Compact x-ray microtomography system for element mapping and absorption imaging.

We have designed and built a compact x-ray microtomography system to perform element mapping and absorption imaging by exploiting scanning fluorescence tomography and full-field transmission microtomography, respectively. It is based on a low power microfocus tube and is potentially appropriate for x-ray diagnostics in space. Full-field transmission tomography yields the three-dimensional inner structure of an object. Fluorescence microtomography provides the element distribution on a virtual section through the sample. Both techniques can be combined for appropriate samples. Microradiography as well as fluorescence mapping are also possible. For fluorescence microtomography a small and intensive microbeam is required. It is generated using a polycapillary optic. Operating the microfocus tube with a molybdenum target at 12 W, a microbeam with a full width at half maximum lateral extension of 16 microm and a flux of about 10(8) photonss is generated. As an example of application, this beam is used to determine the element distribution inside dried plant samples. For full-field scanning tomography, the x-ray optic is removed and the sample is imaged in magnifying projection onto a two-dimensional position sensitive detector. Depending on the sample size, a spatial resolution down to about 10 microm is possible in this mode. The method is demonstrated by three-dimensional imaging of a rat humerus.

Tissue at risk of infarction rescued by early reperfusion: a positron emission tomography study in systemic recombinant tissue plasminogen activator thrombolysis of acute stroke.

Thrombolytic therapy of acute ischemic stroke can be successful only as long as there is penumbral tissue perfused at rates between the thresholds of normal function and irreversible structural damage, respectively. To determine the proportion of tissue at risk of infarction, cerebral perfusion was studied in 12 patients with acute ischemic stroke who underwent treatment with systemic recombinant tissue plasminogen activator (0.9 mg/kg body weight according to National Institute of Neurological Disorders and Stroke protocol) within 3 hours of onset of symptoms, using [15O]-H2O positron emission tomography (PET) before or during, and repeatedly after thrombolysis. The size of the regions of critically hypoperfused gray matter were identified on the initial PET scans, and changes of perfusion in those areas were related to the clinical course (followed by the National Institutes of Health stroke scale) and to the volume of infarcted gray matter demarcated on magnetic resonance imaging 3 weeks after the stroke. Whereas the initial clinical score was unrelated to the size of the ischemic area, after 3 weeks there was a strong correlation between clinical deficit and volume size of infarcted gray matter (Spearman's rho, 0.96; P < 0.001). All patients with a severely hypoperfused (< 12 mL/100 g/min) gray matter region measuring less than 15 mL on first PET showed full morphologic and clinical recovery (n = 5), whereas those with ischemic areas larger than 20 mL developed infarction and experienced persistent neurologic deficits of varying degree. Infarct sizes, however, were smaller than expected from previous correlative PET and morphologic studies of patients with acute stroke: only 22.7% of the gray matter initially perfused at rates below the conventional threshold of critical ischemia became necrotic. Actually, the percentage of initially ischemic voxels that became reperfused at almost normal levels clearly predicted the degree of clinical improvement achieved within 3 weeks. These sequential blood flow PET studies demonstrate that critically hypoperfused tissue can be preserved by early reperfusion, perhaps related to thrombolytic therapy. The results correspond with experimental findings demonstrating the prevention of large infarcts by early reperfusion to misery perfused but viable tissue.

Early intravenous thrombolysis with recombinant tissue-type plasminogen activator in vertebrobasilar ischemic stroke.

BACKGROUND: The optimal therapy of vertebrobasilar ischemic stroke is under debate. In the case of underlying basilar artery occlusion, intra-arterial thrombolysis is recommended. Because this pathologic condition is rarely found and the procedure is time consuming and restricted to specialized centers, the question arises whether early intravenous thrombolysis could also effectively be applied in vertebrobasilar ischemic stroke. OBJECTIVE: To determine if early intravenous thrombolysis could be used effectively in vertebrobasilar ischemic stroke. DESIGN: A case series of 12 consecutive patients with acute vertebrobasilar ischemia were followed up 3 months after thrombolytic treatment at the Department of Neurology of the University Hospital of Cologne, Cologne, Germany, a primary care and referral center. METHODS: Patients with clinically diagnosed moderate to severe vertebrobasilar ischemic stroke with clearly determined symptom onset were treated with intravenous recombinant tissue-type plasminogen activator within 3 hours after symptom onset following a protocol similar to that of the National Institute of Neurological Disorders and Stroke study. RESULTS: On admission, 7 patients exhibited moderate to severe brainstem symptoms without impairment of consciousness and 5 patients had impairment of consciousness, of whom 2 were comatose. Of 12 patients, 10 had a favorable outcome after 3 months defined as full independence (Barthel index score of 100) or return to premorbid condition. One patient had a poor outcome with complete dependency due to reocclusion after primarily successful thrombolysis, and 1 patient died of severe brainstem infarction and additional space occupying parietal hemorrhage. CONCLUSION: Favorable outcome could be achieved in the majority of 12 consecutive patients with moderate to severe vertebrobasilar ischemic stroke treated with intravenous recombinant tissue-type plasminogen activator within 3 hours after symptom onset.

Internet patient care applications in ambulatory care.

Over the next decade, the Internet and related technologies will revolutionize the administrative and clinical practices of ambulatory care, enhancing the ability of physicians to provide quality care, enabling "virtual care teams" to help patients deal effectively with acute episodes and chronic conditions, and reducing the cost of care. Like any major paradigm shift, this change will not happen overnight. Nor will it be without cost. The explosion of venture capital and meteoric rise of the Nasdaq in 1999 reflected the promise of the Internet to revolutionize many aspects of American business. The Nasdaq's equally rapid descent in 2000 reflected a growing realization that this change will not be free--that "creative destruction," to use Schumpeter's term, will inevitably require significant investment and produce substantial losses. This article takes a longer term view than the ups and downs in the stock market. We believe the forces unleashed by the Internet are inexorable and that 10 years from now we will look back at the millennium's first decade as a period when the practice of ambulatory medicine was transformed by communication technology.

A national assessment of the service, support, and housing preferences by persons with chronic fatigue syndrome. Toward a comprehensive rehabilitation program.

Persons with Chronic Fatigue Syndrome (PWCs) completed and returned by mail a brief survey of open- and closed-ended items designed to assess their utilization and preferences for a variety of services. A total of 984 middle-aged adults diagnosed with Chronic Fatique Syndrome (CFS) from across North America returned the survey. During the past 12 months, many of these PWCs reported utilization of a primary care physician, gynecologist, CFS specialist, and self-help group to assist in their recovery from CFS. Most PWCs believed it was important to educate both health-care practitioners and the general public about CFS. In terms of their desire for specific recovery needs, factor analysis of responses indicated that these PWCs preferred self-help/social support services and general advocacy services in the treatment of their illness. The implications of these results for developing rehabilitation programs for PWCs are discussed.

A novel microwave applicator for tailoring the energy input for hydrothermal synthesis of zeolites.

A new applicator system for microwave heating of aqueous solutions for the hydrothermal synthesis of zeolite crystals has been developed and experimentally characterized. It is based on a short-ended coaxial waveguide with the solution being inserted as a lossy dielectric. The electrical and thermal design of the autoclave has been optimized by numerical simulations of the E-field and of the temperature distribution respectively. Different reference temperature profiles--a homogeneous and a gradient one--could be established within the zeolite solution and were held constant over time. From temperature measurements at various positions in the solution the two reference profiles could be verified. Temperature differences of less than 15 degrees C have been measured within the homogeneous autoclave whereas differences up to 55 degrees C have been found in the gradient autoclave. In the first synthesis experiments using this applicator zeolite crystals of the zeolite A and VPI-5-type could be successfully crystallized.

Compact x-ray microradiograph for in situ imaging of solidification processes: bringing in situ x-ray micro-imaging from the synchrotron to the laboratory.

A laboratory based high resolution x-ray radiograph was developed for the investigation of solidification dynamics in alloys. It is based on a low-power microfocus x-ray tube and is potentially appropriate for x-ray diagnostics in space. The x-ray microscope offers a high spatial resolution down to approximately 5 µm. Dynamic processes can be resolved with a frequency of up to 6 Hz. In reference experiments, the setup was optimized to yield a high contrast for AlCu-alloys. With samples of about 150 µm thickness, high quality image sequences of the solidification process were obtained with high resolution in time and space.

Maturational aspects of the human auditory pathway: anatomical and electrophysiological findings.

Anatomical investigations were carried out on 39 human brains ranging in age from the 29th week of development to the 70th year of life. It was demonstrated that myelination, as a prerequisite for functional maturation, takes place during the 1st year of life. Functional maturation was analyzed with electrophysiological techniques. Normal development depends on adequate stimulation during certain sensitive periods in the 1st year of life as well as the continuous use of the central auditory and speech-hearing systems.

[Protracted course of bromazepam poisoning in advanced age]. / Protrahiert verlaufende Bromazepam-Intoxikation im höheren Lebensalter.

HISTORY AND CLINICAL FINDINGS: A 68-year-old woman was found unconscious and hardly breathing. Artificial ventilation was undertaken by an emergency physician who brought her to hospital. Physical examination provided no evidence of relevant organ abnormalities. Neurological examination of the comatose patient revealed absent brain-stem reflexes and spontaneous respiration. But no other focal neurological abnormalities were found. INVESTIGATIONS: Routine laboratory tests, ECG, chest radiogram, Doppler sonography of arteries to the brain, lumbar cerebrospinal fluid and computed tomography of the skull were unremarkable. Toxicological tests discovered bromazepam intoxication (serum level 6 mg/l; maximal serum level after intake of 6 mg of the active constituent: 0.1 mg/dl). DIAGNOSIS, TREATMENT AND COURSE: When bromazepam poisoning was demonstrated elimination of the drug was no longer feasible; the spontaneous course of the poisoning with slowly falling drug levels could thus be observed over 10 days. In parallel with the fall of bromazepam concentration in blood, restitution of breathing and of brain-stem reflexes was recorded until, 12 days after intake of the drug, normal functions had been restored. CONCLUSION: Central respiratory arrest occurred at a bromazepam serum level of 6 mg/l. Without intensive medical care the patient would not have survived.

Incidence of space-occupying brain edema following systemic thrombolysis of acute supratentorial ischemia.

Whether 'malignant' brain edema following ischemic stroke is due to or aggravated by reperfusion and therefore more frequent after thrombolytic therapy of stroke is still under debate. From 3/96 to 1/97, we treated 51 patients with acute supratentorial stroke within 3 h after symptom onset with rt-PA following a protocol similar to the NINDS study. The results of thrombolytic therapy were evaluated by repeated clinical examination and computed tomography (CT) during the first week after ictus. The incidence of space-occupying brain edema following intravenous thrombolytic therapy of acute ischemic stroke was lower than the edema frequency after conventional treatment, but mortality from 'malignant' edema was higher in the patients with thrombolysis. Thus, space-occupying edema after acute ischemic stroke may be aggravated by thrombolytic treatment. Forced reperfusion of already irreversibly damaged tissue increases edema formation and enlarges developing infarcts with a deleterious increase of intracranial pressure.

Stroke following internal carotid artery occlusion - a contra-indication for intravenous thrombolysis?

Between March 1996 and December 1997, 15 consecutive patients with carotid artery occlusion diagnosed with duplex sonography were treated with intravenous recombinant tissue plasminogen activator (rt-PA), following a protocol similar to that of the National Institute of Neurological Disorders and Stroke (NINDS) study. On the basis of ultrasound findings, six of the 15 patients had internal carotid artery dissection (ICD), and the remaining nine had atherothrombotic internal carotid artery (ICA) occlusion. No relevant haemorrhagic complications were observed after rt-PA treatment of ICA occlusion. Excellent late functional outcome was observed in three of the 15 patients with ICA occlusion, moderate and poor outcome in four patients. Four patients died, and mortality was related to stroke severity upon admission. A good outcome seemed to be more likely in the small group of patients with ICD, than in the patients suffering atherothrombotic ICA occlusion. As the results of rt-PA treatment in this case series are by no means devastating, our data do not corroborate the hypothesis that patients with acute ischemic stroke following ICA occlusion should a priori be excluded from intravenous thrombolysis. The possible benefit of rt-PA treatment in stroke following acute or chronic ICA occlusion should be assessed in a larger prospective trial, for which this case series might serve as a pilot study.

Early intravenous thrombolysis for acute ischemic stroke in a community-based approach.

BACKGROUND AND PURPOSE: Controlled multicenter studies have demonstrated the efficacy of systemic recombinant tissue-type plasminogen activator (rtPA) treatment in selected cases of acute ischemic stroke. The feasibility of this therapeutic option in clinical practice was assessed in a community-based approach. METHODS: We offered rtPA treatment to stroke patients in a prospective open-label monocenter study applying inclusion criteria similar to those of the National Institute of Neurological Disorders, and Stroke study. In order to treat patients within 3 hours of symptom onset, a referral system was used by which eligible patients from all over the city of Cologne, Federal Republic of Germany, were rushed to the Department of Neurology of the University Hospital. We present data on the effectiveness of the referral system and the outcome results of the first 100 consecutive patients treated within an 18-month period. RESULTS: Of 453 consecutive patients with a presumed diagnosis of acute stroke referred to our department between March 1996 and August 1997, 100 patients (22%) were treated with intravenous thrombolysis, 26% of them within 90 minutes of symptom onset. The average time from stroke onset to arrival at our department was 78 minutes, and from arrival to treatment 48 minutes. After 3 months, 53 patients recovered to fully independent function. The rates of total, symptomatic, and fatal intracerebral hemorrhage were 11%, 5%, and 1%, respectively. Overall mortality was 12%. CONCLUSIONS: Thrombolysis with rtPA was effectively applied in routine management of stroke patients in a community-based approach with acceptable efforts and without additional costs. Under these circumstances, outcome and complication rates were comparable to those of multicenter trials.

Ultrasonic monitoring of zeolite synthesis in real time

Variations of the phase and amplitude of a transmitted ultrasonic wave package were monitored in real time during the synthesis of zeolite A and zeolite X. For both materials, characteristic changes of the measured attenuation and the sound velocity of ultrasonic waves traveling in the reaction fluid were observed, correlating with the processes of gel formation and zeolite crystallization, respectively. Aging effects of the reaction fluids are demonstrated. The observation of the onset of the zeolite crystallization was verified with ex-situ X-ray diffraction (XRD) measurements.