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Biomedical subjects

C Decker

Publications and source records attributed to C Decker.

At least 19 recordsLinked to original sources
PubMed2003

[Image quality and exposure dose in digital projection radiography].

PURPOSE: Comparison of the imaging capabilities of storage phosphor (computed) radiography and flat plate radiography with conventional film-screen radiography to find new strategies for quality and dose management, i. e., optimizing imaging quality and dose depending on the imaging method and clinical situation. MATERIALS AND METHODS: Images of a CDRAD-phantom, hand-phantom, abdomen-phantom and chest-phantom obtained with different exposure voltages (50 kV, 73 kV, 109 kV) and different speeds (200, 400, 800, 1600) were processed with various digital systems (flat plate detector: Digital Diagnost [Philips]; storage phosphors: ADC-70 [Agfa], ADC-Solo [Agfa], FCR XG 1 [Fuji]) and a conventional film-screen system (HT100G/ Ortho Regular [Agfa]). RESULTS: The evaluation of CDRAD images found the flat plate detector system to have the highest contrast detectability for all dose levels, followed by the FCR XG 1, ADC-Solo and ADC-70 systems. Comparison of the organ-phantom images found the flat plate detector system to be equal to film-screen radiography and especially to storage phosphor systems even for low exposure doses. CONCLUSIONS: Flat plate radiography systems demonstrate the highest potential for high image quality when reducing the exposure dose. Depending on the system generation, the storage phosphor systems also show an improved image quality, but the possibility of a dose reduction is limited in comparison with the flat plate detector system.

Hand↗
PubMed2002

Molecular imaging of perfusion disturbances in glaucoma.

Ocular ischemia resulting from perfusion disturbances may play a major role in initiation of glaucoma. Possibly secondary to ischemia autoimmunogenic events are activated in glaucoma patients with increased prevalence of systemic autoimmune diseases. The determination of potential molecular markers in blood leukocytes could be useful for early noninvasive diagnostics of glaucoma. Our study using subtractive hybridization showed altered gene expression in leukocytes of glaucoma patients in comparison to age and sex matched healthy subjects. Subtracted genes encoding lymphocyte IgE receptor (Fc epsilon RII/CD23), T cell-specific tyrosine kinase, thromboxan A2 receptor, alkaline phosphatase and Na(+)/K(+)-ATPase are differentially expressed in circulating leukocytes of glaucoma patients. These genes show expression profiles characteristic for adherent leukocytes which could be an important contributor to blood-brain barrier breakdown which has been found in glaucoma patients.

Adult↗
PubMed2001

Efficient multi-keV underdense laser-produced plasma radiators.

Novel, efficient x-ray sources have been created by supersonically heating a large volume of Xe gas. A laser-induced bleaching wave quickly ionizes the high- Z gas, and the resulting plasma emits x rays. This method significantly improves the production of hard x rays because less energy is lost to kinetic energy and sub-keV x rays. The conversion efficiency of laser energy into L-shell radiation between 4-7 keV is measured at approximately 10%, an order of magnitude higher than efficiencies measured from solid disk targets. This higher flux enables material testing and backlighting in new regimes and scales well to future high-powered lasers.

Journal Article↗
PubMed2001

Alosetron controls bowel urgency and provides global symptom improvement in women with diarrhea-predominant irritable bowel syndrome.

OBJECTIVES: Bowel urgency is one of the most bothersome symptoms for nonconstipated IBS patients. The efficacy of alosetron in control of bowel urgency and Global Improvement of IBS symptoms were evaluated in a multicenter double-blind, randomized, placebo-controlled study. METHODS: Female IBS patients with lack of satisfactory control of bowel urgency were randomized 2:1 to alosetron 1 mg twice daily or placebo treatment groups. The primary endpoint was the proportion of days with satisfactory control of bowel urgency during the 12-wk treatment period and 2-wk follow-up period. Secondary endpoints included IBS Global Improvement (responder defined as patient-reported moderate or substantial improvement in IBS symptoms) and improvements in bowel function (stool frequency, consistency, and sensation of incomplete evacuation). RESULTS: A total of 801 women were randomized to the alosetron (n = 532) or placebo groups (n = 269). Physicians classified 98% of patients with diarrhea-predominant IBS. Patients treated with alosetron had a significantly greater proportion of days with satisfactory control of urgency compared to placebo for the treatment period (73% vs 57%, p < 0.001). A significantly greater number of patients treated with alosetron were IBS Global Improvement responders compared to placebo at week 12 (76% vs 44%, p < 0.001). IBS Global Improvement responders had more days with satisfactory control of urgency at week 12 (88% vs 48%) as well as firmer stools, fewer stools/day, and fewer days with incomplete evacuation compared with nonresponders. Alosetron-treated patients showed improvements in bowel functions compared to placebo-treated patients. Constipation was the most commonly reported adverse event.

Carbolines↗
PubMed2001

The Psychology Graduate Applicant's Portal (www.psychgrad.org).

Applying to graduate school in psychology can be an intimidating process. Many obstacles must be overcome, such as applying to a program appropriate to the specific applicant, getting good GRE scores, submitting a clear and well-written statement of purpose, and obtaining letters of recommendation, to name just a few. Much information is available to assist applicants in these tasks, but finding this information can cause problems even for experienced Internet users. The goal of this project is to create an easily accessible Web clearing house of information on applying to graduate school in psychology. This Web site, called the Psychology Graduate Applicant's Portal (or PsychGrad.org), contains targeted links to other Web pages with valuable information, book recommendations on the applications process, polls to measure issues important to the graduate applicants, site-unique advice on graduate programs, a message board to exchange information and experiences, and other information relevant to the application process.

Education, Graduate↗
PubMed2000

Charged amino-acid residues in transmembrane domains of the plastidic ATP/ADP transporter from arabidopsis are important for transport efficiency, substrate specificity, and counter exchange properties.

Structure-function relationships of the plastidic ATP/ADP transporter from Arabidopsis thaliana have been determined using site-directed mutants at positions K155, E245, E385, and K527. These charged residues are found within highly conserved domains of homologous transport proteins from plants and bacteria and are located in predicted transmembrane regions. Mutants of K155 to K155E, K155R, or K155Q reduced ATP transport to values between 4 and 16% of wild-type uptake, whereas ADP transport was always less then 3% of the wild-type value. Site-directed mutations in which glutamate at positions 245 or 385 was replaced with lysine, abolished transport. However, conservative (E245D, E385D) or neutral (E245Q, E385Q) replacement at these two positions allowed transport. The fourth reciprocal exchange, K527E, also abolished uptake of both adenylates. K527R and K527Q were unable to transport ATP, but ADP transport remained at 35 and 27%, respectively, of the wild-type activity. There was a 70-fold decreased apparent affinity of K527R for ATP, but only a twofold decrease for ADP. The efflux of ATP, but not ADP, was also greatly reduced in K527R. These observations show strikingly that K527 plays a role in substrate specificity that is manifest in both the influx and efflux components of this antiporter.

Adenosine Diphosphate↗
PubMed2000

Altered gene expression in lymphocytes of patients with normal-tension glaucoma.

BACKGROUND: In glaucoma there is a loss of retinal ganglion cells. There is evidence that this loss can occur by apoptosis. The signal transduction leading to retinal ganglion cell apoptosis in glaucoma is not yet clear. The present study compares the gene expression in lymphocytes of normal tension glaucoma patients (NTG-patients) with the one of healthy controls. METHODS: Subtractive hybridization was used to compare mRNA in lymphocytes of six vasospastic NTG-patients with six age and sex matched healthy subjects. RESULTS: Genes coding for p53-protein, NTP (neural thread protein) and 20 S proteasome subunit XAPC7 were overexpressed, whereas those coding for XPGC (Xeroderma pigmentosum gene), the survivin protein as well as one type of ABC transport protein were underexpressed. CONCLUSION: In comparison to healthy controls, patients with vasospastic NTG seem to over- as well as under-express certain genes in their lymphocytes.

ATP-Binding Cassette Transporters↗
PubMed2000

Accuracy of K-shell spectra modeling in high-density plasmas

We present spectroscopic measurements of the helium-like and lithium-like argon emission supported by Thomson scattering diagnostics on gas bag targets. These data provide critical tests of plasma spectroscopic K-shell models. In particular, we have measured the line radiation in the wavelength region of the He-like Ar 1s(2)-1s3l transition (He-beta) that is of interest for density and temperature measurements of plasmas from gas-filled targets (n(e)</=10(21) cm(-3)), laser ablation targets (n(e)</=10(22) cm(-3)), and inertial confinement fusion capsule implosions (n(e)>/=10(24) cm(-3)). The spectra show lithium-like dielectronic satellites on the red wing of the He-beta line that are temperature sensitive and are known to influence the shape of the Stark-broadened line profiles observed from implosions. To examine the kinetics modeling of this complex, i.e., the He-beta and its associated satellites, we have performed experiments in gas bag plasmas at densities of (0.6-1.1)x10(21) cm(-3) where we independently determine the electron temperature with ultraviolet Thomson scattering. The comparison of the satellite intensities with kinetics modeling shows good agreement for satellites whose upper states are populated by dielectronic capture, but shows discrepancies for inner-shell collisional excited transitions.

Journal Article↗
PubMed1999

Increased soft tissue in the posterior cervical and upper back area of patients on HIV-1 protease inhibitors.

BACKGROUND: Corticosteroids as well as sex hormones affect the redistribution of subcutaneous fat and the percentage of lean body mass. In addition, some stromal cells express steroid receptors, and the quantity and distribution of these receptors vary at different body sites and between sexes. Inhibitors of HIV-1 protease may affect steroid hormone metabolism through their effect on cytochrome P450. OBJECTIVES: To determine the changes in the tissue of the back in three HIV-1+ patients who developed increased soft tissue in posterior cervical and upper back areas while on HIV-1 protease inhibitors. METHODS: Punch biopsies of the involved posterior cervical and upper back areas were done. These included subcutaneous adipose tissue. Routine hematoxylin and eosin-stained sections, along with special stains for elastic and stromal mucin, and immunohistochemical stains for CD34 (HPCA-1 and Factor XIIIa) were evaluated. RESULTS: Histologically all three patients showed identical features. There was expansion of the dermis with decreased periadnexal fat and marked widening of the fibrous septa within the expanded subcutaneous fat. CONCLUSIONS: The posterior cervical and upper back area appears to be a common site for localization of mesenchymal tumours that show some fat differentiation and produce an increase in stromal matrix material. Mesenchymal cell populations within this area are also affected by systemic diseases. A male predominance pattern occurs with these conditions, and steroid receptors are expressed on some mesenchymal cells, that vary with the body location. Thus, this observation may be related to the effects of protease inhibitors on steroid hormone metabolism through their inhibition of cytochrome P-450.

Adipose Tissue↗
PubMed1998

7-Oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridines as novel inhibitors of human eosinophil phosphodiesterase.

High-throughput file screening against inhibition of human lung PDE4 led to the discovery of 3-ethyl-1-(4-fluorophenyl)-6-phenyl-7-oxo-4, 5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine (11) as a novel PDE4 inhibitor. Subsequent SAR development, using an eosinophil PDE assay, led to analogues up to 50-fold more potent than 11 with IC50 values of 0.03-1.6 microM. One such compound, CP-220,629 (22) (IC50 = 0.44 microM), was efficacious in the guinea pig aerosolized antigen induced airway obstruction assay (ED50 2.0 mg/kg, po) and demonstrated a significant reduction in eosinophil (55%), neutrophil (65%), and IL-1beta (82%) responses to antigen challenge in atopic monkeys (10 mg/kg, po).

Airway Obstruction↗
PubMed1997

Analysis of heterocyclic aromatic amines in wine by high-performance liquid chromatography-electrospray tandem mass spectrometry.

High-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS-MS) was used for the analysis of heterocyclic aromatic amines (HAAs) in 25 wines from various regions. In 24 wines under study HAAs were detected in the low ng/l range. 2-Amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C) were found to be the most widely distributed HAAs in the wines under study. There was a difference in the presence of HAAs in white and red wines. In the latter, higher concentrations were found, with MeA alpha C in amount ranging from < 7.5 to 107 ng/l. Compared to the quantities of HAAs evaluated in meat and meat products, the amounts found in wines are 100-1000-fold lower.

Amines↗
PubMed1997

Increased cutaneous toxicity to ionizing radiation in HIV-positive patients. Military Medical Consortium for the Advancement of Retroviral Research (MMCARR).

BACKGROUND: There are reports of increased reactions in HIV-1+ patients to ultraviolet light sometimes in association with medication. In addition, there are also reports of increased morbidity associated with radiation therapy in HIV-1+ patients. METHODS: Three HIV-1+ patients developed cutaneous toxic reactions to radiation therapy; two with Kaposi's sarcoma (KS) and one with non-Hodgkin's lymphoma. CONCLUSIONS: Although the mechanisms which resulted in these reactions are not clear, they may be related to depletion of endogenous scavengers and may be accentuated by the pattern of immune dysregulation present in HIV-1 disease.

Adult↗
PubMed1996

Phorbol ester-sensitive phospholipase D is mainly localized in the endoplasmic reticulum of BHK cells.

The localization of phorbol ester-sensitive phospholipase D (PLD) in baby hamster kidney cells has been investigated by determining the subcellular distribution of the phosphatidylbutanol produced when the cells are incubated with phorbol 12-myristate 13-acetate and n-butanol. Results derived by isolation of plasma membrane vesicles from intact cells or by subcellular fractionation on a sucrose density gradient suggest the PLD is specific for phosphatidylcholine and its primary site of action is not the plasma membrane but the endoplasmic reticulum.

Acetic Acid↗
PubMed1996

Simultaneous Measurement of Local Gain and Electron Density in X-ray Lasers

X-ray lasers (XRLs) have experimental average gains that are significantly less than calculated values and a persistently low level of spatial coherence. An XRL has been used both as an injected signal to a short XRL amplifier and as an interferometer beam to measure two-dimensional local gain and density profiles of the XRL plasma with a resolution near 1 micrometer. The measured local gain is in agreement with atomic models but is unexpectedly spatially inhomogeneous. This inhomogeneity is responsible for the low level of spatial coherence observed and helps explain the disparity between observed and simulated gains.

Journal Article↗
PubMed1996

[Incidence and quality of dreaming during anesthesia with propofol in comparison with enflurane].

UNLABELLED: Since the introduction of propofol into clinical practice, dreaming during general anaesthesia has been frequently reported with this drug. We investigated the incidence and character of these dreams with regard to distinction from intraoperative awareness and in comparison with habitual dreams or dreams during general anaesthesia with enflurane. METHOD: A total of 230 patients (ASA I-II) undergoing minor elective surgery were randomly assigned to one of two groups. Both groups received the same premedication (1 mg flunitrazepam) the previous evening. After induction using etomidate 2 mg/kg, anaesthesia in group I was maintained using 0.8%-1.5% enflurane supplemented in the sense of "balanced anaesthesia" with fentanyl, vecuronium, and nitrous oxide. Anaesthesia in group II was induced with propofol 2 mg/kg. After a saturation phase of approximately 10 mg/kg.h, 5-6 mg/kg.h was administered for maintenance supplemented by fentanyl, Vecuronium, and N2O as in group I. Interviews were conducted preoperatively, just after recovery from anaesthesia, and 24 h later. We inquired about preoperative fears or concerns, sensory perceptions, and the incidence and character (pleasant, unpleasant, indifferent) of habitual dreams. After recovery the patients were asked if they had had any conscious perceptions, whether they believe them to be dreams or reality, and repeated the preoperative questions as to common feelings and the character of sensory perceptions. RESULTS: The two groups were not entirely comparable due to the distribution of sex and age, but we did not find any differences in preoperative grades of fear and incidence of dreams. Of the propofol patients, 60% dreamed intraoperatively versus 11% in the enflurane group. No evidence of any intraoperative awareness was found. Because of the low incidence of dreams in the enflurane group, a comparison of detailed information between the groups could not be provided. Except for 1, all patients in the propofol group had very pleasant dreams compared to their habitual dreams (4.5% in the enflurane group). One day after surgery 37% of all patients in the propofol group remembered having dreamed intraoperatively. We did not found any correlation to the incidence of habitual dreaming, preoperative fear, age, sex, duration of anaesthesia, or total dose of propofol. Furthermore, intraoperative dreams differed from habitual dreams in character and content. CONCLUSIONS: We conclude that sensory experiences during propofol anaesthesia are not stimulus-related perceptions or awareness, but dreams similar to normal ones. In view of the absence of clear signs of stimulus-related response, we presume that dreaming is a specific side effect of propofol. Because of the absence of difficulties, dreaming during propofol anaesthesia appears not to be a disadvantage with regard to the quality of anaesthesia.

Adult↗
PubMed1996

Bacillus piliformis infection (Tyzzer's disease) in a patient infected with HIV-1: confirmation with 16S ribosomal RNA sequence analysis.

Bacillus piliformis is a long, rod-shaped bacterium that has never been grown in cell-free medium and whose taxonomic classification is uncertain. B. piliformis is the causative agent of Tyzzer's disease, which is frequently reported in laboratory, wild, and domesticated animals. The spectrum and severity of this disease is wide in animals. Although many infections are rapidly fatal, subclinical infections are also common. To date, there have been no reports of B. piliformis infection in human beings, although elevated antibody levels have been reported in pregnant women. We describe the first case of human B. piliformis infection, in a man with HIV-1 infection and chronic, localized, crusted verrucous lesions. The diagnosis was confirmed by ribosomal RNA sequencing. The spectrum of organisms leading to infection and the spectrum of diseases caused by these organisms continue to expand, as new infections are identified and as patients with HIV-1 live longer with more severe immune suppression. The extreme difficulty in culturing B. piliformis and the lack of clinical and histopathologic experience with this organism in human beings mean that B. piliformis is potentially another infectious agent to be considered in human beings. Also, when an infectious organism is a strong clinical consideration, silver stains may be of use when results of routine bacterial staining are negative.

AIDS-Related Opportunistic Infections↗
PubMed1994

Mental rehearsal in table tennis performance.

Effects of mental rehearsal were assessed on two measures of table tennis performance, counterattack forehand and counterattack backhand. Mental rehearsal combined with observational and physical techniques (N = 40) appeared to improve table tennis performance both qualitatively and quantitatively. Correlations suggested mental training effects cannot be explained only in terms of visual imagery.

Adult↗