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H Friedrich

Publications and source records attributed to H Friedrich.

At least 19 recordsLinked to original sources
PubMed2005

Comparison of intensity distributions in tomograms from BF TEM, ADF STEM, HAADF STEM, and calculated tilt series.

The three-dimensional (3D) morphology of a nanometer-sized object can be obtained using electron tomography. Variations in composition or density of the object cause variations in the reconstructed intensity. When imaging homogeneous objects, variations in reconstructed intensity are caused by the imaging technique, imaging conditions, and reconstruction. In this paper, we describe data acquisition, image processing, and 3D reconstruction to obtain and compare tomograms of magnetite crystals from bright field (BF) transmission electron microscopy (TEM), annular dark-field (ADF) scanning transmission electron microscopy (STEM), and high-angle annular dark field (HAADF) STEM tilt series. We use histograms, which plot the number of volume elements (voxels) at a given intensity vs. the intensity, to measure and quantitatively compare intensity distributions among different tomograms. In combination with numerical simulations, we determine the influence of maximum tilt angle, tilt increment, contrast changes with tilt (diffraction contrast), and the signal-to-noise ratio (SNR) as well as the choice of the reconstruction approach (weighted backprojection (WB) and sequential iterative reconstruction technique (SIRT)) on the histogram. We conclude that because ADF and HAADF STEM techniques are less affected by diffraction, and because they have a higher SNR than BF TEM, they are better suited for tomography of nanometer-sized crystals.

Journal Article↗
PubMed2005

Solid state and dissolution rate characterization of co-ground mixtures of nifedipine and hydrophilic carriers.

Co-ground powders of the poorly water-soluble drug nifedipine and a hydrophilic carrier, [partially hydrolyzed gelatin (PHG), polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), urea or Pluronic F108] were prepared in order to improve the dissolution rate of nifedipine. The effects of type of grinding equipment, grinding time, and type of hydrophilic carrier on the crystallinity of nifedipine (x-ray diffraction and differential scanning calorimetry) on the interaction between drug and carriers (differential scanning calorimetry), on the particle size and appearance (scanning electron microscopy), on the wettability (contact angle measurements), and on the drug release were investigated. Grinding nifedipine together with these carriers improved the dissolution rate. PHG-ground mixtures resulted in the fastest dissolution rate followed by PVP, SDS, HPMC, Pluronic, urea, and PEG. This effect was not only due to particle size reduction, which increased in the order PHG<PEG=SDS<Pluronic<drug<urea<HPMC<PVP, but also resulted from the ability of some carriers (PVP and HPMC) to prevent reaggregation of the finely divided drug particles. PVP, HPMC, and PHG formed a powder with amorphous drug. The carriers improved the wettability of the ground products in the order HPMC<drug<urea<PVP<SDS<PHG<PEG<Pluronic. Differential scanning calorimetry (DSC) measurements gave valuable information about the nature of drug crystallinity and the interactions with the carriers within the ground mixtures.

Calcium Channel Blockers↗
PubMed2004

Quasi-monoenergetic neutron reference fields in the energy range from thermal to 200 MeV.

Well-characterised neutron fields are a prerequisite for the investigation of neutron detectors. Partly in collaboration with external partners, the PTB neutron metrology group makes available for other users neutron reference fields covering the full energy range from thermal to 200 MeV. The specification of the neutron fluence in these beams is traceable to primary standard cross sections.

Algorithms↗
PubMed2003

[The treatment of flexor tendon injuries in children].

Full functional recovery must always be the aim of flexor tendon reconstruction. This not only applies to adults, but particularly to infants. As customary, also in a child a severed flexor tendon should be attended immediately or with only a short delay. However, we definitively reject a bandaged fist of a hand and rather recommend demobilization by a modified Kleinert plaster. At the University Clinic for Paediatric Surgery in Graz over ten years ago we established a therapeutic protocol dedicated to infants, which we evaluated recently. In this study questions addressed were whether this treatment regimen is applicable for all age groups, notably whether the dynamic post operative treatment with a modified Kleinert plaster is always advisable. A total of 211 severed flexor tendons in children from nine months to 18 years (median 7 years) were treated. 193 lesions were either reconstructed immediately or within 48 hours. As a rule we apply the Kirchmayr-Zechner suturing procedure. We believe that the desired full mobility can thus be obtained within three months. In 95% of the 173 cases followed-up we achieved this goal with good or even excellent results according to Buck-Gramcko's criteria.

Adolescent↗
PubMed1998

Analysis of the 5'-flanking regions of the MHC-linked Hsp70-2 and Hsp70-3 genes of the rat.

We have analyzed the genomic interval between the MHC-linked heat shock protein 70 (Hsp70) genes Hsp70-2 and Hsp70-3 in the rat. The distance between the transcription start sites of both genes which are organized in a head-to-head orientation is 604 bp. Unlike Hsp70-2 the 5'untranslated region of Hsp70-3 is interrupted by an intron of about 3.9 kb. The Hsp70-3 promoter lacks a TATA box and heat shock elements, but contains two CRE elements, one Sp1-GC and two PuF binding sites. Analysis of the Hsp70-2 promoter by CAT assays reveals positive and negative regulatory elements extending into the Hsp70-3 gene.

Animals↗
PubMed1998

[Dynamic splinting after flexor tendon injuries of the hand in childhood].

Ninety severed flexor tendons were repaired in 24 boys and 14 girls in a four-year-period at the Department of Pediatric Surgery in Graz. Mean age was 4.9 years. In 16 patients (42%) additional lesions were found. Direct repair was performed with modified techniques of Kirchmayr (23) or Kleinert (8). In four fingers, flexor tendon reconstructions were carried out. Postoperatively, the dynamic Kleinert splint was used for early nonresistive motion, beginning on average on the second postoperative day. Intensive training of motion was performed in physiotherapeutic sessions during a mean period of five months, postoperatively. In five cases tenolysis was performed; in one case a rupture of a sutured tendon had to be corrected. 27 patients (71%) with 42 injured fingers were followed-up on average 2.7 years after the operation. In accordance with the Buck-Gramcko classification, very good results were achieved in 37 cases (88%), and a poor result in one patient (2%). Atraumatic technique, dynamic splinting, consequent physiotherapeutic training by experienced physiotherapists, and well informed parents will yield excellent results after flexor tendon repair in the paediatric age group.

Child↗
PubMed1996

Endogenous alkaloids in man. XXVI. Determination of the dopaminergic neurotoxin 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) in biological samples using gas chromatography with selected ion monitoring.

Highly chlorinated beta-carbolines have a potential in vivo relevance to Parkinson's disease. In this paper, a gas chromatographic method for the determination of the neurotoxic 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo), the condensation product of tryptamine and chloral hydrate, is described. The specific and sensitive assay involves purification of the biological samples by solid-phase extraction with C18 cartridges, derivatization with heptafluorobutyric anhydride, and chromatography on a non-polar fused-silica capillary column. Detection of TaClo was achieved by the registration of characteristic mass fragments of the TaClo heptafluorobutyric amide derivative using selected ion monitoring. The method was utilized to detect and quantify TaClo in blood, urine, bile, faeces, and brain tissue of rats treated with this alkaloid-type heterocycle. Four-fold deuterium-labelled TaClo was used as an internal standard.

Animals↗
PubMed1996

[Physical complaints, stress and quality of life of oncologic patients. Effects and patient assessment in inpatient rehabilitation].

AIM: To what extent do cancer patients use an inpatient aftercare programme and how is its effect been estimated by them? How is the progress of "general physical complaints", "psychosocial stress" and "satisfaction with life" in some cases over a period of up to eight months? PATIENTS AND METHODS: To 201 patients with breast or intestinal cancer respectively, who were going to be or had already been admitted to an inpatient aftercare, standardised and unstandardized questionnaire were presented to be filled out at 4 or 5 different dates before and during the programme as well as 3 and 6 months later. RESULTS: Many patients tried to take part in the aftercare programme actively. Even 6 months later 95.6% estimated it as being "successful" and 70% said that there had been a lasting positive effect after the treatment. The "general physical complaints" and "psychosocial stress" grew significantly less during the inpatient aftercare programme and "satisfaction with life" improved. After the treatment these effects were declining again. CONCLUSIONS: The results indicate that many patients, who participate in an inpatient aftercare programme, profit by it directly. As the positive effects partially get lost during the following months, the patients should be prepared more intensely for the time after dismission with its higher level of strain and should get an especially attentive ambulant care at home.

Adaptation, Psychological↗
PubMed1995

Consumer product branding strategy and the marketing of physicians' services.

Hospitals have traditionally maintained physician referral programs as a means of attracting physicians to their network of affiliated providers. The advent of managed care and impending healthcare reform has altered the relationship of hospitals and physicians. An exploratory study of marketing approaches used by twelve healthcare organizations representing twenty-five hospitals in a large city was conducted. Strategies encountered in the study ranged from practice acquisition to practice promotion. This study suggests that healthcare providers might adopt consumer product branding strategies to secure market-share, build brand equity, and improve profitability.

Attitude of Health Personnel↗
PubMed1994

Botulinum toxin treatment for lower limb extensor spasticity in chronic hemiparetic patients.

Twelve chronic hemiparetic outpatients with pronounced lower limb extensor spasticity were injected with 400 units of botulinum toxin A, EMG guided into the soleus, tibialis posterior, and both heads of the gastrocnemius muscles. Botulinum toxin A caused a definite reduction of plantar flexor spasticity, in 10 patients two weeks after the injection, as assessed by the Ashworth scale. Four of the patients were able to achieve active dorsiflexion of their affected ankle. Gait analysis including the measurement of vertical ground reaction forces showed a statistically significant (p < 0.01) improvement in velocity, stride length, stance symmetry, and the length of the force point of action under the affected foot. Qualitative improvements on the force diagrams indicated a better loading, advancement of the body, and push off of the affected limb in seven patients. Eight weeks after the injection the effects waned.

Adult↗
PubMed1994

[Pseudo-asthma].

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Airway Obstruction↗