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Biomedical subjects

M Rieger

Publications and source records attributed to M Rieger.

At least 55 records · Page 3Linked to original sources
PubMed2000

Computer-assisted neurosurgery by using a noninvasive vacuum-affixed dental cast that acts as a reference base: another step toward a unified approach in the treatment of brain tumors.

OBJECT: The purpose of the study was to evaluate the use of the Vogele-Bale-Hohner (VBH) mouthpiece, which is attached to the patient's upper jaw by negative pressure, for patient-image registration and for tracking the patient's head during image-guided neurosurgery. METHODS: A dynamic reference frame (DRF) is reproducibly mounted on the mouthpiece. Reference points, optimally distributed and attached to the mouthpiece, are used for registration in the patient's absence on the day before surgery. In the operating room, the mouthpiece and DRF are precisely repositioned using a vacuum, and the patient's anatomical structures are automatically registered to corresponding ones on the image. Experimental studies and clinical experiences in 10 patients confirmed repeated (rigid body) localization accuracy in the range of 0 to 2 mm, throughout the entire surgery despite movements by the patient. CONCLUSIONS: Because of its noninvasive, rigid, reliable, and reproducible connection to the patient's head, the VBH vacuum-affixed mouthpiece grants the registration device an accuracy comparable to invasive fiducial markers.

Adult↗
PubMed1999

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana.

The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

Animals↗
PubMed1999

Locked lateral patellar dislocation: a rare case of irreducible patellar dislocation requiring open reduction.

Irreducible patellar dislocations are rare injuries, but those that do occur are mainly directed intra-articularly. In this case, a 53-year-old woman sustained a locked lateral patellar dislocation when falling from a chair. A preoperative CT-scan revealed bony avulsions at the insertion of the vastus medialis muscle, the medical retinaculum, and partial disruption of the ligamentum patellae from the apex patellae. Open reduction was necessary and the torn structures were reattached with anchor systems and sutures. Postoperative management included intensive physiotherapy. At 1 year after surgery, the patient was without swelling or pain and had a normal gait, but flexion was restricted to 120 degrees. All postoperative radiographs showed the patella correctly placed in the femoral groove.

Accidental Falls↗
PubMed1999

The Saccharomyces cerevisiae CWH8 gene is required for full levels of dolichol-linked oligosaccharides in the endoplasmic reticulum and for efficient N-glycosylation.

The Saccharomyces cerevisiae mutant cwh8 was previously found to have an anomalous cell wall. Here we show that the cwh8 mutant has an N -glycosylation defect. We found that cwh8 cells were resistant to vanadate and sensitive to hygromycin B, and produced glycoforms of invertase and carboxypeptidase Y with a reduced number of N -chains. We have cloned the CWH8 gene. We found that it was nonessential and encoded a putative transmembrane protein of 239 amino acids. Comparison of the in vitro oligosaccharyl transferase activities of membrane preparations from wild type or cwh8 Delta cells revealed no differences in enzyme kinetic properties indicating that the oligosaccharyl transferase complex of mutant cells was not affected. cwh8 Delta cells also produced normal dolichols and dolichol-linked oligosaccharide intermediates including the full-length form Glc3Man9GlcNAc2. The level of dolichol-linked oligosaccharides in cwh8 Delta cells was, however, reduced to about 20% of the wild type. We propose that inefficient N -glycosylation of secretory proteins in cwh8 Delta cells is caused by an insufficient supply of dolichol-linked oligosaccharide substrate.

Amino Acid Sequence↗
PubMed1999

Internal mammary vessels as a model for power Doppler imaging of recipient vessels in microsurgery.

The aim of this interdisciplinary study was to evaluate power Doppler imaging as a method of collecting reliable preoperative data concerning the diameters and topography of exemplary internal mammary vessels as recipient vessels in reconstructive microsurgery. Thirteen female patients (range, 37 to 58 years; mean, 45.6 years) were examined preoperatively with power Doppler imaging from the first to the fifth intercostal space parasternally and bilaterally. These data are compared with measurements obtained intraoperatively in each individual. Mean velocity in the artery in the second intercostal space on the right side is 47.11 cm/sec (range, 15 to 90 cm/sec) and on the left side is 42.25 cm/sec (range, 18 to 95 cm/sec). Mean velocity in the vein in the second intercostal space on the right side is 17.80 cm/sec (range, 10 to 30 cm/sec) and on the left side is 13.06 cm/sec (range, 5.3 to 32 cm/sec). The topographic results are in close agreement with intraoperative measurements and previous anatomical studies. Sonographic preoperative data of arteries (mean, 1.88 mm) show slightly smaller diameters than intraoperative measurements (mean, 2.08 mm), whereas veins show slightly larger diameters in sonography (mean, 2.33 mm) than intraoperatively (mean, 2.12 mm). Mean sonographic diameter of artery ranges from 2.14 mm (second intercostal space) to 1.46 mm (fifth intercostal space), of the vein from 2.76 (second intercostal space) to 1.25 mm (fifth intercostal space). In one case, a vein was not detectable. This noninvasive method leads to confirmation of the preoperative choice of the optimal recipient vessels for free tissue transfer and does not harm the patient.

Adult↗
PubMed1998

Analysis of 1.9 Mb of contiguous sequence from chromosome 4 of Arabidopsis thaliana.

The plant Arabidopsis thaliana (Arabidopsis) has become an important model species for the study of many aspects of plant biology. The relatively small size of the nuclear genome and the availability of extensive physical maps of the five chromosomes provide a feasible basis for initiating sequencing of the five chromosomes. The YAC (yeast artificial chromosome)-based physical map of chromosome 4 was used to construct a sequence-ready map of cosmid and BAC (bacterial artificial chromosome) clones covering a 1.9-megabase (Mb) contiguous region, and the sequence of this region is reported here. Analysis of the sequence revealed an average gene density of one gene every 4.8 kilobases (kb), and 54% of the predicted genes had significant similarity to known genes. Other interesting features were found, such as the sequence of a disease-resistance gene locus, the distribution of retroelements, the frequent occurrence of clustered gene families, and the sequence of several classes of genes not previously encountered in plants.

Arabidopsis↗
PubMed1998

Sunscreens.

Explore the source record for details and available documents.

Humans↗
PubMed1998

Temporary extracorporeal membrane oxygenation in the treatment of acute traumatic lung injury.

PURPOSE: To report two cases of acute life-threatening traumatic lung injury, who required temporary extracorporeal veno-venous membrane oxygenation (ECMO), and airlifting to a level I trauma centre. CLINICAL FEATURES: The first patient suffered a severe motor vehicle accident with prolonged entrapment in the wreckage. After extrication, tracheal intubation, and fluid resuscitation, respiratory therapy failed to result in sufficient ventilation and oxygenation within the first hours after trauma due to severe lung contusion and intraparenychmal bleeding. The second patient was hit by a falling tree and suffered isolated blunt chest trauma. Due to pulmonary contusions and tracheal rupture, subsequent ventilation management was limited by extensive mediastinal emphysema. Both patients were airlifted to a University Hospital and placed on ECMO for four and six days without complications, respectively. After emergency surgery and 21 and 26 days intensive care treatment, both patients were transferred to a general ward, and discharged from the hospital with full recovery. CONCLUSION: These cases demonstrate the role of ECMO in the treatment of traumatic respiratory failure. If ventilatory support strategies fail due to severe lung or airway injury, ECMO may be an option for the temporary management of gas exchange in trauma patients.

Accidents, Traffic↗
PubMed1998

[Ruptures of the medial gastrocnemius muscle: diagnosis with high resolution ultrasound].

AIM: Evaluation of high resolution ultrasound to diagnose rupture of the medial head of gastrocnemius muscle in patients with uncharacteristic calf pain. METHOD: 66 patients with clinically unclear calf pain were examined in a prospective study. RESULTS: Out of 66 patients, 51 showed sonographic criteria of a partial rupture of the medial gastrocnemius head. 47 ruptures were located in musculotendineus transition zone. CONCLUSION: High resolution sonography detect minimal lesions of the medial gastrocnemius muscle in patients with clinically uncharacteristic calf pain.

Adult↗
PubMed1998

Idiopathic thrombocytopenic purpura presenting in a high school football player: a case report.

OBJECTIVE: To alert athletic trainers to the signs and symptoms of idiopathic thrombocytopenic purpura and its clinical presentation in order to facilitate immediate intervention. BACKGROUND: Idiopathic thrombocytopenic purpura (ITP), also known as immune thrombocytopenic purpura, is a hemorrhagic disorder that is primarily immunologic in origin but is sometimes triggered by viral infection in children. It has also been associated with heroin and quinine drug use. A reduced platelet count can result in mucosal or deep tissue bleeding, or both, and most importantly, intracranial bleeding. Because football is a collision sport, it is imperative that any player presenting with ITP-type symptoms be removed immediately from all contact and referred to a physician. DIFFERENTIAL DIAGNOSIS: Leukemia, aplastic anemia, drug side effects, vitamin deficiency, kidney failure, infection, multiple contusions. TREATMENT: The traditional first-line treatment consists of corticosteroid medication and time and removal from all physical activities until the blood platelet count is normal and controlled. In quinine-induced ITP, discontinuation of the drug and bedrest are recommended to reduce the risk of major hemorrhage for a 12-to 14-hour period in order to allow the quinine to clear the system and the platelet count to return to normal. UNIQUENESS: ITP's presentation needs to be differentiated from other disorders. Incorrect diagnosis could seriously jeopardize the athlete, who could develop intracranial and internal bleeding. CONCLUSIONS: Recognition of the signs and symptoms associated with ITP is essential to prevent further participation by the athlete. Immediate intervention is needed to determine the severity and to institute appropriate treatment.

Journal Article↗
PubMed1998

Identification of mutations in the canine von Willebrand factor gene associated with type III von Willebrand disease.

In humans, type III von Willebrand disease is caused by deletions or nonsense mutations. In dogs, the underlying genetic defects have not been determined yet. We searched for the genetic defect in four related type III deficient Dutch Kooiker dogs obtained from one breeder. Mutation analysis was performed with total RNA isolated from platelets or whole blood. The complete coding region of the vWf gene was amplified by RT-PCR and sequenced by the cycle sequencing technique. Two homozygous mutations were found, a G-->A transition at the first position of the donor splice site sequence of intron 16 (TGgtaagt-->TGataagt) and a missense mutation at nt 208 (G-->A) (1). The splice site defect resulted in the generation of a transcript containing 46bp of intron sequence and a stop codon at amino acid position 729 in the propeptide region of the vWf protein. This mutation seems to be causative for the type III phenotype. The effect of the missense mutation in exon 3 which causes a change of Val to Ile on the vWD phenotype is unclear. Probably, this transition represents a polymorphism occurring in Dutch Kooiker dogs. Both mutations were not present in 5 healthy mongrel dogs.

Animals↗
PubMed1997

Sequence analysis of 203 kilobases from Saccharomyces cerevisiae chromosome VII.

The nucleotide sequences of five major regions from chromosome VII of Saccharomyces cerevisiae have been determined and analysed. These regions represent 203 kilobases corresponding to approximately one-fifth of the complete yeast chromosome VII. Two fragments originate from the left arm of this chromosome. The first one of about 15.8 kb starts approximately 75 kb from the left telomere and is bordered by the SK18 chromosomal marker. The second fragment covers the 72.6 kb region between the chromosomal markers CYH2 and ALG2. On the right chromosomal arm three regions, a 70.6 kb region between the MSB2 and the KSS1 chromosomal markers and two smaller regions dominated by the KRE11 marker and another one in the vicinity of the SER2 marker were sequenced. We found a total of 114 open reading frames (ORFs), 13 of which were completely overlapping with larger ORFs running in the opposite direction. A total of 44 yeast genes, the physiological functions of which are known, could be precisely mapped on this chromosome. Of the remaining 57 ORFs, 26 shared sequence homologies with known genes, among which were 13 other S. cerevisiae genes and five genes from other organisms. No homology with any sequence in the databases could be found for 31 ORFs. Furthermore, five Ty elements were found, one of which may not be functional due to a frame shift in its Ty1B amino acid sequence. The five chromosomal regions harboured five potential ARS elements and one sigma element together with eight tRNA genes and two snRNAs, one of which is encoded by an intron of a protein-coding gene.

Chromosome Mapping↗
PubMed1997

Scanning electron microscopic study of primary fracture healing.

Scanning electron microscopy was used to study primary bone healing. This technique, essential for a three-dimensional description, has provided excellent visualization and revealed new aspects of the micromorphology of primary bone healing. Calcifying collagen bundles were responsible for the first mechanical stability, bone healing took place later in fracture vaults generated by compressed fracture fragments which were partially nonvital. A direct bridging of the fracture fragments by sprouting osteons was not observed.

Animals↗
PubMed1996

A novel complex of nucleoporins, which includes Sec13p and a Sec13p homolog, is essential for normal nuclear pores.

In a genetic screen for nucleoporin-interacting components, a novel nuclear pore protein Nup84p, which exhibits homology to mammalian Nup107p, was isolated. Nup84p forms a complex with five proteins, of which Nup120p, Nup85p, Sec13p, and a Sec13p homolog were identified. Upon isolation of Sec13p-ProtA, nucleoporins were still associated, but the major copurifying band was a 150 kDa protein, showing that Sec13p occurs in two complexes. Disruption of any of the genes encoding Nup84p, Nup85p, or Nup120p caused defects in nuclear membrane and nuclear pore complex organization, as well as in poly(A)+ RNA transport. Thus, the Nup84p complex in conjunction with Sec13-type proteins is required for correct nuclear pore biogenesis.

Amino Acid Sequence↗
PubMed1996

The yeast Pan2 protein is required for poly(A)-binding protein-stimulated poly(A)-nuclease activity.

The removal of the mRNA poly(A) tail in the yeast Saccharomyces cerevisiae is stimulated by the poly(A)-binding protein (Pab1p). A large scale purification of the Pab1p-stimulated poly(A) ribonuclease (PAN) identifies a 76-kDa and two 135-Da polypeptides as candidate enzyme subunits. Antibodies against the Pan1p protein, which is the minor 135-kDa protein in the preparation, can immunodeplete Pan1p but not PAN activity. The protein sequence of the major 135-kDa protein, Pan2p, reveals a novel protein that was also found in the previously reported PAN purification (Sachs, A. B., and Deardorff, J. A. (1992) Cell 70, 961-973). Deletion of the non-essential PAN2 gene results in an increase of the average length of mRNA poly(A) tails in vivo, and a loss of Pab1p-stimulated PAN activity in crude extracts. These data confirm that Pan2p and not Pan1p is required for PAN activity, and they suggest that ribonucleases other than the Pab1p-stimulated PAN are capable of shortening poly(A) tails in vivo.

Amino Acid Sequence↗
PubMed1995

Offsetting effects of reduced root hydraulic conductivity and osmotic adjustment following drought.

Root hydraulic conductivity (L(p)) and leaf osmotic potential at full turgor (Psi(pi,o)) were measured in young, drought-stressed and nonstressed peach (Prunus persica (L.) Batsch), olive (Olea europaea L.), citrumelo (Poncirus trifoliata Raf. x Citrus paradisi Macf.) and pistachio (Pistachia integerrima L.). Drought stress caused a 2.5- to 4.2-fold reduction in L(p), depending on species, but Psi(pi,o) was reduced only in citrumelo and olive leaves by 0.34 and 1.4 MPa, respectively. No differences existed in L(p) among species for nonstressed plants. A simple model linking L(p) to osmotic adjustment through leaf water potential (Psi) quantified the offsetting effects of reduced L(p) and osmotic adjustment on the hypothetical turgor pressure difference between drought-stressed and nonstressed plants (DeltaPsi(p)). For olive, the 2.5-fold reduction in L(p) caused a linear decrease in DeltaPsi(p) such that the effect of osmotic adjustment was totally negated at Psi = -3.2 MPa. Thus, no stomatal closure would be required to maintain higher turgor in drought-stressed olive plants than in nonstressed plants over their typical diurnal range of Psi (-0.6 to -2.0 MPa). For citrumelo, osmotic adjustment was offset by reduced L(p) at Psi approximately -0.9 MPa. Unlike olive, stomatal closure would be necessary to maintain higher turgor in drought-stressed citrumelo plants than in nonstressed plants over their typical diurnal range of Psi (0 to -1.5 MPa). Regardless of species or the magnitude of osmotic adjustment, my analysis suggests that a drought-induced reduction in L(p) reduces or eliminates turgor maintenance through osmotic adjustment.

Journal Article↗
PubMed1994

Complete DNA sequence of yeast chromosome II.

In the framework of the EU genome-sequencing programmes, the complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome II (807 188 bp) has been determined. At present, this is the largest eukaryotic chromosome entirely sequenced. A total of 410 open reading frames (ORFs) were identified, covering 72% of the sequence. Similarity searches revealed that 124 ORFs (30%) correspond to genes of known function, 51 ORFs (12.5%) appear to be homologues of genes whose functions are known, 52 others (12.5%) have homologues the functions of which are not well defined and another 33 of the novel putative genes (8%) exhibit a degree of similarity which is insufficient to confidently assign function. Of the genes on chromosome II, 37-45% are thus of unpredicted function. Among the novel putative genes, we found several that are related to genes that perform differentiated functions in multicellular organisms of are involved in malignancy. In addition to a compact arrangement of potential protein coding sequences, the analysis of this chromosome confirmed general chromosome patterns but also revealed particular novel features of chromosomal organization. Alternating regional variations in average base composition correlate with variations in local gene density along chromosome II, as observed in chromosomes XI and III. We propose that functional ARS elements are preferably located in the AT-rich regions that have a spacing of approximately 110 kb. Similarly, the 13 tRNA genes and the three Ty elements of chromosome II are found in AT-rich regions. In chromosome II, the distribution of coding sequences between the two strands is biased, with a ratio of 1.3:1. An interesting aspect regarding the evolution of the eukaryotic genome is the finding that chromosome II has a high degree of internal genetic redundancy, amounting to 16% of the coding capacity.

Base Composition↗