Biomedical subjects

C Fankhauser

Publications and source records attributed to C Fankhauser.

42 records · Page 3Linked to original sources

PubMed1990

Myoinositol gets incorporated into numerous membrane glycoproteins of Saccharomyces cerevisiae; incorporation is dependent on phosphomannomutase (sec53).

We recently described a 125 kd membrane glycoprotein in Saccharomyces cerevisiae which is anchored in the lipid bilayer by an inositol-containing phospholipid. We now find that when S. cerevisiae cells are metabolically labeled with [3H]myoinositol, many glycoproteins become labeled more strongly than the 125 kd protein. Myoinositol is attached to these glycoproteins as part of a phospholipid moiety which resembles glycophospholipid anchors of other organisms. Labeling of proteins with [3H]myoinositol for short times and in secretion mutants blocked at various stages of the secretory pathway shows that these phospholipid moieties can be added to proteins in the endoplasmic reticulum and that these proteins are transported to the Golgi by the regular secretory pathway. sec53, a mutant which cannot produce GDP-mannose at 37 degrees C, does not incorporate myoinositol or palmitic acid into membrane glycoproteins at this temperature, suggesting that GDP-mannose is required for the biosynthesis of these phospholipid moieties. All other secretion and glycosylation mutants tested add phospholipid moieties to proteins normally.

Inositol↗

PubMed1989

The mitochondrial targeting function of randomly generated peptide sequences correlates with predicted helical amphiphilicity.

A pool of oligonucleotides encoding a start methionine and nine random amino acids was inserted at the 5'-end of the gene for the yeast cytochrome oxidase subunit IV lacking its own mitochondrial targeting sequence. Approximately one-quarter of the randomly generated sequences targeted subunit IV to its correct intramitochondrial location in vivo. Sequence analysis of 89 randomly generated sequences showed that their efficiencies as mitochondrial targeting signals correlated with the potential to fold into an amphiphilic alpha-helix. Functional targeting sequences were enriched in arginine and isoleucine residues but contained few aspartate, glutamate, and proline residues. Nonfunctional sequences predicted to have significant helical amphiphilicity often had at least one acidic or multiple helix-breaking residues that would be expected to interfere with targeting functioning. These results support the hypothesis that the signal for targeting a protein into the mitochondrial matrix is usually a positively charged amphiphilic helix.

Amino Acid Sequence↗

PubMed1989

Steroids in rhinoplasty.

A prospective double-blind randomized pilot study was performed to test the benefits of steroids versus placebo in controlling edema and ecchymosis in rhinoplasty within the immediate postoperative period. Thirty consecutive patients who underwent rhinoplasty with osteotomies were entered into the study. Sixteen patients received 10 mg of intravenous dexamethasone before the procedure and 14 patients received placebo. All rhinoplasties were performed by residents under the supervision of staff otolaryngologists. A 4-point scale was used to assess the extent of periorbital edema and ecchymosis at 24 hours postoperatively. A one-time bolus of 10 mg of dexamethasone was beneficial in decreasing edema and ecchymosis in rhinoplasty. This benefit was demonstrated statistically (p less than .005). No complications were attributed to the administration of dexamethasone.

Adolescent↗

PubMed1984

Prospective crossover evaluation of four methods of clinical management of tinnitus.

This article summarizes data obtained from 34 tinnitus-afflicted patients who participated in and completed a prospective crossover evaluation of four methods of clinical management of tinnitus. The methods included a 2-week trial with each of the following: a tinnitus masker, a tinnitus instrument (a combination device consisting of a tinnitus masker and a hearing aid), a hearing aid, and conventional environmental controls. The relative effectiveness of each method of treatment was assessed by interview. The data presented summarize respondents' preferences for each method of treatment. Use of a tinnitus masker, tinnitus instrument, and hearing aid is related to stability of auditory thresholds. Comments are made on our experience with clinical management of the patient afflicted with tinnitus, and observations are offered on continued investigation in this area.

Adult↗

PubMedDate not supplied

Semaphorin III can induce death in sensory neurons.

Semaphorin III has been described to function as a guidance molecule directing growing axons to their target. However, its effect on the neuron cell body has not been characterized. Semaphorin III has a highly dynamic expression pattern, which generally corroborates a chemorepellent guidance function, but also suggests additional functions, different from axon guidance. A number of studies show that some sensory neurons are eliminated, while their axons are still pathfinding. In this study we have investigated whether Semaphorin III also influences the survival of sensory neurons. We here present evidence that Semaphorin III can function in vitro as selective death factor for NGF-dependent sensory neurons. Semaphorin III induces a type of cell death that is characterized by slow onset, cell body shrinking, nuclear condensation, and TUNEL-positive staining of dying neurons. These are all hallmarks of neuronal apoptosis. We also show evidence that neurons can modulate the response to Semaphorin III. The novel function described here may also be relevant in vivo, contributing to active elimination of neurons during development or after injury.

Animals↗

PubMedDate not supplied

Biomechanical evaluation of the less invasive stabilization system for the internal fixation of distal femur fractures.

OBJECTIVE: Comparison between a Less Invasive Stabilization System (LISS) using monocortical screws with angular stability and two conventional plate systems Condylar Buttress Plate (CBP) and Dynamic Condylar Screw (DCS) for the treatment of distal femoral fractures with respect to biomechanical properties. DESIGN: Biomechanical study using paired cadaver femurs. In Test Configuration 1 (distal test), a ten-millimeter gap at the diaphysis-metaphysis junction simulates a supracondylar femoral fracture. Test Configuration 2 (proximal test) has the same configuration, but the gap was cut in the isthmic region. Proximal and distal plate ends were fixed to corresponding cortical bone fragments in both tests. Optical displacement transducers served to quantify the system's ability to withstand a stepwise increased load. Reversible (deflection) and irreversible deformation (subsidence) of the bone-plate construct was investigated. RESULTS: In Test Configuration 1, LISS showed less irreversible deformation in 72 percent of the left-right comparisons. No correlation between bone mineral density, cross-section area of bones and the measured response of the construct under load was found between pairs. In Test Configuration 2, 83 percent of the left-right comparisons showed less permanent deformation but a higher elastic deformation for LISS. CONCLUSIONS: These results suggest an enhanced ability to withstand high loads when using the monocortical screw fixation technique with angular stability. A higher elastic deformation of LISS compared with conventional plating systems in distal femoral fractures can be explained by the lower bending stiffness caused by different design and material properties.

Biomechanical Phenomena↗