Search PubMed⌕ Search

Biomedical subjects

U Fischer

Publications and source records attributed to U Fischer.

At least 181 records · Page 10Linked to original sources
PubMed1996

[Contrast medium assisted dynamic MR-mammography after diagnostic and therapeutic interventions on the breast].

In a retrospective study, the authors evaluated the signal behavior of 150 patients after intervention in the breast (40 fine-needle biopsies, 10 core biopsies, 50 open biopsies, 50 tumor-ectomies with additional irradiation therapy). The MR imaging was performed on 1.5-Tesla whole-body scanners using T1-WI GRE sequences in 2D FLASH technique before and 5 times after i.v. application of 0.1 mmol gadopentetate-dimeglumine per kg body weight. There was no signal enhancement after fine-needle biopsy. Hematoma due to core biopsy caused signal increase in every 5th patient. Enhancement after open biopsy was no more visible 6 months postoperatively. 12 months after tumorectomy and radiation therapy, most patients showed no more signal enhancement. In conclusion, MR mammography can be performed after fine-needle biopsy without problems. In case of core biopsy, hematoma should be excluded by sonography before. MR mammography should not be performed within 6 months after open biopsy, or within 12 months after tumorectomy and radiation therapy.

Biopsy↗
PubMed1996

[Indications for dental-CT. Case reports].

Based on case reports, common indications for dental computed tomography are demonstrated and typical findings are analysed. From a group of 110 patients who had a reformatted computed tomography of the maxilla and mandibular, 10 typical cases were chosen as examples and are presented with a detailed description of the findings. The most important indication was the analysis of the morphology of the alveolar ridge needed in presurgical planning for osseointegrated implants as well as in special cases of postsurgical control. Apart from implantology, the method could be used in cases of mandibular cysts and bony destructions. In conclusion, dental computed tomography has become established mainly in implantology. It can provide valuable results in cases where a demonstration of the bone in all dimensions and free of overlappings and distortions is needed.

Adult↗
PubMed1996

[Neuroendocrine differentiated carcinoma of the uterine cervix].

Cervical neuroendocrine carcinomas (CNC) are rare tumors. The term includes the cervical carcinoid, the small cell (oat-cell) carcinoma and the primitive neuroectodermal tumor (PNET). Between 1979 and 1993 eight CNC out of 788 cervical carcinomas were identified by conventional light microscopy and immunohistochemistry. Three tumors were small cell carcinomas with positive staining for NSE (6/8 tumors) and chromogranin A (2/8). In one case a PNET was diagnosed by identifying rosette like structures and negative immunohistochemistry for neuroendocrine markers. Two patients (including PNET) died of disease 3.1 (1.3 to 4.8) years after diagnosis. The others showed no evidence of disease after a mean follow up to 4.4 years. Three of them got pelvic radiation postoperatively. Four tumors showed foci of squamous cell carcinoma [3] and adenocarcinoma [2]. There is no evidence, that these foci influence the prognosis on CNC. Therefore, it is important to recognize the neuroendocrine component, as this type of carcinoma requires special therapeutic considerations. The authors favour the metaplastic origin of CNC from a multipotent (endocervical) stem cell.

Adenocarcinoma↗
PubMed1995

The HIV-1 Rev activation domain is a nuclear export signal that accesses an export pathway used by specific cellular RNAs.

HIV-1 Rev protein directs nuclear export of pre-mRNAs and mRNAs containing its binding site, the Rev response element (RRE). To define how Rev acts, we used conjugates between bovine serum albumin (BSA) and peptides comprising the Rev activation domain (BSA-R). BSA-R inhibited Rev-mediated nuclear RNA export, whereas a mutant activation domain peptide conjugate did not. BSA-R did not affect the export of mRNA, tRNA, or ribosomal subunits, but did inhibit export of 5S rRNA and spliceosomal U snRNAs. BSA-R was itself exported from the nucleus in an active, saturable manner. Thus, the Rev activation domain constitutes a nuclear export signal that redirects RRE-containing viral RNAs to a non-mRNA export pathway.

Amino Acid Sequence↗
PubMed1995

Amplification of the MET gene in glioma.

We have previously reported the finding of MET amplification linked to double minutes (dmins) in a human glioblastoma (TX3095). Because dmins are found in approximately 50% of glioblastomas, 18 gliomas were analyzed for MET amplification. Three grade IV glioblastomas and one grade II astrocytoma showed amplification. We could also localize the MET amplicon to dmins in glioblastoma TX3095 by fluorescence in situ hybridization.

Base Sequence↗
PubMed1995

Continuous in vivo monitoring in diabetes: the subcutaneous glucose concentration.

The most advanced glucose sensors are measuring amperometrically the hydrogen peroxide generated in a stoichiometric relation to the prevailing glucose concentration during glucose oxidase-mediated glucose oxidation. They proved useful in commercially available glucose analysers and in experimental subcutaneous (sc) monitoring. Here it is shown (a) that under steady state conditions the s.c glucose concentration is nearly identical to that in blood, (b) that sc. inserted glucose electrodes do mirror the intracorporal glucose concentration both under hypo-, normo-, and hyperglycaemic conditions with a clinically relevant accuracy, (c) that automated feedback control of intracorporal glucose concentration is possible applying the output of sc. glucose sensor as an input to the computer that controls the insulin pump, and (d) that stable function of sc. sensor may be accomplished over intervals up to one day; in some cases applications over up to ten days have been reported. The underlying problem consists in an insufficient functional biostability which is a function of biocompatibility and size of the sensor, of its sterility, and of the permanent skin penetration. The latter is still required to get the device in place, to keep it in function, and to make use of the data under any condition. At this time, sc. glucose electrodes to be employed as hypoglycaemia-warning systems over one day are considered clinically important and technically achievable.

Animal Population Groups↗
PubMed1995

Broadband ultrasound attenuation in the diagnosis of osteoporosis: correlation with osteodensitometry and fracture.

PURPOSE: To evaluate the usefulness of broadband ultrasound attenuation in the prediction of osteoporosis. MATERIALS AND METHODS: Broadband ultrasound attenuation measurements of the calcaneus and dual x-ray absorptiometry (DXA) measurements of the lumbar spine and the femoral neck were obtained in 400 patients (295 female and 105 male), 135 of whom were classified as having osteoporosis. Correlation coefficients between broadband ultrasound attenuation and DXA were calculated. RESULTS: Patients with osteoporosis showed a statistically significant decrease in broadband ultrasound attenuation compared with healthy patients (59.7 dB/MHz +/- 1.3 [standard deviation] vs 75.1 dB/MHz +/- 0.8). Broadband ultrasound attenuation correlated statistically significantly with vertebral bone density (r = .49) and femoral neck density (r = .52). At a broadband ultrasound attenuation index of 64 dB/MHz, the sensitivity and specificity were both 85% for patients with osteoporotic fractures. CONCLUSION: Broadband ultrasound attenuation can be used to help differentiate between patients with osteoporosis and healthy patients and seems to be useful in the prediction of fracture risk.

Absorptiometry, Photon↗
PubMed1995

Parenchymal liver enhancement with bolus-triggered helical CT: preliminary clinical results.

A software-driven device for bolus-triggered start of helical computed tomography (CT) was evaluated in liver studies of 30 patients with suspected metastatic liver disease. Compared with results in a control group of 30 patients who underwent conventional contrast material-enhanced helical CT, the study group had significantly higher and more constant parenchymal enhancement (P < .05, Mann-Whitney U test). This technique helps optimize findings at contrast-enhanced helical CT.

Contrast Media↗
PubMed1995

MR imaging-guided breast intervention: experience with two systems.

PURPOSE: To evaluate two different systems for magnetic resonance (MR) imaging-guided breast intervention. MATERIALS AND METHODS: Thirty-four patients with 34 lesions detected exclusively with contrast material-enhanced MR imaging underwent 51 interventional procedures (23 needle biopsies and 28 preoperative wire localizations) with two different systems. An add-on device for surface coils was used in 25 cases, and a dedicated single breast biopsy coil was used in 26. For needle biopsies, material was aspirated with nonmagnetic 19.5-gauge needles. For preoperative localizations, nonmagnetic hook wires were used. RESULTS: Surgical excision or follow-up verified the cytologic findings in 19 of the 23 cases sampled for biopsy. Cytologic diagnosis was impossible in three of the 23 cases. One technical failure occurred with the biopsy coil. Open biopsy performed after MR imaging-guided localization successfully removed 26 of the 28 lesions. One missed carcinoma was found at repeat localization and removed. One technical failure occurred with the biopsy coil. In that case, the lesion was close to the chest wall. CONCLUSION: Both systems are suitable for fine-needle biopsy and preoperative localization of lesions seen exclusively on MR images.

Adult↗
PubMed1995

Generation and characterization of a human chromosome 6-specific hncDNA library from a somatic cell hybrid.

Chromosome specific cDNA libraries are a useful source of candidate genes for disorders which have been linked to particular chromosomes. Here, we report the generation of a cDNA library made from a somatic cell hybrid retaining chromosome 6 as its only human component. In order to ascertain the chromosomal location of cDNAs the library was amplified by inter-Alu-PCR and used as probe for competitive in situ suppression (CISS). To identify human specific cDNA clones the library was screened with PD39, a highly human specific Alu consensus probe. Out of 350,000 clones 360 were found to hybridize with PD39. Nucleotide sequences were determined for 40 clones with inserts larger than 500 basepairs (bp) and a sequence comparison was performed at the National Center for Biotechnology Information using BLASTN. One clone was shown to be identical to Manganese Superoxide Dismutase (MnSOD/SOD2) which has previously been assigned to chromosome 6q25. Localization of 11 clones was determined using PCR and clone-specific primer pairs on a hybrid mapping panel DNA set. Two PCR-localized clones and five additional clones were localized by fluorescence in situ hybridization. Transcripts for five clones were identified by RT-PCR. The generation of chromosome 6-specific hncDNAs from a somatic cell hybrid should aid in the identification of disease-associated genes localized on this chromosome.

Animals↗
PubMed1995

Isolation and localization of transcribed sequences on human chromosome 22.

Recently, we reported the generation of a heteronuclear (hn) cDNA library from a human x rodent somatic cell hybrid retaining human chromosome 22. Here, we report the characterization and localization of 12 cDNA derived clones from this library. Human-specific cDNA sequences have been selectively amplified by inter-Alu PCR. To exclude Alu transcripts, only clones with inserts larger than 500 bp were analyzed. Ten of the 12 clones were localized by PCR on chromosome 22, with four clones mapping on additional chromosomes. One PCR-localized clone and two additional clones were mapped on chromosome 22 by in situ hybridization. Transcripts in human cells were identified for seven of the eight clones analyzed by RT-PCR. None of the clones showed significant sequence similarities within the GenBank and EMBL databases, indicating that these clones represent previously unknown genes. This is the first report on the isolation of chromosome 22-specific transcripts from a human x rodent somatic cell hybrid.

Animals↗
PubMed1995

Value of magnetic resonance imaging in patients with penile induration (Peyronie's disease).

Magnetic resonance imaging (MRI) is a noninvasive procedure that enables exact imaging of penile anatomy. A total of 34 patients with clinical Peyronie's disease underwent palpation, ultrasound and MRI after intracavernous injection of 10 micrograms. prostaglandin E1. MRI images were obtained before and after intravenous application of gadolinium-diethylenetriaminepentaacetic acid. In 34 patients 45 plaques were palpable. Ultrasound revealed evidence of lesions in 66.6% of the cases. On MRI 36 of 45 palpable plaques (80%) were detected. Not palpable or sonographically revealed indurations could be shown in 4 cases. After intravenous application of gadolinium-diethylenetriaminepentaacetic acid 4 plaques demonstrated contrast enhancement, thus indicating local inflammatory activity. The combination of clinical examination and sonography remains the method of choice for diagnosis and observation of patients with Peyronie's disease. MRI enables exact imaging of penile structures but it does not provide a significant advantage over standard investigative procedures.

Adult↗
PubMed1994

Evidence that HIV-1 Rev directly promotes the nuclear export of unspliced RNA.

The Rev trans-activator of human immunodeficiency virus type 1 (HIV-1) is a protein that regulates the simultaneous appearance in the cytoplasm of both spliced and unspliced forms of viral mRNAs from the same viral transcripts by way of recognition of a target sequence termed the Rev-responsive element (RRE). Whether Rev acts directly on RNA export or by inhibition of splicing, or both, is still a matter of debate. We have addressed this issue in Xenopus laevis oocytes by microinjecting RNA molecules containing RRE along with purified recombinant Rev protein into the oocyte nuclei. Adenovirus pre-mRNA containing an RRE in the intron was spliced equally well in the absence and presence of Rev protein. Only in the presence of Rev was non-spliced pre-mRNA exported from the nucleus; more surprisingly, the excised intron lariat (containing RRE) was also exported. Furthermore, an RRE-containing mRNA molecule that lacked intron sequences was also efficiently exported from the nucleus in a Rev-dependent manner. Therefore our results demonstrate that Rev can act directly at the level of nuclear export, independent of any inhibitory effect that it may exert on the splicing of pre-mRNA. Finally, our finding that the Rev mutant M10, shown previously to be inactive in human lymphoid cells, was also unable to export RRE-containing RNA molecules from oocyte nuclei suggests that one or more cellular factors, evolutionarily conserved between humans and Xenopus, interact with Rev in both cell systems to promote nuclear RNA export.

Animals↗
PubMed1994

Coamplification on chromosomes 7p12-13 and 9q12-13 identified by reverse chromosome painting in a glioblastoma multiforme.

DNA amplification is known to occur in approximately 50% of glioblastomas, with the epidermal growth factor receptor (EGFR) gene being the most frequently amplified. Whereas previous amplification studies have largely been limited to the analysis of known tumor-related genes, reverse chromosome painting allows us to search for as yet unidentified amplified domains. Here, we report the analysis of a glioblastoma multiforme by reverse chromosome painting. Hybridization signals were found on chromosome 7p12-13 and chromosome 9q12-13. Standard Southern blot analysis revealed amplification of the EGFR gene, which is localized on band 7p13. These findings corroborate previous reports on coamplification of sequences on different chromosomes in glioblastoma.

Aged↗
PubMed1994

KADIS: model-aided education in type I diabetes. Karlsburg Diabetes Management System.

Education and training in self-management of blood glucose control has become a permanent task for all people involved in the care of diabetic patients. Since this may be facilitated by applying state-of-the-art information technology, we have developed the decision support system KADIS (Karlsburg Diabetes Management System). It comprises computer-aided tools for (1) the evaluation (selection, aggregation, storage, statistics, graphics) of therapeutic data, e.g. from patients' logbooks, and (2) the simulation of daily profiles of glycaemia and insulinaemia on the basis of a mathematical model of the glucose-insulin regulatory system, parameters of which can be adapted to the characteristics of individual patients. The latter tool allows the patient to predict his response to any modification in the therapeutic regime and to learn how variations in timing, formulation and doses of insulin, in carbohydrate equivalents and absorption characteristics of meals, and in exercise may influence the daily pattern in glycaemia. This procedure has been well accepted as an educational tool by those patients who were 'self-managing' their metabolic control.

Computer Graphics↗
PubMed1994

Glucose oxidase electrodes: effect of hydrogen peroxide on enzyme activity?

This paper presents a simple procedure to assess the amount of hydrogen peroxide arising in amperometric glucose oxidase sensors. At an external glucose concentration of 30 mmol/l, which represents the linear range of calibration, a hydrogen peroxide concentration of approximately 0.18 mmol/l is generated. Taking into consideration that in medical applications the main range of interest would be within euglycaemia which is between 4 and 9 mmol/l, it is concluded that in the type of glucose electrode investigated, hydrogen peroxide produced during enzymatic glucose measurement does not appreciably damage the enzyme glucose oxidase.

Biosensing Techniques↗
PubMed1994

DNA amplifications on chromosomes 7, 9 and 12 in glioblastoma detected by reverse chromosome painting.

Biopsies and cell culture, respectively, of four human glioblastoma multiforme (WHO 4) have been evaluated for gene amplification using reverse chromosome painting. Three of the tumours showed amplified domains within chromosome bands 12q13-15. The exact localisation and extension of the amplified domains, however, varies within this region. Southern blot analysis revealed amplification of the GLI oncogene in two of the glioblastomas which were found to contain amplified domains within 12q13-15. Reverse chromosome painting also identified amplified domains within bands 7q21 and 9p23-24. Amplification within region 9p23-24 has previously not been reported in glioblastoma. The amplified domain encompassing 9p23-24 was detected in the same glioblastoma which contained an amplification unit within bands 12q13-14. These data, together with previous reports, indicate that amplifications are predominantly found on chromosomes 7, 9 and 12 in glioblastoma. In addition, this study provides further evidence that coamplification is not a rare event in glioblastoma.

Chromosomes, Human, Pair 12↗