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Biomedical subjects

G Wirnsberger

Publications and source records attributed to G Wirnsberger.

At least 19 recordsLinked to original sources
PubMed2001

Mesostructured materials for optical applications: from low-k dielectrics to sensors and lasers.

Recent advances on the use of mesoporous and mesostructured materials for electronic and optical applications are reported. The focus is on materials which are processed by block-copolymer templating of silica under weakly acidic conditions and by employing dip- and spin-coating as well as soft lithographic methods to bring them into a well-defined macroscopic shape. Several chemical strategies allow the mesostructure architecture to be used for electronic/optical applications: Removal of the block-copolymers results in highly porous, mechanically and thermally robust materials which are promising candidates for low dielectric constant materials. Since the pores are easily accessible, these structures are also ideal hosts for optical sensors, when suitable are incorporated during synthesis. For example, a fast response optical pH sensor was implemented on this principle. As-synthesized mesostructured silica/block-copolymer composites, on the other hand, are excellently suited as host systems for laser dyes and photochromic molecules. Laser dyes like rhodamine 6G can be incorporated during synthesis in high concentrations with reduced dimerization. This leads to very-low-threshold laser materials which also show a good photostability of the occluded dye. In the case of photochromic molecules, the inorganic-organic nanoseparation enables a fast switching between the colorless and colored form of a spirooxazine molecule, attributed to a partitioning of the dye between the block-copolymer chains. The spectroscopic properties of these dye-doped nanocomposite materials suggest a silica/block-copolymer/dye co-assembly process, whereby the block-copolymers help to highly disperse the organic dye molecules.

Electronics↗
PubMed2000

Mirrorless lasing from mesostructured waveguides patterned by soft lithography

Mesostructured silica waveguide arrays were fabricated with a combination of acidic sol-gel block copolymer templating chemistry and soft lithography. Waveguiding was enabled by the use of a low-refractive index (1.15) mesoporous silica thin film support. When the mesostructure was doped with the laser dye rhodamine 6G, amplified spontaneous emission was observed with a low pumping threshold of 10 kilowatts per square centimeter, attributed to the mesostructure's ability to prevent aggregation of the dye molecules even at relatively high loadings within the organized high-surface area mesochannels of the waveguides. These highly processible, self-assembling mesostructured host media and claddings may have potential for the fabrication of integrated optical circuits.

Journal Article↗
PubMed1999

Cytogenetic and CGH studies of four neuroendocrine tumors and tumor-derived cell lines of a patient with multiple endocrine neoplasia type 1.

A malignant insulinoma (LOHG-I), a carcinoid of the lung (LOHG-L), a parathyroid adenoma (LOHG-NSA), and a fibroma (LOHG-F) were obtained from a patient with multiple endocrine neoplasia type 1 (MEN1). Long-term cultures were established. Essential neurobiological properties of the cell lines were proven immunocytochemically and by electron microscopy. Molecular analysis of the germline DNA showed a 4 bp deletion in exon 3 of the MEN1 gene. Cytogenetic and CGH analyses of the tumors/tumor cell lines revealed diploidy and balanced and unbalanced structural aberrations different for each tumor. Chromosomes 6q21, 11q and 17q were most frequently involved in clonal structural aberrations.

Adenoma↗
PubMed1998

First continuous human pheochromocytoma cell line: KNA. Biological, cytogenetic and molecular characterization of KNA cells.

Pheochromocytomas are rare tumours, with an incidence of 1-2 per million which arise from chromaffin cells of the adrenal medulla. They occur sporadically or as part of dominantly inherited cancer syndromes like multiple endocrine neoplasia 2 (MEN2A and 2B) and others. Continuous cell lines, not available so far, are essential tools for studies in these tumours. A continuous cell line (KNA) was established from a sporadic pheochromocytoma of the right adrenal gland of a 73-year-old woman. The KNA cells grow as suspensions of spheroids and show the morphological and immunocytochemical characteristics of neuronal chromaffin cells, such as neuroendocrine granules, and positive reactions to chromogranin- and related peptide-, neuron specific enolase and vasoactive intestinal peptide antibodies. Neurite-like processes are formed after addition of nerve growth factor. Chromosomal analyses revealed a diploid (46,XX,n = 50) to hypodiploid (43-45,XX,n = 15) karyotype. In hypodiploid metaphases most frequently #19, #17, #21 and #22 were missing. Chromosome arms 1p and 4q showed apparently consistent interstitial deletions: 6q, 8q, 13q and 22q showed clonal interstitial deletions. The cell line shows a heterozygous sequence variant TGC (cysteine) to TGG (tryptophan) in codon 611 in exon 10 of the RET proto-oncogene. So far, PC-12, a rat adrenal pheochromocytoma, has been the only continuous pheochromocytoma cell line available. KNA represents the first report on a human continuous pheochromocytoma cell line, the first report of structural chromosome aberrations in pheochromocytomas and the first report of a RET mutation TGC to TGG in exon 10 of the RET proto-oncogene in a sporadic pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1998

Daily oral magnesium supplementation suppresses bone turnover in young adult males.

This study examined the effects of daily oral magnesium (Mg) supplementation on bone turnover in 12 young (27-36 yr old) healthy men. Twelve healthy men of matching age, height, and weight were recruited as the control group. The study group received orally 15 mmol Mg (Magnosolv powder, Asta Medica) daily in the early afternoon with 2-h fasting before and after Mg intake. Fasting blood and second void urine samples were collected in the early morning on days 0, 1, 5, 10, 20, and 30, respectively. Total and ionized Mg2+ and calcium (Ca2+), and intact PTH (iPTH) levels were determined in blood samples. Serum biochemical markers of bone formation (i.e. C-terminus of type I procollagen peptide and osteocalcin) and resorption (i.e. type I collagen telopeptide) and urinary Mg level adjusted for creatinine were measured. In these young males, 30 consecutive days of oral Mg supplementation had no significant effect on total circulating Mg level, but caused a significant reduction in the serum ionized Mg+ level after 5 days of intake. The Mg supplementation also significantly reduced the serum iPTH level, which did not appear to be related to changes in serum Ca2+ because the Mg intake had no significant effect on serum levels of either total or ionized Ca2+. There was a strong positive correlation between serum iPTH and ionized Mg2+ (r = 0.699; P < 0.001), supporting the contention that decreased serum iPTH may be associated with the reduction in serum ionized Mg2+. Mg supplementation also reduced levels of both serum bone formation and resorption biochemical markers after 1-5 days, consistent with the premise that Mg supplementation may have a suppressive effect on bone turnover rate. Covariance analyses revealed that serum bone formation markers correlated negatively with ionized Mg2+ (r = -0.274 for type I procollagen peptide and -0.315 for osteocalcin), but not with iPTH or ionized Ca2+. Thus, the suppressive effect on bone formation may be mediated by the reduction in serum ionized Mg2+ level (and not iPTH or ionized Ca2+). In summary, this study has demonstrated for the first time that oral Mg supplementation in normal young adults caused reductions in serum levels of iPTH, ionized Mg2+, and biochemical markers of bone turnover. In conclusion, oral Mg supplementation may suppress bone turnover in young adults. Because increased bone turnover has been implicated as a significant etiological factor for bone loss, these findings raise the interesting possibility that oral Mg supplementation may have beneficial effects in reducing bone loss associated with high bone turnover, such as age-related osteoporosis.

Adult↗
PubMed1997

Trace element status of hemodialyzed patients.

The trace elements Ba, Bi, Cd, Co, Cs, Cu, Hg, La, Mn, Mo, Pb, Rb, Sb, Sn, Sr, Tl, and Zn were determined by inductively coupled plasma mass spectrometry in plasma samples of 68 hemodialysis patients. The same elements (with exception of La and Mn) were also determined in whole blood after mineralization with high-purity nitric acid/hydrogen peroxide in a closed-pressurized microwave system. The accuracy and precision was checked by analyzing two Seronorm "whole blood" reference materials. All samples were contaminated with barium (heparinized tubes) and the plasma samples with tin (collection tubes). The concentrations for Bi, Hg, Pb, Rb, Sb, and Sr in whole blood were within the literature ranges for healthy adults. All of the concentrations for Co, and some of the concentrations for Cd, Cs, Tl, and Zn were higher than the high limits of the normal ranges. Approximately 14% of the Cu concentrations were lower than the low limit of the normal range. The Mo and Sn concentrations are difficult to evaluate, because the normal ranges appears to be unreliable. All concentrations for Cd, Co, Mo, Pb, Sn, and Sr and some of the concentrations for Cu (15%) and Mn (75%) in the plasma samples were higher than the high limits of the normal ranges. The concentrations for Rb tended to be lower than the normal range. To establish unequivocally the causes for elevated and reduced concentrations of trace elements in whole blood and plasma of dialysis patients, all fluids in the dialysis process must be investigated.

Adult↗
PubMed1995

Development and critical evaluation of an improved comprehensive multicompartment model for the exchange processes during hemodialysis.

An improved comprehensive multicompartment model for the simulation of the most important metabolic state variables in the patient during dialysis is presented. With this approach time courses of urea, creatinine, K+, Na+, Cl-, HCO3-, H+ and CO2 can be predicted. Additionally, osmotic water shifts as well as resting membrane potentials are calculated. The model contains the following extensions compared to classical approaches: For the calculation of osmotic water shifts, not only sodium, but also urea, potassium, chloride and unspecified indiffusable ions are taken into account. Furthermore, hemodynamic aspects are considered by assuming two tissue groups with different perfusion. Thus it is possible to estimate the influence of hemodynamic parameters (e.g. cardiac output or blood flow distribution) on the exchange processes. The model can be adjusted individually by several system parameters. This adjustment is performed by minimizing the sum of the quadratic differences between simulated and measured plasma concentrations of the considered substances. A first validation has been performed successfully with measured data from 18 dialysis patients. After the effective whole-body exchange area of the resting cell membranes for potassium, sodium and chloride had been estimated, rebound effects for those electrolytes could be simulated successfully.

Acid-Base Equilibrium↗
PubMed1993

Application of silver acetate autometallography and gold-silver staining methods for in situ DNA hybridization.

In situ hybridization using biotinylated DNA probes has become an important tool in histopathology. It is well known that the sensitivity of the methods used to demonstrate viral DNA in formalin-fixed and paraffin-embedded specimen depends strongly on the detection system used. In the present study, an optimized in situ DNA hybridization protocol was combined with four different approaches of gold-silver staining methods. For silver enhancement, the recently described method of silver acetate autometallography, a technique allowing highly efficient development without the necessity of dark room illumination has been used. The most efficient detection method found in our experiments was the use of gold-adsorbed anti-biotin antibodies with subsequent silver enhancement. This staining procedure can be completed in 5 hours including hybridization and is a highly sensitive alternative to peroxidase and alkaline phosphatase detection systems.

Cytomegalovirus↗
PubMed1992

False positive prostate specific antigen values in the sera of women with renal cell carcinoma.

The assessment of serum prostate specific antigen (PSA) with a polyclonal radioimmunoassay in 22 women with renal cell carcinoma resulted in measurable values in 6 patients, with the values ranging from 0.5 to 27.0 ng./ml. Tumor stage was T3 in all of these patients and the morphological features showed an eosinophilic subtype according to the German nomenclature. Additional measurements with a monoclonal radioimmunoassay in 3 of these 6 patients were negative as were all subsequent measurements postoperatively, although performed with the polyclonal radioimmunoassay. Immunohistochemical staining was negative for PSA. However, positivity for alpha-1-antichymotrypsin was detected, which was reported to occur in complexes with PSA and other proteases. Cross reaction between the polyclonal antibodies of the radioimmunoassay and 1 of these complexes is concluded. As far as clinical considerations are concerned, such cross reaction must be considered just as likely in male patients. Thus, it is recommended that therapeutic considerations in patients who underwent radical prostatectomy, for example, should not be exclusively based on PSA measurement performed with a polyclonal assay.

Antigens, Neoplasm↗
PubMed1992

The predictive value of human papilloma virus (HPV) typing in the prognosis of bronchial squamous cell papillomas.

Five solitary squamous papillomas of bronchus with variable degrees of dysplasia, one combined with a laryngeal papilloma and with a neuroendocrine carcinoma in the contralateral lung, and five papillomas combined with invasive squamous cell carcinomas were investigated for their expression of human papilloma virus DNA by in situ hybridization. Benign squamous cell papillomas showed an association with papilloma virus type 11 and rarely type 6, whereas types 16 or 18, sometimes in combination with types 31/33/35 were found in papillomas associated with carcinomas. In one patient a benign papilloma containing human papilloma virus type 18 and 31/33/35-positive preceded a recurrence combined with carcinoma by 2 years; this recurrent papilloma and the carcinoma were also positive for human papilloma virus 18 DNA. We suggest that human papilloma virus typing should be performed in every squamous cell papilloma of bronchus. Patients with papillomas exhibiting human papilloma virus 16 or 18 positivity are at high risk for the development of squamous cell carcinoma. Furthermore, virus typing may be of prognostic importance in relation to the development of squamous carcinoma.

Aged↗
PubMed1992

Biologic and cytogenetic characterization of three human medullary thyroid carcinomas in culture.

Neuroendocrine features and cytogenetic abnormalities of one continuous cell line (MTC-SK) and two long-term cultures (GER, STAH) derived from three sporadic cases of human medullary thyroid carcinomas (MTCs) were studied. Specific neuroendocrine markers (NSE, chromogranins, calcitonin, calcitonin gene-related peptide) were identified by electron microscopy and immunocytochemistry. In situ hybridochemistry and Northern blot analysis confirmed endocrine activity. Cytogenetic studies of the cell line MTC-SK revealed three consistent marker chromosomes, t(3;10), 11p+, and 22p+. Cells of long-term cultures GER and STAH exhibited a consistent translocation t(2;18), a trisomy 7, and two consistent marker chromosomes der3 and 5p+, respectively. Recently, we have isolated 12 stable clones of this MTC-SK cell line, which showed two different growth patterns. Quantitative measurement of mitotic activity flow cytometry and semiquantitative analysis of AgNOR-, Ki67-, and Cyclin/PCNA-(immuno)reactivity showed different DNA composition and duplication rates, indicating at least two subpopulations. Some of our clones developed a new consistent marker (i.e., an unbalanced translocation between mar11p+ and 1q). However, no correlations between chromosome findings, growth rate, and neuroendocrine markers were observed.

Carcinoma↗
PubMed1991

Co-expression of cytokeratin and vimentin filaments in rete testis and epididymis. An immunohistochemical study.

In 11 testes of different developmental stages (from 10-week-old embryos to adult) the cytokeratin and vimentin expression patterns of rete testis and epididymis were investigated immunohistochemically in formaldehyde-fixed paraffin-embedded material. In addition, immunofluorescence microscopy including double immunofluorescence was performed on frozen sections of 3 of these 11 cases. Rete testis and epididymis cells displayed a heterogeneous co-expression of cytokeratin and vimentin. In double immunohistochemistry, differences in distribution of keratin and vimentin intermediate filaments with predominance of cytokeratins in the apical cytoplasmic regions and of vimentin filaments in the basal portions of the cells were found. Cytokeratin expression preceded the appearance of vimentin: cytokeratin was already detectable in 10-week-old embryos, while weak vimentin immunoreactivity was first seen in 12-week-old embryos and became conspicuous in testes around the perinatal period. In testes of children up to 2 years of age the cytoplasmic distribution of cytokeratin and vimentin was more homogeneous. Predominance of the basal cell portions for vimentin and the apical regions for cytokeratin staining were less pronounced than in adult testes. In the proximal and distal parts of the epididymis a different intermediate filament expression pattern was found with a clear predominance of cytokeratin near the rete.

Adult↗