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Biomedical subjects

U Sommer

Publications and source records attributed to U Sommer.

At least 19 recordsLinked to original sources
PubMed2007

Increasing the sensitivity of delta13C and delta15N abundance measurements by a high sensitivity elemental analyzer connected to an isotope ratio mass spectrometer.

A common elemental analyzer system connected to a temperature-controlled gas chromatography (GC) column and coupled to an isotope ratio mass spectrometer was improved to decrease the determination limit for a simultaneous stable isotope ratio measurement of nitrogen and carbon dioxide. The additional use of a special ashtray system to collect the combustion residuals permitted more time-efficient work. These modifications to the elemental analyzer allowed precise measurements to be made down to 1.5 microg nitrogen and 10 microg carbon for stable isotope analysis. Low system background values and an acceptable signal-to-noise ratio have made an additional blank correction for these low sample measurements unnecessary. We provide a precision of this stable isotope analysis for lowest amounts of 1.2-2 microg nitrogen with a standard deviation of +/-0.496 per thousand (n = 27) and for 8.2-15 microg carbon with a standard deviation of +/-0.257 per thousand (n = 31) across different sample runs under stipulated conditions. This application can be established in an automatic mode without cryofocusing procedures.

Carbon Isotopes↗
PubMed2006

Spring bloom succession, grazing impact and herbivore selectivity of ciliate communities in response to winter warming.

This study aimed at simulating different degrees of winter warming and at assessing its potential effects on ciliate succession and grazing-related patterns. By using indoor mesocosms filled with unfiltered water from Kiel Bight, natural light and four different temperature regimes, phytoplankton spring blooms were induced and the thermal responses of ciliates were quantified. Two distinct ciliate assemblages, a pre-spring and a spring bloom assemblage, could be detected, while their formation was strongly temperature-dependent. Both assemblages were dominated by Strobilidiids; the pre-spring bloom phase was dominated by the small Strobilidiids Lohmaniella oviformis, and the spring bloom was mainly dominated by large Strobilidiids of the genus Strobilidium. The numerical response of ciliates to increasing food concentrations showed a strong acceleration by temperature. Grazing rates of ciliates and copepods were low during the pre-spring bloom period and high during the bloom ranging from 0.06 (Delta0 degrees C) to 0.23 day(-1) (Delta4 degrees C) for ciliates and 0.09 (Delta0 degrees C) to 1.62 day(-1) (Delta4 degrees C) for copepods. During the spring bloom ciliates and copepods showed a strong dietary overlap characterized by a wide food spectrum consisting mainly of Chrysochromulina sp., diatom chains and large, single-celled diatoms.

Animals↗
PubMed2006

Osseous integration of calcium phosphate in osteoporotic vertebral fractures after kyphoplasty: initial results from a clinical and experimental pilot study.

INTRODUCTION: This study evaluated the radiological changes at the bone-cement interface of calcium phosphate cement (CPC) and polymethylmethacrylate (PMMA) 12 months after kyphoplasty. In a pilot experiment, we additionally performed a histomorphometric analysis in osteopenic foxhounds to analyze the process of osseous integration of CPC and PMMA. METHODS: Twenty postmenopausal female patients with 46 vertebral compression fractures (VCF) were treated by kyphoplasty, utilizing CPC (N=28) or PMMA (N=18) for intravertebral stabilization. After a 12-month follow-up, we measured the density changes of border voxels at the bone-cement interface by computed tomography (CT) using dedicated software algorithms. We defined the border-voxel density (BVD) as a parameter of cement resorption at the interface. We also investigated the bone-implant interface in three osteopenic foxhounds by histomorphometry 3, 6, and 12 months after cement implantation. RESULTS: Twelve months after kyphoplasty, only CPC showed a significant decrease of the BVD compared to PMMA (p<0.01), indicating a slow progress of resorption at the interface. Histomorphometry of the dog vertebrae showed near total bone coverage of CPC implants, whereas the PMMA surface exhibited only 30% direct bone contact (p<0.01). We also observed a time-dependent increase in the number of discernable osteons close to the interface of CPC, but no bone tissue within PMMA (p<0.01). CONCLUSIONS: The decrease of the BVD 12 months after kyphoplasty may indicate osseous integration of CPC by: (1) the ingrowth of bone tissue and (2) osteonal penetration close to the interface.

Animals↗
PubMed2005

[Use of mitomycin C (MMC) for dacryocystorhinostomy interventions].

Mitomycin C (MMC) has been described as having a positive effect in different types of dacryocystorhinostomy (DCR) surgery such as external DCR, endonasal and transcanalicular DCR. MMC, an antineoplastic antibiotic, acts as an alkylating agent by inhibiting DNA, RNA and protein synthesis. Topical use of MMC can modulate the scarring process, which is useful in glaucoma surgery and pterygium excision. In DCR, MMC is also useful because it reduces the scarring process and thus prevents the occlusion of the osteotomy site related to the fibroblast activity. An increase in the success rate for long-term results has been observed by different authors, resulting from a larger osteotomy size as well as a decrease in the density and cellularity of the mucosa. No complications have been seen with topical use of MMC.

Cicatrix↗
PubMed2005

Endothelin-1 levels in patients with Paget's disease of bone.

A locally accelerated bone turnover is the pathophysiological basis of Paget's disease of bone (PD) and may result in severe bone deformations and pain. Affected bone sites are hypervascularized. Secreted endothelial products such as endothelin-1 (ET-1), influence bone metabolism. We investigated a possible correlation between ET-1 plasma concentrations and bone metabolism in patients with PD and whether ET-1 plasma levels are regulated by i. v. bisphosphonate treatment. Plasma ET-1 levels were determined in 22 patients with PD and found to be significantly (p = 0.006) elevated (0.75 +/- 0.48 fmol/ml) compared to 19 healthy controls (0.20 +/- 0.24 fmol/ml). In a group of five patients with PD, plasma ET-1 levels were determined before and after treatment with i. v. pamidronate. On the average, ET-1 levels decreased by 21 % after pamidronate infusions (p = 0.045). The results suggest that bone metabolism in pagetic bone affects endothelial cell metabolism and may also be modulated by endothelial cell products. ET-1 plasma levels may indicate PD activity.

Aged↗
PubMed2004

Olfactory function in patients with idiopathic Parkinson's disease: effects of deep brain stimulation in the subthalamic nucleus.

Decrease of olfactory function in patients with Parkinson's disease (PD) is a well-investigated fact. The present study aimed to investigate olfaction in PD patients with a specific focus on the effects of deep brain stimulation in the subthalamic nucleus. Eleven patients (age 42-67 years) participated in this study. Using the "Sniffin' Sticks", olfactory function was assessed based on butanol odor thresholds and the patients' ability to discriminate odors. Measures were taken with the stimulator being switched ON and OFF, respectively. While deep brain stimulation had no effect on odor thresholds, in hyposmic PD patients odor discrimination was found to be significantly higher during the ON period. This may indicate that deep brain stimulation has a positive effect on the cognitive processing of olfactory information in PD patients.

Adult↗
PubMed2004

Fluid shear of low magnitude increases growth and expression of TGFbeta1 and adhesion molecules in human bone cells in vitro.

Deformation of the bone matrix by mechanical strain causes fluid shifts within the osteocytic canaliculi which affect osteocytic cell metabolism. We applied low fluid shear (1 - 63 micro Pa for 10 - 48 h) to human osteoblastic cells (HOB) in vitro to study its impact on cell proliferation and differentiated functions. Proteins involved in translating the physical force into a cellular response were characterised. Low fluid shear stress stimulated proliferation of HOB 1.2-fold when stress was applied intermittently for 24 h. Shear stress also increased differentiated cellular properties such as alkaline phosphatase (ALP) activity (121 % of control), fibronectin (FN) and fibronectin receptor (FNR) expression (290 % and 200 %, respectively). Prostaglandin E (2) (PGE (2)) and TGFbeta1 release into the medium were significantly stimulated when shear stress was applied for 6 - 12 h and 24 - 48 h, respectively. TGFbeta1 + 2 neutralising antibodies or the presence of indomethacine inhibited the mitogenic effect of fluid shear and reduced ALP activity to its control level. Furthermore, TGFbeta treatment induced a dose-dependent increase in FN and FNR expression. Therefore, fluid shear stress of low magnitude (a) suffices to affect HOB metabolism and (b) regulates anchorage of HOB via FN and FNR by stimulating osteoblastic PGE (2) and TGFbeta secretion.

Aged↗
PubMed2004

Tritrichomonas foetus induces apoptotic cell death in bovine vaginal epithelial cells.

Tritrichomonas foetus is a serious veterinary pathogen, causing bovine trichomoniasis, a sexually transmitted disease leading to infertility and abortion. T. foetus infects the mucosal surfaces of the reproductive tract. Infection with T. foetus leads to apoptotic cell death of bovine vaginal epithelial cells (BVECs) in culture. An affinity-purified cysteine protease (CP) fraction yielding on sodium dodecyl sulfate-polyacrylamide gel electrophoresis a single band with an apparent molecular mass of 30 kDa (CP30) also induces BVEC apoptosis. Treatment of CP30 with the protease inhibitors TLCK (Nalpha-p-tosyl-l-lysine chloromethyl ketone) and E-64 [l-trans-epoxysuccinyl-leucylamide-(4-guanido)-butane] greatly reduces induction of BVEC apoptosis. Matrix-assisted laser desorption ionization-time-of-flight MALDI-TOF mass spectrometry analysis of CP30 reveals a single peak with a molecular mass of 23.7 kDa. Mass spectral peptide sequence analysis of proteolytically digested CP30 reveals homologies to a previously reported cDNA clone, CP8 (D. J. Mallinson, J. Livingstone, K. M. Appleton, S. J. Lees, G. H. Coombs, and M. J. North, Microbiology 141:3077-3085, 1995). Induction of apoptosis is highly species specific, since the related human parasite Trichomonas vaginalis and associated purified CPs did not induce BVEC death. Fluorescence microscopy along with the Cell Death Detection ELISA(PLUS) assay and flow cytometry analyses were used to detect apoptotic nuclear condensation, DNA fragmentation, and changes in plasma membrane asymmetry in host cells undergoing apoptosis in response to T. foetus infection or incubation with CP30. Additionally, the activation of caspase-3 and inhibition of cell death by caspase inhibitors indicates that caspases are involved in BVEC apoptosis. These results imply that apoptosis is involved in the pathogenesis of T. foetus infection in vivo, which may have important implications for therapeutic interference with host cell death that could alter the course of the pathology in vivo.

Animals↗
PubMed2003

Discrimination of patients with and without vertebral fractures as measured by ultrasound and DXA osteodensitometry.

This study compares dual X-ray absorptiometry (DXA) measurements of the hip and spine with quantitative ultrasound (QUS) parameters measured simultaneously at the calcaneal and phalangeal bone in 174 patients with and without vertebral fractures. The aim of this study was to compare the ability of DXA and QUS measurements to discriminate patients with and without osteoporotic vertebral fractures and to evaluate whether QUS measurements in addition to the DXA measurements improve the clinical discrimination between patients with and without osteoporotic vertebral fractures. T-scores determined by DXA measurements at the spine and hip and QUS measurements at the calcaneus provide similar information regarding the discrimination of women with and without vertebral fractures. Phalangeal QUS measurements did not discriminate between patients with and without vertebral fractures. The discriminative power of the combined use of DXA and calcaneal QUS measurements to discern between patients with and without vertebral fractures increases in women. In contrast, the combined use of DXA and phalangeal QUS measurements resulted in decreased discriminative power as compared to DXA measurements alone. The number of fractures was higher in the quartiles with lower T-scores of the DXA and calcaneal QUS measurements whereas no difference was seen in the T-score quartiles of the phalangeal QUS device. These findings suggest that DXA and QUS measurements at weight-bearing skeletal sites provide useful information for assessing women with an anamnestic risk of osteoporotic bone loss. For DXA and calcaneal QUS measurements in men as well as for phalangeal QUS, however, a clinical algorithm remains to be established to understand the diagnostic implications and related therapeutic consequences of the obtained measurements.

Absorptiometry, Photon↗
PubMed2003

Switching and combining dopamine agonists.

Switching from one dopamine agonist to another is common practice in the treatment of patients with Parkinson's disease. This paper describes some ideas on the most practical way to perform switching. In addition, it describes the possibilities of combining various dopamine agonists and discusses pros and cons for doing so.

Antiparkinson Agents↗
PubMed2003

Endothelin-1 levels in patients with disorders of the thyroid gland.

The endothelium derived peptide endothelin-1 (ET-1) is the major isoform of the endothelin peptide family, which is produced and secreted in the endothelial cell system. We measured plasma levels in patients with thyroid diseases and investigated associations between laboratory and clinical markers of thyroid metabolism and ET-1 plasma levels. ET-1 plasma levels were determined in patients with Graves' disease (n = 54), endemic goiter (n = 26), patients with Hashimoto's thyroiditis (n = 21) and compared to healthy controls (n = 60). ET-1 plasma levels were significantly elevated in patients with Hashimoto's thyroiditis (p < 0.0001) and in patients with Graves' disease (p = 0.003), when compared to healthy controls. In patients with endemic goiter, no significant differences were found compared to healthy controls (p = 0.298) and when compared to patients with Graves' disease (p = 0.16). We did not observe an association between ET-1 plasma levels and parameters of thyroid disease (e.g. thyroidea-stimulating hormone, thyroxine, volume of the thyroid). Furthermore, patients with and without endocrine thyroid disease showed no significantly different ET-1 plasma levels (p = 0.78). These data suggest that the autoimmunologically induced inflammatory response of the thyroid gland in Hashimoto's thyroiditis and Graves' disease is responsible for increased ET-1 plasma levels. Furthermore, our data do not support a role for ET-1 as a valid quantitative indicator for stage or progression in endemic goiter, Graves' disease or Hashimoto's thyroiditis.

Adult↗
PubMed2003

HLA typing and Parkinson's disease.

Idiopathic Parkinson's disease (IPD) is a neurodegenerative disorder of unknown aetiology. Several antigens have been associated with IPD using serological methods. We systematically analysed HLA class I and II alleles in 45 German Caucasian IPD patients using sequence-specific oligonucleotides and sequence-specific primer technology. Applying Bonferroni adjusted p values, we demonstrate a statistically significant increase of the DQB1*06 allele (p = 0.002) in IPD which may indicate an association between IPD and the immune system. Alternatively, HLA alleles might be in linkage disequilibrium with genes located next to the HLA locus.

Adult↗
PubMed2002

[Entacapone for treatment of motor fluctuations in idiopathic Parkinson syndrome].

The treatment of idiopathic Parkinson's disease becomes rather difficult if levodopa-induced late complications such as motor fluctuations or dyskinesias occur. This prospective and open study shows that an add-on therapy with entacapone can significantly lower wearing-off and end-of-dose akinesia. This treatment is well tolerated and easy to perform.

Aged↗
PubMed2002

Deep-brain stimulation for Parkinson's disease.

Deep brain simulation (DBS) is a powerful new therapeutic approach for patients with Parkinson's disease. However, patient selection is critical for a valuable therapeutic result. Dopa sensitivity of the target symptoms, severe disability and low neurosurgical risks are among the major criteria for this indication. Other criteria like age or cognition must still be addressed in future prospective studies. The preferred target for DBS in PD is the subthalamic nucleus for various good reasons. However, prospective studies for this procedure are lacking and some clinical problems may be more easily solved with targeting the internal pallidum or the thalamus. Despite major progress in this field, much work remains to be done.

Electric Stimulation Therapy↗
PubMed2001

High-dose therapy with ropinirole in patients with Parkinson's disease.

Ropinirole is effective as mono- and combination therapy in PD. Previous studies have used a maximal dose of 24 mg/day; the present study assesses the effect of higher doses (up to 36 mg/day) on patients with motor fluctuations. Outcome measures were changes in the motor function score of the Unified Parkinson's Disease Rating Scale, the duration of dyskinesias and reductions in levodopa dose. 21/22 patients completed the study. The mean daily ropinirole dose at endpoint was 26.2 mg (SD, 4.43 mg, range 20-36 mg). Improvements in motor function (29%) and the duration of dyskinesias (45%) from baseline to endpoint were significant (p < 0.01 and p < 0.05, respectively). The mean levodopa dose fell by 32% during the study (from 599 mg to 409 mg; p = 0.007). Side effects were mild. High-dose ropinirole (20-36 mg/day) was well tolerated and conferred significant clinical benefit on patients with motor fluctuations.

Aged↗
PubMed2001

Light and electron microscopic investigation of the lectin-binding pattern in the oxyntic gland region of bovine abomasum.

For the first time the expression of glycoconjugate residues in the oxyntic gland region of bovine abomasum has been investigated by means of lectin histochemistry. For light microscopic investigations, a battery of ten lectins, Con A, PSA, UEA I, WGA, LEA, SNA, RCA120, MPA, DBA and SBA was used. For electron microscopic examinations, WGA and RCA120 were utilized. The staining pattern of the lectins in all exocrine cell types of the oxyntic gland region is described. Compared to the results of monogastric species our study reveals some similarities, but just as many differences in the composition of glycoconjugate residues in bovine exocrine cell types. Typical for surface mucous cells is the amount of L-fucose, N-acetyl glucosamine residues and Galbeta1, 4GlcNAc sequences in the secretory granules. SNA could serve as a marker for surface mucous cells, because this lectin exclusively stains the plasma membrane and the secretory granules of surface mucous cells and the extracellular mucus. L-fucose and N-acetyl glucosamine are typical for the secretory granules of mucous neck cells. In addition, the secretory granules show the highest amount of N-acetyl galactosamine residues of all exocrine cells, so that DBA and SBA are recommended as marker lectins for mucous neck cells. Most lectins strongly stain the intracellular membrane system of oxyntic cells. The cocktail of glycoconjugates in the vicinity of the HCI production site provide protection against chemical injury. In chief cells only the apical plasma membrane is more or less labeled with all lectins apart from SNA. Specific marker lectins for oxyntic cells or chief cells of the bovine have not been characterized.

Abomasum↗