Biomedical subjects

A Baumann

Publications and source records attributed to A Baumann.

At least 37 records · Page 2Linked to original sources

PubMed2001

3D contrast-enhanced MR angiography of the run-off vessels: value of image subtraction.

The diagnostic gain associated with image subtractions was assessed regarding contrast-enhanced 3D magnetic resonance angiography (MRA) image sets of the pelvic and lower extremity arteries. The MRA strategy combined a dedicated vascular coil with a single injection, two-station protocol. Voxel-by-voxel signal intensity subtraction was performed on MRA image sets obtained before and during dynamic infusion of a para-magnetic contrast agent. Non-subtracted and subtracted MRA image sets were assessed for the presence of occlusive (four grades) disease, using DSA as the standard of reference. In addition, SNR and CNR were recorded for each vascular segment on both the non-subtracted and subtracted images. While CNR values of subtracted images exceeded those of non-subtracted images (P < 0.05), there was no difference in diagnostic performance. For the detection of hemodynamically significant disease, non-subtracted and subtracted MRA provided overall sensitivity and specificity of 90.2%/90.3% and 95.1%/95.6%, respectively. Concordance between non-subtracted and subtracted MRA was excellent (Kappa = 0.86).

Aged↗

PubMed2001

Forecasting models for human resources in health care.

This article is a review of the approaches published between 1996 and 1999 that have been used to forecast human resource requirements for nursing. Much of the work to date generally does not consider the complex factors that influence health human resources (HHR). They also do not consider the effect of HHR decisions on population health, provider outcomes such as stress, and the cost of a decision made. Supply and demand approaches have dominated. Forecasting is limited, too, by the availability of reliable and valid data bases for examining supply and use of nursing personnel across sectors. Three models--needs based, utilization based, and effective demand based--provide substantially different estimates of future HHR need. The methods of analysis employed for forecasting range from descriptive to predictive and are borrowed from demography, epidemiology, economics, and industrial engineering. Simulation models offer the most promise for the future. The forecasting methods described have demonstrated their accuracy and usefulness for specific situations, but none has proven accurate for long-term forecasting or for estimating needs for large geographical areas or populations.

Forecasting↗

PubMed2001

Use of the preseptal transconjunctival approach in orbit reconstruction surgery.

PURPOSE: This report evaluated the advantages of the preseptal transconjunctival approach in reconstruction of the orbit. PATIENTS AND METHODS: Ninety-nine preseptal incisions were used in 80 patients for different indications (blowout fracture, complex zygoma fracture, enophthalmos correction, midface hypoplasia, secondary incision). All operative procedures were performed without an additional lateral canthotomy. The infraorbital rim was stabilized with miniplates or microplates. RESULTS: There was no ectropion or entropion in any patients. Complications included 1 laceration of the tarsal plate and 1 temporary entropion after a primary subciliary incision. The overall complication rate was 2%. CONCLUSIONS: The preseptal transconjunctival incision without lateral canthotomy provides good exposure of the orbital floor and the caudal parts of the lateral and medial wall. This approach is preferable to a retroseptal approach in reconstructive orbital surgery because of minimal disturbance of the intraorbital connective tissue framework. The anatomic optimal dissection line also results in a lower complication rate.

Adolescent↗

PubMed2001

A computer-based method for calculation of orbital floor fractures from coronal computed tomography scans.

PURPOSE: A computer program recently developed for the calculation of the orbital floor and fracture areas from coronal computed tomography (CT) scans was used in a study to evaluate the accuracy and ability of this new method. MATERIAL AND METHODS: The size of orbital floors and fabricated fractures in 14 dried, anatomic specimens were measured in coronal CT scans by 3 independent observers. Based on this data set, the orbital floor and fracture regions were calculated with the newly developed computer program. These calculated regions were then compared with a direct measurement of the specimens that had been obtained by digital photography. The accuracy of the computer-based calculations was assessed using Lin's concordance correlation coefficient. RESULTS: The size of the orbital floor (mean +/- SD) was found to be 5.21 +/- 0.39 cm(2) by direct measurement of the specimens and 5.30 +/- 0.52 cm(2) by calculation with the computer program. The region of the fracture (mean +/- SD) was 1.05 +/- 0.64 cm(2) by direct measurement and 1.01 +/- 0.62 cm(2) by computer calculation. The between-method mean difference (direct measurement minus computer based calculation) was -0.09 cm(2) (or 1.7% of mean orbital floor region) for orbital floor region and 0.04 cm(2) (or 3.8% of mean fracture region) for fracture region. CONCLUSIONS: This accurate and time-saving method is practicable for determining the size and location of orbital floor fractures. This calculation program can be advantageously applied in the clinical management of blowout fractures of the orbit.

Algorithms↗

PubMed2001

Midfacial degloving: an alternative approach for traumatic corrections in the midface.

Midfacial degloving was used as an approach in 14 patients to correct post-traumatic deformities in the midface. In eight patients, deformities in the naso-orbito-ethmoid region were corrected by orbitonasal osteotomy, telecanthus correction, orbital grafting and nasal augmentation procedures. Zygomatic osteotomies were performed in five patients with orbitozygomatic deformity. In one patient, a midface fracture (Le Fort II/III) was reconstructed after midfacial degloving. By combination of transoral vestibular, intranasal and preseptal transconjunctival incisions a complete degloving of the midface up to the nasofrontal angle and the zygoma prominence was possible. All osteotomies could be completed after midfacial degloving. Additional coronal incisions were not required. Orbitonasal osteotomies for nasal lengthening as well as fixation of the medial canthal ligament by a miniplate could be performed under direct vision. There were no postoperative complications such as stenosis of the nasal aperture or disturbances of the mimic musculature. Midfacial degloving offers good exposure, specially of the central part of the midface, without leaving an external scar. It is useful for reconstructive procedures in patients after midface trauma.

Adult↗

PubMed2001

Reperfusion of autotransplanted teeth--comparison of clinical measurements by means of dental magnetic resonance imaging.

OBJECTIVE: Dental magnetic resonance imaging (dMRI) with administration of contrast material is one method of assessing pulpal perfusion. The purpose of this study was to evaluate the level of contrast enhancement displayed by means of dMRI after transplantation of teeth and to compare these findings with the results of tooth mobility, pocket depth, cold, and electrical tests. STUDY DESIGN: Twenty-three teeth with either complete root formation or incomplete root formation (IRF) were investigated by using dMRI and were clinically examined at intervals of 2, 4, 8, and 12 weeks, as well as 6 months and 12 months after transplantation. RESULTS: An analysis of the enhancement in the dental images revealed a significant difference between teeth with IRF and teeth with complete root formation. In addition, the time to occurrence of a positive reaction to the cold test was significantly longer for teeth with IRF. CONCLUSIONS: The findings of this study indicate that transplanted IRF teeth are associated with reperfusion seen by means of dMRI as well as with delayed occurrence of a positive cold test.

Adolescent↗

PubMed2001

Nurses' experiences of restructuring in three Ontario hospitals.

PURPOSE: To describe the effects of restructuring, particularly redeployment, on nurses' personal and work lives, and to compare the utility of "survivor syndrome" and empowerment as alternative concepts for understanding these effects and planning change. METHODS: Twenty-six focus groups or interviews were held with 59 nurses working in three hospitals in Ontario, Canada. FINDINGS: Participants described how restructuring strategies had affected them as individuals, as members of nursing teams, and as employees. In each of these aspects of their work lives, relationships became less integrated, their work activities became less controllable, and the changes compromised their ability to deliver effective care. CONCLUSIONS: Restructuring intensifies structural weaknesses in professions, such as nursing, whose members are primarily employed by bureaucracies. Nurses may not find survivor syndrome a useful model to explain their low morale following restructuring because it identifies nurses as "patients" in need of therapy. An empowerment model that takes into account nurses' concerns about uncertainty and integration may be more fruitful for devising strategies to enhance their ability to practice effectively in hospital settings.

Adaptation, Psychological↗

PubMed2000

The use of marine molluskan shells for Roman glass and local raw glass production in the Eifel area (western Germany).

Relatively high strontium concentrations and their isotopic composition in Roman glass of the Imperial period indicate the general use of shells as carbonate raw material. Lead, iron, and barium concentrations and lead isotopes of glass of the late fourth century from Hambach and Gellep (western Germany) are conformable with the use of glass sand from Eifel rivers. Each of three pairs of six simultaneously operating Roman glasshouses in the Hambach area made its own raw glass from different quartz sands.

Animals↗

PubMed2000

Application of the buccal fat pad in oral reconstruction.

PURPOSE: This report evaluates the use of the buccal fat pad in reconstruction of defects of the hard and soft palate. PATIENTS AND METHODS: Twenty-nine patients with different indications (oroantral fistula, tumor of the hard and soft palate, posterior fistula in cleft patients, covering of bone transplants in augmentation procedure) were treated with a pedicled buccal fat pad without lining. The maximum reconstructed defect was 5.5 x 4 cm. RESULTS: All inserted fat grafts healed well without any aesthetic disturbances. The surface of the fat converted to normal mucosa. CONCLUSIONS: Use of the buccal fat pad is a safe and easy method to reconstruct defects in the posterior maxilla and soft palate. Good vascularization, ease of access, and minimal donor site morbidity make it a reliable soft tissue graft.

Adipose Tissue↗

PubMed2000

Amtyr1: characterization of a gene from honeybee (Apis mellifera) brain encoding a functional tyramine receptor.

Biogenic amine receptors are involved in the regulation and modulation of various physiological and behavioral processes in both vertebrates and invertebrates. We have cloned a member of this gene family from the CNS of the honeybee, Apis mellifera. The deduced amino acid sequence is homologous to tyramine receptors cloned from Locusta migratoria and Drosophila melanogaster as well as to an octopamine receptor cloned from Heliothis virescens. Functional properties of the honeybee receptor were studied in stably transfected human embryonic kidney 293 cells. Tyramine reduced forskolin-induced cyclic AMP production in a dose-dependent manner with an EC50 of approximately 130 nM. A similar effect of tyramine was observed in membrane homogenates of honeybee brains. Octopamine also reduced cyclic AMP production in the transfected cell line but was both less potent (EC50 of approximately 3 microM) and less efficacious than tyramine. Receptor-encoding mRNA has a wide-spread distribution in the brain and subesophageal ganglion of the honeybee, suggesting that this tyramine receptor is involved in sensory signal processing as well as in higher-order brain functions.

Amino Acid Sequence↗

PubMed2000

In vitro model of the human liver parenchyma to study hepatotoxic side effects by Dy-EOB-DTPA.

RATIONALE AND OBJECTIVES: In vivo studies have shown species-specific toxicity after application of the liver-specific contrast agent Dy-ethoxybenzyl (EOB)-DTPA. To predict species differences in the laboratory, an in vitro model of the liver was used to examine the divergent results. METHODS: Rat, canine, porcine, and human hepatocytes were isolated and embedded between layers of collagen. During and after 48 hours of incubation with different concentrations of Dy-EOB-DTPA (maximum concentration 50 mmol/L), morphological changes and enzyme leakage were determined. RESULTS: The response to the contrast agent varied for hepatocytes from different species. For canine cells, morphological changes and cell death were evident with as little as 5 mmol/L Dy-EOB-DTPA. Rat hepatocytes tolerated up to 50 mmol/L Dy-EOB-DTPA, and enzyme leakage was transient. Only after incubation with 50 mmol/L Dy-EOB-DTPA was the formation of intracellular vacuoles evident. In contrast, even the highest concentration of Dy-EOB-DTPA did not cause an enzyme leakage of porcine or human hepatocytes, although similar vacuoles were seen. CONCLUSIONS: These data demonstrate a species-dependent toxicity for Dy-EOB-DTPA in vitro, with similar responses in porcine and human hepatocytes.

Animals↗

PubMed2000

Health human resource planning in home care: how to approach it--that is the question.

In her paper, MacAdam refers to future challenges in health human resources for the home-care sector. This paper builds on her comments and discusses conceptual and practical approaches to future planning of health human resources. Necessary national data requirements are identified for this type of planning. The authors point out the limitations of traditional supply-side modelling and describe a new framework linking population health needs to outcomes that builds upon earlier conceptual work in needs-based, utilization-based and effective demand-based models.

Canada↗

PubMed2000

[Results of voice rehabilitation with Provox prostheses].

From 1992 to 1998, 105 patients of the Department of Otorhinolaryngology, Head and Neck Surgery in Berne underwent laryngectomy with primary implantation of a Provox prosthesis. These patients were followed up in an open prospective study and evaluated by the HRS scale, based on speaking ability and quality as well as on prosthesis care. 46 patients (44%) attained successful rehabilitation of the voice, defined as 12-15 points according to the HRS scale. Age, tumour stage and postoperative irradiation did not influence the results. Compared to the patient group with less than 12 HRS points, frequent replacements or short in situ lifetime of the prosthesis improve the results of rehabilitation. Patient compliance is an important factor in achieving success with the Provox prosthesis.

Adult↗

PubMed2000

Transcaruncular approach for reconstruction of medial orbital wall fracture.

Medial orbital wall fractures can cause horizontal diplopia and enophthalmos. Therefore, reconstruction of displaced medial wall fractures should be considered. We used a transcaruncular approach in five male patients to reconstruct the medial orbital wall after acute injuries and also as a secondary procedure for enophthalmos correction. Four of these patients had a concomitant orbital floor fracture. The incision was made in the caruncule and extended in the conjunctiva superior and inferior into the fornices for 10-12 mm. The tissue was bluntly dissected in an anteroposterior direction. The periosteum was incised dorsal of the posterior lacrimal crest and after elevation of the periosteum, the fractured orbital wall was visible. Transplants up to a height of 2 cm could be inserted for reconstruction of the medial orbital wall. In the cases of acute trauma, the medial wall was reconstructed using a resorbable polydioxanone plate. Cortical bone was used for the reconstruction of late enophthalmos. No postoperative complications were found. The transcaruncular approach gave a rapid entry to the fractured medial orbital wall without a visible scar.

Adult↗

PubMed1999

UV-responsive genes of arabidopsis revealed by similarity to the Gcn4-mediated UV response in yeast.

A UV response that involves the Ras proteins and AP-1 transcription factors has recently been described in mammals and yeast. To test whether an equivalent response exists in plants, we monitored the expression of Arabidopsis histidinol dehydrogenase gene (HDH), a homologue of the yeast HIS4 gene, which is strongly induced by UV light and is a target of the transcriptional activator Gcn4. We show that HDH mRNA levels increase specifically in response to UV-B light. Only small increases were detected upon exposure to other wavelengths. To isolate plant genes involved in this UV response, a gcn4 mutant was transfected with an Arabidopsis thaliana cDNA library. A new type of nucleotide diphosphate kinase (NDPK Ia) with a significant homology to the human tumor suppressor protein Nm23 rescued the gcn4 phenotype. NDPK Ia specifically binds to the HIS4 promoter in vitro and induces HIS4 transcription in yeast. In Arabidopsis, the NDPK Ia protein is located in the nucleus and cytosol. Expression studies in seedlings revealed that the level of NDPK Ia mRNA, like that of HDH, increases in response to UV-B light. It appears that NDPK Ia and HDH are components of a novel UV-responsive pathway in A. thaliana.

Alcohol Oxidoreductases↗

PubMed1999

Individual subunits contribute independently to slow gating of bovine EAG potassium channels.

The bovine ether à go-go gene encodes a delayed rectifier potassium channel. In contrast to other delayed rectifiers, its activation kinetics is largely determined by the holding potential and the concentration of extracellular Mg2+, giving rise to slowly activating currents with a characteristic sigmoidal rising phase. Replacement of a single amino acid in the extracellular linker between transmembrane segments S3 and S4 (L322H) strongly reduced the prepulse dependence and accelerated activation by 1 order of magnitude. In addition, compared with the wild type, the half-activation voltage of this mutant was shifted by more than 30 mV to more negative potentials. We used dimeric and tetrameric constructs of the bovine eag1 gene to analyze channels with defined stoichiometry of mutated and wild-type subunits within the tetrameric channel complexes. With increasing numbers of mutated subunits, the channel activation was progressively accelerated, and the sigmoidicity of the current traces was reduced. Based on a quantitative analysis, we show that the slow gating, typical for EAG channels, is mediated by independent conformational transitions of individual subunits, which gain their voltage dependence from the S4 segment. At a given voltage, external Mg2+ increases the probability of a channel subunit to be in the slowly activating conformation, whereas mutation L322H strongly reduces this probability.

Animals↗

PubMed1999

Molecular determinants of a Ca2+-binding site in the pore of cyclic nucleotide-gated channels: S5/S6 segments control affinity of intrapore glutamates.

Cyclic nucleotide-gated (CNG) channels play an important role in Ca2+ signaling in many cells. CNG channels from various tissues differ profoundly in their Ca2+ permeation properties. Using the voltage-dependent Ca2+ blockage of monovalent current in wild-type channels, chimeric constructs and point mutants, we have identified structural elements that determine the distinctively different interaction of Ca2+ with CNG channels from rod and cone photoreceptors and olfactory neurons. Segments S5 and S6 and the extracellular linkers flanking the pore region are the only structural elements that account for the differences between channels. Ca2+ blockage is strongly modulated by external pH. The different pH dependence of blockage suggests that the pKa of intrapore glutamates and their protonation pattern differ among channels. The results support the hypothesis that the S5-pore-S6 module, by providing a characteristic electrostatic environment, determines the protonation state of pore glutamates and thereby controls Ca2+ affinity and permeation in each channel type.

Amino Acid Sequence↗

PubMed1999

[Minimally invasive sinus lift. Limits and possibilities in the atrophic maxilla].

The minimal invasive sinus lift is a procedure done by osteotome technique via a crestal approach in contrast to the sinus elevation via lateral osteotomy to achieve adequate bone-height for setting of implants. The purpose of this anatomical and clinical study was to evaluate by endoscopic control if the minimal sinus lift is practicable by a residual bone height of less than 8 mm without mucosal damage. An endoscopic controlled sinus lift was done on 10 fresh cadavers. The original bone height was 3-6 mm in the lateral maxilla. The sinus mucosa was elevated by an osteotome at least up to 10 mm. A sinus augmentation was performed with a bone substitute material (Algipore) over the implant bed. There was no tear visible on endoscopic control. Finally, the maxilla was removed and the mucosa inspected. No laceration of the mucosa was found in any case. The clinical study included 7 patients. 5 Patients had bone condensation, augmentation of bone and implantation of 13 mm implants in a one stage procedure. The originally bone height was between 6-8 mm in all patients. One of the five patients did show a small perforation of the mucosa during mucosal elevation at one implant-bed. The implant was inserted and an endoscopic control after 6 weeks showed regular mucosa. 2 patients received augmentation only at a primary bone height of only 3-5 mm. A post-operative CT-scan showed that the bone height was augmented to a total height of 13-16 mm. As a result of our study a sufficient bone height can be achieved by the minimal invasive sinus lift procedure. The advantage of this crestal approach is the protection of the intraosseous vessels in the maxilla and less postoperative morbidity. As a disadvantage, the insertion of bone material limited only to the area surrounding the implant bed, might be discussed.

Aged↗