A versatile soft X-ray transmission system for time resolved in situ microscopy with chemical contrast.

We present the design and operation of a versatile soft X-ray transmission system for time resolved in situ microscopy with chemical contrast. The utility of the setup is demonstrated by results from following a corrosion process of iron in saline environment, subjected to a controlled humid atmosphere. The system includes a transmission flow-cell reactor that allows for in situ microscopic probing with soft X-rays. We employ a full field technique by using a nearly collimated X-ray beam that produces an unmagnified projection of the transmitted soft X-rays (below 1.1 keV) which is magnified and recorded by an optical CCD camera. Time lapse series with chemical contrast allow us to follow and interpret the chemical processes in detail. The obtainable lateral resolution is a few mum, sufficient to detect filiform corrosion on iron.

Closed source experimental system for soft x-ray spectroscopy of radioactive materials.

An instrumental and experimental setup for soft x-ray spectroscopy meeting the requirements of a closed source for radioactivity is described. The system consists of a vacuum sealed cell containing the sample, mounted on a tubing system to ensure compatibility with most standard manipulators. The soft x rays penetrate a thin x-ray window separating the interior of the cell from the vacuum in the experimental chamber. Our first results for single crystal PuO(2) confirm the feasibility of experiments using the setup. The results are consistent with results of first principles calculations and previously recorded spectra obtained using a standard open source setup. The results show that the closed source experimental system can be used to collect valuable experimental data from radioactive materials.

NeuN expression correlates with reduced mitotic index of neoplastic cells in central neurocytomas.

In the developing brain, neuronal differentiation is associated with permanent exit from the mitotic cycle. This raises the possibility that neuronal differentiation may suppress proliferative activity, even in neoplastic cells. As a first step towards understanding the relation between neuronal differentiation and mitotic cycling in brain tumours, we studied the expression of NeuN (a neuronal marker) and Ki-67 (a mitotic marker) by double-labelling immuno-fluorescence in 16 brain tumours with neuronal differentiation. The tumours included a series of 11 central neurocytomas, and five single cases of other tumour types. In the central neurocytomas, NeuN(+) cells had a 15-fold lower Ki-67 labelling index, on average, than did NeuN(-) cells (P < 0.01). In the other tumours (one extraventricular neurocytoma, one desmoplastic medulloblastoma, one olfactory neuroblastoma, one ganglioglioma and one anaplastic ganglioglioma), the Ki-67 labelling index was always at least fourfold lower in NeuN(+) cells than in NeuN(-) cells. These results indicate that neuronal differentiation is associated with a substantial decrease of proliferative activity in neoplastic cells of central neurocytomas, and suggest that the same may be true across diverse types of brain tumours. However, tumours with extensive neuronal differentiation may nevertheless have a high overall Ki-67 labelling index, if the mitotic activity of NeuN(-) cells is high. The correlation between NeuN expression and reduced mitotic activity in neurocytoma cells is consistent with the hypothesis that neuronal differentiation suppresses proliferation, but further studies will be necessary to determine causality and investigate underlying mechanisms.

Postnatal shifts of interneuron position in the neocortex of normal and reeler mice: evidence for inward radial migration.

During development, interneurons migrate to precise positions in the cortex by tangential and radial migration. The objectives of this study were to characterize the net radial migrations of interneurons during the first postnatal week, and to investigate the role of reelin signaling in regulating those migrations. To observe radial migrations, we compared the laminar positions of interneurons (immunoreactive for GABA or Dlx) in mouse neocortex on postnatal days (P) 0.5 and P7.5. In addition, we used bromodeoxyuridine birthdating to reveal the migrations of different interneuron cohorts. To study the effects of reelin deficiency, experiments were performed in reeler mutant mice. In normal P0.5 cortex, interneurons were most abundant in the marginal zone and layer 5. By P7.5, interneurons were least abundant in the marginal zone, and were distributed more evenly in the cortical plate. This change was attributed mainly to inward migration of middle- to late-born interneurons (produced on embryonic days (E) 13.5 to E16.5) from the marginal zone to layers 2-5. During the same interval, late-born projection neurons (non-immunoreactive for GABA or Dlx) migrated mainly outward, from the intermediate zone to upper cortical layers. In reeler cortex, middle- and late-born interneurons migrated from the superplate on P0.5, to the deep cortical plate on P7.5. Late-born projection neurons in reeler migrated in the opposite direction, from the intermediate zone to the deep cortical plate. We conclude that many middle- and late-born interneurons migrate radially inward, from the marginal zone (or superplate) to the cortical plate, during the first postnatal week in normal and reeler mice. We propose that within the cortical plate, interneuron laminar positions may be determined in part by interactions with projection neurons born on the same day in neurogenesis.

adrift, a novel bnl-induced Drosophila gene, required for tracheal pathfinding into the CNS.

Neurons and glial cells provide guidance cues for migrating neurons. We show here that migrating epithelial cells also contact specific neurons and glia during their pathfinding, and we describe the first gene required in the process. In wild-type Drosophila embryos, the ganglionic tracheal branch navigates a remarkably complex path along specific neural and glial substrata, switching substrata five times before reaching its ultimate target in the CNS. In adrift mutants, ganglionic branches migrate normally along the intersegmental nerve, but sporadically fail to switch to the segmental nerve and enter the CNS; they wind up meandering along the ventral epidermis instead. adrift encodes a novel nuclear protein with an evolutionarily conserved motif. The gene is required in the trachea and is expressed in the leading cells of migrating ganglionic branches where it is induced by the branchless FGF pathway. We propose that Adrift regulates expression of tracheal genes required for pathfinding on the segmental nerve, and FGF induction of adrift expression in migrating tracheal cells promotes the switch from the intersegmental to the segmental nerve.

Translational readthrough in the hdc mRNA generates a novel branching inhibitor in the drosophila trachea.

A central question in the development of many branched tubular organs, including the Drosophila trachea, concerns the mechanisms and molecules that control the number and pattern of new branches arising from preexisting vessels. We report on a branching inhibitor, Fusion-6 (Fus-6) produced by specialized tracheal cells to prevent neighboring cells from branching. In Fus-6 mutants, cells that are normally quiescent acquire the branching fate and form an increased number of sprouts emanating from the primary branches. Fus-6 is identified as the headcase (hdc) gene and is expressed in a subset of the cells that extend fusion sprouts to interconnect the tracheal network. hdc expression is regulated by the transcription factor escargot (esg) because it is not expressed in the fusion cells of esg mutants and is ectopically activated in the trachea in response to esg misexpression. We show that the hdc mRNA encodes two overlapping protein products by an unusual suppression of translational termination mechanism. Translational readthrough is necessary for hdc function because rescue of the tracheal mutant phenotype requires the full-length hdc mRNA. In ectopic expression experiments with full-length and truncated hdc constructs, only the full-length cDNA encoding both proteins could inhibit terminal branching. We propose that hdc acts non-autonomously in an inhibitory signaling mechanism to determine the number of cells that will form unicellular sprouts in the trachea.

Expression pattern of glutamate decarboxylase (GAD) in the developing cortex of the embryonic chick brain.

The development of the GABAergic system in the chick embryo telencephalon has been studied. Special emphasis was placed on the development of glutamate decarboxylase (GAD) between embryonic day 8 (E8) and E17. The GABA immunoreactivity and neuron-specific enolase expression was detected simultaneously in glutardialdehyde fixed sections, which confirmed that GABAergic cells exhibit neuronal phenotype. The GAD expression was studied by means of immunohistochemistry on cryo-sectioned material both at the light and electron microscopic levels. Furthermore, the presence and localization of GAD65 and GAD67 mRNAs were studied with an in situ hybridization technique with digoxigenin-labeled RNA probes. Protein expression as well as mRNA appearance mostly coincided both temporally and spatially. In the parahippocampal area, as well as in other regions of the developing cortex, GAD staining was seen from E8 onwards. The number of positive cells increased as did the intensity of staining up to E14. As observed in the electron microscope, the GAD protein was co-localized with GABA in most cases, although some GAD-positive cells devoid of GABA-staining also were observed. The pattern of GAD mRNA expression was in general similar to that of GAD immunostaining. Both GAD65 and GAD67 mRNA were detected during the entire period. Furthermore, GAD67 mRNA localization spatially was more correlated with GAD protein expression. The study provides evidence for the notion that development of the GABAergic system occurs rapidly during embryogenesis and, as suggested from mRNA data, that two forms of GAD with slight difference in distribution can contribute to this.

Visual display format affects the ability of anesthesiologists to detect acute physiologic changes. A laboratory study employing a clinical display simulator.

BACKGROUND: Anesthesiologists use data presented on visual displays to monitor patients' physiologic status. Although studies in nonmedical fields have suggested differential effects on performance among display formats, few studies have examined the effect of display format on anesthesiologist monitoring performance. METHODS: A computer-based clinical display simulator was developed to evaluate the efficacy of three currently used display formats (numeric, histogram, or polygon displays) in a partial-task laboratory simulation. The subjects' task consisted solely of detecting any changes in the values of the physiologic variables depicted on a simulated clinical display. Response latency and accuracy were used as measures of performance. RESULTS: Thirteen anesthesia residents and five nonmedical volunteers, were enrolled as subjects. Use of either the histogram or polygon displays significantly improved response latencies and allowed greater accuracy compared with the numeric display in the anesthesia residents. Neither response latency nor accuracy improved with additional exposure to these displays. In contrast, display format did not significantly affect response latency or accuracy in the nonmedical volunteers. CONCLUSIONS: The results of this study suggest that graphic displays may enhance the detection of acute changes in patient physiologic status during anesthesia administration. This research also demonstrates the importance of assessing performance on clinical devices by studying actual users rather than random subjects. Further research is required to elucidate the display elements and characteristics that best support different aspects of the anesthesiologist's monitoring tasks.

Health effects of sleep deprivation.

This report provides information supporting the conclusion that sleep deprivation produces only very small biomedical effects. It nonetheless concludes that chronic partial sleep deprivation may contribute to gastrointestinal disorders, cardiovascular disease, and other medical conditions that occur more often in shiftworkers than in permanent dayworkers.

Changes in fitness and shipboard task performance following circuit weight training programs featuring continuous or interval running.

Pre- and post-physiological data were collected on 57 Navy men (mean age = 19.5 years) who participated in either circuit weight training/continuous run (CWT/CR) (N = 31) or circuit weight training/interval run (CWT/IR) (N = 26) programs. Measured variables included 4 measures of upper torso dynamic strength (one repetition maximum [1 RM] for arm curl, bench press, shoulder press, and lat pull-down); two measures of lower torso dynamic strength (1 RM) for knee extension and leg press); one measure of power (number of revolutions completed on an arm ergometer (Monark) at maximum drag); three measures of muscular endurance (number of repetitions at 60% 1 RM for bench press and leg press and maximal number of bent-knee sit-ups in 120 s); one stamina measure (time to exhaustion on a cycle ergometer (Monark) maximal work capacity [MWC] test; and three simulated shipboard tasks: manikin shoulder drag, open/secure a water tight door and paint bucket carry. Composite shipboard performance derived from the summed time (s) required to complete the three tasks was also calculated. Results show performance on the manikin shoulder drag and majority of evaluative fitness measures was significantly (p less than 0.05) enhanced following both circuit weight training/run formats. Significantly (p less than 0.05) higher values for shoulder press (F = 7.2), arm ergometer (F = 5.3), and sit-ups (F = 6.8) and lower values for leg press muscular endurance (F = 5.1) were observed in CWT/IR when compared to CWT/CR.(ABSTRACT TRUNCATED AT 250 WORDS)

Decrements in logical reasoning performance under conditions of sleep loss and physical exercise: the factor of sentence complexity.

Baddeley's Logical Reasoning Test was used in a series of Sustained Operations (SUSOP) studies involving 100 US Marine Corps enlisted subjects, to assess the effects of sleep loss and long-term physical exercise on the ability to process complex information. The percent correct answers to the eight Logical Reasoning sentence types involving different voice (active vs passive), use of negatives, and outcome (true vs false) were analyzed over three days across three levels of exercise and rest conditions in the seven studies. A multivariate analysis of variance indicated no differences on the baseline day among the seven studies. Analyses on the baseline day and throughout the next two continuous workdays (CWs) showed consistently higher percent correct for the actively worded than for the passively worded sentences. The sleep loss over the two CWs resulted in a significant decrease in percent correct for the statements which had active wording. Sleep loss had no effect on statements with passive wording. There were no differences in comprehension between groups which had different rest conditions (no rest, 3- or 4-hr. nap, 8-hr. sleep) between the two CWs for any of the sentences; and there was no recovery from prerest to postrest. Fatigue due to exercise during either CW had no effect on comprehension for any of the sentence types. The sleep loss effects on comprehension seem due to a lessening of the attention given to those more simple sentences in active voice, whereas increased arousal may have been elicited by the more complex sentences in passive voice. The increased attention to the passive statements may have overcome the effects of sleep loss. The present study shows the usefulness of analyzing responses to the logical reasoning test by sentence complexity for indicating selective cognitive changes in the processing of information.

Altered circadian periodicities in oral temperature and mood in men on an 18-hour work/rest cycle during a nuclear submarine patrol.

A group of nuclear submariners was studied to examine whether an 18-h routine (6-h on, 12-h off watch) during a 10-week submerged patrol affected the 24-h circadian rhythm in oral temperature, Thayer's activation, Mood 'Activity' (MA) and Mood 'Happiness' (MH). They were observed during three phases of the patrol: Phase 1, the beginning 8-day period; Phase 2, the middle of the voyage; and Phase 3, the last 7-8 day period. The group-synchronized 24-h rhythm in oral temperature disappeared during Phase 3. The group-synchronized 24-h rhythms in Thayer's activation and in MA and MH disappeared during Phases 2 and 3. A group-synchronized 18-h rhythm was not produced in any of the variables in any phase, except MH during Phase 2. Periodicity analysis of the individuals' data showed that a loss of 24-h rhythmicity in oral temperature was due not only to reduced circadian amplitude but also to a dispersion of Time of Peak (TOPs). Loss of 24-h rhythm in 'Activation', 'Happiness', and 'Activity' was predominantly due to a wider dispersion of TOPs. The 18-h routine did appear to exert a small modulating effect on rhythmic activity in the variables examined in this study. Since the sleep/wakefulness cycle was well entrained by the 18-h routine, the submariners experienced a spontaneous internal desynchronization between the activity cycle and the cycles or oral temperature and psychological states. The performance and health consequences of this chronic dyschronism have yet to be explored. We suggest further research to determine the usefulness of an index of synchronization among the physiological and psychological variables, and the relationship of the desynchronizing effects to performance.

An attempted validation study of the birthdate-based biorhythm (BBB) hypothesis.

The birthdate-based biorhythm (BBB) hypothesis was examined for utility as a predictor of human performance. Data from quizzes of 26 students taken periodically throughout a semester, and measures over 1 month of landing performance by seven pilots were analyzed by multiple regression/correlation methods. Regression equations were developed to test the correspondence between performance and cycle phases. A second analysis used a nonorthogonal least-square spectrum method to determine if the data contained any systemic rhythms in the intradian range. No significant results were obtained whcih would support the BBB hypothesis as a predictor of human performance. Also, no evidence was found to substantiate the existence of the three proposed BBB cycles.

Lymphocyte cytotoxicity in X-irradiation-induced adenocarcinoma of the rat small bowel. I. Measurement of target cell destruction by release of radioiodinated membrane proteins: brief communication.

A cell-mediated immune response as denoted by lymphocyte cytotoxicity was detected in Holtzman rats with X-irradiation-induced adenocarcinomas of the small bowel. Cytotoxicity was measured by target cell destruction as determined by release of intracellular 51Cr or radioiodinated (125I) membrane proteins. The radioiodination assay possessed an important advantage over the 51Cr technique in that the radiolabel was spontaneously lost slowly, thus permitting long-term studies.

Identification and characterization of a circulating tumor-associated oncofetal protein from a radiation-induced adenocarcinoma of the rat small bowel.

A tumor-associated protein from the cellular membranes of a radiation-induced rat small bowel adenocarcinoma was identified, found to be serologically unaltered in the circulatory system, and was observed to be susceptible to acid hydrolysis. The immunochemical reactivity was unchanged by heat, alkali, or neuraminidase digestion. The protein appeared to be a single immunologically active species, but it was structurally composed of a heterogeneous group of proteins.