Event-related potentials during arithmetic and mental rotation

In separate studies of arithmetic and mental rotation, similar posterior negative slow waves have been found. This similarity was surprising given the difference in cognitive processing required by these tasks. Furthermore, delayed responses were employed in these studies, so that it was not possible to determine the extent to which the slow wave activity was too late to be associated with processing that was specific to performance of the tasks. This experiment was intended to clarify the task-specific and non-specific nature of the slow wave activity. Subjects performed either an arithmetic or mental rotation task at two levels of difficulty on a random, trial-to-trial basis and gave an immediate response. There were a number of late posterior negativities, each with a different timing and topography, which were sensitive to type of task and/or task difficulty. Some components were associated with early task processing that was synchronized to the stimulus while others, revealed by response-synchronized averaging, were associated with later stages of task processing. There also was post-task activity that was sensitive to the difficulty level of the prior operations. In both tasks, there was a pre-frontal positive wave that persisted over most of the pre-response epoch, evidently related to a process that was active throughout the task. There also was centro-frontal phasic negativity, with a large peak at 380 msec in mental rotation, and a smaller, longer latency peak in arithmetic, apparently related to the complexity of the stimulus. Thus we conclude that arithmetic and mental rotation each elicit task-specific slow wave activity.

Evidence for the effects of HIV antibody counseling and testing on risk behaviors

OBJECTIVE

To review published abstracts, journal articles, and presentations for evidence of the effects of human immunodeficiency virus (HIV) antibody counseling and testing on risk behaviors. Studies reviewed focused on homosexual men, intravenous drug users in treatment programs, pregnant women, and other heterosexuals.

DATA SOURCES

Peer-reviewed journals (January 1986 through July 1990) and published abstracts and oral presentations from the second (1986) through the sixth (1990) International Conferences on AIDS.

STUDY SELECTION

We identified 66 studies that included data on the behavioral effects of HIV antibody counseling and testing. By consensus of the authors, 16 of these were excluded because of small sample size or inadequate study design.

DATA EXTRACTION

Studies were assessed by the authors according to methodological strength (sample selection, inclusion of appropriate comparison groups, and inclusion of statistical tests of significance).

DATA SYNTHESIS

All longitudinal studies of homosexual men reported reductions in risky behavior among both tested and untested men, and a few reported greater decreases among seropositive men than among seronegative men and those untested or unaware of their serostatus. For intravenous drug users in treatment, we found reductions in intravenous drug use and sexual risk behaviors regardless of counseling and testing experience. We found little evidence for the impact of counseling and testing on pregnancy and/or pregnancy termination rates for either seropositive or seronegative high-risk women. We noted substantial risk reduction among heterosexual couples with one infected partner. Findings among other heterosexuals at increased risk were scanty and mixed.

CONCLUSIONS

Further studies should specifically address the behavioral consequences of counseling and testing in various settings.

Identification of signaling states of a sensory receptor by modulation of lifetimes of stimulus-induced conformations: the case of sensory rhodopsin II

Lifetimes of stimulus-induced conformations of the phototaxis receptor sensory rhodopsin II (SR-II) from Halobacterium halobium are modulated with seven receptor analogues. By monitoring the receptor dynamics in vitro and physiological responses of the cell in vivo, we observe receptor signaling efficiency increases with decreasing cycling frequency (turnover number) of the receptor. The results demonstrate that modulating lifetimes of protein conformations at the SR-II photoactivation site with chromophore analogues alters the lifetime of the active conformation at the signaling site. We further explore the relationship between photocycle intermediates and the signaling efficiency by analyzing the time-averaged concentrations of the two long-lived spectral intermediates of the SR-II photocycle: S-II350 and S-II530. The results are consistent with the signaling site being activated during formation of S-II350, but not reset by the transition of S-II350 into S-II530; rather deactivation appears to require subsequent decay of S-II530. The results indicate the structural changes at the photoactivation site in the S-II350----S-II530 transition do not reset the signaling site. The procedure used here, applicable in principle to any photoactivated or ligand-activated receptor, provides an initial approach to identify structural alterations key to the receptor activation process.

A clinical study of ferric sulfate as a pulpotomy agent in primary teeth

Pulpotomies were performed on 83 primary molars in 62 patients. Ferric sulfate or formocresol was placed on the pulpal stumps, and teeth were followed for 3-, 6-, and 12-month periods. After the one-year follow-up, 28 of 29 teeth treated with ferric sulfate (FS group) were considered successful and 21 of 27 teeth treated with formocresol (FC group) were judged to be successful. The FS group demonstrated greater combined clinical and radiographic success than the FC group at the one-year recall (P < 0.05). Although the results of this study are promising, further study with longer observation periods is warranted before this technique can be recommended.

Depression and panic attacks related to phenol-formaldehyde composite material exposure in an aerospace manufacturing plant

In a case series study we evaluated 53 composite-materials workers in an aerospace plant who filed workers' compensation claims for illness allegedly related to phenol-formaldehyde resin exposure. Symptoms ranged from mucosal and skin irritation to depression and cognitive impairment. Certain health practitioners implying they had immunologic dysfunction and organic brain injury, led workers to believe they were chemically poisoned. Industrial hygiene evaluation failed to show levels of chemicals above permissible levels. Thorough evaluation by our multidisciplinary panel failed to find significant objective abnormalities by physical exam and laboratory testing. Thirty-nine percent of the workers had sensory irritation and/or skin complaints that generally resolved rapidly with removal from exposure. Psychiatric diagnoses (including major depression and/or panic attacks) were made in 74% of the workers, but only 26% of these had antecedent disease. Fourteen (26%) had multiple somatic complaints that generally persisted despite removal from exposure, but they also had long histories of significant pre-existing psychological illness. Detailed neuropsychologic testing failed to show any definite evidence or organic brain dysfunction in any of the workers tested. We speculate that sensory irritation from low-level volatile organic compounds with autonomic arousal, reinforced by the belief they were "chemically poisoned," led to psychogenic illness.

Regional deformation of the canine diaphragm

To follow regional deformation of the diaphragm in dogs, radiopaque markers were implanted under surgical anesthesia into different anatomic regions of the muscle in triangular arrays (approximately 1 cm to a side). After recovery from surgery, changes in area and shape of the triangles were followed with biplane cinefluorography during quiet breathing and during inspiratory efforts against an occluded airway (Mueller maneuvers). From changes in shape of the triangles during contraction, area changes were decomposed into a major direction and magnitude of shortening (Eg1) and a minor length change (Eg2) perpendicular to Eg1, both expressed as a fraction of initial length at end expiration. With the use of these techniques, systematic differences in regional area change were observed in different parts of the diaphragm during inspiratory efforts at different lung volumes. Regional area always decreased during contraction in the crural and midcostal zones of apposition to the rib cage. Area decreased less and often increased during inspiratory efforts in the costal dome near the central tendon and in the costal region near its rib cage insertion. Differences in regional area change were not due to differences in the Eg1 in different parts of the diaphragm but were a consequence of differences in widening of the muscle along Eg2 perpendicular to the direction of Eg1. As lung volume was passively increased above functional residual capacity, regional area decreased in all parts of the diaphragm except in the costal regions near rib cage insertion, where area increased.

Intraoperative cholangiography: use of portable fluoroscopy and transmitted images

Intraoperative cholangiograms were obtained with portable fluoroscopy in 53 patients during laparoscopic cholecystectomy, and the images were transmitted to the radiology department. Each image was assessed for diagnostic quality and bile duct abnormalities (eg, retained stones and duct aberrancies). The aberrancy rate was 5.7% with the aberrant duct in the region of surgical dissection. The fluoroscopic technique provided diagnostic images with the advantage of real-time visualization, immediate communication with the surgeon, and the potential to decrease the risk of bile duct injury.

Concentration of azithromycin in human prostatic tissue

Prostatic tissue was obtained from 36 patients at two study locations and assayed for azithromycin by HPLC or bioassay. The mean concentration of azithromycin in human prostatic tissue (2.54 micrograms/ml) 14 h after 500 mg oral dosing (two 250 mg doses 12 h apart) was much greater than plasma concentrations (less than or equal to 0.1 micrograms/ml). Azithromycin was slowly eliminated from prostatic tissue (half-life 60 h) and a mean concentration of 0.62 micrograms/ml remained 137 h after dosing.

A strategy for service--Disney style

The organization's customer service philosophy was established over 35 years ago by its founder. Today, every aspect of the resorts and theme parks is geared to serve--and satisfy--its "guests."

Confocal microscopy of genome exposure in normal, cancer, and reverse-transformed cells

Genome exposure studies were carried out on malignant CHO-K1 and C6 rat glioma cells and their respective, phenotypically normal counterparts (reverse-transformed CHO-K1, and both reverse-transformed C6 glioma and normal rat fibroblasts). Cells were subjected to the nick-translation technique previously developed to make visible the exposed (i.e., DNase I-sensitive) nuclear DNA, and examined by both epifluorescence and confocal microscopy. The confocal microscopy, by permitting examination of sections throughout the nucleus, made possible clearer identification of the regions of exposed and sequestered DNA in the cells studied. A peripheral shell of exposed DNA with some discontinuities was displayed in the great majority of the cells with normal phenotype, but in none of the cancer cells. Both types of cells displayed regions of exposed DNA in the nuclear interior, particularly surrounding the nucleoli. In accordance with previous theoretical proposals we postulate: the peripheral nuclear shell of exposed DNA contains differentiation-specific genes that include the specific growth-control genes and that are functional in normal cells but not in cancer; the exposed genes surrounding the nucleoli may represent housekeeping genes active in both normal and cancer cells; and the DNase I-resistant DNA in the interior of the nucleus we postulate to consist for the most part of genes specific to alternative differentiation states and to be sequestered and inactive. Previous differences in evaluation of roles of peripheral and internal DNA sensitivity to DNAse I hydrolysis appear to be reconciled by this formulation. Identification of exposed DNA may be useful in cancer diagnosis.

Photoisomerization of retinal at 13-ene is important for phototaxis of Chlamydomonas reinhardtii: simultaneous measurements of phototactic and photophobic responses

A real-time automated method was developed for simultaneous measurements of phototactic orientation (phototaxis) and step-up photophobic response of flagellated microorganisms. Addition of all-trans retinal restored both photoresponses in a carotenoid-deficient mutant strain of Chlamydomonas reinhardtii in a dose-dependent manner. The phototactic orientation was biphasic with respect to both the light intensity and the concentration of retinal. All-trans retinal was more effective than 11-cis retinal to regenerate both photobehavioral responses. Analogs having locked 11-cis configurations and a phenyl ring in the side chain also induced photoresponses, although at concentrations more than two orders of magnitude higher than all-trans retinal. According to the present assay method, the responses were hardly detectable in cells incubated with retinal analogs in which the 13-ene was locked in either its trans or cis configuration. The results strongly suggest that the isomerization of the 13-14 double bond is important for photobehavioral signal transduction and that a single retinal-dependent photoreceptor controls both phototactic and photophobic responses.

Progressive supranuclear palsy: altered sensory processing leads to degraded cognition

We studied the latencies, amplitudes, and scalp distributions of the early and late components of the event-related brain potential (ERP) in patients with progressive supranuclear palsy (PSP) and matched normal controls. In separate choice reaction time (RT) tasks, the subjects pressed buttons to visual stimuli presented randomly at probabilities of either 20/80 or 50/50. Compared with normal controls, PSP patients had significantly reduced amplitudes and increased latencies for both the visual P2 and P300 components at all levels of probability. RTs and percent errors were significantly greater in the patients compared with controls. Neither the amplitude nor latency of the visual N1 component was significantly altered in these patients. There were no significant group differences in the distribution of electrical activity over the scalp for any of these ERP components, a finding which suggests that the neural structures responsible for generating these potentials were intact in these patients. The decreased ERP component amplitudes and increased ERP component latencies, combined with intact scalp distributions and increased RTs and error rates, present a pattern of results suggesting that the stimulus identification or categorization processes in these patients are significantly degraded.

The effectiveness of a layered baseplate training aid in the preclinical instruction of second-year dental students

The effectiveness of the Cavidrill baseplate in the training of second-year dental students in cavity preparations in primary ivorine teeth was assessed. The preclinical class of 112 students was divided into four groups: Cavidrill-only group, two groups combining Cavidrill training with traditional typodont training, and a typodont-only group. The Cavidrill baseplate was found not to improve the students' performance in cavity preparation when assessed on midterm and final examinations.

The tyrosinase-related protein-1 gene has a structure and promoter sequence very different from tyrosinase

We have determined the exon structure of the mouse tyrosinase-related protein-1 (TRP-1) gene. The gene is only 15kb in length, but contains seven introns, in contrast to the tyrosinase gene which is almost 100kb long with only four introns. Only two introns are located in homologous positions in both genes. Intron I of TRP-1 has three alternative 5' splice sites clustered within 21bp, which all splice to the same 3' site. Intron V has a very unusual 5' splice site, which has the dinucleotide GC rather than the conventional GT. We show that as little as 370bp of 5'-flanking DNA is sufficient to direct cell-specific expression of the chloramphenicol acetyl transferase gene. The flanking DNA of TRP-1, unlike tyrosinase, does not contain a TATA box or a CCAAT box. Both mouse genes, however, share an 11bp sequence, also found in human tyrosinase, which we suggest may be a melanocyte-specific promoter element.

Overexpression of the cAMP receptor 1 in growing Dictyostelium cells

cAR1, the cAMP receptor expressed normally during the early aggregation stage of the Dictyostelium developmental program, has been expressed during the growth stage, when only low amounts of endogenous receptors are present. Transformants expressing cAR1 have 7-40 times over growth stage and 3-5-fold over aggregation stage levels of endogenous receptors. The high amounts of cAR1 protein expressed constitutively throughout early development did not drastically disrupt the developmental program; the onset of aggregation was delayed by 1-3 h, and then subsequent stages proceeded normally. The affinity of the expressed cAR1 was similar to that of the endogenous receptors in aggregation stage cells when measured either in phosphate buffer (two affinity states with Kd's of approximately 30 and 300 nM) or in 3 M ammonium sulfate (one affinity state with a Kd of 2-3 nM). When expressed during growth, cAR1 did not appear to couple to its normal effectors since these cells failed to carry out chemotaxis or to elevate cGMP or cAMP levels when stimulated with cAMP. However, cAMP stimulated phosphorylation, and loss of ligand binding of cAR1 did occur. Like aggregation stage control cells, the cAR1 protein shifted in apparent molecular mass from 40 to 43 kDa and became highly phosphorylated when exposed to cAMP. In addition, the number of surface cAMP binding sites in cAR1 cells was reduced by over 80% during prolonged cAMP stimulation. These results define a useful system to express altered cAR1 proteins and examine their regulatory functions.

Storage of platelet concentrates after high-dose ultraviolet B irradiation

Ultraviolet B (UVB) irradiation of platelet concentrates (PCs) may prevent the development of posttransfusion HLA alloimmunization. As irradiation performed in a blood center or a hospital will probably be associated with a variable postirradiation delay before transfusion, the ability to store PCs after UVB irradiation becomes important. The effects have been studied of a UVB dose of 10,000 mJ per cm2, the dose used in our institution for UVB clinical trials, on PCs pooled and stored for up to 96 hours after irradiation. Results showed that after 96 hours of storage, though there were no changes in pH, platelet count, white cell count, percent discharge of lactate dehydrogenase, or beta-thromboglobulin, there were significant decreases in morphology score and osmotic recovery. These changes, however, were not evident after 24 hours of storage. Similarly, there was a 60-percent decrease in immunoreactive membrane glycoprotein (GP) Ib after 96 hours of storage, but these changes were not seen after 48 hours of storage. No changes were seen in levels of GPIIb/IIIa in either group during the 96 hours of storage. On computer-analyzed two-dimensional polyacrylamide gel electrophoresis, PCs irradiated at 10,000 mJ per cm2 and stored for 72 hours had changes in over 50 platelet proteins as compared to those proteins in nonirradiated age-matched control PCs. It can be concluded that UVB irradiation of PCs at 10,000 mJ per cm2 does not lead to significant platelet deterioration after short-term storage (24-48 hours) but is likely to be deleterious after long-term (72-96 hours) storage.(ABSTRACT TRUNCATED AT 250 WORDS)

Myristic acid auxotrophy caused by mutation of S. cerevisiae myristoyl-CoA:protein N-myristoyltransferase

The S. cerevisiae myristoyl-CoA:protein N-myristoyltransferase gene (NMT1) is essential for vegetative growth. NMT1 was found to be allelic with a previously described, but unmapped and unidentified mutation that causes myristic acid (C14:0) auxotrophy. The mutant (nmt1-181) is temperature sensitive, but growth at the restrictive temperature (36 degrees C) is rescued with exogenous C14:0. Several analogues of myristate with single oxygen or sulfur for methylene group substitutions partially complement the phenotype, while others inhibit growth even at the permissive temperature (24 degrees C). Cerulenin, a fatty acid synthetase inhibitor, also prevents growth of the mutant at 24 degrees C. Complementation of growth at 36 degrees C by exogenous fatty acids is blocked by a mutation affecting the acyl:CoA synthetase gene. The nmt1-181 allele contains a single missense mutation of the 455 residue acyltransferase that results in a Gly451----Asp substitution. Analyses of several intragenic suppressors suggest that Gly451 is critically involved in NMT catalysis. In vitro kinetic studies with purified mutant enzyme revealed a 10-fold increase in the apparent Km for myristoyl-CoA at 36 degrees C, relative to wild-type, that contributes to an observed 200-fold reduction in catalytic efficiency. Together, the data indicate that nmt-181 represents a sensitive reporter of the myristoyl-CoA pools utilized by NMT.

Accordion right coronary artery: an unusual complication of PTCA guidewire entrapment

The contour of the epicardial coronary vessels may change considerably during coronary angioplasty. We report the extreme and unique "accordion-like" wrinkling of the mid right coronary artery as a result of distal guidewire entrapment during coronary angioplasty. Recognition of this artifact and its treatment may prevent further complications of coronary angioplasty.