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Biomedical subjects

B Marks

Publications and source records attributed to B Marks.

At least 19 recordsLinked to original sources
PubMed2006

Electrophysiological proof of diffusion-weighted imaging-derived depiction of the deep-seated pyramidal tract in human.

In the living human brain the pyramidal tract (PT) can be displayed with magnetic resonance diffusion-weighted imaging (DWI). Although this imaging technique is already being used for planning and performing neurosurgical procedures in the PT vicinity, there is a lack of verification of DWI accuracy in other areas outside the directly subcortical PT parts. Before definitive electrode placement into the subthalamic nucleus (STN) in patients with Parkinson disease (PD) for chronic stimulation, the stimulation effect on PD symptoms and the side-effects, namely PT activation at the level of the internal capsule (IC), are electrophysiologically tested. To analyze DWI accuracy by matching the stereotactic coordinates of the electrophysiologically proven IC position with these of the DWI-derived IC display, DWI was added to the routine MRI work-up in the stereotactic frame prior to functional surgery in 6 patients. In all of the 10 displayed fiber tracts, concordant findings for imaging and macrostimulation were made. The authors proved for the first time that DWI correctly depicts the deep seated, principle motor pathways in the living human brain. Due to methodical limitations of this study the accuracy of the proven IC display is limited to 3 mm which has proven to be sufficient for the planning and performance of neurosurgical procedures in the vicinity of large fiber tracts.

Adult↗
PubMed2005

[Tubercular osteomyelitis of the clivus and the nasopharynx].

Involvement of the skull base is rare in tuberculosis. We report here the case of a 28-year-old female patient with an osteolytic process of the clivus with compression of the brain stem and involvement of the nasopharynx. She reported suffering from headaches for the last 6 months, and diplopia had occurred 1 week before her diagnosis as a result of paresis of the VIth cranial nerve on the right side. A biopsy was obtained endoscopically via a transnasal approach, revealing a granulomatous inflammation with acid-fast rods and thus confirming the diagnosis of a tuberculoma. When the biopsy was taken there was no evidence of any further tuberculomas in this patient. The clinical picture, diagnosis, and treatment of tuberculosis of the skull base and nasopharynx are discussed and the literature on this rare clinical entity is reviewed with reference to this patient's case report.

Adult↗
PubMed2005

A novel method for in vivo knee prosthesis wear measurement.

Wear remains an important cause of failure in knee replacement. Of the current methods of early performance assessment or prediction, simulators have been un-physiological, single X-ray film analyses remain limited by accuracy and retrieval and survival methods have a prohibitive time scale. An accurate method is needed to allow a timely assessment of polyethylene component wear in vivo, when a new design is introduced, in order to predict likely outcome. We present a new method for measuring wear in vivo that we believe will allow this prediction of long-term wear. X-ray film pairs were taken of implanted prosthetic metal components. When the X-ray system was calibrated, projections of the appropriate Computer Aided Design (CAD) model could be matched to the shapes on the scanned X-ray films to find component positions. Interpenetration of the metal femoral component into the polyethylene component could then be established and represents our estimate of "wear". This method was used to measure in vivo prosthesis wear to an accuracy of 0.11 mm.

Arthroplasty, Replacement, Knee↗
PubMed2002

Does fetal tracheal fluid flow during fetal breathing movements change before the onset of labour?

OBJECTIVE: To examine changes in intra-tracheal fluid flow parameters during fetal breathing movements throughout the second half of pregnancy in the normally developing human fetus. DESIGN: Prospective cross-sectional study. SETTING: Fetal medicine unit at the Charité University Hospital in Berlin. METHODS: Assessment of tracheal fluid flow was attempted in 340 healthy fetuses (GA 20-40 weeks) in which fetal breathing movements were seen by B-mode scan. Colour Doppler was applied to visualise the tracheal fluid flow, followed by spectral Doppler to record the velocity waveforms. The records of 53 fetuses divided into five gestational age groups (20-23, 24-27, 28-31, 32-35 and 36-40 weeks of gestation) containing 40 or more continuous breathing cycles (inspiration and expiration) were considered for analysis. Only regular breathing phases were examined and the volume obtained by integration of the tracheal fluid flow displaced during fetal breathing movements was calculated. RESULTS: The intra-tracheal flow volume moved during inspiration (Vi) and expiration (Ve) increased until 36 weeks of gestation after which there was a flattening until term. This suggests either a reduction of lung liquid production or a diminished lung liquid volume. The median difference between Vi and Ve was positive in the first four age groups and negative in the last one suggesting that, in mature fetuses, the effect of fetal breathing movements no longer results in an influx. CONCLUSIONS: Our data demonstrate a modification in fetal behaviour that manifests itself during the last four weeks before birth and has the potential to reduce lung liquid volume.

Body Fluids↗
PubMed2002

Phase II study with docetaxel and cisplatin in the treatment of recurrent and/or metastatic squamous cell carcinoma of the head and neck.

PURPOSE: Since the combination of cisplatin and docetaxel have demonstrated activity in squamous cell carcinomas of the lung and oesophagus before, promising results in recurrent metastatic head and neck cancer were expected. PATIENTS AND METHODS: Between September 1998 and October 2000, 40 patients entered this trial, 38 of whom were evaluable. Six patients were previously untreated, 24 had surgery and/or radiotherapy and 13 had received chemoradiation and/or surgery. Therapy consisted of 75 mg/m(2) docetaxel (1-hour infusion) and 75 mg/m(2) cisplatin (90-min infusion) on day 1, repeated every three weeks for a maximum of 6 courses. All patients received corticosteroids routinely, 5-HT3-antagonists, and hydration. RESULTS: The overall response rate was 52.5% (95% confidence interval, 36.1 to 68.5%) including 7 complete (17.5% complete response; CR) and 14 partial remissions (35% partial response; PR). The overall response rate in patients who had no prior treatment (n = 6) was 100%, including 3 CR and 3 PR. In patients who had prior surgery and/or radiotherapy (n = 21) an overall response rate of 42.8% was observed, including 2 CR and 7 PR; 8 patients (38.1%) had stable disease, while disease progressed in 3 (14.3%). Six of 13 patients (46.2%) who had prior chemoradiation +/- surgery responded, including 2 CR (15.4%) and 4 PR (30.8%), no change was seen in 4 patients (30.8%) and tumour progressed in 2 (15.4%). The median response duration for all patients was 10 months (range, 3-20), the median overall survival was 11 months (range, 1-30). Myelosuppression was commonly observed; WHO grade 3 or 4 neutropenia occurred in 12 patients (30%) each, and was complicated by septicaemia in 5 cases. WHO grade 3 anaemia was observed in only 3 patients (7.5%). Severe non-hematologic toxicity except for alopecia was rarely observed, and included diarrhea in 2 (5%), nausea/vomiting in 2 patients (5%) and stomatitis in 1 patient (2.5%). CONCLUSION: Our data suggest that docetaxel and cisplatin in combination is an effective and fairly well tolerated regimen for the treatment of head and neck cancer with an excellent response rate in previously untreated patients.

Adult↗
PubMed2001

GTPase activity of dynamin and resulting conformation change are essential for endocytosis.

Dynamin is a large GTPase with a relative molecular mass of 96,000 (Mr 96K) that is involved in clathrin-mediated endocytosis and other vesicular trafficking processes. Although its function is apparently essential for scission of newly formed vesicles from the plasma membrane, the nature of dynamin's role in the scission process is still unclear. It has been proposed that dynamin is a regulator (similar to classical G proteins) of downstream effectors. Here we report the analysis of several point mutants of dynamin's GTPase effector (GED) and GTPase domains. We show that oligomerization and GTP binding alone, by dynamin, are not sufficient for endocytosis in vivo. Rather, efficient GTP hydrolysis and an associated conformational change are also required. These data argue that dynamin has a mechanochemical function in vesicle scission.

Amino Acid Sequence↗
PubMed2001

Efficacy and safety of an oral formulation of cetirizine and prolonged-release pseudoephedrine versus xylometazoline nasal spray in nasal congestion.

The aim of this study was to compare the decongestant properties and tolerability of the sympathomimetic xylometazoline hydrochloride 0.1% (CAS 1218-35-5, XMZ) and an oral formulation of cetirizine hydrochloride 5 mg and pseudoephedrine hydrochloride 120 mg (CAS 83881-51-0 and 90-82-4, CTZ/PSE; Cirrus). Thirty-six asymptomatic patients suffering from perennial allergic rhinitis from house dust mite were randomized to this open two-period crossover study. Patients received the study medications for four days each. In each period, treatments were taken twice a day. On day 1 in each period, immediately after the first dose of medication, patients were challenged with Dermatophagoides pteronyssinus extract 1 in the Vienna Challenge Chamber for 5 h. Primary efficacy parameters were nasal congestion evaluated by digital analysis of nasal cavity photographs and nasal airflow. Furthermore amounts of nasal secretions, nasal and ocular symptoms were recorded. In addition, 5 independent Ear-Nose-Throat specialists also assessed nasal cavity photographs. Statistical analyses were conducted at the 5% level of significance. Digital analysis of the nasal cavity photographs as well as nasal airflow measurements did not differentiate XMZ from CTZ/PSE. Ratings of the photographs of the nasal cavity emphasized the rapid onset of XMZ. No clinically relevant adverse events were recorded. This rapid onset of action but short-lived effect of topical xylometazoline 0.1% should be balanced against the consistent and prolonged effect of systemic cetirizine/pseudoephedrine combination in the treatment of perennial allergic rhinitis as no significant differences between these 2 medications were noted regarding their decongestant properties. With the exception of nasal obstruction, all subjective symptoms as well as the global condition were significantly better under CTZ/PSE. Amounts of nasal secretions during these sessions were significantly lower with CTZ/PSE.

Administration, Intranasal↗
PubMed2000

Upper airway findings in patients with nocturnal breathing disorders.

This prospective open study was performed to examine the relation between pathologic findings of the upper respiratory tract and the types of noncentral sleep disorders (rhonchopathy, obstructive sleep apnea). 312 men and 274 women aged between 35-75 years attended our outpatient department for relief of their nocturnal breathing disorder. About 1/3 of the patients suffered only of habitual rhonchopathy and 2/3 were obstructive. No findings of the head and neck examination could predict the degree of oxygen desaturation, although pathologies of the nose (73.68%), the soft palate (94.1%) and narrowing of the oro- and hypopharynx (74.19%) were very common in patients with sleep disorder. At least one pathology could be found in every patients. The more pathologies were found the higher was the risk of obstructive sleep apnoea with desaturation below 70%. Unrelated tonsillectomy (51.36%) did not prevent nocturnal breathing disorders.

Adult↗
PubMed1999

Importance of the pleckstrin homology domain of dynamin in clathrin-mediated endocytosis.

The GTPase dynamin plays an essential role in clathrin-mediated endocytosis [1] [2] [3]. Substantial evidence suggests that dynamin oligomerisation around the necks of endocytosing vesicles and subsequent dynamin-catalysed GTP hydrolysis is responsible for membrane fission [4] [5]. The pleckstrin homology (PH) domain of dynamin has previously been shown to interact with phosphoinositides, but it has not been determined whether this interaction is essential for dynamin's function in endocytosis [6] [7] [8] [9]. In this study, we address the in vivo function of the PH domain of dynamin by assaying the effects of deletions and point mutations in this region on transferrin uptake in COS-7 fibroblasts. Overexpression of a dynamin construct lacking its entire PH domain potently blocked transferrin uptake, as did overexpression of a dynamin construct containing a mutation in the first variable loop of the PH domain. Structural modelling of this latter mutant suggested that the lysine residue at position 535 (Lys535) may be critical in the coordination of phosphoinositides, and indeed, the purified mutant no longer interacted with lipid nanotubes. Interestingly, the inhibitory phenotype of cells expressing this dynamin mutant was partially relieved by a second mutation in the carboxy-terminal proline-rich domain (PRD), one that prevents dynamin from binding to the Src homology 3 (SH3) domain of amphiphysin. These data demonstrate that dynamin's interaction with phosphoinositides through its PH domain is essential for endocytosis. These findings also support our hypothesis that PRD-SH3 domain interactions are important in the recruitment of dynamin to sites of endocytosis.

Animals↗
PubMed1999

Radiological findings in acute adult epiglottitis.

Acute epiglottitis is a rare but life-threatening disease that commonly occurs in children, and also rarely in adults. The symptoms may be mild and non-specific before a rapid onset of airway obstruction occurs. Early diagnosis is essential, as delayed treatment is associated with a high rate of complications including death. We present the clinical and radiological findings of this unusual condition in an adult.

Acute Disease↗
PubMed1999

The influence of female sex hormones on nasal reactivity in seasonal allergic rhinitis.

BACKGROUND: This study aimed to investigate whether the hormone peaks of estrogen and progesterone could influence the extent of the allergic reaction in grass-pollen-allergic women. METHODS: Twenty-three allergic women with seasonal allergic rhinitis due to grass pollen were included in this trial. Twelve were taking oral contraceptives (OC) (control group), and 11 were taking no pill (target group). The subjects were challenged with grass pollen by nasal provocation test around day 14 of their menstrual cycle (ovulation day) and again at the end of the cycle (day 27). The primary criteria were the subjective nasal symptoms rhinorrhea, nasal blockage, itching, and sneezing. A further criterion was the objectively measured nasal mucosal swelling, assessed by active anterior rhinomanometry. All criteria were evaluated before and 15 min after provocation, and the hormone status was determined on each investigation day. RESULTS: Comparisons of symptoms between the groups resulted in P values of > 0.05 for all symptoms at both visits except the symptom blocked nose, which was significantly lower (P=0.03) in the patients with OC intake at visit 2, and the symptom sneezing, which showed a significantly (P=0.02) higher increase in patients taking OC at the end of the cycle. The flow decrease reached a greater extent in the target group than in the controls. CONCLUSIONS: These results indicate a correlation of the hormonal situation and the nasal allergic reactivity. OC intake led to an intensifying of neurogenic symptoms near the end of pill intake, a result which could be due to a protective effect of the endogenous progesterone, in contrast to the orally administered hormones.

Adult↗
PubMed1999

Nucleotide-dependent conformational changes in dynamin: evidence for a mechanochemical molecular spring.

The GTPase dynamin plays an essential part in endocytosis by catalysing the fission of nascent clathrin-coated vesicles from the plasma membrane. Using preformed phosphatidylinositol-4,5-bisphosphate-containing lipid nanotubes as a membrane template for dynamin self-assembly, we investigate the conformational changes that arise during GTP hydrolysis by dynamin. Electron microscopy reveals that, in the GTP-bound state, dynamin rings appear to be tightly packed together. After GTP hydrolysis, the spacing between rings increases nearly twofold. When bound to the nanotubes, dynamin's GTPase activity is cooperative and is increased by three orders of magnitude compared with the activity of unbound dynamin. An increase in the Kcat (but not the K(m) of GTP hydrolysis accounts for the pronounced cooperativity. These data indicate that a novel, lengthwise ('spring-like') conformational change in a dynamin helix may participate in vesicle fission.

Animals↗
PubMed1998

Rhinoresistometry versus rhinomanometry--an evaluation.

Allergic nasal hyperreactivity is a common problem and many patients suffer from daily symptoms. Rhinomanometry is so far the only well established clinical method for objective assessment of nasal patency, although several expressions of nasal patency have been reported. Universal standardisation was achieved in 1983 in Brussels by Clement et al. [1], but many specialists are looking for a system giving more information on the functional aspects of the nose. A new development arising from active anterior rhinomanometry is rhinoresistometry. We tested this equipment, which has been introduced with new software for calculation and graphic presentation. 24 adult volunteers with proven allergy to grass pollen were examined immediately after long-term challenge in the Vienna Challenge Chamber [3] and 15 minutes after decongestion by application of 5% ephedrine solution. The similarity and differences between rhinomanometry and rhinoresistometry, as well as the value of the additional parameters are pointed out. Our data indicate that rhinoresistometry is a rapid, reproducible and non-invasive technique, which gives extended information in comparison to classic rhinomanometry. The results correlate very well with the findings obtained by the standard method. This pilot study demonstrates the benefit of the new parameters.

Adult↗
PubMed1998

Calcium triggers calcineurin-dependent synaptic vesicle recycling in mammalian nerve terminals.

BACKGROUND: Following exocytosis at the synapse, synaptic vesicle components are recovered by endocytosis. Morphological analysis has suggested that this occurs by a clathrin-mediated pathway, and the GTPase dynamin is thought to be involved in 'pinching off' endocytosing vesicles. The finding that the calcium-dependent phosphatase calcineurin can dephosphorylate dynamin and two other proteins implicated in endocytosis (amphiphysin and synaptojanin) has suggested a potential role for calcium and dephosphorylation in regulating synaptic vesicle endocytosis. RESULTS: We tested this hypothesis with an endocytosis assay in isolated nerve terminals (synaptosomes) that relies on the use of the fluorescent dye FM2-10. In synaptosomes, vesicle recycling occurs predominantly via a pathway dependent on both dynamin and amphiphysin. We found that endocytosis could be stimulated maximally at calcium concentrations that yielded only low levels of exocytosis, suggesting that the two processes had different calcium sensitivities cyclosporin A and Fk506, we identified calcineurin as a calcium sensor for endocytosis and showed that its activity is essential for synaptic vesicle endocytosis in synaptosomes. CONCLUSIONS: Our results suggest that dynamin-dependent synaptic vesicle endocytosis is triggered by calcium influx occurring upon nerve-terminal depolarisation. An essential mediator of calcium's effect is calcineurin, the activation of which leads to dephosphorylation of at least four proteins implicated in endocytosis-dynamin, amphiphysin 1, amphiphysin 2 and synaptojanin. Our findings also imply that endocytosis and exocytosis may occur in tandem in vivo simply because they share a responsiveness to calcium influx, rather than because they are mechanistically coupled.

Animals↗
PubMed1998

Synovial effusion in reflex sympathetic dystrophy: an additional sign for diagnosis and staging.

PURPOSE: To improve the present MRI criteria for diagnosis and staging of reflex sympathetic dystrophy (RSD) by including increased joint fluid as an additional MRI sign of RSD. DESIGN AND PATIENTS: One hundred and fourteen extremities (69 affected and 45 contralateral controls) in 57 consecutive patients with RSD were evaluated using a 1.5-T unit. T1- and T2-weighted pulse sequences, often with fat suppression, were used before and after administration of intravenous contrast enhancement (Gd). Following T2-weighted image digitization the volume of synovial fluid was measured with a computer model. RESULTS: Effusions were detected in 61% of the extremities suspected of RSD and in 44% of the contralateral control joints. The mean fluid quantity measured in the symptomatic articulation was 201 mm3. MRI diagnosis of RSD based on previously described criteria was done in 62% of the patients, yielding a sensitivity of 60%. Effusions were present in 79% of the false negative MRI cases. Retrospectively considering the presence of fluid as a potential positive criterion for RSD increases the sensitivity by 31% (to 91%). CONCLUSIONS: Joint effusions are probably associated with early stages of RSD. Adding effusion to the list of radiological criteria for RSD increases the sensitivity of MRI from 60% to 91%.

Adult↗
PubMed1998

Diffuse idiopathic skeletal hyperostosis causing obstructing laryngeal edema.

Diffuse idiopathic skeletal hyperostosis (DISH), or ankylosing hyperostosis ("Forestier's disease"), is an ossifying diathesis of unknown etiology. Diagnosis is primarily radiologic: osseous bridging of at least four contiguous vertebral bodies, a radiolucent line between the deposited bone and the anterior vertebral surface, large osteophytes and preservation of disk height especially in the cervical and lumbar spine. Although DISH is found in 6-12% of autopsy cases, clinical features are rare and consist primarily of swallowing disorders. A case of DISH is reported in which excessively enlarged cervical osteophytes led to edema of the laryngeal inlet and consequent severe dyspnea, necessitating emergency tracheotomy. Surgical excision of the osteophytic masses resulted in relief of symptoms. Symptomatology, radiographic features and individual treatments are discussed, with the latter dependent on clinical symptoms.

Aged↗
PubMed1998

Effect of continuous allergen challenge on clinical symptoms and mediator release in dust-mite-allergic patients.

This study investigated the early, prolonged immediate, and late-phase reactions of dust-mite-sensitive subjects undergoing long-term challenge in the Vienna challenge chamber (VCC) in terms of clinical symptoms and inflammatory mediator level patterns in nasal lavage fluids. A concentration of 70 ng Der p 1/m3 of air (feces of Dermatophagoides) was maintained over 8 h in the VCC. To show the clinical impact of this challenge model, the effect of a histamine H1-receptor antagonist that also has some antiallergic properties (loratadine) was also investigated. The study followed a double-blind, placebo-controlled, crossover design. Medication was given orally over 7 days before the provocation at a dose of 10 mg once daily. All 12 patients, whose dust-mite sensitivity was confirmed by disease history, skin prick test, and RAST, completed the challenge session. The documentation of the chosen parameters was performed every 30 min. Subjective nasal and ocular symptoms were assessed via a visual analog scale of 100 mm, nasal flow was recorded by active anterior rhinomanometry, and mediator release was evaluated with nasal lavages. Clinical aspect: the whole sample population showed a rise of nasal and ocular symptom severity and a nasal flow reduction, which were perceptibly, but not significantly attenuated by active drug treatment. Mediator pattern: in each patient, prostaglandin (PG)D2 and leukotriene (LT)C4 levels peaked within the first 2 h of provocation, PGD2 then moving toward baseline levels, and LTC4 then again rising continuously. Eosinophil cationic protein (ECP) exhibited a constant level increase over the whole provocation period, and tryptase levels did not change significantly. Whereas the area under the curve values of tryptase and ECP were higher in drug-treated patients than the placebo group, the early PGD2 peak occurring during the first two challenge hours seemed to be mitigated by loratadine. These results reveal that there is no link between the clinical symptoms, the drug efficacy, and the released mediators (LTC4, PGD2, ECP, and tryptase).

Adult↗