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Biomedical subjects

H Fankhauser

Publications and source records attributed to H Fankhauser.

At least 37 records · Page 2Linked to original sources
PubMed1995

Growth of a mutant defective in a putative phosphoinositide-specific phospholipase C of Schizosaccharomyces pombe is restored by low concentrations of phosphate and inositol.

A mutant (plc1-1) of Schizosaccharomyces pombe unable to grow on a minimal medium containing high amounts of phosphate was selected. On yeast-extract agar its growth is temperature sensitive. Tests in liquid synthetic medium show that growth of the mutant is partially restored by lowering the phosphate and inositol concentrations in the growth medium. The growth defect is fully suppressed by a plasmid encoding a putative protein having the structural features of phosphoinositide-specific phospholipases C (PI-PLC). This protein, of 899 amino-acids, contains the characteristic X and Y domains found in all PI-PLCs of higher and lower eucaryotes and reveals, in addition, an EF-hand motif (putative Ca(2+)-binding site). Like the corresponding enzyme from Saccharomyces cerevisiae, the S. pombe PI-PLC is most similar to the delta form of PI-PLC isoenzymes. The cloned gene integrates at the plc1 site indicating that plc1 codes for a putative PI-PLC. Plc1 physically maps on the left arm of chromosome II between rad11 and mei3.

Amino Acid Sequence↗
PubMed1995

Life-threatening hemorrhagic diathesis due to disseminated intravascular coagulation during elective brain tumor surgery.

Disseminated intravascular coagulation (DIC) is an extremely rare complication during elective brain tumor surgery. We report the case of a life-threatening intraoperative hemorrhagic diathesis due to a fulminating DIC during the removal of a grade III parietooccipital astrocytoma in a patient with a history of three pulmonary embolisms. Intraoperatively, the patient required 13 U of blood, 9 U of fresh-frozen plasma, and 5.45 L of colloids and crystalloids (total volume infused during the procedure: 12.5 L). Bleeding persisted for 24 h and required further blood component therapy. Laboratory data support the diagnosis of DIC: decreased fibrinogen and platelet count, prolonged thrombin and prothrombin times, and the presence of fibrin monomers. With aggressive and swift treatment of the DIC, the patient survived with transient neurological worsening.

Blood Component Transfusion↗
PubMed1995

Idiopathic orbital inflammation (orbital inflammatory pseudotumour): an unusual cause of transient ischaemic attack.

A patient with idiopathic inflammation of the right orbit, established by biopsy, developed episodes of transient left sensorimotor hemiparesis. Neuroimaging showed intracranial extension of the disease with pronounced narrowing of the right internal carotid artery in its intracavernous portion. Oral cyclophosphamide induced gradual improvement. Transient ischaemic attack is rarely found in association with orbital disease and indicates possible intracranial extension.

Administration, Oral↗
PubMed1995

Biodistribution of boron sulfhydryl for boron neutron capture therapy in patients with intracranial tumors.

The biodistribution of boron sulfhydryl (BSH) was evaluated for boron neutron capture therapy of brain tumors. A selective boron delivery to the neoplasm is a prerequisite for successful therapy. The uptake of BSH after intravenous administration was analyzed in neoplastic and normal tissues in 61 patients undergoing craniotomies for intracranial tumors. The patients received 10 to 100 mg of BSH/kg (5-50 mg of 10B/kg) body weight, 2 to 72 hours before surgery. The tumor boron concentrations ranged from 0.2 ppm (micrograms/g) in a low-grade glioma to 19.5 ppm in a high-grade glioma. The tumor to blood boron ratio rose above 1 in 15 of 24 high-grade intracerebral tumors, 18 h or more after BSH infusion. The boron concentration in high-grade tumors was heterogeneous. Low-grade intracerebral tumors showed a low boron concentration with a tumor to blood ratio below 1. Extracerebral tumors, mainly meningiomas, showed boron concentrations comparable with high-grade tumors, with a tumor to blood ratio above 1 in 10 of 17 patients. The boron concentrations in skin and muscle compared roughly with the blood values. Boron did not enter normal brain in any significant amount. In high-grade tumors, tumor to brain ratios were above 2. Low boron concentrations in normal brain make BSH safe for a Phase I normal tissue tolerance study. Computed tomographic contrast enhancement was evaluated to tumor boron uptake for 30 patients. Tumor enhancement on computed tomography does not permit the prediction of individual tumor boron concentrations; however, the absence of a contrast enhancement was always associated with low boron uptake.

Adult↗
PubMed1994

Thiamine-repressible genes in Schizosaccharomyces pombe are regulated by a Cys6 zinc-finger motif-containing protein.

Our previous genetic data indicate that the product of the Schizosaccharomyces pombe thi1 gene acts as an activator of several thiamine-repressible genes which are involved in the control of thiamine metabolism [Schweingruber et al., Genetics 130 (1992) 445-449; Zurlinden and Schweingruber, Gene 117 (1992) 141-143]. In this communication, we report the cloning and sequencing of thi1 and show that it carries an open reading frame which translates into a 775-amino-acid protein with the characteristics of a Cys6 zinc-finger-motif-containing transcription factor, as typified by Saccharomyces cerevisae GAL4. We, therefore, suggest that the thi1-encoded protein binds to upstream activator sequences of thiamine-repressible genes.

Amino Acid Sequence↗
PubMed1994

Spinal tumour due to primary hyperparathyroidism causing sciatica: case report.

We report a unilateral intraspinal cyst-like lesion adjacent to the lamina and facet joint at the L4-L5 level producing sciatica. Histological examination revealed multinucleate giant cells suggesting a brown tumour. Further studies disclosed primary hyperparathyroidism, whose first manifestation was the lumbar nerve root compression. Previous cases of compression of neural structures by spinal brown tumours are reviewed and a radiological differential diagnosis is presented.

Bone Neoplasms↗
PubMed1994

Extreme lateral lumbar disc herniation: clinical presentation in 178 patients.

A retrospective analysis of clinical characteristics of 178 consecutive patients with extreme lateral lumbar disk herniation, amongst 3047 patients operated on for herniated lumbar disc, is presented. The level specific incidence of extreme lateral disc herniation (ELLDH) ranged from a low of 4.5% at L4-5 to peak of 17.4% at L3-4 although the largest number of ELLDH occurred at L4-5 and L5-S1 for a total number of 139 cases (78.1%). 43.6% of all L3 radiculopathies were caused by an L3-4 ELLDH, whereas only 4.4% of all L5 radiculopathies were caused by an L5-S1 ELLDH. Leg pain, either of the sciatic or the femoral type, was the first and dominant clinical symptom of radiculopathy, but pain radiation occurred not always in the appropriate dermatomal segment. ELLDH at upper levels (L2-3 and L3-4) caused usually none or only minor low back signs (76.2%), whereas ELLDH at lower levels more often caused moderate or major lumbar symptoms and signs (59.6%). Positive femoral nerve traction test with upper ELLDH showed a high frequency (84.4%) and reliability and is therefore an important clinical parameter in this situation. Motor deficits occurred more often (78.8%) than sensory deficits (46.6%), were usually of the monoradicular type and were therefore a more reliable clinical sign than sensory disturbances.

Adolescent↗
PubMed1994

Robot for CT-guided stereotactic neurosurgery.

At the 1989 meeting of the World Society for Stereotactic and Functional Neurosurgery in Maebashi, the authors presented the concept and design of a stereotactic neurosurgical robot. The first prototype has now been completed and has entered clinical testing. The characteristics are as follows. The robot is positioned behind the CT scan and operates inside the CT gantry. It is linked to the CT table and moves freely along its longitudinal axis, allowing for intraoperative scanning at any cranial level. The patient's body rests on the CT table, but the stereotactic headframe is fixed to the robot, allowing precise measurements of the head position under stereotactic conditions. During scanning, each CT slice appears immediately on the robotic workstation for selection of target and trajectory. In addition to the tool for automatic penetration of the skin, skull, and meninges, the robot is able to handle two other stereotactic instruments and to perform a complete stereotactic procedure without physical intervention by the physician. So far, depth electrodes and biopsy instruments have been developed for use by the robot. Since all parts of the robot were designed solely for stereotactic neurosurgery, integration of safety aspects was optimized. The first operations using an aspiration biopsy probe were successfully performed on 2 patients with malignant intracerebral cystic lesions on September 4, 1993.

Humans↗
PubMed1994

Assessment of MR image deformation for stereotactic neurosurgery using a tagging sequence.

A tagging sequence is used to assess MR image deformations before a stereotactic neurosurgical procedure, in a test model and in two patients. This pulse sequence super-imposes narrow parallel orthogonal tag lines on an image, which can be used as an internal reference frame. Image deformation is directly related to surface area variations in the squares produced by the tagging-sequence pulses. Small spatial deformations of the tags can be detected on the images used for measuring stereotactic-target spatial coordinates. A threshold of 2 SD guarantees that the distortion is smaller than one pixel.

Biopsy↗
PubMed1992

Osseous metastases from a benign intraventricular meningioma. Case report.

The authors report a case of a 6 month-old male presenting with increasing head circumference and a large benign intraventricular meningioma which was grossly removed at the initial surgery. Twenty-four months later, the patient returned with subcutaneous and osseous metastatic lesions at the site of the previous craniotomy, revealing the same histology as the original tumour. The presentation, pathology and management of this unique case are discussed.

Cerebral Ventricle Neoplasms↗
PubMed1992

Microsurgical anatomy and operative technique for extreme lateral lumbar disc herniations.

The anatomy of the lateral aspect of the lumbar spine and our lateral microsurgical technique for extreme lateral lumbar disc herniations (ELLDH) is described. This study was based on the microdissection of 4 cadavers, on the morphometric evaluation of these as well as 6 dried cadaver spines and 8 lumbar CT scans, and on the use of this technique on over 200 cases. Level dependent changes in the posterior arch cause a shift of the disc space distally relative to the facet joint, an increasing amount of bone to overlie the intervertebral foramen, and a decreasing amount of working space within the exposure in the caudal direction. Therefore, more bone removal from the lateral aspect of the pars interarticularis and supero-lateral aspect of the facet joint is required in the lower lumbar spine. When the exposed ligamentum flavum is resected, the dorsal root ganglion is seen and access to the herniation and disc space is achieved. Level dependent changes in the pedicles and transverse processes lead to an alteration in the course and relationships of the nerves, thereby influencing the pathophysiology of and surgical technique for the ELLDH. The operative target is the lateral aspect of the pars interarticularis and not the intertransverse space as has been previously described. Our techniques allows for the early identification of the nerve with minimal risks of injury to it, to the adjacent vessels and to the structural integrity of the facet joint and pars interarticularis.

Humans↗
PubMed1992

Isolation and characterization of regulatory mutants from Schizosaccharomyces pombe involved in thiamine-regulated gene expression.

Mutants from Schizosaccharomyces pombe deficient in the regulation of thiamine-repressible acid phosphatase have been isolated. Mutants expressing derepressed levels of the enzyme in the presence and absence of thiamine map in three genes, tnr1, tnr2 and tnr3. mRNA levels of the pho4 gene (coding for thiamine repressible acid phosphatase) and another thiamine-regulatable gene, thi3 (coding for a thiamine biosynthetic enzyme and corresponding to nmt1) are constitutively synthesized in the mutants. The mutants also exhibit constitutive thiamine transport which is thiamine repressible in wild type. The tnr3 mutants reveal a 10-20-fold higher intracellular thiamine level than tnr1 and tnr2 mutants and wild type. Mutants expressing repressed levels of thiamine-repressible acid phosphatase map in gene thi1. No or little amounts of pho4- and nmt1-specific mRNA can be detected. These mutants are impaired in thiamine uptake and are thiamine auxotrophic due to the inability to synthesize the thiazole moiety of the thiamine molecule. All tested tnr and thi1 alleles are recessive, and thi1 mutations are epistatic over tnr mutations. We assume that the thi1 and tnr genes are involved in thiamine-mediated transcription control.

Acid Phosphatase↗
PubMed1992

A software tool to assist placement of multiple parallel brachytherapy sources using the Brown-Roberts-Wells stereotactic system.

The authors present a simple software written in Turbo Pascal which allows placement of multiple parallel sources for interstitial brachytherapy using the Brown-Roberts-Wells CT stereotactic system. The user can choose any direction in space, independently from the CT plane, and any number of linear sources arranged on one or more hypothetical cylinders of variable radius. The sources can be rotated on the cylinder in order to avoid critical structures. This small program runs on any IBM compatible computer.

Brachytherapy↗
PubMed1991

Cyst of the ligamentum flavum: report of six cases.

Six cases of cyst of the ligamentum flavum with compression of a lumbar nerve root are reported. All patients exhibited recurrent back pain and sciatica. Investigation included computed tomography, myelography, or both. The correct diagnosis was reached before operation in only half the patients. High-resolution computed tomography performed in the four last patients outlined the cystic lesion with its low-density center. Surgical excision was performed in all patients. Microscopic examination showed a dense fibrous cyst arising from the ligamentum flavum. The lumen contained myxoid or necrotic material, but no epithelial lining. Cysts of the ligamentum flavum must be considered in the differential diagnosis of causes of sciatica. A firm radiological diagnosis may, at present, still require myelography combined with high-resolution computed tomography. Differentiation from synovial or ganglion cysts of the spine is discussed.

Aged↗