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Biomedical subjects

H Steffen

Publications and source records attributed to H Steffen.

At least 19 recordsLinked to original sources
PubMed2006

[Diagnosis of supranuclear eye movement disorders. Part I: different types of eye movements].

The hallmark of a supranuclear eye movement disorder is a functional impairment of one or several types of different eye movements while other types of eye movements still work. All eye movement information is conveyed via the nuclei of the eye muscle nerves. However, the information for a specific type of eye movement is generated in prenuclear cortical and subcortical areas which are activated depending on the type of eye movement performed. Knowledge about the anatomy of these areas enables us to make a clinical diagnosis or to localize the pathological process to a specific area in many neurological conditions. Examination of eye movements are thus a valuable clinical tool in many neurological and neuroophthalmological diseases. The first part of this two-part contribution presents the different types of eye movements, the concept of neural integration, and prenuclear structures important for horizontal eye movement as well as the pertinent pathology. The second part will appear in the next issue and deals with the cerebral structures that are relevant for vertical eye movements including their pathology.

Diagnosis, Differential↗
PubMed2006

[Diagnosis of supranuclear eye movement disorders. Part II: Vertical and torsional oculomotoricity].

The hallmark of a supranuclear eye movement disorder is functional impairment of one or several types of different eye movements while other types of eye movement remain unchanged. All eye movement information is conveyed via the nuclei of the eye muscle nerves. However, the information for a specific type of eye movement is generated in prenuclear cortical and subcortical areas which are activated depending on the type of eye movement performed. The structures responsible for vertical and torsional oculomotoricity are described as well as the functional relationship between them. A summary of the development of saccades and movements arising from them is also given and the influence of the cerebellum on oculomotor processes is dealt with. In many neurological conditions knowledge about the areas of the brain relevant for eye movement enables a clinical diagnosis to be made or the pathological process to be localized to a specific anatomical area. Examination of eye movements is thus a valuable clinical tool in many neurological and neuro-ophthalmological diseases.

Brain Stem↗
PubMed2006

Naturally processed dermcidin-derived peptides do not permeabilize bacterial membranes and kill microorganisms irrespective of their charge.

Dermcidin (DCD) is a recently described antimicrobial peptide, which is constitutively expressed in eccrine sweat glands and transported via sweat to the epidermal surface. By postsecretory proteolytic processing in sweat the dermcidin protein gives rise to several truncated DCD peptides which differ in length and net charge. In order to understand the mechanism of antimicrobial activity, we analyzed the spectrum of activity of several naturally processed dermcidin-derived peptides, the secondary structure in different solvents, and the ability of these peptides to interact with or permeabilize the bacterial membrane. Interestingly, although all naturally processed DCD peptides can adopt an alpha-helical conformation in solvents, they have a diverse and partially overlapping spectrum of activity against gram-positive and gram-negative bacteria. This indicates that the net charge and the secondary structure of the peptides are not important for the toxic activity. Furthermore, using carboxyfluorescein-loaded liposomes, membrane permeability studies and electron microscopy we investigated whether DCD peptides are able to permeabilize bacterial membranes. The data convincingly show that irrespective of charge the different DCD peptides are not able to permeabilize bacterial membranes. However, bacterial mutants lacking specific cell envelope modifications exhibited different susceptibilities to killing by DCD peptides than wild-type bacterial strains. Finally, immunoelectron microscopy studies indicated that DCD peptides are able to bind to the bacterial surface; however, signs of membrane perturbation were not observed. These studies indicate that DCD peptides do not exert their activity by permeabilizing bacterial membranes.

Amino Acid Sequence↗
PubMed2006

Chemo-mechanical dentine caries removal with Carisolv using a rotating brush.

AIM: The aim of this study was to assess the efficacy of removing dentine caries using carbide burs, Carisolv with hand instruments and Carisolv in combination with a new mechanical excavation method using a rotating brush. METHODS: 36 extracted permanent teeth, with dentine caries, were assigned into 3 groups according to caries removal technique. Caries removal was monitored by checking the properties of the dentine with a dental explorer. After embedding and sectioning (400 microm), remaining caries was assessed by using a caries detector. In microscope images (7x) of the samples, the mean stain depth of the remaining carious tissue per tooth was calculated by AnalySIS computer software. RESULTS: Four to 8 applications (mean time = 10.9 min) of Carisolv were necessary for caries removal with the new method using rotating brushes. The mean thickness of residual dentine caries by this procedure (226 microm, +/- 136) was higher than the one using Carisolv with hand instruments (57 microm, +/- 39) or carbide burs (32 microm, +/- 20). Even in areas with good access to the lesion, an unacceptable amount of residual caries was observed. CONCLUSION: Thus, it seems that Carisolv using rotating brushes does not reach the degree of caries removal reached by additional mechanical abrasion of Carisolv using hand instruments or conventional rotating carbide burs.

Coloring Agents↗
PubMed2004

Diagnostic occlusion test in cases of unilateral strabismus sursoadductorius.

PURPOSE: To investigate the diagnostic occlusion test (OT) according to Marlow in strabismus sursoadductorius (StS; also known as 'unilateral superior oblique palsy') and its implications for surgical treatment. METHODS: In 67 cases of StS, angles of strabismus were measured before and after patching the affected eye for three days. Horizontal, vertical and torsional deviations were measured in front of the tangent screen of Harms in nine directions of gaze. RESULTS: After OT, most cases of StS showed the following distribution of vertical deviation (VD) on horizontal versions: setting the VD in 30 degrees adduction to 100%, VD in primary position (PP) was 50%, VD in abduction 14%, excyclotropia in PP about 40% of the amount of VD. Those StS-cases showing the same distribution of VD on horizontal versions before and after OT were called 'typical' ones (27% of the patients). However, 73% of the patients showed a different distribution before OT: 68% VD in PP, 36% VD in abduction, excyclotropia of 20% in PP. After OT these cases converted to the normal pattern described above: VD in PP was 53 % and VD in 30 degrees abduction was 19%, excyclotropia in PP was 36%. CONCLUSION: In 'typical' StS-cases, OT is not necessary. 'Atypical' cases, however, can be converted into 'typical' ones: they get more incomitant VD on horizontal versions and greater excyclotropia in PP. As VD in adduction remains almost the same in both groups after OT, surgery can be based on the angle in adduction. In individual 'atypical' patients the amount of oblique muscle surgery has to be modified after OT.

Diagnostic Techniques, Ophthalmological↗
PubMed2003

[Laparoscopic treatment of small bowel obstruction with intussusception, volvulus and appendicitis caused by an inflammatory Meckel's diverticulum].

Indications and contraindications for diagnostic laparoscopy in cases of intestinal obstructions are discussed in connection with a 16-year-old patient's case report with small bowel obstruction including intussusception, volvulus and appendicitis caused by an inflammatory Meckel's diverticulum. The use of diagnostic laparoscopy in cases of intestinal obstructions is controversial. In the described case we performed completely laparoscopically the derevolving and desusception of the volvulus and intussusception, the appendectomy and resection of the diverticulum. The procedure itself and the postoperative course were uneventful.

Adolescent↗
PubMed2002

Kinetic aspects of the formation of aluminium oxide by use of a microwave-induced plasma.

The oxidation of thin aluminium layers in a microwave plasma has been investigated to determine the kinetics of oxide growth. Thin Al-coatings were oxidized by means of a variety of gas mixtures, characterized by different partial pressures of oxygen, in microwave-induced plasmas of different power. To study the whole kinetic process the Al-metal and the oxide formed were investigated by means of a combination of grazing incidence X-ray reflectometry (GIXR) and grazing incidence X-ray diffractometry (GIXRD). XPS and FTIR spectroscopy confirmed the formation of stoichiometric Al(2)O(3). The alumina formed is X-ray amorphous. Quantitative description of oxide formation was achieved indirectly by determination of the decrease in the integrated intensity of the Al(111)-peak and the total thickness of the whole coating. These values enabled calculation of kinetic data. It was found that oxide growth was a combination of two simultaneous processes - diffusion and sputter processes. The diffusion coefficient D (cm(2) s(-1)) and the sputter rate S (nm s(-1)) were determined. The effect of the composition of the gas mixture, microwave power, and concentration of activated oxygen species on the oxidation process will be discussed. For calculation of the activation energy, E(A), of this plasma-enhanced diffusion process the temperature-dependence of D was investigated.

Journal Article↗
PubMed2002

Contribution of intraoperative cholangiography to incidence and outcome of common bile duct injuries during laparoscopic cholecystectomy.

BACKGROUND: In the present study we examined, in a meta-analysis of the literature, the contribution of intraoperative cholangiography (IOC) to incidence, type, and time of diagnosis of common bile duct (CBD) injuries during laparoscopic cholecystectomy (LC). MATERIALS AND METHODS: Forty of 2104 reports were enrolled for analysis. In 26 reports we found exact information on type, location and repair of 405 major injuries and in a subgroup examination we selected 103 major injuries with detailed information as to the event and size of CBD injury in association with IOC. RESULTS: The main incidence of CBD injuries was 0.36%. Using the method of routine IOC the incidence was 0.21% and the rate of diagnosis at the time of cholecystectomy 87% in contrast to selective use of IOC with 0.43% and 44.5%. In 405 cases of major CBD injuries, severe injuries predominated in 83.9% of the cases. Reconstruction with the help of a bilio-digestive anastomosis was necessary in 45.7% of all patients. In 34.8% of the cases a second intervention had to be made in the follow-up of 4 years after LC. The analysis of type, severity, recognition, and follow-up of CBD injuries during LC w/wo IOC showed significant advantages for doing routine IOC. CONCLUSIONS: The use of IOC can avoid severe types of CBD injuries during LC, increase the recognition at the time operation, and influence the success of repair and outcome of the patients.

Anastomosis, Surgical↗
PubMed2002

[Orbital floor reconstruction. Comparison of a new perforated 0.15 mm thick PDS layer with established titanium dynamic mesh].

INTRODUCTION: For surgical reconstruction of the orbital floor after blow-out fractures, a new perforated PDS (poly-p-dioxanon) foil (0.15 mm thickness) has recently become available. The main target of this prospective and randomized interdisciplinary clinical study was to compare this new PDS foil with the proven titanium dynamic mesh (0.3 mm thickness). PATIENTS/METHODS: Aside from the common diagnostic procedures, an extensive ophthalmologic examination was performed and documented preoperatively (U1), 4 days (U3), 1 month (U4), and 6 months (U5) postoperatively. RESULTS: In both groups the surgical procedure was tolerated well. The new perforated PDS foil turned out to be easier to handle intraoperatively because of smooth and clean cutting edges. The surgical treatment was well tolerated in all randomized groups. In contrast to the control group, the PDS and TD groups showed postoperatively a slight increase of the preoperative exophthalmos (mean 0.5 mm). CONCLUSION: The new perforated PDS foil is comparable concerning cosmetic and functional aspects. Especially with regard to stability after blow-out fractures, the new perforated PDS foil is equal to titanium dynamic mesh up to 20 mm in diameter. PDS foil is felt to be superior regarding bioresorption and due to the more convenient handling.

Adolescent↗
PubMed2001

Effectiveness of a new perforated 0.15 mm poly-p-dioxanon-foil versus titanium-dynamic mesh in reconstruction of the orbital floor.

Introduction: In recent years a new perforated PDS (poly-p-dioxanon) foil (0.15 mm) has become available and has not yet been proven to be successful in reconstruction of the orbital floor after blow-out-fractures in randomized studies. The main aim of this clinical trial is to compare this new PDS foil with titanium dynamic mesh (0.3 mm) (TD), which is well established in reconstruction of the orbital floor. Patients and Methods: In a prospective multicentre randomized trial, conducted between 1997 and 1998, out of 42 patients with fractures of the orbital floor, 28 patients needing material for reconstruction were randomized to receive either PDS foil or TD. In a comprehensive preoperative and postoperative protocol patients were monitored by the surgeon, radiologist and ophthalmologist with a postoperative follow-up of least 6 months. Results: Maximum defects of the orbital floor were comparable in both groups (PDS group: 13.3 mm, TD group: 13.9 mm). In both groups the surgical procedure was well tolerated, and functional and cosmetic results were evaluated as satisfactory by all patients. Ophthalmological evaluation, performed up to 6 months postoperatively, revealed double vision or vertical strabismus in nine patients (five PDS group, four titanium group). This was not confirmed subjectively in each single patient. Also ex- or enophthalmos, registered in seven patients of the PDS and four of the TD group (mainly +/-1 mm) were not considered as relevant by the patients. Conclusion: The new 0.15 mm perforated PDS foil was comparable to 0.3 mm titanium mesh concerning functional and cosmetic outcome. Obviously, persisting ophthalmometric disorders were compensated very well in both groups. PDS foil is felt to be the preferred material since it is bioresorbable and more convenient to handle. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗
PubMed2001

The influence of surface configuration on the retention of posts designed for use with a cast-on technique.

OBJECTIVES: The combination of an individually cast core and a prefabricated metal post is one of the many techniques to restore endodontically treated teeth. The surface characteristics of commercially available posts vary considerably and likely influence retention. In this study, the surface configuration of 11 castable prefabricated post systems and their retention at the post-cement interface were investigated. METHOD AND MATERIALS: Scanning electron microscopic photos were made to assess surfaces of the posts. Etchant residues or applied surface layers were also analyzed with an electron beam microprobe. For the retention measurements, 6 posts from each system were cemented in artificial root canals with a zinc phosphate cement. Retention was measured on a universal testing machine. RESULTS: Analysis of variance and the Ryan-Einot-Gabriel-Welsch F test revealed significant differences in retention between posts; these differences were related to the microstructure of the surfaces of the posts. In general, the coarser the surfaces, the better the retention. Gold plating of the etched surface for one manufacturer resulted in less retention compared to posts of the same type and size that were not plated. CONCLUSION: The surface configuration of a post could be an important factor when selecting a prefabricated post system.

Acid Etching, Dental↗
PubMed2000

[Motor and sensory responses in fusion of vertical disparities in different convergence places].

UNLABELLED: To study motor and sensory responses in vertical fusion at different angles of horizontal vergence in normal humans. METHODS: The study included 12 normal subjects. A cross (+) extending 3.4 degrees x3.2 degrees was presented dichoptically. Vertical disparity was introduced by changing the vertical position of the cross in front of one eye. The disparity was incremented by 0.08 degrees every 8 s. Distance viewing was tested with 1 degrees of convergence demand, near vision with 6-15 degrees convergence demand. Eye movements were recorded using three-axis search coils. RESULTS: Vertical fusion capability was larger at near vision than at distance in 9 of 12 subjects. For the entire group, total vertical fusion capability (motor plus sensory response) differed between distance (mean 1.68 degrees ) and near (mean 2.39 degrees ). The motor component differed significantly between distance (mean 1.42 degrees ) and near (mean 2.13 degrees ). No difference in the sensory component was seen between distance (mean 0.26 degrees ) and near (mean 0.27 degrees ). CONCLUSIONS: Vertical fusion capability increases with convergence. This increase is mainly due to an increase of the motor response.

Accommodation, Ocular↗
PubMed2000

Caries prevention with chlorhexidine-thymol varnish in high risk schoolchildren.

In a prospective, randomised and blinded cohort study, the acceptance and effectiveness of a 3-monthly chlorhexidine-thymol varnish application was assessed in 8- to 10-yr-old children (n=29) with high caries incidence after brushing with a 1.23% fluoride gel. The children of the control group (n=25) brushed with a fluoride gel only. The standardised interview showed good acceptance of the varnish applications in spite of the bitter taste. Caries incidence in one year was 1.2 DMFS (SD 1.5, median 1; 95% confidence interval 0-1) for the test group and 2.1 DMFS (SD 2.3, median 2; 95% confidence interval 0-3) for the control group. Due to a slightly lower reduction in caries incidence (42.3%) than in other studies and a higher standard deviation than in unselected study groups, the power of the present study was not high enough to prove this difference in caries incidence to be statistically significant in the Mann-Whitney test (P=0.11). This was also found for the difference of 0.4 initial lesions. The distribution patterns of caries incidence for tooth groups (70% in the first permanent molar) and surfaces (58% on occlusal surfaces) did not differ between the test and the control group. The reductions of caries incidence which have been found in highly caries active children of the present study should be evaluated further with a larger study sample.

Anti-Infective Agents, Local↗
PubMed2000

Rotation of Listing's plane with convergence: independence from eye position.

PURPOSE: To determine whether asymmetrical vergence results in a rotation of Listing's plane independent of vergence-associated changes of eye position in the orbit. METHODS: Six normal subjects were required to fixate on a 3x3 array (40 degrees on a side) of light-emitting diodes arranged on a flat screen 124 cm from the subject. Disparity-induced vergence was elicited with a horizontal Fresnel prism (30 cm/m, approximately 17 degrees) placed in front of one eye. In four subjects accommodative vergence (10 degrees to 15 degrees) was produced by placing a minus spherical lens in front of one eye while the other eye was covered. Eye position was measured binocularly using three-axis search coils. Control data were collected without prisms during monocular and binocular viewing. For all data a planar regression was used to fit torsional eye position as a function of horizontal and vertical position to calculate the horizontal and vertical primary positions that define the orientation of Listing's plane. RESULTS: In the prism experiment, the horizontal primary position of the eye not wearing the prism rotated temporally by 3.9 degrees +/-1.7 degrees compared with the both eyes viewing control condition. The rotation of the prism eye was in a similar range (3.4 degrees +/-2.0 degrees). With accommodation, the horizontal primary position of the viewing eye rotated temporally by 4.4 degrees +/-1.4 degrees compared with the monocular viewing control. In both the accommodation and the prism paradigms there was usually a rotation of vertical primary position downward. CONCLUSIONS: Vergence-induced changes in Listing's plane can be independent of changes in orbital position associated with vergence. This finding supports a role for changes in central innervation in the elaboration of Listing's law.

Accommodation, Ocular↗
PubMed1999

Immune-mediated retinopathy in a patient with stiff-man syndrome.

BACKGROUND: Stiff-man syndrome is a rare neurological disorder characterised by rigidity and violent spasms of the body musculature. In the majority of patients, presence of antibodies against glutamic acid decarboxylase (GAD), the enzyme synthesizing gamma-aminobutyric acid (GABA), suggests an autoimmune attack against GABA-ergic inhibitory neurons. We report a 32-year-old patient with stiff-man syndrome and anti-GAD antibodies who developed subacute progressive loss of vision in the right eye, and in the left eye 18 months thereafter. METHODS: Ophthalmological work-up included electro-retinogram (ERG), visual evoked potentials (VEP) and fluorescein angiography. Antiretinal antibodies were investigated using an indirect immunofluorescence technique on frozen sections of macaque retina with patients serum and FITC-conjugated goat antihuman immunoglobulin. Staining with monoclonal anti-GAD65 antibodies and with serum from three healthy normals served as controls. RESULTS: Visual acuity of both eyes decreased to 0.16 within a span of 6 weeks. Perimetry revealed a central scotoma in the visual field of both eyes. VEP and flash ERG were progressively disturbed on the right eye. On the left eye, initially only pattern ERG and photopic responses were abnormal. Follow-up recordings revealed widespread pathology of photopic single and flicker responses. Immunofluorescence revealed strong reactivity of the inner plexiform layer and to a lesser extent staining of the outer plexiform layer at dilutions of 1:1000 with patients serum. The same retinal staining pattern was obtained with monoclonal anti-GAD65 antibodies. CONCLUSIONS: These findings suggest autoimmune retinopathy, mediated by anti-GAD65 autoantibodies as the underlying cause of visual loss.

Adult↗