An observed population of intermediate-mass helium stars that have been stripped in binaries.

The hydrogen-rich outer layers of massive stars can be removed by interactions with a binary companion. Theoretical models predict that this stripping produces a population of hot helium stars of ~2 to 8 solar masses (M☉), however, only one such system has been identified thus far. We used ultraviolet photometry to identify potential stripped helium stars then investigated 25 of them using optical spectroscopy. We identified stars with high temperatures (~60,000 to 100,000 kelvin), high surface gravities, and hydrogen-depleted surfaces; 16 stars also showed binary motion. These properties match expectations for stars with initial masses of 8 to 25 M☉ that were stripped by binary interaction. Their masses fall in the gap between subdwarf helium stars and Wolf-Rayet stars. We propose that these stars could be progenitors of stripped-envelope supernovae.

[Innovative 3D imaging]. / Innovative 3D-Bildgebung.

Intraoperative 2D fluoroscopy is often performed for repositioning and implant control. However, this does not always provide the details needed to reliably detect joint steps or incorrect repositioning. Over the last few years, intraoperative 3D imaging has been established and further developed. Multiple studies demonstrate an advantage and better intraoperative control through 3D imaging. Examples are the upper ankle, the proximal tibia and the distal radius; the rates of intraoperative revisions with digital volume tomography (DVT) are between 20-30%. Technical advancements, such as metal artifact reductions, automated plane setting, automated screw detection, and robotic DVT devices, facilitate intraoperative operation, shorten surgical time, and provide improved image quality. By processing the data sets in the form of an immersive, computer-simulated image in terms of "augmented reality" (AR), increased precision can be achieved intraoperatively while reducing radiation exposure. The implementation of these systems is associated with costs, which are offset by cost savings from avoided revisions. Adequate counter-financing is still lacking at the present time. Intraoperative 3D imaging represents an important tool for intraoperative control. The current data situation makes it necessary to address the routine use of 3D procedures, especially in the joint area. The indications are becoming increasingly broader. Technical innovations such as robotics and AR have significantly improved 3D devices in recent years and offer high potential for integration into the OR.

Boston biorepository, recruitment and integrative network (BBRAIN): A resource for the Gulf War Illness scientific community.

AIMS: Gulf War Illness (GWI), a chronic debilitating disorder characterized by fatigue, joint pain, cognitive, gastrointestinal, respiratory, and skin problems, is currently diagnosed by self-reported symptoms. The Boston Biorepository, Recruitment, and Integrative Network (BBRAIN) is the collaborative effort of expert Gulf War Illness (GWI) researchers who are creating objective diagnostic and pathobiological markers and recommend common data elements for GWI research. MAIN METHODS: BBRAIN is recruiting 300 GWI cases and 200 GW veteran controls for the prospective study. Key data and biological samples from prior GWI studies are being merged and combined into retrospective datasets. They will be made available for data mining by the BBRAIN network and the GWI research community. Prospective questionnaire data include general health and chronic symptoms, demographics, measures of pain, fatigue, medical conditions, deployment and exposure histories. Available repository biospecimens include blood, plasma, serum, saliva, stool, urine, human induced pluripotent stem cells and cerebrospinal fluid. KEY FINDINGS: To date, multiple datasets have been merged and combined from 15 participating study sites. These data and samples have been collated and an online request form for repository requests as well as recommended common data elements have been created. Data and biospecimen sample requests are reviewed by the BBRAIN steering committee members for approval as they are received. SIGNIFICANCE: The BBRAIN repository network serves as a much needed resource for GWI researchers to utilize for identification and validation of objective diagnostic and pathobiological markers of the illness.

Broadband, millimeter-wave antireflection coatings for large-format, cryogenic aluminum oxide optics.

We present two prescriptions for broadband ($ {\sim} 77 - 252\;{\rm GHz} $), millimeter-wave antireflection coatings for cryogenic, sintered polycrystalline aluminum oxide optics: one for large-format (700 mm diameter) planar and plano-convex elements, the other for densely packed arrays of quasi-optical elements-in our case, 5 mm diameter half-spheres (called "lenslets"). The coatings comprise three layers of commercially available, polytetrafluoroethylene-based, dielectric sheet material. The lenslet coating is molded to fit the 150 mm diameter arrays directly, while the large-diameter lenses are coated using a tiled approach. We review the fabrication processes for both prescriptions, then discuss laboratory measurements of their transmittance and reflectance. In addition, we present the inferred refractive indices and loss tangents for the coating materials and the aluminum oxide substrate. We find that at 150 GHz and 300 K the large-format coating sample achieves $ (97 \pm 2)\% $ transmittance, and the lenslet coating sample achieves $ (94 \pm 3)\% $ transmittance.

Converting neural signals from place codes to rate codes.

The nervous system uses two basic types of formats for encoding information. The parameters of many sensory (and some premotor) signals are represented by the pattern of activity among an array of neurons each of which is optimally responsive to a different parameter value. This type of code is commonly referred to as a place code. Motor commands, in contrast, use rate coding: the desired force of a muscle is specified as a monotonic function of the aggregate rate of discharge across all of its motor neurons. Generating movements based on sensory information often requires converting signals from a place code to a rate code. In this paper I discuss three possible models for how the brain does this.

Afferent delays and the mislocalization of perisaccadic stimuli.

Determining the precise moment a visual stimulus appears is difficult because visual response latencies vary. This temporal uncertainty could cause localization errors to brief visual targets presented before and during eye movements if the oculomotor system cannot determine the position of the eye at the time the stimulus appeared. We investigated the effect of varying neural processing time on localization accuracy for perisaccadic visual targets that differed in luminance. Although systematic errors in localization were observed, the effect of luminance was surprisingly small. We explore several hypotheses that may explain why processing delays are not more disruptive to localization performance.

Eye position influences auditory responses in primate inferior colliculus.

We examined the frame of reference of auditory responses in the inferior colliculus in monkeys fixating visual stimuli at different locations. Eye position modulated the level of auditory responses in 33% of the neurons we encountered, but it did not appear to shift their spatial tuning. The effect of eye position on auditory responses was substantial-comparable in magnitude to that of sound location. The eye position signal appeared to interact with the auditory responses in at least a partly multiplicative fashion. We conclude that the representation of sound location in primate IC is distributed and that the frame of reference is intermediate between head- and eye-centered coordinates. The information contained in these neurons appears to be sufficient for later neural stages to calculate the positions of sounds with respect to the eyes.

Segregation of object and background motion in visual area MT: effects of microstimulation on eye movements.

To track a moving object, its motion must first be distinguished from that of the background. The center-surround properties of neurons in the middle temporal visual area (MT) may be important for signaling the relative motion between object and background. To test this, we microstimulated within MT and measured the effects on monkeys' eye movements to moving targets. We found that stimulation at "local motion" sites, where receptive fields possessed antagonistic surrounds, shifted pursuit in the preferred direction of the neurons, whereas stimulation at "wide-field motion" sites shifted pursuit in the opposite, or null, direction. We propose that activating wide-field sites simulated background motion, thus inducing a target motion signal in the opposite direction. Our results support the hypothesis that neuronal center-surround mechanisms contribute to the behavioral segregation of objects from the background.

[Continuous peridural analgesia vs patient - controlled intravenous analgesia for pain therapy after thoracotomy]. / Kontinuierliche Periduralanalgesie versus patientenkontrollierte intravenöse Analgesie.Schmerztherapie nach Thorakotomien.

OBJECTIVES: Continuous epidural analgesia (EA) and patient-controlled intravenous analgesia (PCA) are widely used for postoperative pain control. Studies indicate that both analgesic regimens provide good analgesia after major surgery. However, because of the following reasons it is still unclear whether one of the two modes of application is superior. First, there are conflicting data regarding the differences in pain relief and drug use between epidural and intravenous administration of opioids. Second, in many studies epidural analgesia is performed by a combination of local anaesthetics and opioids. Third, reduced morbidity was observed only in some of the studies, in which epidural analgesia provided better pain relief than systemic opioid supply. Despite these conflicting results, EA with local anaesthetics and fentanyl as well as PCA with piritramid, a highly potent mu-agonist, are routinely used in Germany. The purpose of this study was to compare these two treatments for analgesic efficacy, pulmonary function, incidence of side effects and complications in patients undergoing thoracotomy. METHODS: In this prospective randomized trial 50 patients were included. For postoperative pain control 25 patients (EA group) received thoracic epidural infusion of local anaesthetics (bupivacaine 0.125% or ropivacaine 0,2%) and fentanyl 4,5 microg/ml with a flow rate of 4-10 ml/h. 25 patients received intravenous PCA with piritramid (bolus 2, 5 mg, lock out 15 minutes, maximum of 25 mg/4 h, no background infusion). RESULTS: Analgesia at rest and while coughing, as evaluated by visual analogue scale, was significantly better in the EA group. EA also resulted in superior values of pulmonary function tests, general condition and a lower incidence of sedation and nausea. In contrast, patients with EA reported distinctly more pruritus than patients with PCA. Duration of hospital stay was shorter in the EA group, but this difference did not reach statistical significance. There was one atelectasis in the EA group. No major complications related to EA or PCA were observed. CONCLUSION: In this study EA with local anaesthetics and fentanyl provided superior postoperative pain control and a lower incidence of sedation and nausea compared to intravenous PCA with piritramid, but there was no superiority as to pulmonary complications and duration of hospital stay.

[Unilateral phrenic nerve paralysis after vertical infraclavicular plexus block] . / Unilaterale Phrenicusparese bei vertikaler infraklavikulärer Plexusblockade (VIP).

We present a case of a rapid onset reversible phrenic nerve block following vertical infraclavicular blockade of the brachial plexus. Five minutes after injection of local anaesthetics the SpO2 fell to 80%. Oxygen supplementation was required during the perioperative period to maintain normoxemia. The postoperative X-ray showed an elevated diaphragm of the ipsilateral side. After five hours oxygen supply could be terminated, an X-ray control the next day showed normal bilateral diaphragm position.

Lung procurement by low-potassium dextran and the effect on preservation injury. Munich Lung Transplant Group.

BACKGROUND: This clinical study was performed to evaluate the effect of low-potassium dextran (LPD) solution on organ function in human lung transplantation. METHODS: A total of 80 patients were included in this study. Donor lungs were flushed with Euro-Collins (EC) solution in 48 cases or LPD (Perfadex) in 32 cases. Subsequently, single- (EC: n = 31; LPD: n = 15) or double-lung transplantations (EC: n = 17; LPD: n = 17) were performed. The evaluation parameters of transplant function were the reperfusion injury score (grade I to V); the alveolar/arterial oxygen ratio; the duration of respirator therapy; and the length of intensive care treatment and survival. RESULTS: Incidence and severity of reperfusion injury score were more severe in the EC group (31 of 48: grade I: n = 13; II: n = 8; III: n = 5; IV: n = 2; V: n = 3; LPD group: 17 of 32 patients; grade I: n = 12; II: n = 1; III: n = 3; IV: n = 0 grade V: n = 0), leading to death in three patients. In the LPD group, despite of the use of cardiopulmonary bypass, alveolar/arterial oxygen ratio values were significantly (P = 0.009) better during the early postoperative phase. Thirty-day mortality was 12% in the EC group and 6% in the LPD group. The one-year survival rate was 79% after the use of LPD (vs. EC: 62%). CONCLUSIONS: Graft preservation using LPD leads to better immediate and intermediate graft function after pulmonary transplantation and also results in better long-term survival.

Leukocyte sequestration in pulmonary microvessels and lung injury following systemic complement activation in rabbits.

Inflammatory reactions are associated with sequestration of leukocytes in the lung. Complement activation leads to accumulation of leukocytes in alveolar septa and alveoli, to lung edema and hemorrhage. Although in organs other than the lung leukocytes interact with the vascular endothelium only in postcapillary venules, alveolar capillaries are considered to be the site of leukocyte sequestration in the lung. However, pulmonary venules and arterioles have not been investigated systematically after complement activation so far. A closed thoracic window was implanted in anesthetized rabbits; leukocytes and red blood cells were stained, and the movement of these cells was measured in superficial pulmonary arterioles, venules and alveolar capillaries using fluorescence video microscopy before and 30 and 60 min after infusion of cobra venom factor (CVF). Erythrocyte velocity and macrohemodynamic conditions did not change after CVF infusion and were not different from the sham-treated controls. The number of sticking leukocytes increased significantly compared to baseline and control: by 150% in arterioles and in venules and by 740% in alveolar capillaries within 60 min after CVF infusion. The width of alveolar septa in vivo was significantly enlarged after CVF infusion, indicating interstitial pulmonary edema. At the end of the experiments, myeloperoxidase activity was higher in the CVF group, showing leukocyte sequestration in the whole organ. It is concluded that complement activation by CVF induces leukocyte sequestration in lung arterioles, venules and alveolar capillaries and leads to mild lung injury.

Cardiopulmonary exercise testing before and after lung and heart-lung transplantation.

Heart-lung (HLT) and lung transplantation (LT) have been shown to be effective procedures for patients with end-stage cardiopulmonary disorders. As yet, few data exist on the exercise performance of patients before and after thoracic transplantation except with regard to 6-min walk tests. In this article we report cardiopulmonary exercise test results of lung and heart-lung transplant recipients in comparison with their pretransplant values. We studied 103 consecutive recipients of single-lung (n = 46), bilateral lung (n = 32), and heart-lung (n = 25) transplants. Cardiopulmonary exercise testing with a cycle ergometer was performed before and shortly after surgery. Before transplantation, all patients showed severe exercise intolerance and markedly impaired parameters reflecting cardiopulmonary function (e.g., work capacity: 20 +/- 11% predicted; oxygen uptake: 34 +/- 12% predicted; oxygen pulse: 50 +/- 18% predicted; functional dead space ventilation: 57 +/- 10% of minute ventilation; alveolar-arterial oxygen difference during exercise: 79 +/- 15 mm Hg). At 55 +/- 9 d after transplantation, transplant recipients reached maximum oxygen uptakes in the range of 22 to 71% of predicted values; the peak oxygen uptake was increased after transplantation (13.1 +/- 3.4 ml/min/kg versus 10.4 +/- 3.8 ml/min/kg; p < 0.001). Work capacity, oxygen pulse, tidal volume, and peak minute ventilation did not differ in patients following single- or double-lung tranplantation or HLT. Ventilatory factors did not appear to limit exercise capacity in any group. Despite the persistent limitations in aerobic capacity and work rate seen in many of the recipients, cardiopulmonary performance is reasonably well restored shortly after LT and HLT.

Expression of adhesion molecules on circulating polymorphonuclear leukocytes during orthotopic liver transplantation.

After ischemia-reperfusion, polymorphonuclear leukocytes (PMNLs) become activated by inflammatory mediators, adhere to the vascular endothelium via the interaction of specific adhesion molecules, and cause tissue injury by the release of cytotoxic oxygen radicals and enzymes. Results obtained in animal experiments suggest a key role for PMNLs in ischemia-reperfusion injury of transplanted livers; therefore, we studied the expression of adhesion molecules on circulating PMNLs (beta2-integrins [CD18] and L-selectin [CD62L]) in 20 patients undergoing orthotopic liver transplantation (study group). To determine the effects of surgical trauma to the liver in the absence of ischemia and reperfusion, the expression of PMNL adhesion molecules was measured in 10 patients scheduled for elective partial liver resection without hepatic vascular exclusion (control group). Patients were classified as responders or nonresponders based on changes in the expression of adhesion molecules elicited by reperfusion. In the control group, all patients remained nonresponders, showing that surgical trauma of the liver alone does not cause activation of circulating PMNLs. In contrast, 8 of 20 patients in the study group were classified as responders. In responders, postoperative serum liver enzyme activities were significantly higher than in nonresponders, indicating that activation of PMNL was associated with damage to hepatocellular integrity. Because expression of adhesion molecules was already changed during surgery, monitoring of the expression of beta2-integrins and L-selectin on circulating PMNLs during orthotopic liver transplantation might be useful in prediction of early graft dysfunction.

Neurophysiology: electrically evoking sensory experience.

Monkeys trained to distinguish touch stimuli that 'flutter' with different frequencies can similarly distinguish electrical stimulation of the somatosensory cortex according to its frequency; the implication is that the electrically-evoked patterns of cortical activity cause flutter sensations similar to those induced by touch.

Microhemodynamics and leukocyte sequestration after pulmonary ischemia and reperfusion in rabbits.

OBJECTIVE: Investigation of leukocyte sequestration in alveolar capillaries and of microhemodynamic changes after pulmonary ischemia/reperfusion injury. METHODS: The kinetics of leukocyte passage and the hemodynamics in pulmonary microcirculation were investigated in 16 rabbits by intravital microscopy. Mean red blood cell velocity and the number of sticking leukocytes were measured in pulmonary arterioles, venules, and capillaries after 1 hour of tourniquet ischemia and 10 minutes and 1 hour after reperfusion. RESULTS: The decrease of red blood cell velocity after reperfusion was associated with a largely increased heterogeneity of blood flow. Immediately after the onset of blood flow, sequestered leukocytes were found in all microvascular segments. An increased number of leukocytes was present in arterioles, venules, and alveolar capillaries 10 minutes and 1 hour after reperfusion. Concomitantly, width of alveolar septa was increased while arterial oxygen tension was reduced, indicating the development of interstitial pulmonary edema. CONCLUSION: Leukocytes are sequestered after pulmonary ischemia and reperfusion not only in alveolar capillaries but also in arterioles and venules, and they may contribute to the development of reperfusion edema.

Perioperative management of patients undergoing lung transplantation.

This review focuses on recent developments in the perioperative management of patients undergoing lung transplantation. Relevant current literature and the experience of the Munich Lung Transplant Group were taken into consideration. Recent advances include the use of inhalational nitric oxide for the treatment of early graft dysfunction and the use of aerosolized cyclosporine for the treatment of recurrent and steroid-resistant acute rejection. Opportunistic infections remain a major source of morbidity and mortality in lung transplant recipients.

How is a sensory map read Out? Effects of microstimulation in visual area MT on saccades and smooth pursuit eye movements.

To generate behavioral responses based on sensory input, motor areas of the brain must interpret, or "read out," signals from sensory maps. Our experiments tested several algorithms for how the motor systems for smooth pursuit and saccadic eye movements might extract a usable signal of target velocity from the distributed representation of velocity in the middle temporal visual area (MT or V5). Using microstimulation, we attempted to manipulate the velocity information within MT while monkeys tracked a moving visual stimulus. We examined the effects of the microstimulation on smooth pursuit and on the compensation for target velocity shown by saccadic eye movements. Microstimulation could alter both the speed and direction of the motion estimates of both types of eye movements and could also cause monkeys to generate pursuit even when the visual target was actually stationary. The pattern of alterations suggests that microstimulation can introduce an additional velocity signal into MT and that the pursuit and saccadic systems usually compute a vector average of the visually evoked and microstimulation-induced velocity signals (pursuit, 55 of 122 experiments; saccades, 70 of 122). Microstimulation effects in a few experiments were consistent with vector summation of these two signals (pursuit, 6 of 122; saccades, 2 of 122). In the remainder of the experiments, microstimulation caused either an apparent impairment in motion processing (pursuit, 47 of 122; saccades, 41 of 122) or had no effect (pursuit, 14 of 122; saccades, 9 of 122). Within individual experiments, the effects on pursuit and saccades were usually similar, but the occasional striking exception suggests that the two eye movement systems may perform motion computations somewhat independently.