +/- 57 pg/mL), and concentrations of this inhibin dimer increased throughout postnatal development, reaching maximum values in adulthood. Circulating inhibin A concentrations in neonatal and juvenile monkeys were undetectable (< 7 pg/mL). Both forms of inhibin were generally undetectable in castrate sera. The ratio of inhibin B concentrations in testicular venous blood to those in the peripheral circulation was 1.4:1. These findings indicate that, in the male monkey, inhibin B is the principal form of circulating dimeric inhibin, and that this hormone is derived exclusively from the testis. The elevated levels of circulating inhibin B in the juvenile male monkey suggest that, during this phase of development, testicular inhibin B secretion is relatively gonadotropin independent. Additionally, we found that the concentration of circulating inhibin A in castrate animals that had earlier received an iv infusion of rh-inhibin A (832 ng/h/kg BW) was 9881 +/- 2135 pg/mL, indicating that this mode of inhibin replacement may not have been entirely physiological.

Development of a two-site solid-phase immunochemiluminescent assay for measurement of dimeric inhibin-A in human serum and other biological fluids

Inhibin is a heterodimeric glycoprotein that inhibits the secretion of follitropin from the pituitary and has been isolated in two distinct forms composed of a common alpha subunit and either a beta A or beta B subunit. Utilizing paired monoclonal antibodies specific to the alpha and beta A subunit, we have developed an immunochemiluminescent assay for dimeric inhibin-A. The assay is capable of quantifying free and bound inhibin-A in human serum and follicular fluid. The limit of detection is 10 ng/L. Related proteins exhibit little cross-reactivity or interference. Recovery is excellent. Whereas samples from men and postmenopausal women are near the detection limit of the assay, inhibin-A is higher in the luteal than the follicular phase of normally cycling women, 20-fold higher during in vitro fertilization treatment, and approximately 200-fold greater in pregnancy. The assay measures inhibin-A in follicular fluid from a variety of other species.

Development of a two-site solid-phase immunochemiluminescent assay for measurement of dimeric inhibin-A in human serum and other biological fluids

Inhibin is a heterodimeric glycoprotein that inhibits the secretion of follitropin from the pituitary and has been isolated in two distinct forms composed of a common alpha subunit and either a beta A or beta B subunit. Utilizing paired monoclonal antibodies specific to the alpha and beta A subunit, we have developed an immunochemiluminescent assay for dimeric inhibin-A. The assay is capable of quantifying free and bound inhibin-A in human serum and follicular fluid. The limit of detection is 10 ng/L. Related proteins exhibit little cross-reactivity or interference. Recovery is excellent. Whereas samples from men and postmenopausal women are near the detection limit of the assay, inhibin-A is higher in the luteal than the follicular phase of normally cycling women, 20-fold higher during in vitro fertilization treatment, and approximately 200-fold greater in pregnancy. The assay measures inhibin-A in follicular fluid from a variety of other species.

A two-site monoclonal antibody immunoradiometric assay for human follistatin: secretion by a human ovarian teratocarcinoma-derived cell line (PA-1)

The follistatin/activin/inhibin system increasingly appears to have important growth and differentiating effects in a variety of cell types, including cancer. We have developed a two-site immunoradiometric assay for measurement of human follistatin using two monoclonal antibodies against recombinant human follistatin. This cloned protein donor assay is sensitive (0.5 ng/mL), specific for free human follistatin, and precise (<5% within assay coefficient of variation). Using this assay, native human follistatin could be measured in human pituitary extracts, follicular fluid, and granulosa-luteal cell-conditioned medium. To identify and characterize human follistatin secreted by ovarian cancer cells, we screened five human ovarian carcinoma cell lines currently available from the American Type Culture Collection (Rockville, MD). One of these, a cell line derived from a teratocarcinoma (designated PA-1, American Type Culture Collection, CRL1572), secreted large (3 microg/10(6) cells per 24 h) quantities of immunoreactive follistatin constituitively. Increasing volumes of conditioned medium from these cultured cells generated response curves parallel to those of recombinant human follistatin 288 reference protein, human follicular fluid, or culture medium from human granulosa-luteal cells. Secretion of follistatin by PA-1 cells was time and cell-number dependent with 297.9 +/- 15.2, 654 +/- 29.8, and 940 +/- 49.1 ng follistatin secreted over 24 h by 1 x 10(5), 2 x 10(5), and 3 x 10(5) cells, respectively. Western and ligand blot analysis revealed that the immunoreactive follistatin secreted by PA-1 cells and isolated by sulfate-cellufine chromatography was identical to the molecular weight variants (32,000 and 35,000 Mr) of recombinant human follistatin 288. PA-1 cell-conditioned medium suppressed basal secretion of FSH by cultured rat anterior pituitary cells in a dose-dependent fashion. This follistatin bioactivity was completely removed by adsorption with either solid-phase monoclonal antifollistatin or a dextran-sulfate chromatography gel. Because activin suppressed the proliferation of PA-1 cells, secretion of bioactive follistatin may represent an autocrine mechanism opposing activin to maintain the rapid growth rate of PA-1 cells. These observations demonstrate that the ovarian teratocarcinoma cell line, PA-1, secretes considerable amounts of human follistatin that is biologically active, capable of binding human activin, and antigenically similar to recombinant human follistatin 288. The monoclonal antibodies and two-site assay reported herein should be useful in assessing the regulation of follistatin secretion and as a diagnostic tool, especially if follistatin measurements prove to be a marker for some ovarian cancers.

Noninvasive assessment of lipid disposition in treated and untreated atherosclerotic rabbits

In an effort to visualize whole body cholesteryl ester (CE) deposition using the nuclear medicine imaging technique of gamma camera scintigraphy, 125I-cholesteryl iopanoate (125I-CI), a nonhydrolyzable CE analogue, was used as a marker for CE deposition in atherosclerotic New Zealand white rabbits. Groups of animals were fed either a cholesterol-enriched diet (2%, w/w) or the same diet supplemented with the hypolipidemic drugs colestipol (1%, w/w) and/or clofibrate (0.3%, w/w). Injections of 125I-CI were administered biweekly. At the end of 15 weeks, animals were scintigraphically scanned and sacrificed for tissue analysis. The results demonstrated that while drug treatment had no significant effect on plasma lipid levels, it substantially lessened atherosclerotic involvement in the thoracic-abdominal aorta. These differences in aortic lipid accumulation were reflected in the whole-body scans which showed a reduction in tissue accumulation of 125I-CI in the drug-treated groups. Gamma camera scintigraphy thus represents a rapid means of visualizing tissue CE accumulation which could facilitate the evaluation of lipid-lowering drug efficacy and possible antiatherosclerotic effect.

Lipoprotein incorporation enhances radioiodinated cholesteryl ester uptake into steroid hormone-secreting tissues

This study was undertaken to determine whether incorporation of radioiodinated cholesterol derivatives into plasma lipoproteins prior to administration to animals could lead to improvements in adrenal localization of radioactivity. Rat high density lipoproteins (HDL) were labeled with [125I]cholesteryl iopanoate, a nonhydrolyzable ester of cholesterol. No enhancement in adrenal uptake of radioactivity was noted at 30 min following administration of the HDL preparation to control rats when compared with [125I]NP-59. However, when animals were made hypolipidemic by treatment with either 4-APP or ethinyl estradiol, the adrenal radioactivity after i.v. administration of the HDL preparation was found to be over 15 times greater than that achieved with [125I]NP-59. Scans of hypolipidemic rats taken at 30 min correlated well with the tissue distribution results.