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Biomedical subjects

W Lang

Publications and source records attributed to W Lang.

At least 55 records · Page 3Linked to original sources
PubMed2001

Bilateral subthalamic nucleus stimulation does not improve prolonged P300 latencies in Parkinson's disease.

Bilateral deep brain stimulation is an effective treatment for most motor signs of Parkinson's disease (PD), but the effects on cognitive functions are less clear. We therefore examined the effects of bilateral deep brain stimulation on central information processing, using the event-related auditory P300 potential as an electrophysiological index of mental chronometry. Eight PD patients with bilateral stimulators within the subthalamic nuclei (STN) and eight age-matched controls participated. Patients were examined after overnight withdrawal of antiparkinson medication, both "on" and "off" stimulation (in random sequence). The P300 and reaction times were recorded using an auditory oddball paradigm. P300 latencies were prolonged in PD patients off stimulation (440 +/- 45 ms) compared to controls (397 +/- 16 ms; P < 0.05). STN stimulation significantly reduced clinical disease severity (as indexed by the Unified Parkinson's Disease Rating Scale) and markedly improved reaction times, but did not improve the prolonged P300 latencies in PD patients (429 +/- 36 ms). These results confirm that P300 latencies are prolonged in PD. Significantly, bilateral STN stimulation did not improve this electrophysiological measure of cognitive impairment, even though motor disability was markedly reduced. This suggests that some dopa-responsive features are resistant to STN stimulation, possibly due to involvement of dopaminergic deficits outside the nigrostriatal pathway, which are not influenced by outflow from the STN.

Aged↗
PubMed2001

Cortical responses to object-motion and visually-induced self-motion perception.

We investigated the spatiotemporal cortical dynamics during the perception of object-motion and visually-induced self-motion perception in six normal subjects, using a 143-channel neuromagnetometer. Object-motion specific tasks evoked early transient activity over the right temporooccipital cortex, while self-motion perception, or vection, additionally was followed by sustained bilateral activity in the temporoparietal area. The specific signal distributions suggest to represent the different perceptual modes of object-motion and self-motion sensation.

Adult↗
PubMed2001

False recognition depends on depth of prior word processing: a magnetoencephalographic (MEG) study.

Brain activity was measured with a whole head magnetoencephalograph (MEG) during the test phases of word recognition experiments. Healthy young subjects had to discriminate between previously presented and new words. During prior study phases two different levels of word processing were provided according to two different kinds of instructions (shallow and deep encoding). Event-related fields (ERFs) associated with falsely recognized words (false alarms) were found to depend on the depth of processing during the prior study phase. False alarms elicited higher brain activity (as reflected by dipole strength) in case of prior deep encoding as compared to shallow encoding between 300 and 500 ms after stimulus onset at temporal brain areas. Between 500 and 700 ms we found evidence for differences in the involvement of neural structures related to both conditions of false alarms. Furthermore, the number of false alarms was found to depend on depth of processing. Shallow encoding led to a higher number of false alarms than deep encoding. All data are discussed as strong support for the ideas that a certain level of word processing is performed by a distinct set of neural systems and that the same neural systems which encode information are reactivated during the retrieval.

Adult↗
PubMed2001

Physiological evidence of gender differences in word recognition: a magnetoencephalographic (MEG) study.

Magnetic field recordings were made in order to describe brain processes during a word recognition experiment. We investigated 26 healthy young subjects (14 females) and focused on gender differences related to recognition performance and brain activity. From about 200 ms to 350 ms after word onset the event-related field (ERF) patterns differed significantly between women and men, although the mean recognition performances did not. Differences were due to different strengths of activation as well as due to the involvement of different neural structures as underlined with statistical analysis. We interpret that our physiological findings demonstrate that different mental strategies are used for correct word recognition in the brains of women and men as assessed with magnetoencephalography (MEG). Our data might be linked to previous findings about the hemispheric asymmetry in male subjects (left lateralized) compared to women in whom both hemispheres seem to be equally involved in word processing.

Adult↗
PubMed2001

A medial to lateral shift in pre-movement cortical activity in hemi-Parkinson's disease.

OBJECTIVE: Recent evidence suggests that cortical activity associated with voluntary movement is relatively shifted from medial to lateral premotor areas in Parkinson's disease. This shift occurs bilaterally even for unilateral responses. It is not clear whether the shift in processing reflects an overall change in movement strategy, thereby involving alternate cortical areas, or reflects a compensatory change whereby, given the appropriate conditions, less impaired cortical areas are able to provide a similar function in compensation for those areas which are more impaired. This issue was examined in patients with hemi-Parkinson's disease, in whom basal ganglia impairment is most pronounced in one hemisphere. METHODS: Fourteen patients with hemi-Parkinson's disease and 15 age-matched control subjects performed a Go/NoGo finger movement task and the contingent negative variation (CNV) was recorded from 21 scalp positions. RESULTS AND CONCLUSIONS: Maximal CNV amplitudes were found over central medial regions for control subjects, but were shifted more frontally for Parkinson's disease patients, reduced in amplitude over the midline and lateralized towards the side ipsilateral to the greatest basal ganglia impairment. This shift in cortical activity from medial to lateral areas in Parkinson's disease patients appears to reflect a compensatory mechanism operating predominantly on the side of greatest basal ganglia impairment.

Action Potentials↗
PubMed2001

Acute occlusion of the left iliac artery after long-distance-running.

We report a case of spontaneous iliac occlusion in a 44-year-old male patient after long-distance running. Atherogenic risk factors like hypertension, diabetes, hypercholesterolemia and smoking were missing. Spontaneous iliac occlusion is extremely rare and only a few cases have been documented. Angiography showed occlusion of the left iliac artery with collateral flow via the obturator artery to the common femoral artery. Thrombectomy was performed but reocclusion occurred. An iliacofemoral bypass, arterial lysis and bypass thrombectomy was necessary within a few months. At the last follow-up visit two years afterwards the patient was symptom-free. This case indicates that exercise-dependent blood flow disturbances in long-distance-runners could produce changes of the intima.

Adult↗
PubMed2001

Do African-American and Caucasian overweight women differ in oxygen consumption during fixed periods of exercise?

OBJECTIVE: To examine whether there are ethnic differences in oxygen consumption during fixed periods of exercise. DESIGN: Cross-sectional. SUBJECTS: Twenty-seven African-American and 120 Caucasian overweight adult women (body mass index=32.8+/-4.1 kg/m(2), age=36.7+/-5.6 y) prior to initiating a weight loss program. MEASUREMENTS: Measurement of oxygen consumption occurred during four stages of a graded exercise test, with body composition assessed by dual-energy X-ray absorptiometry. RESULTS: There were no significant differences between overweight African-American and Caucasian women for absolute oxygen consumption or oxygen consumption adjusted for either body weight or fat-free mass across four levels of a submaximal graded exercise test. CONCLUSION: The results from this study suggest that African-American and Caucasian women do not differ in energy expenditure during fixed workloads of exercise, suggesting that this may not contribute to differences in energy balance and body weight regulation between women in these two ethnic groups.

Absorptiometry, Photon↗
PubMed2001

[Diagnosis and therapy of progressive thrombophlebitis of epifascial leg veins].

INTRODUCTION: The thrombophlebitis is generally regarded as a harmless disease. However, the progressive varicophlebitis represents a subgroup of thrombophlebitis in which the proximal portion of the thrombus can ascend into the deep vein system with the complication of deep vein thrombosis or pulmonary embolism. PATIENTS AND METHODS: In a period of 15 months ten patients were operated upon in whom a progressive varicophlebitis was diagnosed with color-flow duplex scanning. Eight of them were men, two were women. The average age was 56 years. RESULTS: Nine patients had an ascending thrombosis of the greater saphenous vein. One patient had the origin of the thrombus in the shorter saphenous vein. In one patient the ascending thrombosis of the greater saphenous vein was the reason for a segmental pulmonary embolism. The indication for operation was given when the proximal portion of the thrombus was within 10 cm of the confluence to the deep vein system. The operative procedure comprised the ligature of the epifascial vein. CONCLUSION: The diagnosis of thrombophlebitis should not be restricted only to clinical examination. Color-flow duplex scanning is preferred to compression venous ultrasonography. The ascending contrast venography as invasive diagnostic procedure should only be performed for the clarification of further questions. In ascending varicophlebitis ligature of the confluence from the superficial to the deep vein system is a safe procedure to avoid a progression of the disease or embolism. In case of postoperative recanalisation of the superficial varicose vein a second operation with stripping of the vein can be performed.

Adult↗
PubMed2001

[Development of perforator vein surgery from the Linton and Cockett procedure to endoscopic dissection].

Interruption of incompetent perforator veins (PV) is regarded as one of the principles of therapy in cases of severe stages of chronic venous insufficiency. This paper is to demonstrate the development of PV surgery from the original procedure (termed the radical Linton's operation after its originator) to minimal invasive approaches as the subfascial endoscopic perforator vein surgery (SEPS). Subfascial or epifascial interruption is frequently complicated by poor postoperative wound healing (sometimes more than 50%) even in cases with smaller incisions as the former Linton's procedure. PV interruption by hooks and special knives has been in wide use, however, the procedure is not as precise as a direct subfascial approach. The blind subfascial perforator interruption and fasciotomy by Hach has been advocated in severe forms of chronic venous insufficiency. It was Hauer at the beginning of the eighties who introduced a video-controlled surgical approach using a scope with fiberoptic lighting and video camera. At this time, a variety of instruments and modified techniques exists, but the effect of SEPS on venous hemodynamics and clinical outcome is not totally proven due to an additional reflux or obstruction in the deep or saphenous veins and concurrent epifascial surgery. A lower rate of complications of the endoscopic procedures is described, however, there is still a rate of about 5% hematoma and about 7% delayed wound healing. SEPS is an important adjunct in severe cases of PV insufficiency with chronic venous ulcers and lipodermatosclerosis. SEPS will fail in circular crural ulceration where the lesion should be totally excised and covered with skin transplantation. Up to now there is no study to demonstrate the efficacy of SEPS in patients with primary saphenous vein incompetence without deep reflux.

Endoscopy↗
PubMed2001

Cerebral expression and serum detectability of secretagogin, a recently cloned EF-hand Ca(2+)-binding protein.

Recently we identified a novel EF-hand Ca-binding protein termed secretagogin, which is expressed in neuroendocrine cells. Immunohistochemical investigations, using a murine monoclonal and an affinity purified rabbit polyclonal anti-secretagogin antibody as well as Northern-blot and Western-blot analysis revealed a neuron-specific cerebral expression pattern. Secretagogin was detected in high quantity in basket and stellate cells of the cerebellar cortex, in secretory neurons of the anterior part of the pituitary gland and in singular neurons of the frontal and parietal neocortex. Remarkable staining intensity was observed in hypothalamic and in hippocampal neurons. Using a newly developed sandwich capture ELISA we show presence of secretagogin in serum of patients suffering from hypoxic neuronal damage. In sera obtained from 32 patients with different forms of neurological symptoms due to focal cerebral ischemia, secretagogin levels ranged from 3 to 236 pg/ml, with highest levels observed on days 2 and 3 after infarction. Three patients exhibiting minor, reversible neurological deficits had nondetectable serum secretagogin levels at time points of testing. In 50 control sera, secretagogin was below the detection limit of our ELISA. Parallel analysis of secretagogin and the established neurobiochemical marker S-100B in 14 representative patients revealed comparable results. However, S-100B levels were higher and exhibited different kinetics than secretagogin. Our data present the cerebral expression pattern of secretagogin and give evidence that this protein might represent a clinically relevant serum marker indicative for neuronal damage.

Adult↗
PubMed2001

Pharmacokinetic study of human immunodeficiency virus protease inhibitors used in combination with amprenavir.

In an open-label, randomized, multicenter, multiple-dose pharmacokinetic study, we determined the steady-state pharmacokinetics of amprenavir with and without coadministration of indinavir, nelfinavir, or saquinavir soft gel formulation in 31 human immunodeficiency virus type 1-infected subjects. The results indicated that amprenavir plasma concentrations were decreased by saquinavir soft gel capsule (by 32% for area under the concentration-time curve at steady state [AUC(ss)] and 37% for peak plasma concentration at steady state [C(max,ss)]) and increased by indinavir (33% for AUC(ss)). Nelfinavir significantly increased amprenavir minimum drug concentration at steady state (by 189%) but did not affect amprenavir AUC(ss) or C(max,ss). Nelfinavir and saquinavir steady-state pharmacokinetics were unchanged by coadministration with amprenavir compared with the historical monotherapy data. Concentrations of indinavir, coadministered with amprenavir, in plasma decreased in both single-dose and steady-state evaluations. The changes in amprenavir steady-state pharmacokinetic parameters, relative to those for amprenavir alone, were not consistent among protease inhibitors, nor were the changes consistent with potential interactions in CYP3A4 metabolism or P-glycoprotein transport. No dose adjustment of either protease inhibitor in any of the combinations studied is needed.

Adult↗
PubMed2001

Carotid artery stenting: effect of learning curve and intermediate-term morphological outcome.

PURPOSE: To assess the impact of learning on the rate of success and complications of carotid stenting in a single-center, one-operator series and prospectively follow a patient cohort with regard to restenosis. METHODS: In 303 patients (mean age 70 +/- 8.8 years), 320 internal carotid arteries (ICA) were treated with carotid stenting for stenoses > or = 70%. Four groups of 80 consecutive interventions were compared with regard to primary technical success and periprocedural complications. Stent patency in follow-up was assessed using duplex scanning. RESULTS: Stenting was successful in 298 (93%) arteries. The combined neurological complications (transient ischemic attacks and all strokes) and 30-day death rate was 8.2% (n = 25), but the all stroke and 30-day death rate was 3.0% (n = 9). A significant reduction in the frequency of neurological complications after the initial 80 interventions was observed (p = 0.03), but technical success was not appreciably improved with increasing experience thereafter. Over a median 12 months (interquartile range 6 to 24), cumulative patency rates were 91%, 90%, and 91% at 6, 12, and 36 months, respectively. CONCLUSIONS: Elective carotid stenting can be performed with excellent technical success, an acceptable frequency of periprocedural complications, and good intermediate-term patency. However, our findings suggest that a larger number of interventions should be performed to overcome the negative effects of the initial learning phase.

Aged↗
PubMed2001

[Fully automated floating table MR angiography of pelvic and leg arteries: initial clinical results].

The aim of this study was to obtain first clinical experiences with magnetic resonance angiography (MRA) with digital subtraction (MR-DSA) using an automatic floating table for visualization peripheral arteriosclerotic occlusive disease (paod). We examined 10 patients on a 1.5 T MR unit applying a fast MRA technique (3D FLASH) with intravenous application of positive contrast agent. MR-DSA examinations were compared with the gold standard intraarterial (i.a.) DSA. MR-DSA proved to be useful for routine application which could be performed sufficiently in all patients. MR-DSA and i.a. DSA showed comparable results for imaging of the pelvic and upper leg arteries. Looking at the thighs image quality of MR-DSA did not match the image quality of i.a. DSA in every case. This was due to venous overlap and in comparison to i.a. DSA reduced signal-to-noise ratios. However, clinical findings, obtained with MR-DSA, were sufficient for adequate therapy planning. Our preliminary results reveal the potential of this new technique to become a realistic, robust, and non-invasive alternative to i.a. DSA in the diagnosis of paod.

Aged↗
PubMed2001

[Stroke unit: requirements for diagnostic imaging and interventions].

Stroke Units are specialised centers of expertise with the aim to optimize acute therapy of stroke. More specifically, the aims are (a) to reduce the area of brain infarction, (b) to prevent or appropriately react to complications, (c) to ensure an optimal strategy of secondary stroke prevention after having clarified etiopathogenesis, and (d) to establish a basis for subsequent rehabilitation. Stroke Units should collaborate for the evaluation and development of new diagnostic and therapeutic means. Patients' medical history, their clinical presentation and brain imaging create the basis for therapeutical decisions. The value of interventional therapy is presently evaluated for acute stroke therapy (e.g. intra-arterial thrombolysis) and secondary stroke prevention (Stent-protected angioplasty of carotid stenosis).

Austria↗
PubMed2001

[Late outcome after management of vascular injuries].

Long-term results of vascular repair in patients with trauma are influenced by diagnosis and therapy in the acute stage. Reconstructions of major venous or arterial injuries of the extremities demonstrate a higher rate of early occlusion compared with the follow-up period. The optimal management of major venous injuries remains controversial, however, there is a tendency to vascular repair whenever it can performed safely. Venous repair of the complex type is associated with a higher rate of early occlusion. The patency rate of arterial reconstructions after vascular trauma is even more than 90% in most cases with a large proportion of fully functional limbs. Endovascular treatment of acute vascular trauma may increase, however, there are only a few cases demonstrating long-term results.

Arm↗
PubMed2000

[Bed rest after lumbar puncture: a nation-wide survey in Austria].

BACKGROUND: Recommendations in medical textbooks concerning bed rest after lumbar puncture to prevent postpunctional headache vary between immediate mobilisation and 24 hours bed rest. AIM OF THE STUDY: The aim of the study was to evaluate the current practice in neurological departments. METHODS: We contacted all neurological departments in Austria by fax and asked about standards concerning bed rest after lumbar puncture and about the number of punctures per month. RESULTS: 28 out of 32 departments replied (88%). Fifty percent (n = 14) of the departments recommend 24 hours bed rest after lumbar puncture, recommendations of the other departments vary between immediate mobilisation (one department) and 16 hours bed rest. CONCLUSION: Current practice concerning bed rest after lumbar puncture varies widely in Austria and most patients are confined to bed for several hours. Even though there is evidence that bed rest does not prevent post lumbar puncture headache, there is so far no systematic review published in the medical literature.

Austria↗
PubMed2000

Intra-arterial thrombolysis for the treatment of perioperative childhood cardioembolic stroke.

Local intra-arterial lysis using recombinant tissue plasminogen activator (rTPA) was performed in a 6 and 2/3-year-old patient with major cardioembolic ischemic stroke 48 hours after intracardiac surgery. Selective application of 2.5 mg rTPA (0.11 mg/kg body weight) resulted in recanalization of the occluded cerebral vasculature with good neurologic recovery.

Cardiac Surgical Procedures↗