Apparent Deficit Research Articles

The role of the hippocampus in object recognition in rats: Examination of the influence of task parameters and lesion size

Studies examining the effects of hippocampal lesions on object recognition memory in rats have produced conflicting results. The present study investigated how methodological differences and lesion size may have contributed to these discrepancies. In Experiment 1 we compared rats with complete, partial (septal) and sham hippocampal lesions on a spontaneous object recognition task, using a protocol previously reported to result in deficits following large hippocampal lesions [10]. Rats with complete and partial hippocampal lesions were unimpaired, suggesting the hippocampus is not required for object recognition memory. However, rats with partial lesions showed relatively poor performance raising the possibility that floor effects masked a deficit on this group. In Experiment 2, we used a second spontaneous object recognition protocol similar to that used by the two other studies that have reported deficits following hippocampal lesions [6,26]. Rats with complete hippocampal lesions were significantly impaired, whereas rats with partial lesions were unimpaired. However, the complete lesion group showed less object exploration during the sample phase. Thus, the apparent recognition memory deficit in Experiment 2 may be attributable to differential encoding. Together, these findings suggest that the hippocampus is not required for intact spontaneous object recognition memory. These findings suggest that levels of object exploration during the sample phase may be a critical issue, and raise the possibility that previous reports of object recognition deficits may be due to differences in object exploration rather than deficits in object recognition per se.

Loss of forebrain cholinergic neurons and impairment in spatial learning and memory in LHX7‐deficient mice

The identification of the genetic determinants specifying neuronal networks in the mammalian brain is crucial for the understanding of the molecular and cellular mechanisms that ultimately control cognitive functions. Here we have generated a targeted allele of the LIM-homeodomain-encoding gene Lhx7 by replacing exons 3-5 with a LacZ reporter. In heterozygous animals, which are healthy, fertile and have no apparent cellular deficit in the forebrain, b-galactosidase activity reproduces the pattern of expression of the wild-type Lhx7 locus. However, homozygous mutant mice show severe deficits in forebrain cholinergic neurons (FCNs), while other classes of forebrain neurons appear unaffected. Using the LacZ reporter as a marker, we show that in LHX7-deficient mice FCN progenitors survive but fail to generate cholinergic interneurons in the striatum and cholinergic projection neurons in the basal forebrain. Analysis of behaviour in a series of spatial and non-spatial learning and memory tasks revealed that FCN ablation in Lhx7 mutants is associated with severe deficits in spatial but only mild impairment of non-spatial learning and memory. In addition, we found no deficit in long-term potentiation in mutant animals, suggesting that FCNs modulate hippocampal function independently of its capacity to store information. Overall our experiments demonstrate that Lhx7 expression is required for the specification or differentiation of cholinergic forebrain neurons involved in the processing of spatial information.

Temporal variation in the surface‐water chemistry of a blanket bog on Dartmoor, southwest England: analysis of 5 years' data

SummaryBlanket‐bog peats, mapped as the Winter Hill and Crowdy associations by the Soil Survey of England and Wales, are an oceanic manifestation of the ombrotrophic ‘raised‐bog’ (Hochmoor) peats that cover large tracts in the boreal zone of the northern hemisphere. This paper examines monthly analyses from 1992 to 1997 of major ions and other variables from an upland blanket bog in southwest England in relation to seasonality, rainfall, and the chemical composition of rainwater. Average ionic composition of surface water (and peat) integrates variable atmospheric solute inputs over the years. The dominant ions in the surface water, Na+ and Cl–, showed only weak seasonality, but divalent cations a stronger seasonal pattern with a summer maximum. Mean pH ranged from c. 4.4 in February to c. 4.2 in August. Changes in concentration of different cations were closely interlinked by cation exchange. The anion deficit, accounted for by anionic groups on the dissolved organic matter, was strongly seasonal with a summer maximum, as was optical absorbance at 320 nm. Nitrate and NH4+ were both at much smaller concentrations than in rain. Nitrate exceeded 1 μmol l−1 only during cold periods in winter, mainly following drought in the summer of 1995; NH4+ reached a few μmol l−1 only in summer. There was evidence of net retention of S by the peat in wet sites and during wet periods, and of net release of SO42– (and acidity) under dry conditions. The 1995 summer drought and ensuing dry year in 1996 had marked and persistent effects on pH, apparent ion deficit (DEF), SO42–, the divalent cations and Fe.

Testing forelimb placing “across the midline” reveals distinct, lesion-dependent patterns of recovery in rats

We describe a new test of vibrissae-elicited forelimb placing ability that allows testing of sensorimotor integration across the midline. Rats were given unilateral brain lesions using one of three methods: (1) middle cerebral artery occlusion (MCAo) causing significant damage to the cortex and striatum, (2) aspiration lesions to remove tissue from the sensorimotor cortex, and (3) infusions of the catecholamine neurotoxin 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle, producing a parkinsonian syndrome. Application of the new test to these animals revealed that with some lesion types, the ability of vibrissae on the unimpaired side of the body to trigger placing in the functionally impaired forelimb recovers before vibrissae on the impaired side can elicit placing. This occurs despite the lack of any apparent vibrissae sensory deficit, since the contralesional vibrissae maintained the ability to trigger placing in the unimpaired forelimb in all lesions studied. Chronically, MCAo-lesioned rats do not place the impaired forelimb upon stimulation of the impaired-side vibrissae, but do place if the vibrissae on the good side are stimulated (i.e., when the placing is triggered “across the midline”). This is in contrast to 6-OHDA-lesioned rats which, consistent with parkinsonian akinesia, cannot place the impaired limb regardless of sensory trigger. Also, differences in the pattern of recovery between MCAo- and aspiration-lesioned rats suggest a possible anatomical substrate for cross-midline placing ability and its recovery. Unlike other tests, cross-midline placing methods can readily distinguish between severe stroke and severe parkinsonism in rats.

The cognitive deficits responsible for developmental dyslexia: Review of evidence for a selective visual attentional disorder

There is strong converging evidence suggesting that developmental dyslexia stems from a phonological processing deficit. However, this hypothesis has been challenged by the widely admitted heterogeneity of the dyslexic population, and by several reports of dyslexic individuals with no apparent phonological deficit. In this paper, we discuss the hypothesis that a phonological deficit may not be the only core deficit in developmental dyslexia and critically examine several alternative proposals. To establish that a given cognitive deficit is causally related to dyslexia, at least two conditions need to be fulfilled. First, the hypothesized deficit needs to be associated with developmental dyslexia independently of additional phonological deficits. Second, the hypothesized deficit must predict reading ability, on both empirical and theoretical grounds. While most current hypotheses fail to fulfil these criteria, we argue that the visual attentional deficit hypothesis does. Recent studies providing evidence for the independence of phonological and visual attentional deficits in developmental dyslexia are reviewed together with empirical data showing that phonological and visual attentional processing skills contribute independently to reading performance. A theoretical model of reading is outlined in support of a causal link between a visual attentional disorder and a failure in reading acquisition.

Net community production and metabolic balance at the oligotrophic ocean site, station ALOHA

To test the hypothesis that in oligotrophic areas of the ocean respiration exceeds production, a 12-month study was undertaken of in vitro-determined net oxygen production and consumption in the top 150m of the water column at the extreme oligotrophic site, Station ALOHA, in the North Pacific subtropical gyre. Throughout the year the water column was observed to be in metabolic deficit, the calculated cumulative shortfall being 9±1.7mol O2m−2a−1 (approximately 100g Cm−2a−1), an amount equivalent to 40% of measured production (annual estimated rates of production and consumption were, respectively, 22 and 31mol O2m−2a−1).We consider three possible explanations for the observed deficit: (1)the in vitro oxygen rate measurements, in themselves, are fundamentally flawed and should be discounted,(2)the observations are correct and the observed deficit is a true account of the balance of oxygen (and organic carbon) at Station ALOHA, or(3)the observations are correct as they stand, but need not be interpreted as organic carbon imbalance for that ecosystem.We find no error unique to the oxygen rate measurements themselves. We find also no evidence that the associated organic carbon deficit can be sustained over the long-term by internal organic reserves or by external subsidy. Accordingly we accept the geochemical findings that calculated in situ oxygen flux requires the euphotic zone of the water column at this site to be slightly (circa 2mol Cm−2a−1) autotrophic, in contrast to the simple analysis of our observations which gives a net heterotrophic water column. We discuss a number of processes that may give rise to the observed discrepancy. In part it may derive from the difficulty of reproducing the variations in the light field experienced by an algal cell due to vertical advection. It may also derive from the intermittency of production. This latter effect would manifest itself in the following manner. Because of its universal distribution in the food web, respiration has greater integrating properties than photosynthesis and so will give a more accurate estimate of the long-term mean in studies with coarse sampling frequencies. If the system is undersampled, then short bursts of photosynthesis are prone to be missed from the integration of the production term but will be seen in the consumption term: hence the apparent deficit. The corollary of this line of reasoning is that, in undersampled systems, respiration has the potential to give a more accurate measurement of integrated system production than photosynthesis.

Exploring the Upper Red Giant and Asymptotic Giant Branches: The Globular Cluster M5

We have tabulated lists of upper red giant, horizontal-, and asymptotic giant branch (RGB, HB, and AGB) stars in the globular cluster M5 that are complete to over 10' from the core for the RGB and AGB samples, and 8' for the HB sample. The large samples give us the most precise value of R2 = NAGB/NHB to date for a single globular cluster (0.176 ± 0.018). This is incompatible with theoretical calculations using the most recent physical inputs. The discrepancy can probably be attributed to the dependence of observed R2 values on HB morphology. We identify the cluster M55 as another possible example of this effect. Samples of HB and AGB stars in populous clusters may provide a means of calibrating the masses of HB stars in globular clusters. The cumulative luminosity function of the upper RGB shows an apparent deficit of observed stars near the tip of the branch. This feature has less than a 2% chance of being due to statistical fluctuations. The slope of the cumulative luminosity function for AGB stars is consistent with the theoretically predicted value from stellar models when measurement bias is taken into account. We also introduce a new diagnostic Rclump that reflects the fraction of the AGB lifetime that a star spends in the AGB clump. For M5 we find Rclump = 0.42 ± 0.05, in marginal disagreement with theoretical predictions. Finally, we note that the blue half of M5's instability strip (where first-overtone RR Lyrae stars reside) is underpopulated, based on the large numbers of fundamental mode RR Lyrae stars and on the nonvariable stars at the blue end of the instability strip. This fact may imply that the evolutionary tracks (and particularly the colors) of stars in the instability strip are affected by pulsations.

Asian Americans and Voting Participation: Comparing Racial and Ethnic Differences in Recent U.S. Elections

This research assesses the significance of race and ethnicity in the participation of Asian Americans in recent U.S. elections. It reviews the major characteristics of the nonwhite, multiethnic population in recent census surveys and discusses the necessity for voting behavior research to address effects of international migration on eligibility issues in voting participation. Results from analyzing U.S. Current Population Survey Voter Supplement files, 1994–2000, indicate that Asian Americans’ apparent deficit in voting participation among voting-age persons can be reduced, removed, or even reversed when restricting analyses only to eligible persons. Multivariate analyses controlling for a set of institutional, contextual, and individual factors show that being Asian and foreign born may have the net effect of increasing voting registration, while being U.S. born and Asian may have the contrary effect, compared to non-Hispanic whites of comparable background. Nativity is not significant in impacting turnout among registered Asians as a whole, but U.S.-born Asians are less likely to turn out compared to their white counterparts. Among other findings, being foreign born may enhance the registration likelihood for Chinese, Korean, and Asian Indian American citizens and the turnout likelihood of registered Korean Americans.

Evidence for an error monitoring deficit in attention deficit hyperactivity disorder.

We studied error monitoring in ADHD and control children in a task requiring inhibition of a motor response. The extent of slowing following successful (stopped) and failed (nonstopped) inhibition was compared across groups. We also measured the time required to inhibit a response (stop signal reaction time, SSRT). Compared to controls, ADHD participants slowed less following nonstopped responses. Slowing did not vary with comorbid reading, oppositional, conduct or anxiety disorder, sex or ADHD subtype. Slowing after nonstopped responses was marginally, although significantly correlated with total ADHD symptoms and with age. ADHD participants had significantly longer SSRT than controls, but SSRT was not significantly correlated with slowing. The apparent deficit in error monitoring in ADHD and its independence from the inhibition deficit observed in ADHD has implications for executive control models of ADHD, performance problems associated with the disorder and for component theories of executive control.

Doublet craters on Venus

Of the impact craters on Earth larger than 20 km in diameter, 10–15% (3 out of 28) are doublets, having been formed by the simultaneous impact of two well-separated projectiles. The most likely scenario for their formation is the impact of well-separated binary asteroids. If a population of binary asteroids is capable of striking the Earth, it should also be able to hit the other terrestrial planets as well. Venus is a promising planet to search for doublet craters because its surface is young, erosion is nearly nonexistent, and its crater population is significantly larger than the Earth's. After a detailed investigation of single craters separated by less than 150 km and “multiple” craters having diameters greater than 10 km, we found that the proportion of doublet craters on Venus is at most 2.2%, significantly smaller than Earth's, although several nearly incontrovertible doublets were recognized. We believe this apparent deficit relative to the Earth's doublet population is a consequence of atmospheric screening of small projectiles on Venus rather than a real difference in the population of impacting bodies. We also examined “splotches,” circular radar reflectance features in the Magellan data. Projectiles that are too small to form craters probably formed these features. After a careful study of these patterns, we believe that the proportion of doublet splotches on Venus (14%) is comparable to the proportion of doublet craters found on Earth (10–15%). Thus, given the uncertainties of interpretation and the statistics of small numbers, it appears that the doublet crater population on Venus is consistent with that of the Earth.

In vivo micro magnetic resonance imaging signal changes in scrapie infected mice

Signal abnormalities on magnetic resonance imaging (MRI) T2-weighted images (T2WI) have been described in patients with Creutzfeldt–Jakob disease; however, the pathology underlying these findings remains to be fully described. We investigated the time-course of signal alterations in a murine model of prion disease using in vivo 9.4 Tesla micro magnetic resonance imaging (μMRI). The topography of μMRI signal changes was correlated with the accumulation of proteinase resistant PrP Sc in corresponding brain sections. Increased signal intensity on T2WI was observed in the septum and in the hippocampus of presymptomatic mice 120 days post infection (dpi). Mildly symptomatic animals (150 dpi) and animals with apparent neurological deficit (180 dpi) had a greater increase of signal intensity on T2WI in the septum and the hippocampus; in addition, abnormalities in the cortex and in the thalamus were found. Neuropathological evaluation demonstrated accumulation of PrP Sc and astrogliosis but only minimal or no spongiform changes in structures where abnormal signal was detected. These observations suggest that early pathological changes related to the accumulation of PrP Sc may be detectable in presymptomatic subjects using MRI systems with higher magnetic field strength.

Steroid control of longevity in Drosophila melanogaster.

Ecdysone, the major steroid hormone of Drosophila melanogaster, is known for its role in development and reproduction. Flies that are heterozygous for mutations of the ecdysone receptor exhibit increases in life-span and resistance to various stresses, with no apparent deficit in fertility or activity. A mutant involved in the biosynthesis of ecdysone displays similar effects, which are suppressed by feeding ecdysone to the flies. These observations demonstrate the importance of the ecdysone hormonal pathway, a new player in regulating longevity.

Syllogistic reasoning and cognitive ageing.

Gilinsky and Judd (1994) demonstrated that age-related impairment in syllogistic reasoning was in part due to reduced working-memory capacity. A total of 30 older (average age 66 years) and 34 younger persons (average age 24 years) were tested on syllogisms of various types as well as on other measures. Syllogistic reasoning was significantly correlated with education, processing speed, word span, and word fluency. Correlations with visuo-spatial processing and random letter generation were just short of significance. Syllogistic reasoning performance declined with age, although the deficit was no longer statistically significant following control for age-related differences in information-processing speed. On the other hand the inclusion of word fluency as an additional covariate boosted the apparent age effect, returning it to statistical significance. Thus it is possible that cognitive processes outside of working memory might underpin at least part of the apparent age deficit. This possibility is evaluated in the light of neuropsychological evidence implicating the prefrontal cortex in both the processing of syllogisms and more generally in cognitive ageing.

Shortening budgets and the role of continental subduction during the India–Asia collision

The India–Asia collision provides a remarkable example of diffused deformation because the zone of compressive strain extends far into the Hinterland of the Himalaya. Molnar and Tapponnier's [Science 189 (1975) 419] concept of India as a rigid indenter responsible for the diffused deformation has been widely accepted, perhaps uncritically. This review gives a reappraisal of landmark papers by Dewey et al. [Philos. Trans. R. Soc. London, A 327 (1988) 379; Eclogae Geol. Helv. 82 (1989) 717] which discussed the shortening budget in SE Asia and the evidence for the amount and the rate of the convergence between India and Asia taking place after the initial collision of these continents at roughly 55–50 Ma. Evidence for the total convergence comes from magnetic anomaly, palaeomagnetic and volumetric balancing studies. The results are consistent in showing about 1800–2100 km convergence between India and Asia in the western sector, 2475 km in the central and 2750–2800 km in the eastern sector. The rate of convergence between India and Asia over the period since initial collision is roughly 5 cm/year. However, the possible long-term rate of convergence within the Himalaya is considerably less, i.e. 1.5–2.0 cm/year, a fraction of the total convergence. This shortfall can be made up by adding to the rate for the Himalaya alone the convergence rates in other parts of the diffused zone of compressive strain, i.e. Tibet, Tien Shan, Altai. This works well for the post-Oligocene but not for the earlier post-collisional history when the areal extent of thrust/fold tectonics was much more limited. Possibly, the apparent shortening deficit before the Miocene was made up by strike–slip faulting but with the notable exception of the Red River Fault evidence for widespread pre-Miocene strike–slip faults is not convincing. Summation of the amount of shortening in thrust/fold regimes in the Himalaya and its Hinterland falls short of that required by the total convergence figures quoted above. The deficit arises firstly because of the likelihood that pre-collisional crustal shortening (of uncertain areal extent) in Tibet reduces Tibet's contribution (>40% according to Dewey et al. [Philos. Trans. R. Soc. London, A 327 (1988) 379; Eclogae Geol. Helv. 82 (1989) 717]) to the shortening budget for the Cenezoic. Revised shortening budgets are presented on the assumption that most of the Lhasa Block (Southern Tibet) was already thickened prior to collision: this thickening is difficult to quantify. Secondly, balanced cross-sections from various parts of the Himalaya give 60–70% shortening, that is only about 500 km, roughly half of the shortening proposed by Dewey et al. The conclusion of Le Pichon et al. [Tectonics 11 (1992) 1085] that only Indian mid/upper crust is involved in the Himalayan thrust sheets is supported but it needs to be reassessed in the light of the recognition of Eocene–Oligocene thickening in the Himalaya. This early crustal thickening antedates the sequence of thrusts which started with the Main Central thrust and therefore the shortening estimates based on balanced cross-sections probably underestimate the total shortening in the Himalaya. The prospect of substantial underthrusting of India beneath Tibet minimizes the amount of horizontal shortening of Tibetan lithosphere during the Cenozoic. The conclusion is that either the total convergence deduced from geophysical and volumetric work is too large or the deficit must be made up by shortening mechanisms other than thrust/fold regimes, i.e. strike–slip faulting which serves to move rocks out of the way of India.

Removal of ammoniacal nitrogen from landfill leachate by irrigation onto vegetated treatment planes

Leachate is a contaminated liquor resulting from the disposal of solid and liquid wastes at landfill sites that must be treated before discharge. Vegetated leachate treatment planes have been used at landfill sites in the UK but have received little scientific attention. This paper describes studies of model leachate treatment planes with a focus on the removal of ammoniacal nitrogen (NH 3-N). Small-scale and field-scale experimental treatment planes were constructed, filled with clay loam soil and vegetated with grass ( Agrostis stolonifera). Landfill leachate was applied at hydraulic loading rates ranging from 17–217 l/m 2/d. An exponential relationship was used to characterise the pattern of NH 3-N removal. No relationship was observed between the hydraulic loading rate and the NH 3-N removal rate constants ( R 2=0.0039). The daily specific NH 3-N mass removal rate was found to be linearly related to the NH 3-N concentration at the start of that day of treatment ( R 2=0.35). Possible causes of variation in the rate of NH 3-N removal between experiments are discussed. A simple inorganic nitrogen balance indicated that the mass of NH 3-N and NO 2-N removed was not accounted for by NO 3-N production. Explanations for this apparent nitrogen deficit are discussed.

Resolving the solar neutrino problem: Evidence for massive neutrinos in the Sudbury Neutrino Observatory

or more than 30 years, experiments have detected neutrinos produced in the thermonuclear fusion reactions which power the Sun. These reactions fuse protons into helium and release neu­ trinos with an energy of up to 15 MeY. Data from these solar neutrino experiments were found to be incompatible with the predictions of solar models. More precisely, the flux of neutrinos detected on Earth was less than expected, and the relative intensi­ ties of the sources of neutrinos in the sun was incompatible with those predicted by solar models. By the mid-1990's the data were beginning to suggest that one could not even in principle adjust solar models sufficiently to account for the effects. Novel proper­ ties of neutrinos seemed to be called for. With the recent measurements of the Sudbury Neutrino Observatory (SNO), it has finally become possible to test the solar model predictions and the particle properties of neutrinos independently. Solar models that simulate the interior of the Sun and explain stellar evolution have been developed using experimental and theoretical inputs from nuclear physics, astrophysics, and particle physics. These models are based on the assumption of light ele­ ment fusion in the Sun. As more and more astrophysical data have become available, solar models were tested through a variety of observables and found to be successful in many respects. A variety of hypotheses that require new particle physics have been postulated to explain the discrepancy between the solar model expectations and the apparent deficit of solar neutrinos detected on Earth. In the Standard Model, neutrinos belong to the family ofleptons. Neutrinos were believed to be massless particles with three distinct flavors (electron, muon, and tau) depending on the weak interaction process that created them. One flavor could not transform into another. All three types of neutrinos SNO

Neuron-Specific Expression of Mutant Superoxide Dismutase 1 in Transgenic Mice Does Not Lead to Motor Impairment

Mutations were identified in the Cu/Zn superoxide dismutase gene (SOD1) in approximately 15% of patients with familial amyotrophic lateral sclerosis. Transgenic animals expressing mutant SOD1 in all tissues develop an ALS-like phenotype. To determine whether neuron-specific expression of mutant SOD1 is sufficient to produce such a phenotype, we generated transgenic animals carrying the G37R mutation that is associated with the familial form of ALS (FALS), which is driven by the neurofilament light chain promoter. The transgenic animals express high levels of the human SOD1 protein in neuronal tissues, especially in the large motor neurons of the spinal cord, but they show no apparent motor deficit at up to 1.5 years of age. Our animal model suggests that neuron-specific expression of ALS-associated mutant human SOD1 may not be sufficient for the development of the disease in mice.

A Case of Fatal Paradoxical Fat Embolism Syndrome Detected by Intraoperative Transesophageal Echocardiography

We report a case of paradoxical fat embolism syndrome (PFES) detected by intraoperative transesophageal echocardiography (TEE). Case Report A 30-yr-old male truck driver with no history of cardiac or cerebral disease was admitted to the intensive care unit after his truck was struck by another truck from behind, and the dashboard trapped him. On arrival, he had no apparent neurological deficit, with normal findings on brain computed tomography (CT). Tachypnea (36 breaths/min), tachycardia (81 bpm), and hypercapnia (Paco2: 55.0 mm Hg) with normal oxygenation and normal arterial blood pressure were observed. Surgery was performed to fixate the closed fractures of the right femoral shaft fracture with intramedullary nails (with 12-mm diameter and 38-cm length) during general anesthesia. Approximately 90 min after starting the operation, a decreased end-tidal CO2 and oxygen saturation (Spo2) occurred followed by hypercapnia, hypoxia, tachycardia, hypotension, and pulmonary hypertension (pulmonary artery pressure was 46/29 mm Hg). TEE revealed multiple small vesicles in all four heart chambers (Fig. 1), marked pulmonary artery dilation, and depression of contraction of the right ventricle. PFES was strongly suspected, and the operation was completed as quickly as possible.Figure 1: Transesophageal echocardiographic four-chambers’ view, showing massive fat emboli in the left atrium (LA), left ventricle (LV), and Aorta (Ao). Shown are multiple small echogenic vesicles in the LA, LV, and Ao. Contraction of the right ventricle (RV) was decreased, and ventricular septum was overhung toward the LV.Postoperatively, the patient remained in a coma. Brain CT findings were almost the same as those of preoperative examination both immediately after, and 3 h after, the operation. However, there was severe global edema in both cerebral hemispheres at 8 h after the operation. After hypothermic therapy with a blood temperature of 34°C for 3 days, the patient remained in a coma; cerebral edema was observed on brain CT, which did not improve. Contrast TEE using plasma protein fraction revealed the appearance of microbubbles in both atria almost simultaneously. However, the location of the shunt was not identified by color Doppler echocardiography. Phagocytosis of fat vesicles by macrophages was also demonstrated in both pulmonary and arterial blood samples (Fig. 2) and a bronchoalveolar lavage fluid sample. The patient died on the ninth hospital day of severe hypotension caused by brain herniation. The request to perform an autopsy was denied by his family.Figure 2: Phagocytosis of fat vesicles by macrophages was demonstrated in arterial blood samples on the second hospital day. The triangle shows macrophages, including fat vesicles with Sudan stain.Discussion Intraoperative TEE yields real-time information on the frequency of embolic events during intramedullary procedures (1–3). In our case, the appearance of fat vesicles was observed continuously independently of surgical manipulations. However, it was difficult to distinguish between fat particles and microbubbles. No definitive treatment for PFES has been established. It has generally been reported that early stabilization of fracture sites decreases the incidence of fat embolism (4). When PFES is suspected, intramedullary procedures should be discontinued and other treatment options for long-bone fracture considered (5,6). We selected general anesthesia for the patient, because massive intraoperative bleeding was anticipated. However, mechanical positive-pressure ventilation would increase both intrathoracic pressure and right atrial pressure, possibly causing functional right-to-left shunt. One possible option to prevent an increase in intrathoracic pressure would be the use of other anesthetic techniques, such as continuous epidural or spinal anesthesia.

Survival After Failed Intraoperative Resuscitation: A Case of “Lazarus Syndrome”

Survival After Failed Intraoperative Resuscitation: A Case of “Lazarus Syndrome”

Order in CdS nanoparticles in glass

We have employed X-ray absorption spectroscopy to study the local bonding of Cd atoms in borosilicate glasses doped with Cd and S after heat treatment at temperatures from 550 to 750°C. Varying temperature and time can form CdS particles with average size from a few to several nanometers. In crystals grown below ∼700°C, the apparent number of second neighbors found from analysis of X-ray absorption fine structure is only a small fraction of that expected for well-ordered crystallites of these sizes. We attribute this apparent coordination deficit to substantial short-range structural disorder.