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Biomedical subjects

C Raab

Publications and source records attributed to C Raab.

At least 19 recordsLinked to original sources
PubMed2003

[From endoscopic mucosa ressection to gastrectomy. How radical must surgery be for stomach cancer?].

The aim of surgical treatment is complete resection (Ro-resection) of the tumor in all dimensions of its growth, i.e. resection of the tumor infiltrated stomach including the locoregional lymph nodes. This can be achieved by stage- or histology adapted surgery resulting in subtotal distal and total gastrectomy as complementary procedures. Local excision of gastric carcinoma in curative intent is indicated only in mucosal carcinoma of the intestinal type. The extent of lymph node dissection is still under discussion; the results depend on the experiences of the surgeon. Several studies have shown a prognostic improvement after systematic (D2) lymphadenectomy in stage II/IIIA-disease or in patients with a low incidence of lymph node metastases. Pancreas preserving splenectomy is suggested in tumors of the proximal stomach or after direct infiltration of these organs. The Roux-en-Y procedure represents the most commonly used method of reconstruction after subtotal distal or total gastrectomy. The importance of the duodenal passage as well as of the pouch construction must be investigated in prospective studies in the future. This is true for the value of perioperative multimodal treatment options.

Gastrectomy↗
PubMed2001

Light interference from single atoms and their mirror images.

A single atom emitting single photons is a fundamental source of light. But the characteristics of this light depend strongly on the environment of the atom. For example, if an atom is placed between two mirrors, both the total rate and the spectral composition of the spontaneous emission can be modified. Such effects have been observed using various systems: molecules deposited on mirrors, dye molecules in an optical cavity, an atom beam traversing a two-mirror optical resonator, single atoms traversing a microwave cavity and a single trapped electron. A related and equally fundamental phenomenon is the optical interaction between two atoms of the same kind when their separation is comparable to their emission wavelength. In this situation, light emitted by one atom may be reabsorbed by the other, leading to cooperative processes in the emission. Here we observe these phenomena with high visibility by using one or two single atom(s), a collimating lens and a mirror, and by recording the individual photons scattered by the atom(s). Our experiments highlight the intimate connection between one-atom and two-atom effects, and allow their continuous observation using the same apparatus.

Journal Article↗
PubMed2001

Estimation of large-scale dimension densities.

We propose a technique to calculate large-scale dimension densities in both higher-dimensional spatio-temporal systems and low-dimensional systems from only a few data points, where known methods usually have an unsatisfactory scaling behavior. This is mainly due to boundary and finite-size effects. With our rather simple method, we normalize boundary effects and get a significant correction of the dimension estimate. This straightforward approach is based on rather general assumptions. So even weak coherent structures obtained from small spatial couplings can be detected with this method, which is impossible by using the Lyapunov-dimension density. We demonstrate the efficiency of our technique for coupled logistic maps, coupled tent maps, the Lorenz attractor, and the Roessler attractor.

Journal Article↗
PubMed2001

A photoactivatable prenylated cysteine designed to study isoprenoid recognition.

Protein prenylation, involving the alkylation of a specific C-terminal cysteine with a C(15) or C(20) isoprenoid unit, is an essential posttranslational modification required by most GTP-binding proteins for normal biological activity. Despite the ubiquitous nature of this modification and numerous efforts aimed at inhibiting prenylating enzymes for therapeutic purposes, the function of prenylation remains unclear. To explore the role the isoprenoid plays in mediating protein-protein recognition, we have synthesized a photoactivatable, isoprenoid-containing cysteine analogue (2) designed to act as a mimic of the C-terminus of prenylated proteins. Photolysis experiments with 2 and RhoGDI (GDI), a protein which interacts with prenylated Rho proteins, suggest that the GDI is in direct contact with the isoprenoid moiety. These results, obtained using purified GDI as well as Escherichia coli (E. coli) crude extract containing GDI, suggest that this analogue will be an effective and versatile tool for the investigation of putative isoprenoid binding sites in a variety of systems. Incorporation of this analogue into peptides or proteins should allow for even more specific interactions between the photoactivatable isoprenoid and any number of isoprenoid binding proteins.

Binding, Competitive↗
PubMed2001

[Multimodality therapy concepts in stomach carcinoma].

The prognosis of gastric cancer is still poor even after curative R0 resection. Therefore, among various multimodality treatments a lot of phase II/III studies have been carried out evaluating preoperative chemotherapy. Although some positive results have been obtained after this procedure, neoadjuvant chemotherapy is still an experimental approach. In the future the prediction and evaluation of response must be defined more exactly. Using intraoperative radio- or intraperitoneal (hyperthermal) chemotherapy reduction of regional relapse or peritoneal carcinomatosis could be obtained without increased survival in general. According to experience in Japan adjuvant (immuno-)chemotherapy can increase the overall survival rates and even in the Western hemisphere some actual studies with adjuvant chemo- +/- radiotherapy could demonstrate a benefit of survival in patients with lymph node metastases. Nevertheless, multimodality treatment strategies must be investigated in further uniform prospective study protocols.

Clinical Trials as Topic↗
PubMed2000

The knowledge, attitudes, and practices of dietitians licensed in Oregon regarding functional foods, nutrient supplements, and herbs as complementary medicine.

OBJECTIVE: To examine the perceived knowledge and attitudes of dietitians licensed in Oregon (LDs) regarding the effectiveness and safety of functional foods, nutrient supplements, and herbs as complementary medicine as well as their personal use, recommendations for the use of others, and training needs. DESIGN: A mailed survey was used to gather data. The questionnaire was developed and face-validated after a focus group discussion. SUBJECTS/SETTING: A geographically stratified, random sample of 202 Oregon LDs was surveyed; usable data were collected from 162 LDs (80%). STATISTICAL ANALYSES: Descriptive statistics and chi 2 tests were used to analyze data. The data were weighted to take account of the sampling method and yield population estimates. RESULTS: LDs considered themselves to be knowledgeable of functional foods and nutrient supplements. More than 80% were confident of the effectiveness of functional foods and nutrient supplements for prevention of illness and treatment of chronic illness, and at least 89% were confident of their safety for these uses. Fewer than 75% considered herbs to be safe and only about 50% were confident of the effectiveness of herbs. Only 10% or fewer LDs considered themselves to be knowledgeable about herbs for prevention and treatment of illness. Interest in training about each of these less-traditional nutrition therapies was high. APPLICATIONS/CONCLUSIONS: Oregon LDs consider themselves to be actively practicing in the area of complementary medicine and have a strong desire for further training. The dietetics profession can capitalize on this interest by taking the lead in training dietitians about the role of functional foods, nutrient supplements, and herbs in health.

Complementary Therapies↗
PubMed1999

The effects of interleukin-2 treatment on endothelin and the activation of the hypothalamic-pituitary-adrenal axis.

OBJECTIVE: Recent reports suggest that complex interactions exist between the neuroendocrine and immune systems. It has been shown for example that cytokines are able to stimulate the hypothalamo-pituitary-adrenal axis. In addition, some studies present evidence that endothelin is able to modulate the activity of several hypothalamic-pituitary axes, e.g. by inducing the ACTH production. DESIGN: We investigated the effects of interleukin-2 on endothelin levels and the hypothalamo-pituitary-adrenal axis. We determined the interleukin-6, big-endothelin, endothelin-1, ACTH, cortisol and AVP responses to intravenously and subcutaneously administered interleukin-2 in 8 cancer patients in a randomized placebo controlled trial. PATIENTS: 8 Patients (2 female and 6 male), age 44 +/- 4.8 years, were enrolled. All patients had a World Health Organization performance status of 1 or less and a Karnofsky Index of at least 80%. MEASUREMENTS: Blood-samples were taken before and 15, 30, 45, 60, 120, 180, 240, 300 and 360 min after interleukin-2 injection. Cytokine serum levels and the plasma levels of big-endothelin, endothelin, ACTH and AVP were analysed using radioimmuno-assays. Cortisol was assayed by an enzyme-linked immunosorbent assay. RESULTS: Interleukin-2 treatment significantly increased plasma big-endothelin levels (P < 0.01 vs basal) and endothelin-1 levels (P < 0.05 vs basal) within two hours and this was followed by an increase in ACTH (P < 0.01 vs basal) and cortisol (P < 0.05 vs basal) within three hours. Interleukin-6 levels increased two hours after interleukin-2 administration (P < 0.01 vs basal). Interleukin-2 had no detectable effect on AVP, blood pressure or heart rate. CONCLUSIONS: Our data demonstrate that cytokines are able to activate the human hypothalamo-pituitary-adrenal axis in vivo. On the basis of the observed time kinetics and in connection with previous findings from in vitro and animal models, we conclude that endothelin may be a link between cytokines and corticotrophin-releasing hormone, most probably functioning as a cytokine-induced neuromodulator controlling pituitary functions.

Adrenocorticotropic Hormone↗
PubMed1999

Studies on cytochrome P-450-mediated bioactivation of diclofenac in rats and in human hepatocytes: identification of glutathione conjugated metabolites.

The nonsteroidal anti-inflammatory drug diclofenac causes a rare but potentially fatal hepatotoxicity that may be associated with the formation of reactive metabolites. In this study, three glutathione (GSH) adducts, namely 5-hydroxy-4-(glutathion-S-yl)diclofenac (M1), 4'-hydroxy-3'-(glutathion-S-yl)diclofenac (M2), and 5-hydroxy-6-(glutathion-S-yl)diclofenac (M3), were identified by liquid chromatography-tandem mass spectrometry analysis of bile from Sprague-Dawley rats injected i.p. with a single dose of diclofenac (200 mg/kg). These adducts presumably were formed via hepatic cytochrome P-450 (CYP)-catalyzed oxidation of diclofenac to reactive benzoquinone imines that were trapped by GSH conjugation. In support of this hypothesis, M1, M2, and M3 were generated from diclofenac in incubations with rat liver microsomes in the presence of NADPH and GSH. Increases in adduct formation were observed when incubations were performed with liver microsomes from phenobarbital- or dexamethasone-treated rats. Adduct formation was inhibited by polyclonal antibodies against CYP2B, CYP2C, and CYP3A (40-50% inhibition at 5 mg of IgG/nmol of CYP) but not by an antibody against CYP1A. Maximal inhibition was obtained when the three inhibitory antibodies were used in a cocktail fashion (70-80% inhibition at 2.5 mg of each IgG/nmol of CYP). These data suggest that diclofenac undergoes biotransformation to reactive metabolites in rats and that CYP isoforms of the 2B, 2C, and 3A subfamilies are involved in this bioactivation process. With respect to CYP2C isoforms, rat hepatic CYP2C7 and CYP2C11 were implicated as mediators of the bioactivation based on immunoinhibition studies using antibodies specific to CYP2C7 and CYP2C11. Screening for GSH adducts also was carried out in human hepatocyte cultures containing diclofenac, and M1, M2, and M3 again were detected. It is possible, therefore, that reactive benzoquinone imines may be formed in vivo in humans and contribute to diclofenac-mediated hepatic injury.

Animals↗
PubMed1994

Elevated endothelin-1 levels after cigarette smoking.

The effect of short-term nicotine consumption on endothelin-1 (ET-1) levels was studied in 10 male healthy smokers. Volunteers smoked in random order on 3 separate days a low-tar cigarette or a high-tar cigarette, or were studied without having smoked (no-cigarette experiment). ET-1, corticotropin, and cortisol levels, heart rate, and blood pressure were determined before and 1, 3, 5, 10, 20, and 30 minutes after smoking. In contrast to results obtained after smoking a low-tar cigarette or not smoking, smoking a high-tar cigarette resulted in a significant increase in ET-1 levels within 10 minutes, followed by an increase in corticotropin levels within 20 minutes after smoking. Thirty minutes after smoking, cortisol levels were higher after a high-tar cigarette compared with a low-tar cigarette or no smoking. Increases in heart rate and systolic blood pressure were likewise higher after smoking a high-tar cigarette than after smoking a low-tar cigarette. In conclusion, it is tempting to speculate that ET-1 may indeed act as the long-searched-for link between vasopressin and corticotropin-releasing hormone (CRH) and thus play an essential role in the stimulation of the hypothalamic-pituitary-adrenal axis. In addition, these results suggest that the increase in the level of ET-1, a powerful vasoconstrictor and mitogen, may play an important part in the disease mechanisms of atherosclerosis arising from smoking.

Adrenocorticotropic Hormone↗
PubMed1989

Vitamin and mineral supplementation practices of adults in seven western states.

Seven western states (Arizona, California, Idaho, Nevada, New Mexico, Oregon, and Wyoming) were surveyed in 1986 to determine the extent of vitamin/mineral supplementation and dosage levels of single supplements. Questionnaires were mailed to 3,500 individuals. A 57.8% response rate was obtained from the deliverable surveys, with a sample size of 1,730. The sample consisted of 54% women and 46% men and was predominantly white (88.9%). Fifty-four percent of the sample consumed some type of supplement; multiple vitamin/minerals were consumed with the greatest frequency. For single supplements, vitamin C was reported with the greatest frequency (23.1%), followed by some type of calcium supplement (22.5%) and vitamin E (11.1%). More than 80% of the vitamin C users indicated a dosage of 250 mg/day. Most respondents consumed calcium dosages of less than 1,000 mg/day. For vitamin E, 75% of the users consumed more than 200 IU/day. The data suggest that the potential for toxicity due to excess supplementation levels exists in the western states studied.

Adolescent↗
PubMed1981

Evaluation of the new Beckman electrophoretic method for CK-MB: comparison with ion exchange chromatography and investigation of a reference outpatient population.

We evaluated the performance of a CK isoenzyme kit utilizing agarose electrophoresis with fluorescence scanning of an overlay paper rather than the gel. We compared this method to ion exchange chromatography with mini-columns of DEAE Sephadex using samples from hospitalized patients and from a reference population of ambulatory outpatients with common, chronic medical conditions. The detection limit, precision and linearity of the electrophoretic method were acceptable, but the method overestimated CK-MB, requiring a different reference range for clinical application. There were inter-racial differences within the reference population for total CK and for the percent of CK-MB using either method. We discuss the significance of our findings with respect to clinical decision limits for CK-MB.

Adult↗