[Objective tooth color determination. Error source elimination].
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Color↗
Biomedical subjects
H Weber
Publications and source records attributed to H Weber.
[The mobile rheumatoid health unit--an ambulatory consultation from the viewpoint of the physician and patient].
The acceptance of a university-based outpatient department (Department of Rheumatology, Hannover Medical School, FRG) has been investigated. Ninety-five former patients with RA, previously treated in the department were interviewed by phone. 312 general practitioners from the city of Hannover received a mailed questionnaire. Patients were asked why they had left outpatient department care; questions for general practitioners dealt with types of referral. Despite high satisfaction with the outpatient unit in both groups, we found several shortcomings which possibly might influence discontinuation of treatment and non-utilization of the department: patients and physicians criticized the scheduling system and waiting times. Both groups complained of frequently changing doctors. The general practitioners wanted more contact with the department and more information about the unit. A small group of patients and referring physicians expressed resignation.
Ambulatory Care Facilities↗
Crossover from three- to two-dimensional behavior of the vortex energies in layered XY models for high-Tc superconductors.
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Journal Article↗
Factors determining the frequency of plasmid cointegrate formation mediated by insertion sequence IS3 from Escherichia coli.
Transposition events mediated by plasmidborne copies of the insertion sequence IS3 of Escherichia coli are difficult to detect because of a low frequency of cointegrate formation. We found that cointegration activity could be strongly enhanced by using plasmid constructions in which a second IS3 element, disabled by a large deletion, was placed adjacent to an intact IS3 copy. Attempts to construct plasmids containing two adjacent intact IS3 copies were unsuccessful, probably because of instability. Transpositional hyperactivity of tandemly duplicated IS sequences was previously described for spontaneous duplications of IS21 and IS30 and may well be a more general phenomenon. The frequency of cointegration events was also strongly increased in an E. coli strain deficient in Dam methylation, suggesting that IS3, like some other Dam site-containing IS elements, is regulated by the Dam methylation system. Insertion sites were strongly clustered within the target lambda repressor gene: however no sequence specificity determinants could be identified. All insertions analyzed carried the IS element in the same orientation; target sequence duplications were mostly 3 bp, but in some cases 4 bp long. To obtain information about the roles of the open reading frames (ORFs) in IS3, we constructed plasmid-borne mutant elements in which potentially functional reading frames were inactivated by site-directed mutations; the mutants were introduced into partial tandem constructions and tested in cointegration assays. Mutations inactivating the putative initiation condons of ORF I and II in the intact element reduced insertion activity to less than 4% of the wild type, whereas the introduction of a termination codon into ORF IV had no effect on cointegration frequency.(ABSTRACT TRUNCATED AT 250 WORDS)
Base Sequence↗
Comparative analysis of the influences of IL-1, IL-3 and GM-CSF on the commitment of granulocyte-macrophage progenitors in vitro.
Our experiments were directed towards the detection of the influence of interleukin-1 (IL-1); interleukin-3 (IL-3), and granulocyte-macrophage colony-stimulating factor (GM-CSF) on the generation of granulocyte-macrophage progenitor cells. We also set out to examine whether this process is connected with changes within the early precursor cell compartment. Bone marrow suspension cultures (12 days) supplemented with these cytokines were tested for the presence of GM colony-forming cells (GM-CFC) in a colony-forming unit assay. The percentage of CD34+ and HLA-DR+ as well as the number of blasts and promyelocytes were estimated cytofluorometrically and morphologically. The proliferative effect of GM-CSF was associated with a net increase of GM-CFC and HLA-DR+ myeloid cells and a decrease in the percentage of CD34+ early precursor cells. IL-3 acted similarly and also caused an absolute decrease of CD34+ cells in the cultures. IL-1 did not stimulate the generation of blasts or GM-CFC but elevated the number of CD34- as well as HLA-DR-expressing cells in the cultures. These results imply that GM-CSF supported the maintenance of hematopoiesis in vitro. The transition from early precursor cells to committed myeloid progenitor cells (GM-CFC) and more mature precursor cells (G-CFC, M-CFC) may be supported by GM-CSF without affecting the self-renewing capacity of CD34+ early precursors. In contrast, the blast-generating and proliferation-inducing action of IL-3 is associated with a drop in the total number of CD34+ stem cells. An efficient renewal of this population obviously depends on the presence of IL-1.
Antigens, CD↗
New surface modification for Ti-6Al-7Nb alloy: oxygen diffusion hardening (ODH).
PVD-TiN coating and N+ implantation of Ti-6Al-7Nb alloy resulted in surface hardening to a depth of less 3 microns. The new oxygen diffusion hardening (ODH) treatment increased the hardness gradually to 50 microns. PUD-TiN showed an improvement in the tribological properties, while N+ implantation increased the PE wear rate. The wear rate of the ultrahigh-molecular-weight as well as the friction coefficient were reduced to one-half of the values achieved with the combination of CoCrMo-alloy when paired against the ODH-treated surface. In pairing with ZrO2-containing bone cement the ODH-treated surface showed only a minimal reaction.
Corrosion↗
Occurrence of express saccades under isoluminance and low contrast luminance conditions.
Saccadic reaction times (SRTs) of three human subjects were analyzed. The gap paradigm was used (i.e. fixation point offset precedes target onset) to obtain high proportions of express saccades (i.e. saccades of extremely short reaction times) in the SRT distributions. In one set of experiments, the luminance of the (red) saccade target was varied from brighter to darker than the (green) background including an isoluminance condition. Express saccades were obtained in response to pure color contrast stimuli with about the same frequency and reaction time as to stimuli with both color and luminance contrast. In a second experiment, the luminance contrast of a white target on a white background was lowered below 10%. Again the number of express saccades was not reduced. Thus, in contrast to other perceptual phenomena the visual neural mechanisms underlying the generation of express saccades are not affected by isoluminance nor low contrast luminance.
Color Perception↗
[Closure of septum perforation using an individual obturator].
Alternatively to operative procedures we present the production of an individually formed septal obturator to close an iatrogenic septal perforation. After taking the impression from the perforation the obturator was casted out of silicone via a plaster mould. This possibility can help in those cases where septal perforation cannot be closed by operative procedures.
Adult↗
Plasma propafenone concentration in the evaluation of anti-arrhythmic efficacy.
The anti-arrhythmic drug efficacy of oral propafenone therapy (300 mg to 900 mg per day) was studied in relation to propafenone and hydroxy-propafenone plasma concentrations in 70 outpatients (46 males, 24 females, mean age 57 +/- 12 years) followed up for 24 +/- 32 months. On average 1.7 plasma concentration measurements were performed per patient. The arrhythmias were effectively controlled in 32 patients, but in another 32 patients propafenone therapy was ineffective; in six patients the evaluation was unclear. The therapy was effective in 66% of patients with ventricular premature beats, in 50% with complex ventricular arrhythmias, in 40% with ventricular tachycardia and in 20% with supraventricular tachycardia. Fifty per cent of patients with coronary heart disease and electrical disease, but only 20% with dilated cardiomyopathy and Wolff-Parkinson-White syndrome were effectively treated. Measurement of peak plasma propafenone levels performed 4.5 +/- 2 h after oral drug administration revealed no statistically significant dose-plasma concentration relation. Optimal propafenone drug efficacy was documented at propafenone plasma concentrations ranging from 0.20 to 0.60 micrograms/ml (63% of patients considered as effectively treated). There was a trend to decrease propafenone efficacy at plasma concentrations below 0.20 micrograms/ml and above 0.60 micrograms/ml. Analysis of hydroxypropafenone identified four patients as poor metabolizers with unusually high propafenone and low hydroxypropafenone plasma concentrations; only one of these four patients showed drug efficacy. Monitoring of propafenone and hydroxypropafenone plasma concentrations was a practical procedure to assess patient's compliance, to identify poor metabolizers and to guide anti-arrhythmic drug therapy.
Adult↗
Determinants of subsidiary ventricular pacemaker suppression in man.
To investigate the relative contribution of the duration and rate of overdrive to subsidiary ventricular pacemaker suppression, in six patients with complete heart block after His-bundle ablation, ventricular overdrive stimulation studies were performed. The studies, which were spread over a mean follow-up period of 745 days, were carried out invasively with a temporary lead (one patient) as well as noninvasively with the implanted pacemakers and chest wall inhibition (five patients). The overdrive pacing rate was increased in steps of 10 beats/min, and the pacing duration was 15, 30, 60, 90, and 120 seconds at each level. A recovery period of 2 minutes was allowed after each overdrive stimulation. Incremental ventricular overdrive stimulation at increasing pacing durations consistently caused progressive suppression of ventricular impulse formation. Nonparametric variance analysis demonstrated a significant (P less than 0.0001) influence of both the pacing rate and duration on ventricular recovery time. Nonlinear regression showed an exponential increase in recovery time with incremental pacing rate and a biphasic increase in recovery time with incremental pacing duration. Beyond a pacing duration of 60 seconds ventricular impulse suppression was primarily dependent upon the pacing rate. A nonlinear regression model was applied to predict the number of beats required for return of the escape rhythm toward prepacing control values. The predicted maximum mean number of beats was 15.4 +/- 5.9 and independent of the rate and duration of pacing, although, the initial temporary instability of the escape rhythm was directly related to the degree of overdrive.
Adult↗
Human atherosclerotic coronary artery xenografts: a model for investigation of transluminal recanalization.
A model for testing transluminal recanalization techniques was developed. Fragments of human atherosclerotic coronary arteries were transplanted into carotid arteries of dogs and evaluated by angiographic, angioscopic, and histologic study within a three-month period. An inflammatory response was most intense within the first week. By two weeks no inflammation was noted. Total occlusion (n = 13) and stenosis (n = 11) of the carotid arteries were achieved without complications. The model is easy to produce within a short period and the arterial occlusion resembles human vascular disease. This model has been used to evaluate laser recanalization of vascular obstructions.
Animals↗
Thermal effects and histologic changes from Nd:YAG laser irradiation on normal and diseased aortic tissue using a novel angioplasty catheter with a mobile optical fiber: an in vitro assessment.
Although various laser angioplasty devices are currently being examined, thermal damage and perforation of the vessel wall remains the major acute complication of vascular laser recanalization. Consequently, the aim of this study was to investigate the thermal effects and histologic changes from laser irradiation (Nd:YAG, 1064 nm) on normal and diseased aortic tissue using a novel angioplasty device. During laser emission the coaxially guided optical fiber tip was positioned in reference to the end hole of the metallic capped probe as follows: (1) at the end hole (metal-cap position), (2) protruding 10 mm from that end hole (bare-fiber position), (3) withdrawn 5 mm into the metal cap's lumen (hot-tip position). In total, 96 laser impacts (25 joule: 5 W, 5 s, each) were produced on normal and atherosclerotic aorta in air through a 0.2-mm-core-diameter silica quartz fiber, with direct contact on the intimal surface of the target tissue by both the fiber and the metal cap and by either the fiber or the metal cap (n = 32 each). Tissue temperature was measured by means of special sensors positioned opposite the irradiated intimal spot in direct contact with the adventitial surface. Morphohistologic evaluation of lesions was performed and injury indexes were determined.
Angioplasty, Laser↗
[Joint prostheses components of warm-forged and surface treated Ti-6Al-7Nb alloy].
In 1978 development of a TiAl alloy with the inert alloying element niobium was initiated. In 1984, the optimal composition was found to be Ti-6Al-7Nb (Protasul-100). This custom-made alloy for implants has the same alpha/beta micro-structure and equally good mechanical properties as Ti-6Al-4V. The corrosion resistance of Ti-6Al-7Nb is better than that of pure titanium and Ti-6Al-4V, due to the very dense and stable passive layer. Since 1985, highly stressed anchoring stems of various hip prosthesis designs have been manufactured from hot-forged Ti-6Al-7Nb/Protasul-100. Polished surfaces of hip, knee or wrist joints made of Ti-6Al-7Nb intended to articulate with polyethylene are surface-treated by the application of a very hard, 3-5 microns thick titanium nitride coating (Tribosul-TiN), or by oxygen diffusion hardening (Tribosul-ODH) to a depth of 30 microns.
Alloys↗
Custom-made resin-bonded attachments supporting a removable partial denture using the spark erosion technique: a case report.
A removable partial denture supported by resin-bonded precision attachments was constructed for a patient with intraoral symptoms of a cleidocranial dysostosis. Because of the anatomic situation, the youth, and the preprosthetic orthodontic treatment of the patient, a conventional prosthetic solution seemed inappropriate. Custom-made attachments were constructed with the spark erosion technique. They were fixed to the abutment teeth with resin-bonded retainers. The combination of the resin-bonding technique with the modern technology of spark erosion thus allowed a conservative approach to the oral rehabilitation of a young patient.
Adolescent↗
[Diagnosis of arrhythmogenic right ventricular disease using magnetic resonance tomography].
In our study, 12 patients with ventricular arrhythmias, but without any documented cardiac disease, and 10 healthy volunteers were investigated by spin echo magnetic resonance tomography (MRT) using a 0.5 Tesla magnet. Axial T1-weighted spin-echo sequences, as well as double angulated, multislice-multiphase sequences were acquired. Left- and right-ventricular volumes were then evaluated by outlining the endocardium in an end-systolic and an end-diastolic frame. The right-ventricular free wall and the right-ventricular outflow tract were investigated for myocardial thickness and intramural fat.
Adipose Tissue↗
[Pharmacokinetics of bendamustin (Cytostasan) in B6D2F1-mice].
The pharmacokinetics of bendamustine, (1; Cytostasan), an alkylating antineoplastic agent of the N-lost group, was investigated in B6D2F1 mice. After i.v. injection of the maximally tolerated dose of 50 mg/kg a rapid decrease of the unchanged drug in plasma (MRT 21.9 min) and slowly decreasing levels of mono-, dihydroxy and beta-hydroxy-1 were observed. Variations of the age of the animals as well as of the dose administered did not alter the short MRT of 1. 1 is excreted via the kidneys to a considerable extent showing a similar metabolite pattern in urine as in plasma. The absorption of the drug from the gastrointestinal tract is incomplete resulting in an absolute bioavailability of about 40%.
Administration, Oral↗
Morphogenetic development of the area octavolateralis in the cichlid fish Oreochromis mossambicus.
In the cichlid fish Oreochromis mossambicus the area octavolateralis in the brain stem was studied using histological techniques and labelling of afferents from the inner ear and the lateral line system with horseradish peroxidase (HRP). Adult fish and fish larvae aged 2, 4, 7, 10, and 15 days post hatching were investigated in order to analyze the ontogenetic development of these sensory systems during the critical phase of maturation from relatively immobile stages to actively swimming larvae. In adult Oreochromis seven nuclei can be detected in the octavolateral area while in the larvae a steady differentiation from a mostly periventricular concentration of perikarya in the first two days post hatching via increasing accumulations of neuronal cell bodies in the more peripheral regions up to four discernible nuclei in the age of 15 days post hatching was observed. The HRP-labelling of afferents from the lateral line organ and the inner ear in early stages indicates that the sensory organs precedes the histologically detectable differentiation in the octavolateral area. Both sensory components are clearly separated already in very early developmental stages.
Aging↗
[The effect of bedding type on implant and abutment tooth in tooth/implant-supported bridgework].
17 distal extension cases were treated with IMZ implants supporting a fixed-removable bridge connected to a natural tooth abutment with a precision attachment. Instead of the polyoxmethylene internal shock absorber an identically dimensioned titanium element was incorporated in the implants of every second patient. Patients were monitored on a recall schedule. Implant and tooth mobility, pocket probing depth, and bone loss were the parameters evaluated. The results after a mean incorporation time of 16.5 months indicate that, at least during this initial time of function, there are no differences between a mobile and rigid bedding of the superstructure on the implants.
Aged↗