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Biomedical subjects

M Kuhl

Publications and source records attributed to M Kuhl.

15 recordsLinked to original sources
PubMed2003

A comparative clinical outcome evaluation of smooth (10-13 year results) versus rough surface finish (5-8 year results) in an otherwise identically designed cemented titanium alloy stem.

BACKGROUND: We retrospectively compared the influence of surface finish with respect to the long-term durability of a cemented titanium alloy stem of the same design but different surface finish. METHODS: From 1984 to 1994, the stem was made of a titanium-aluminum-vanadium alloy. A total of 201 patients with 220 smooth stems (mean follow-up 11 years and 4 months) out of 612 implanted between 1984 and 1987 and 319 patients with 343 rough stems (mean follow-up 5 years and 10 months) out of 812 implanted between 1991 and 1993 could be reviewed clinically and radiologically for comparison. The average age of the patients with the smooth stem was 58.1 years and of the patients with the rough stem, 62.2 years. In both groups, 35% of patients were male and 65% female. RESULTS: The mean Merle d'Aubigné hip score increased from 10.5 to 16.0 points in the smooth stem group and from 11.0 to 16.9 points in the rough stem group. The distribution of radiolucent lines, according to the zones of Gruen, was similar in both groups. The smooth stem required revision in 18 cases after a mean follow-up of 11 years and 4 months and the rough stem in 30 cases after a mean follow-up of 5 years and 10 months. The survival analysis (Kaplan-Meier) revealed 95.4% survival after 13 years for the smooth femoral component and 76.7% survival after 8 years for the rough femoral component. CONCLUSIONS: The implantation of titanium alloy stems with a rough surface finish cannot be recommended because of its high aseptic loosening rate.

Alloys↗
PubMed2000

Identification of two regulatory elements within the high mobility group box transcription factor XTCF-4.

Some members of the Wnt family of extracellular glycoproteins regulate target gene expression by inducing stabilization and nuclear accumulation of beta-catenin, which functions as a transcriptional activator after binding to transcription factors of the T-cell factor/lymphoid enhancer factor (TCF/LEF) family. Three different members of this family have been identified in Xenopus laevis thus far that differ in their ability to influence mesodermal differentiation and to activate expression of the Wnt target gene fibronectin. Here we report on the isolation and characterization of additional variants of XTCF-4. We show that the differential ability of these proteins and other members of the TCF family to activate target genes is neither due to preferential interaction with transcriptional cofactors of the groucho family or SMAD4 nor to different DNA binding affinities. Expression of these proteins in an epithelial cell line reveals differences in their ability to form a ternary complex with DNA and beta-catenin. Interestingly, formation of this ternary complex was not sufficient to activate target gene expression as previously thought. Our experiments identify two amino acid sequence motifs, LVPQ and SFLSS, in the central domain of XTCF-4 that regulate the formation of the DNA-TCF-beta-catenin complex or activation of target genes, respectively. Biochemical studies reveal that the phosphorylation state of these XTCF-4 variants correlates with their ability to form a ternary complex with beta-catenin and DNA but not to activate target gene expression. The described variants of XTFC-4 with their different properties in complex formation provide strong evidence that in addition to the regulation of beta-catenin stability the isoforms of TCF/LEF transcription factors and their posttranslational modifications define the cellular response of a Wnt/wingless signal.

Amino Acid Sequence↗
PubMed2000

Physical model for the spectroscopic analysis of cortical intrinsic optical signals.

We used Monte Carlo simulations and the diffusion approximation to estimate correction terms for the analysis of reflectance spectra of cortical intrinsic optical signals. These corrections depend on scattering and absorption properties, i.e. they are dependent on assumptions on the tissue blood content and oxygen saturation. The analysis was applied to reflectance spectra acquired during whisker barrel stimulation in the rat where attenuation spectra were converted to changes in oxygenated and deoxygenated haemoglobin concentration. The description of the experimental data as judged by the residual and sensitivity to variations of wavelength was considerably improved when the correction terms were included. Inclusion of the correction does have a considerable impact on the time course of deoxyhaemoglobin concentration changes. In contrast to the calculation without correction terms, there is no indication for an early increase in deoxyhaemoglobin ('early dip'). This finding might further current interpretation of the coupling between neuronal activation and oxygen extraction and supply.

Absorption↗
PubMed1997

A nitrite microsensor for profiling environmental biofilms.

A highly selective liquid membrane nitrite microsensor based on the hydrophobic ion-carrier aquocyanocobalt(III)-hepta(2-phenylethyl)-cobrynate is described. The sensor has a tip diameter of 10 to 15 (mu)m. The response is log-linear in freshwater down to 1 (mu)M NO(inf2)(sup-) and in seawater to 10 (mu)M NO(inf2)(sup-). A method is described for preparation of relatively large polyvinyl chloride (PVC)-gelled liquid membrane microsensors with a tip diameter of 5 to 15 (mu)m, having a hydrophilic coating on the tip. The coating and increased tip diameter resulted in more sturdy sensors, with a lower detection limit and a more stable signal than uncoated nitrite sensors with a tip diameter of 1 to 3 (mu)m. The coating protects the sensor membrane from detrimental direct contact with biomass and can be used for all PVC-gelled liquid membrane sensors meant for profiling microbial mats, biofilms, and sediments. Thanks to these improvements, liquid membrane sensors can now be used in complex environmental samples and in situ, e.g., in operating bioreactors. Examples of measurements in denitrifying, nitrifying, and nitrifying/denitrifying biofilms from wastewater treatment plants are shown. In all of these biofilms high nitrite concentrations were found in narrow zones of less than 1 mm.

Journal Article↗
PubMed1993

[Premature tracheoesophageal fistula as a complication after short- term intubation of the patient after craniocerebral trauma].

We have described a rare case of early tracheo-esophageal fistula after short-term intubation. 18-year old male patient was admitted to ICU after craniocerebral trauma. After 6 days of intubation the tracheo-esophageal fistula appeared. We suggest that tracheoesophageal fistula was caused by compression of the trachea by tracheostomies tube cuff, shock and poor general condition.

Adolescent↗
PubMed1992

Continuous quality improvement of Pap smears in an ambulatory care facility.

This article describes how the H. Claude Hudson Comprehensive Health Center (Los Angeles) implemented a continuous quality improvement program to reduce the unacceptably high rate of nonrepresentative Papanicolaou (Pap) smears (those lacking endocervical component). A review of the literature and telephone surveys indicated that the optimal Pap smear technique includes the use of a cervical cytobrush. Several cytobrushes were evaluated and one was chosen to be used facilitywide. Clinicians were given in-services on the proper cervical sampling techniques using the cytobrush. The rate of nonrepresentative Pap smears decreased approximately 12% during a five-month period; this has been attributed to uniform implementation of the cytobrush technique in nonpregnant patients, in-service education, and cooperative teamwork.

Clinical Laboratory Techniques↗
PubMed1990

[Esophagotracheal fistula as a complication of radiotherapy of lung cancer].

A case report is presented of a patient with lung cancer treated with chemotherapy followed by radiotherapy due to increasing dysphagia. A few months after radioterapy an esophago-tracheal fistula developed, which was diagnosed by a radiological contrast study and esophagofiberoscopy. Post mortem examination did not reveal malignant invasion of the fistula and surrounding tissues. It seems that the fistula was a late complication of radiotherapy.

Cobalt Radioisotopes↗
PubMedDate not supplied

Bone metastases in vulvar cancer: a rare metastatic pattern.

Bone metastases from a vulvar carcinoma are exceptionally rare with only five reported cases in the literature. We report on a patient who was initially treated with radical vulvectomy and bilateral inguinal lymphadenectomy for a vulvar cancer (pT2, pN2 (6/37), M0; G2). Due to a positive nodal status, adjuvant radiation of the vulva and the pelvis was performed additionally. The patient presented 4 months after initial therapy with severe pain in the right humeral shaft due to a pathologic fracture based on an osteoclastic metastasis. During osteosynthetic stabilization histologic and immunohistochemical stain gave evidence of a metastasis of the known vulvar carcinoma. Bone scan showed enhancements in both humeral heads as well as the right distal femur, whereas plain radiographs confirmed further metastases in all suspected areas. In conclusion, bone metastases should be considered in the differential diagnoses of unclear osseous pain in women with a history of vulvar cancer. Immunohistochemical examinations might be important to depict the epithelial character of the tissue and allude to the metastatic nature of such rare lesions. The atypical location should alert the physician to suspect distant metastasis, rather than locoregional disease.

Aged↗