Scopolamine Reduces Electrophysiological Indices of Distractor Suppression: Evidence from a Contingent Capture Task

Limited resources for the in-depth processing of external stimuli make it necessary to select only relevant information from our surroundings and to ignore irrelevant stimuli. Attentional mechanisms facilitate this selection via top-down modulation of stimulus representations in the brain. Previous research has indicated that acetylcholine (ACh) modulates this influence of attention on stimulus processing. However, the role of muscarinic receptors as well as the specific mechanism of cholinergic modulation remains unclear. Here we investigated the influence of ACh on feature-based, top-down control of stimulus processing via muscarinic receptors by using a contingent capture paradigm which specifically tests attentional shifts toward uninformative cue stimuli which display one of the target defining features In a double-blind, placebo controlled study we measured the impact of the muscarinic receptor antagonist scopolamine on behavioral and electrophysiological measures of contingent attentional capture. The results demonstrated all the signs of functional contingent capture, i.e., attentional shifts toward cued locations reflected in increased amplitudes of N1 and N2Pc components, under placebo conditions. However, scopolamine did not affect behavioral or electrophysiological measures of contingent capture. Instead, scopolamine reduced the amplitude of the distractor-evoked Pd component which has recently been associated with active suppression of irrelevant distractor information. The findings suggest a general cholinergic modulation of top-down control during distractor processing.

Cortical processing of head- and eye-gaze cues guiding joint social attention

Previous fMRI experiments showed an involvement of the STS in the processing of eye-gaze direction in joint attention. Since head-gaze direction can also be used for the assessment of another person's attentional focus, we compared the mechanisms underlying the processing of head- and eye-gaze direction using a combined psychophysical and fMRI approach. Subjects actively followed the head- or eye-gaze direction of a person in a photograph towards one of seven possible targets by moving their eyes. We showed that the right posterior superior temporal sulcus (STS) as well as the right fusiform gyrus (FSG) were involved in both processing of head- as well as eye-gaze direction. Another finding was a bilateral deactivation of a distinct area in the middle STS (mSTS) as well as the left anterior STS (aSTS), that was stronger when subjects followed eye-gaze direction than when they followed head-gaze direction. We assume that this deactivation is based on an active suppression of information arising from the distracting other directional cue, i.e. head-gaze direction in the eye-gaze direction task and eye-gaze direction in the head-gaze direction task. These results further support the hypothesis that the human equivalent of the gaze sensitive area in monkeys lies in more anterior parts of the STS than previously thought.

Valaciclovir for chronic hepatitis B virus infection after lung transplantation

We report on a chronic asymptomatic hepatitis B surface antigen (HBsAg) carrier who developed an increase in aminotransferase and HBsAg levels 1 year after lung transplantation. During treatment for cutaneous herpes simplex virus (HSV) infection with oral valaciclovir there was a marked decrease in replicating hepatitis B virus (HBV)-DNA and aminotransferase levels, which was sustained for 9 months by continuing low-dose valaciclovir. A second rise in aminotransferase levels again responded to a valaciclovir dose increase and the HBV-DNA levels declined further. Although we cannot exclude a spontaneous variation of the serologic parameters, our observation suggests that valaciclovir may represent a valuable therapeutic option in the treatment of chronic hepatitis B after lung transplantation.

Acute Respiratory Failure and Cerebral Hemorrhage due to Primary Epstein-Barr Virus Infection

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus with worldwide distribution. Primary infection with EBV occurs early in life and typically presents as infectious mononucleosis. The usual course of the disease is benign and most patients recover uneventfully. Severe infections are reported particularly in immunocompromised patients. Mild, asymptomatic pneumonitis is reported in about 5-10% of cases of infectious mononucleosis, but severe pneumonitis with hypoxemia is very rare in immunocompetent individuals. We report a young female adolescent in whom an acute EBV infection led to severe bilateral pneumonitis, a systemic inflammatory response and intracerebral bleeding. The clinical course and results of quantitative viral DNA determinations in plasma are presented.

[Falling asleep at the steering wheel--a dangerous sequel of sleep apnea]

Excessive sleepiness is a common but underrecognised and preventable cause of road traffic accidents. Acute and chronic sleep deprivation, inadequate sleep hygiene, and sleep disorders are important causes of hypersomnolence. Since the latter is one of the cardinal manifestations of the obstructive sleep apnoea syndrome, affected patients are at particular risk of being involved in traffic accidents. Counselling of hypersomnolent drivers on appropriate behavioural modification, early diagnosis and treatment of sleep disorders, as well as information of the public on the risks of accidents related to sleepiness are important preventive measures.

Two years' outcome of lung volume reduction surgery in different morphologic emphysema types

BACKGROUND

Lung volume reduction surgery (LVRS) improves dyspnea, pulmonary function, and quality of life in selected patients with severe emphysema. We investigated the role of emphysema morphology in 37 patients as an outcome predictor for up to 2 years after operation.

METHODS

Patients selected for bilateral thoracoscopic LVRS were divided, according to a simplified emphysema morphology classification, into three groups (homogeneous, moderately heterogeneous, and markedly heterogeneous) based on a preoperative chest computed tomogram. Pulmonary function, walking distance, and dyspnea were assessed.

RESULTS

Functional improvement after LVRS was best in markedly heterogeneous emphysema with an increase from preoperative forced expiratory volume in 1 second of 31% +/- 2% (mean +/- standard error of the mean) to 52% +/- 4% of predicted postoperatively. It was significantly higher than in homogeneous emphysema (from 26% +/- 1% to 38% +/- 2% predicted) and in intermediately heterogeneous emphysema (from 29% +/- 2% to 44% +/- 45% predicted). At 24 months postoperatively, forced expiratory volume in 1 second and dyspnea score continued to be significantly better than preoperative levels in all three morphologic groups. The survival rate was highest in patients with markedly heterogeneous emphysema.

CONCLUSIONS

Functional and subjective improvements were maintained after LVRS for at least 24 months in patients with heterogeneous or homogeneous emphysema type.

Practicability and safety of dipyridamole cardiac imaging in patients with severe chronic obstructive pulmonary disease

We tested the practicability of dipyridamole myocardial nitrogen-13 ammonia positron emission tomography (dipyridamole (13)NH(3 )PET) for the perioperative risk assessment of coronary artery disease (CAD) in a cohort of patients with severe chronic obstructive pulmonary disease (COPD) undergoing lung volume reduction surgery (LVRS). Twenty consecutive LVRS candidates, 13 men and 7 women (mean age 57+/-2 years), without symptoms of CAD were prospectively studied by dipyridamole (13)NH(3 )PET. Side-effects and overall tolerance were assessed by a questionnaire and visual analogue scale. Repeated pulmonary function tests were performed before and 4, 12, 16 and 30 minutes after dipyridamole injection. All dipyridamole (13)NH(3 )PET studies were negative for CAD. Seventeen patients underwent LVRS without cardiac complications; three patients did not undergo LVRS for other reasons. Nine patients suffered intolerable dyspnoea requiring i.v. aminophylline. Mean FEV(1) decreased significantly after dipyridamole infusion: in nine patients the reduction in FEV(1)exceeded 15% from baseline. We found that dipyridamole is not well tolerated and causes significant bronchoconstriction in patients with severe COPD. Although all dipyridamole-induced side effects can be promptly reversed by aminophylline, dipyridamole cannot be recommended as a pharmacological stress in this setting.

[Noninvasive ventilation in chronic obstructive lung disease]

Non-invasive ventilation refers to ventilatory support without establishing an endotracheal airway. The advent positive-pressure ventilation delivered through a nasal or face mask has greatly expanded the use of non-invasive ventilation. In patients with acute respiratory failure due to chronic obstructive lung disease, non-invasive positive pressure ventilation reduces the need for intubation and related complications, shortens the duration of hospital stay and improves survival. The role of intermittent non-invasive long-term ventilation in the management of chronic respiratory failure related to chronic obstructive lung disease remains to be defined. The advantages of this therapy as an adjunct to conventional medical treatment and long-term oxygen therapy are not well established. Introduction of non-invasive ventilation requires close monitoring by experienced staff. Technical advances in delivery systems have improved the results and acceptance of this promising therapy.

[Noninvasive ventilation in chronic obstructive lung disease]

Noninvasive mechanical ventilation is provided without establishing an endotracheal airway. In acute respiratory failure due to chronic obstructive lung disease, noninvasive positive-pressure ventilation delivered through a nasal or face mask may eliminate the need for intubation and related complications, reduce the duration of hospitalisation and improve survival compared to assisted ventilation through an endotracheal tube. In chronic respiratory failure related to neuromuscular diseases and thoracic deformities, the advent of noninvasive intermittent longterm ventilation is well established. However, it is not clear, whether addition of noninvasive ventilation to standard treatment with medication and longterm oxygen improves symptoms and survival in chronic respiratory failure due to chronic obstructive lung disease. During introduction of noninvasive ventilation, patients must be monitored closely. Patient selection and information, meticulous optimization of the ventilator settings and delivery system, education and experience of the personnel have an important impact on the success of this novel way of providing mechanical ventilatory support.

[Pseudomonas pneumonia--an important differential pulmonary infiltration diagnosis in AIDS]

Bacterial pneumonias are the most common pulmonary complication in HIV-infected patients. Up to now, H. influenzae and S. pneumoniae have been described as the most important germs. Within a period of 4 years we diagnosed 15 cases of pneumonia caused by P. aeruginosa. All patients were in HIV stage C3; 3F, 12M; median age 34 (24-54) years; median CD4 count 10 (0-130) microliters. Except for 3 nosocomial pneumonias, all others were community-acquired. Only 3 patients had neutropenia < 1000/microliter; 7 were intravenous drug abusers. Morphologically there were 6 cases of abscess pneumonia, in 3 of which pleural drainage was necessary because of pyopneumothorax. 4 patients showed bilateral infiltrates that could not be differentiated from those of P. carinii pneumonia. Our diagnosis was based on quantitative cultures of broncho-alveolar lavage fluid (9 cases, two of them with concurrent positive blood cultures/positive cultures of the pleural fluid), pleural puncture (one case), sputum in pneumonias responding only to antipseudomonas therapy (3 cases), and autopsy (2 cases). 8 patients died of pseudomonas pneumonia within 1-3 months despite therapy. 7 patients received pseudomonas-specific combination therapy, but all died after median 9 (4-15) months of the underlying illness. In 3 cases recurrent pseudomonas pneumonia could be documented bacteriologically. We conclude that in HIV-infected patients pneumonia caused by P. aeruginosa is a significant and severe pulmonary complication.

Role of lung perfusion scintigraphy in relation to chest computed tomography and pulmonary function in the evaluation of candidates for lung volume reduction surgery

Lung perfusion scintigraphy is employed to evaluate patients with severe emphysema who are candidates for lung volume reduction surgery (LVRS). Our purpose was to investigate the role of scintigraphy in relation to chest computed tomography (CT) and lung function in this setting. Six observers blinded to clinical data retrospectively scored preoperative scintigrams of 70 patients undergoing bilateral video-assisted LVRS according to the distribution of lung perfusion as homogeneous, intermediately heterogeneous, or markedly heterogeneous. Heterogeneity of emphysema distribution was also assessed by chest CT. Dyspnea and pulmonary function were measured preoperatively and 3 mo postoperatively. In 42 patients with markedly heterogeneous, in 18 with intermediately heterogeneous, and in 10 with homogeneous perfusion, mean (+/- SE) FEV1 increased by 57 +/- 8% (p < 0.0001), 38 +/- 9% (p < 0.001), and 23 +/- 9% (p = NS) (p = NS for intergroup comparisons). In a multiple regression analysis, functional improvement after LVRS was more closely correlated with preoperative hyperinflation and the degree of emphysema heterogeneity estimated by chest CT than with the degree of perfusion heterogeneity assessed by scintigraphy. In 16 of 22 patients with homogeneous emphysema distribution in the chest CT scintigraphy revealed intermediately or markedly heterogeneous perfusion. We conclude that lung perfusion scintigraphy has a limited role in prediction of outcome, but it may help to identify target areas for resection in LVRS candidates with homogeneous CT morphology.

Accidents related to sleepiness: review of medical causes and prevention with special reference to Switzerland

Sleepiness is a major cause of traffic accidents. Our purpose was to review determinants of accidents related to sleepiness and measures to prevent them. We performed a systematic literature review on the topic and studied official accident statistics and legislation regarding medical driving ability in Switzerland. In 1997, 79,178 road traffic accidents, each causing bodily injury or property damage in excess of 500 Swiss francs, occurred in Switzerland. According to official statistics, sleepiness accounted for only 1% of identified causes. However, scientific studies performed in other countries suggest that sleepiness is a contributing factor in up to 30% of traffic accidents. Causes of hypersomnolence are sleep restriction, sleep disturbance by external environmental factors, inappropriate sleep hygiene, and sleep disorders. Several reports suggest an increased crash rate in patients with obstructive sleep apnoea syndrome. At our clinic, every sixth sleep apnoea patient reports sleepiness-related driving problems which resulted in traffic accidents in one third of them. Long monotonous motorway drives, late night, early morning and late afternoon hours are associated with an increased crash rate. Drivers with excessive sleepiness should not drive until the cause of hypersomnolence is determined and treated appropriately. Medical assessment of driving ability in patients with sleep disorders involves a specific history including standardised questionnaires, sleep studies and vigilance tests. Swiss legislation authorizes physicians to report sleepy drivers to the authorities if they are thought to represent an accident risk for themselves or others. We conclude that sleepiness is a common but under-recognised cause of traffic accidents. Enhancing awareness of the problem in the public, early recognition and treatment of sleep disorders, and counselling of drivers with excessive sleepiness may contribute to prevention.

[Extrapulmonary infections with Mycobacterium tuberculosis complex]

In a retrospective study we reviewed all records of patients with newly diagnosed Mycobacterium tuberculosis complex infection during the years 1990-1994. Of the 45 patients identified, 27 (60%) had only pulmonary tuberculosis and 18 (40%) had extrapulmonary tuberculosis with (5 patients, 11%) or without (13 patients, 18%) concomitant pulmonary infection. The extrapulmonary manifestations were as follows: miliary 5, joint 3, meningeal 2, pleural 2, kidney 1, peritoneal 1, bone 1, psoas 1, lymphatic 1, and anal 1. In the 18 patients with extrapulmonary tuberculosis the infection was due to Mycobacterium tuberculosis 14 times, Mycobacterium bovis twice, and Mycobacterium bovis BCG once.

[Chest pain, dyspnea, syncope]

We report about the history of a 53-year-old female who suffered from dyspnea as well as leg and chest pain for six months; in addition she experienced two syncopal events. Recurrent pulmonary embolism was suspected, which was subsequently confirmed by positive scintigraphical findings. Acute cor pulmonale may have caused the syncopes. Therapy with heparin and oral warfarin was started. Within few days the patients condition improved markedly. Signs of pulmonary hypertension disappeared within five months.