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Biomedical subjects

A Ulrich

Publications and source records attributed to A Ulrich.

At least 19 recordsLinked to original sources
PubMed2006

Excimer laser pumped by an intense, high-energy heavy-ion beam.

High-energy heavy ions are an ideal tool to generate homogeneously excited, extended volumes of nonthermal plasmas. Here, the high-energy loss (dE/dx) and absolute power deposition of heavy ions interacting with matter has been used to pump an ultraviolet laser. A pulsed 70 MeV/u 238U beam with up to 2.5 x 10(9) particles in approximately 100 ns beam bunches was stopped in a 1.2 m long laser cell filled with a 1.6 bar Ar-Kr-F2 mixture (typically 50%:49.9%:0.1%). Laser effect on the 248 nm KrF* excimer transition is clearly demonstrated.

Journal Article↗
PubMed2006

[Fiction and facts about multi-modal therapy in rectal cancer].

The prognosis of patients with rectal cancer has been improved significantly after introduction of the total mesorectal excision (TME). Just by performing TME, the local recurrence rates could be decreased to less than 10 %, independent of multi-modal therapeutic concepts. In contrast, the local recurrence rate reached 4 to 55 % (median 20 %) in a German multicenter study in 1995 prior to the nationwide introduction of TME. The goal of this overview is to compare the different concepts in the multi-modal therapy of rectal cancer with their advantages and disadvantages based on the current literature. Mentioned will be local recurrence rates and survival, but also toxicity, costs and acceptance of patients. Furthermore, a preview is given about future developments.

Antineoplastic Agents↗
PubMed2006

Seasonal profiles of sulphur, phosphorus, and potassium in Norway spruce wood.

Seasonal profiles of sulphur, phosphorus, and potassium content in the wood of trees have been established for the first time. This became possible by using a novel laser ablation system coupled to HR-ICP-MS for measuring these elements in Norway spruce drill cores. This technique combines excellent spatial resolution with superior detection power, and makes it possible to measure low element concentrations even in relatively narrow annual rings. Despite its low quantity in wood, sulphur is an important macronutrient for plants and seems to display seasonal variations of its concentration, which correspond to actual theories of sulphur metabolism in plants. A similar seasonal pattern was also found for phosphorus, another crucial element in tree nutrition. This was unexpected, because it was previously assumed that the distribution of phosphorus remains constant throughout the year. Potassium, the third element measured, seems to be especially accumulated in the latewood. The profiles presented in this article suggest a seasonal variation, revealing some new aspects of Norway spruce (PICEA ABIES) metabolism.

Lasers↗
PubMed2005

Energy-transfer processes in neon-hydrogen mixtures excited by electron beams.

Energy- and charge-transfer processes in neon-hydrogen mixtures (500-1400 hPa neon and 0.001-3 hPa hydrogen partial pressures) excited by a pulsed low-energy (approximately 10 keV) electron beam were investigated using time-resolved spectroscopy. Time spectra of the hydrogen Lyman-alpha line, neon excimer emission (second continuum), and neon atomic lines (3p-3s transitions) were recorded. The time-integrated intensity of the Lyman-alpha emission was measured for the same range of gas mixtures. It is shown that direct energy transfer from Ne*2 excimers and neon atoms in the four lowest excited states as well as recombination of H3+ ions are the main channels populating atomic hydrogen in the n=2 state. A rate constant of (4.2+/-1.4)x10(-11) cm3 s(-1) was obtained for the charge transfer from Ne2+ ions to molecular hydrogen. A lower limit for the depopulation rate constant of Ne*2 excimers by molecular hydrogen (combination of energy transfer and ionization) was found to be 1.0 x 10(-10) cm3 s(-1).

Journal Article↗
PubMed2005

Single photon ionization time-of-flight mass spectrometry with a pulsed electron beam pumped excimer VUV lamp for on-line gas analysis: setup and first results on cigarette smoke and human breath.

Single-photon ionization (SPI) using vacuum ultraviolet (VUV) light produced by an electron beam pumped rare gas excimer source has been coupled to a compact and mobile time-of-flight mass spectrometer (TOFMS). The novel device enables real-time on-line monitoring of organic trace substances in complex gaseous matrixes down to the ppb range. The pulsed VUV radiation of the light source is employed for SPI in the ion source of the TOFMS. Ion extraction is also carried out in a pulsed mode with a short time delay with respect to ionization. The experimental setup of the interface VUV light source/time-of-flight mass spectrometer is described, and the novel SPI-TOFMS system is characterized by means of standard calibration gases. Limits of detection down to 50 ppb for aliphatic and aromatic hydrocarbons were achieved. First on-line applications comprised real-time measurements of aromatic and aliphatic trace compounds in mainstream cigarette smoke, which represents a highly dynamic fluctuating gaseous matrix. Time resolution was sufficient to monitor the smoking process on a puff-by-puff resolved basis. Furthermore, human breath analysis has been carried out to detect differences in the breath of a smoker and a nonsmoker, respectively. Several well-known biomarkers for smoke could be identified in the smoker's breath. The possibility for even shorter measurement times while maintaining the achieved sensitivity makes this new device a promising tool for on-line analysis of organic trace compounds in process gases or biological systems.

Electrons↗
PubMed2005

The transverse coloplasty pouch.

BACKGROUND: The introduction of the total mesorectal excision (TME) and the use of modern staplers have improved outcome and increased the rate of sphincter-preserving low anterior resections in rectal cancer. Consequently, the interest in functional results after rectal reservoir reconstruction increased significantly. METHODS: A review of the current literature was conducted on the development of colon pouch procedures with a particular focus on the transverse coloplasty pouch compared with the colon J-pouch and other current techniques of reconstruction after TME such as the side-to-end anastomosis. RESULTS: The colon J-pouch (CJP) became the "gold standard" for rectal reservoir reconstruction owing to better early functional results compared with the straight coloanal anastomosis (CAA). However, 30% of the patients with CJP faced late evacuation problems requiring the chronic use of enemas or laxatives. This rate could be decreased by shortening the limb of the CJP from 8-10 to 5-6 cm, but the late evacuation problems remained in approximately 10% of the patients. An overview of the current knowledge on technical and functional aspects as well as indications and results of the transverse coloplasty pouch (TCP) is presented. CONCLUSION: The TCP was developed to provide early functional results comparable to the CJP while avoiding the late evacuation problems. Functional results after TCP, small colon J-pouch and side-to-end anastomosis are similar. Evacuation problems after TCP have not been reported.

Colectomy↗
PubMed2005

Single-photon ionization quadrupole mass spectrometry with an electron beam pumped excimer light source.

The application of soft ionization methods for mass spectrometry (MS), such as single-photon ionization (SPI) using vacuum ultraviolet (VUV) light, provides powerful analytical instrumentation for real-time on-line monitoring of organic substances in gaseous matrixes. A compact and mobile quadrupole mass spectrometer (QMS) system using a novel electron beam pumped rare gas VUV lamp for SPI has been developed for on-line analysis of organic trace compounds (ppb concentrations). The VUV radiation of the light source is employed for SPI in the ion source of the QMS. The concept of the interfacing of the VUV light source with the QMS is described and the SPI-QMS is characterized. On-line detection limits down to 50 ppb for benzene, toluene, and m-xylene were achieved. The instrument is well suited for continuous measurements of aromatic and aliphatic trace compounds and can therefore be used for on-line monitoring of trace compounds in dynamically fluctuating process gases. First measurements of gas standards, petrochemical samples, and on-line monitoring of automotive exhaust are presented.

Journal Article↗
PubMed2005

Fast-track surgery: the Heidelberg experience.

Fast-track surgery is an interdisciplinary multimodal concept of minimally invasive surgery or new incision lines and "cutting old plaits" (e.g., the use of drains or tubes). It uses modern intraoperative anesthesia (e.g., fluid restriction) and analgesia, including new drugs and novel ways of administration (e.g., thoracic epidural analgesia) for postoperative pain relief, in combination with the immediate mobilization of the patient and early oral nutrition after the operation. This approach requires a cooperating team of motivated nurses, physiotherapists, anesthesiologists, and surgeons, in addition to continuous improvement of the processes involved. Moreover, extended patient education and information about the procedures and the expected time course are of the highest importance, as the active role of the patient is to be emphasized. This chapter describes the development and implementation of fast-track surgery in colorectal diseases at the Department of Surgery of the University Hospital of Heidelberg, Germany. Preliminary results of fast-track surgery suggest a significant and clear overall benefit for the patient. A shorter hospital stay and reduced systemic morbidity in addition to no increase in postoperative complications on an out-patient basis were found. However, to exclude a "bloody discharge" of the patients, thorough follow-up and quality control are mandatory. Although in the initial phase increased personnel care is necessary, in the new German reimbursement system with G-DRGs (German diagnosis-related groups) fast-track surgery seems to save resources in the long term.

Clinical Protocols↗
PubMed2004

[The transverse coloplasty pouch after low anterior resection: early postoperative results].

INTRODUCTION: A colon J pouch (CJP) still represents the standard rectal reservoir after low anterior resection. Though the CJP shows favourable early functional results, pouch evacuation problems tend to occur in the long term. The transverse coloplasty pouch (TCP), developed by our group allows comparable early functional results while avoiding evacuation problems. We report our experience with the TCP at the University Hospital of Heidelberg, Germany, and examine the risk of anastomotic leaks with this technique. METHODS: Between 1 October 2001 and 31 May 2003, 201 patients with rectal tumours underwent resection. Eighty-two patients with formation of TCP were enrolled in the study. RESULTS: During the creation of the TCP, no technical problems occurred, and the overall morbidity was 28%, including anastomotic leaks in seven patients (8.5%) and bleeding in two. The reoperation rate was 8.5%. An association between postoperative morbidity and preoperative radiation therapy could not be established. The hospital mortality rate was 3.6%. CONCLUSIONS: The use of TCP is a safe procedure which has gained worldwide acceptance in a short time, representing a technically straightforward procedure. Independently of patient size, habitus, and bulkiness of the colon, a TCP can always be performed after low rectal resection.

Adult↗
PubMed2002

Analysis of fiber content in flax stems by near-infrared spectroscopy.

The conventional means of measuring the fiber content of flax is time-consuming and laborious, and the results obtained vary with the analysis technique used. The plant tissues must first be "retted", a process by which the fibers are separated from the rest of the stem, either by indigenous organisms in the soil when the stems are left in the field or by water (anerobic bacteria) or enzymatic retting. The fiber content is then determined by mechanical or manual separation. In this study, fiber content of flax stems was measured rapidly and objectively by near-infrared spectroscopy (NIRS) using whole pieces of stem in a large cell, in reflectance mode. Compared to the conventional method, the standard error of performance of the NIRS method was between 0.96 and 1.45% (dry matter basis), depending on the model and data processing used. NIRS calibrations were generated by hand separation of fiber from water-retted specimens. The water retting procedure takes several days to complete and requires considerable trained labor to complete the hand separation step. The NIRS procedure was conducted on pieces of stem to simulate measurement in the field.

Flax↗
PubMed2002

Single photon ionization (SPI) via incoherent VUV-excimer light: robust and compact time-of-flight mass spectrometer for on-line, real-time process gas analysis.

Fast on-line detection of organic compounds from complex mixtures, such as industrial process gas streams, require selective and sensitive analytical methods. One feasible approach for this purpose is the use of mass spectrometry (MS) with a selective and soft (fragment-free) ionization technique, such as chemical ionization (CI) or photo ionization (PI). Single photon ionization (SPI) with vacuum ultraviolet (VUV) light is a particularly sof tionization technique, well-suited for detection of both aromatic and aliphatic species. Problematic, however, is the generation of the VUV light. In general, the vacuum ultraviolet (VUV) light sources for SPI-MS are based either on lasers (e.g., 118-nm radiation generated by frequency-tripling of the third harmonic of a Nd:YAG laser) or on conventional VUV lamps, such as deuterium lamps. Althoughthe laser-based techniques are very sophisticated and expensive, the conventional lamps have serious drawbacks regarding their optical parameters, such as low-output power, low spectral power density, and broad emission bands. In this work, a novel excimer VUV light source, in which an electron beam is used to form rare gas excimer species, is used. The excimer VUV light sourceproduces brilliant and intense VUV light. The novel VUV light source was coupled to a compact and mobile time-of-flight mass spectrometer (TOFMS). A special interface design, including optical (VUV optics) as well as electronic measures (e.g., pulsed ion extraction) was realized. The use of the excimer VUV lamp for SPI will allow the realization of very compact, rugged, and sensitive SPI-TOFMS devices, which preferably will be adapted for process analytical application or monitoring issues (e.g., chemical warfare detection). The excimer VUV-lamp technology delivers VUV light with a good beam quality and high-output power at low costs. Furthermore, it allows changing the emitted wavelength as well as the bandwidth of the excimer VUV lamp in t he 100-200-nm region by changing the gas filling. Consequently, SPI-TOFMS with an excimer light source is a fast detection technique that can be used for online monitoring, for example, in environmental studies or industrial manufacturing processes. In this paper, technology and characteristics of the new excimer light source, as well as the combination with the TOFMS, are presented. Furthermore, a first characterization of the SPI-TOFMS instrument, regarding analytical parameters such as detection limits and selectivity, is given. This includes a discussion of potential improvements that probably will be achievable within a future prototype genertation. Finally, first applications of the system for on-line measurement of organic trace species in a complex gas mixture (here, motorcycle exhaust gas) are presented.

Journal Article↗
PubMed2001

Flt3 ligand and granulocyte-macrophage colony-stimulating factor preferentially expand and stimulate different dendritic and T-cell subsets.

OBJECTIVE: Mechanisms of T-cell stimulation by Flt3 ligand (Flt3L) and granulocyte-macrophage colony-stimulating factor (GM-CSF) remain unclear. Herein, we compared the effects of Flt3L and GM-CSF on the expansion of dendritic cells (DC) and T-cell subsets and cytokine expression. METHODS: Naïve and effector/memory T cells were analyzed by flow cytometry (FC). CD4(+) and CD8(+) T cells and CD11c(+)CD11b(dull/-)(DC1) and CD11c(+)CD11b(+) (DC2) subsets were isolated and the frequency of IFN-gamma-, IL-12- (type 1) and IL-4-, IL-10 (type 2)-producing cells and cytokine mRNA expression evaluated. RESULTS: Flt3L expanded both DC1 and DC2 subsets with a significantly higher percentage and number of DC1 than DC2, while GM-CSF preferentially expanded the DC2 subset. Isolated DC1 from Flt3L-injected mice had significantly higher levels of IL-12 (p40) than IL-10, while the converse occurred with DC2. The numbers of naïve and memory T cells were elevated in mice that received Flt3L or GM-CSF. However, the number of memory CD4(+) and CD8(+) T cells was significantly increased in Flt3L as compared to GM-CSF cohorts. While GM-CSF increased the frequency of both type 1 and type 2 cytokine-producing cells, Flt3L significantly augmented the frequency of type 1 T cells. CONCLUSIONS: In contrast to GM-CSF, Flt3L preferentially induces the expansion of type 1 T cells. The mechanism of Flt3L-induced T-cell stimulation is associated with the expansion of the IL-12 (p40)-producing DC1 and memory T cells.

Animals↗
PubMed2001

Population dynamics and antagonistic potential of enterococci colonizing the phyllosphere of grasses.

AIMS: To investigate the spatial and temporal dynamics of enterococci colonizing forage grass and their ability to produce bacteriocins. METHODS AND RESULTS: Enterococci could be detected on above-ground plant parts throughout the growing season, with high continuity but low cell numbers (2.60 x 101-6.16 x 104 cfu g-1 fresh matter). A total of 750 strains were isolated and identified by their whole-cell protein patterns as Enterococcus faecalis (7.9%), Ent. mundtii (7.9%), Ent. casseliflavus (5.5%), Ent. faecium (5.2%) and Ent. sulfureus (0.1%). The vast majority of the strains (69.7%) formed a homogeneous 16S rDNA genotype that differed from those of known enterococci. A screening for antagonistic activity using an agar spot test revealed that 18.4% of all isolates were potential antagonists. Partially-purified proteins extracted from cell-free culture supernatant fluids of various species were characterized as pH- and heat-stable bacteriocins active against a wide range of lactic acid bacteria, clostridia and Listeria. The producing strains were antagonistically active even on 'phylloplane agar' at temperatures between 4 and 37 degrees C. CONCLUSION: Enterococci are a common part of the epiphytic microflora of grasses, displaying probably some antagonistic activity. SIGNIFICANCE AND IMPACT OF THE STUDY: The results provide new information on the distribution, species diversity and antagonistic potential of enterococci in the phyllosphere.

Antibiosis↗
PubMed2001

Identification of plant-associated enterococci.

AIMS: Enterococcus isolates from forage grass were subjected to taxonomical investigations and tested for antibiotic resistance. METHODS AND RESULTS: The identification procedure included phenotypic characterizations, restriction analyses of polymerase chain reaction-amplified 16S rDNA, whole-cell protein profile analyses and 16S rDNA sequence analyses. Agar diffusion tests were performed to detect antibiotic resistance. CONCLUSION: The isolates were identified as belonging to the species Enterococcus faecium, Ent. mundtii, Ent. casseliflavus, Ent. faecalis and Ent. sulfureus. However, the majority of isolates differed distinctly in their restriction patterns from those of known species. They formed a group of a homogeneous 16S rDNA genotype (VI). The 16S rDNA sequence of a representative isolate revealed the closest relationship to the species Ent. faecalis (similarity of 97.4%). All isolates were sensitive to vancomycin, but almost all were resistant to gentamycin and streptomycin. SIGNIFICANCE AND IMPACT OF THE STUDY: The taxonomical investigations suggest that the isolates of the 16S rDNA genotype VI represent a new plant-associated Enterococcus species.

Bacterial Typing Techniques↗
PubMed2001

Prevention of pancreatic cancer induction in hamsters by metformin.

BACKGROUND AND AIMS: Our previous study suggested that the known promotional effect of a high fat diet, which in hamsters induces peripheral insulin resistance, is related to a compensatory proliferation of islet cells. The present study was to examine whether the prevention of islet cell proliferation can inhibit the promotional effect of a high-fat diet in pancreatic carcinogenesis. METHODS: Two groups of high fat-fed hamsters were used. One group received Metformin in drinking water for life (HF+Met group), and the other group served as a control (HF group). At the time when the normalization of the plasma insulin level was expected, all hamsters were treated with the pancreatic carcinogen, N-nitrosobis-(2-oxopropyl)amine, and the experiment was terminated 42 weeks later. RESULTS: Although 50% of the hamsters in the high-fat group developed malignant lesions, none was found in the HF+Met group (P < 0.05). Also, significantly more hyperplastic and premalignant lesions, most of which were found within the islets, were detected in the high-fat group (8.6 lesions/hamster) than in the HF+Met group (1.8 lesions/hamster). CONCLUSIONS: The results lend further support on the significant role of islet cells in pancreatic carcinogenesis and may explain the association between pancreatic cancer and obesity, which is usually associated with peripheral insulin resistance.

Adenocarcinoma↗
PubMed2001

Pacinian corpuscle in the human pancreas.

During our systematic examination of the distribution of cytochrome P450 enzymes in the normal and diseased human pancreas, we observed a Pacinian corpuscle in a serial section of a tissue from a pancreatic cancer patient. We report the histologic and immunohistochemical patterns in this corpuscle and review the literature. The Pacinian corpuscle was situated within the pancreas of a 76-year-old woman with cancer in the head of the pancreas. We could demonstrate immunoreactivity within the corpuscle for the neurofilament protein. neuron-specific enolase, S-100 Protein, and for four cytochrome P450-isozymes. The possible function of Pacinian corpuscles in the mammalian and human pancreas is discussed.

Aged↗
PubMed2001

Transdifferentiation of human islet cells in a long-term culture.

It has been established that ductal cells or precursor cells within the ductal tree of the pancreas can differentiate into islet cells. Although islet cells can also form exocrine cells, it is unclear whether they arise from precursor (stem) cells or from mature endocrine cells by transdifferentiation. Using a defined culture medium and technique for islet purification, for the first time we were able to maintain human islets in culture for more than a year. Multilabeling immunohistochemical and immunoelectron microscopic examination of the islets at different days of culture using islet cell markers (antibodies to hormones, neuron-specific enolase, chromogranin A) and ductal cell markers (cytokeratins 7 and 19, carbonic anhydrase II, DU-PAN2, CA 19-9, and MUC1) revealed that endocrine cells gradually transdifferentiate to ductal, acinar, and intermediary cells. Although islet hormone secretion ceased after day 28 in culture, endocrine cells were still detectable at day 60. However, later, all endocrine and exocrine cells were replaced by undifferentiated cells that expressed neuron-specific enolase, chromogranin A, laminin, vimentin, cytokeratin 7 and 19, alpha-1-antitrypsin, transforming growth factor-alpha, and epidermal growth factor receptor. Our data thus show that, under proper conditions, human islets can be maintained in vitro over a long period and that, in the culture condition, islet cells seem to transdifferentiate to exocrine cells and undifferentiated cells, which may be considered pancreatic precursor (stem) cells.

Biomarkers↗