Biomedical subjects

C Rode

Publications and source records attributed to C Rode.

10 recordsLinked to original sources

PubMed2006

Detection limit of methods to assess fluid status changes in dialysis patients.

Technical systems for an accurate and practicable fluid management of dialysis patients are urgently needed, since current clinical methods are partially subjective, imprecise, and time consuming. Such new systems should not only allow the determination of the target normohydration weight, but also must be able to detect clinically relevant changes in fluid volume ( approximately 1 l). This study focuses on the systematic analysis of the detection limit of several candidate methods for fluid management. In a cohort of 16 new dialysis patients, several candidate methods were applied in parallel during each treatment of the initial weight reduction phase: the measurement of vena cava diameter (VCD), vena cava collapsibility index (CI), the blood volume drop during an ultrafiltration (UF) bolus (Deltarelative blood volume (RBV)-), the rebound after the UF bolus (DeltaRBV+), and the extracellular fluid volume determined with whole body bioimpedance spectroscopy (BIS). A clinical reference method was used to manage the fluid status of patients. All methods showed significant correlations with predialysis weight. The detection limits W(lim) of candidate methods for changes in fluid status were assessed as W(lim)=0.87 kg+/-0.64 kg (BIS), 1.74 kg+/-1.56 kg (VCD), 2.3 kg+/-1.0 kg (DeltaRBV-), 7.4 kg+/-8.5 kg (CI), 40 kg+/-108 kg (DeltaRBV+). Only BIS shows a satisfactorily low detection limit W(lim), whereas W(lim) was rated as critical for the VCD and DeltaRBV- methods, and as unacceptable for the CI and DeltaRBV+ methods. Bioimpedance spectroscopy appears to be the most promising method for a practical fluid management system in dialysis.

Adult↗

PubMed2002

Extracorporeal pressure monitoring and the detection of vascular access stenosis.

Prospective monitoring of static venous pressure is an established tool to detect outflow stenoses in a vascular access. However, with this method it is not possible to identify vascular stenoses which are localized between the arterial and venous dialysis needle. We describe a new approach based on both static arterial and venous extracorporeal pressures. Pressure data of 9 dialysis patients with normal vascular access function and 9 patients with stenotic access were analyzed. Extracorporeal pressure was found to depend on the position of the heart relative to the extracorporeal blood circuit. All patients with venous outflow stenoses had an elevated ratio of arterial and venous intra-access pressure to mean arterial pressure. In case of access stenosis between arterial and venous needle the ratio of venous pressure to mean arterial pressure was normal, and only the arterial pressure ratio was elevated. We conclude that combined arterial and venous intraaccess pressure measurement normalized by mean blood pressure detects venous stenosis as well as stenosis between the arterial and venous dialysis needle. To minimize the rate of access thrombosis both arterial and venous intra-access pressure should be monitored.

Arteriovenous Shunt, Surgical↗

PubMed1999

When and why do people avoid unknown probabilities in decisions under uncertainty? Testing some predictions from optimal foraging theory.

When given a choice between two otherwise equivalent options - one in which the probability information is stated and another in which it is missing - most people avoid the option with missing probability information (Camerer & Weber, 1992). This robust, frequently replicated tendency is known as the ambiguity effect. It is unclear, however, why the ambiguity effect occurs. Experiments 1 and 2, which separated effects of the comparison process from those related to missing probability information, demonstrate that the ambiguity effect is elicited by missing probabilities rather than by comparison of options. Experiments 3 and 4 test predictions drawn from the literature on behavioral ecology. It is suggested that choices between two options should reflect three parameters: (1) the need of the organism, (2) the mean expected outcome of each option; and (3) the variance associated with each option's outcome. It is hypothesized that unknown probabilities are avoided because they co-occur with high outcome variability. In Experiment 3 it was found that subjects systematically avoid options with high outcome variability regardless of whether probabilities are explicitly stated or not. In Experiment 4, we reversed the ambiguity effect: when participants' need was greater than the known option's expected mean outcome, subjects preferred the ambiguous (high variance) option. From these experiments we conclude that people do not generally avoid ambiguous options. Instead, they take into account expected outcome, outcome variability, and their need in order to arrive at a decision that is most likely to satisfy this need.

Adult↗

PubMed1997

Discovery of disseminated J96-like strains of uropathogenic Escherichia coli O4:H5 containing genes for both PapG(J96) (class I) and PrsG(J96) (class III) Gal(alpha1-4)Gal-binding adhesins.

The pyelonephritis-associated adhesin gene papG of Escherichia coli occurs in three variants. Whereas the class II and class III variants are common among human urinary tract infection isolates, the class I allele, despite being the first cloned, has previously been found only in source strain J96. Five strains have been discovered from geographically diverse locales that, like J96, contain both the class I and class III papG alleles. One strain caused bacteremia, whereas 4 caused cystitis. Like J96, all 5 had group III capsule genes, expressed the H5 flagellar antigen and the F13 fimbrial antigen, and exhibited similar genomic patterns and virulence factor profiles. These findings demonstrate that the class I papG allele is not unique to J96 but is present in a group of extraintestinal isolates of E. coli O4:H5 that represent a disseminated virulent clonal group.

Adhesins, Escherichia coli↗

PubMed1996

Bcl-xS enhances adenoviral vector-induced apoptosis in neuroblastoma cells.

bcl-x is a member of the bcl-2 family of genes and by alternative splicing gives rise to two distinct mRNAs: bcl-xL and bcl-xS. We have previously investigated the expression of Bcl-x in neuroblastoma (NB) cell lines and have shown that Bcl-xL is expressed and functions to inhibit chemotherapy-induced apoptosis. However, none of the NB cell lines expressed Bcl-xS. The aim of the present study was to determine the effects of Bcl-xS expression on the viability of NB cells. A panel of NB cell lines (CHP-382, GOTO, SHEP-1, SHSY-5Y, and GI-CA-N) were infected with either a bcl-xS adenovirus (pAdRSV-bcl-xS) or a control virus (pAdRSV-lac-z). NB cells showed loss of viability with both viruses, although the bcl-xS virus was most toxic. Importantly, infection with the bcl-xS adenovirus resulted in rapid loss of cell viability, DNA fragmentation, and morphological features of apoptosis even in NB cells transfected to overexpress Bcl-2 and Bcl-xL. These findings suggest that deregulated expression of Bcl-xS using an adenovirus may provide a novel mechanism for initiating cell death in tumors that express Bcl-2 or Bcl-xL.

Adenoviridae↗

PubMed1996

Residual leukemia and immunomagnetic bead purging in patients with BCR-ABL-positive acute lymphoblastic leukemia.

Residual leukemia was evaluated in autologous bone marrow grafts harvested in first (n = 11) or second (n = 3) complete remission from 14 patients with BCR-ABL-positive acute lymphoblastic leukemia after treatment according to the German multicenter ALL protocols. The intervals from diagnosis to BM harvest were median 159 (range 78-463) and from preceding chemotherapy to BM harvest median 39 (range 26-69) days, respectively. A limiting log(10)-dilution RT-PCR was used to semiquantify BCR-ABL-positive cells. All autografts appeared to be significantly contaminated with residual leukemic cells. The BCR-ABL-specific titers ranged from 1:10(3) to 1:10(6) (median 1:10(4)) above the limit of detection. This was the rationale to purge the grafts using two cycles of IgM anti-CD10, CD19, and AB4 MoAbs-coated immunomagnetic beads (IMB). Purging depleted median 3 (range 2-4) logs of residual leukemia, resulting in a median 1:10(1) (range 1:10(0) to 1:10(3)) postpurge BCR-ABL-specific titer. The second purging cycle accounted for 1 log of depletion. The mean +/- s.e.m. post-purge recoveries of MNC and CFU-GM were 59 +/- 4%, and 61 +/- 9%, respectively. We conclude that all BCR-ABL-positive ALL patients achieving CR by cytological criteria have critically high levels of residual leukemia in their bone marrow, which can be reduced by median 3 log using immunomagnetic bead purging.

Adolescent↗

PubMed1995

Menstrual cycle affects functional cerebral asymmetries.

Cerebral lateralization in females is probably modulated by the menstrual cycle such that a part of hemispheric asymmetries are diminished with an increase of the steroids estrogen and progesterone during the follicular and luteal phase and enhanced with steroid decreases during the menstrual phase. However, previous data were contradictory with regard to the hemispheric side of modulation and could not analyze which steroid is mainly responsible for cycle dependent lateralization shifts. Therefore, in the present study estrogen and progesterone changes were assessed separately and related to changes in cerebral asymmetry. Plasma levels of estrogen and progesterone were measured once during luteal and once during menstrual cycle phase while 20 females subjects performed a verbal and a figural lateralized matching task. The results showed a significant cycle phase x lateralization interaction for the right hemisphere dominated figural comparison task but not for the left hemispheric lexical condition. Although the lateralization was modulated by the menstrual cycle, a within-subject regression analysis demonstrated that the asymmetry shift was not under direct influence of estrogen or progesterone. Thus, the present study provides further empirical support for cycle dependent alterations in lateralization but makes it unlikely that this effect is directly caused by estrogen or progesterone plasma level variations.

Adult↗

PubMed1995

Virulence characteristics of Escherichia coli causing first urinary tract infection predict risk of second infection.

Escherichia coli causes most urinary tract infections (UTIs) in ambulatory populations. Several bacterial virulence factors occur more frequently among urinary E. coli isolates than among fecal isolates, but none have been reported to predict risk of second UTIs. DNA hybridization was used to characterize the bacterial virulence profiles of urinary E. coli isolates from 174 women with first UTI and compared for risk of second UTI. Of the women, 28 (16%) had a culture-confirmed second UTI within 6 months of a negative test-of-cure. Three virulence factors were associated with a significantly lower risk of second UTI: cytotoxic necrotizing factor (relative risk [RR] = 0.0; 95% confidence interval [CI], 0.0, 0.42); hemolysin (RR, 0.10; 95% CI, 0.01, 0.69), and S fimbrial adhesin (RR, 0.25; 95% CI, 0.06, 1.00). Dr binding was associated with a 2-fold increased risk of second UTI (RR, 2.30; 95% CI, 1.23, 4.29). Half of all paired first and second UTI isolates from the same subject were apparently the same.

Adult↗

PubMed1995

Purging of peripheral blood stem cells yields BCR-ABL-negative autografts in patients with BCR-ABL-positive acute lymphoblastic leukemia.

Remission marrow from patients with BCR-ABL+ acute lymphoblastic leukemia (ALL) achieving clinical remission (CR) after induction or consolidation chemotherapy according to the German multicenter adult ALL (GMALL) protocol showed high titers of residual BCR-ABL+ cells. Therefore, we initiated a pilot study to monitor circulating BCR-ABL+ cells and to collect, purge, and autograft peripheral blood stem cells (PBSC) in these patients. After GMALL 05/93 high-risk phase II of induction chemotherapy (high-dose AraC 3 g/m2 x 8 does and mitoxantrone 10 mg/m2 x 3 doses), patients received 5-10 micrograms/kg subcutaneous recombinant human granulocyte colony-stimulating factor (rhG-CSF) daily. Mobilized CD34+ cells peaked between 20 and 26 days after starting chemotherapy at 4.8-75.6 (median 10.8) x 10(4)/mL peripheral blood (PB) (n = 5). Patients treated with additional chemotherapy cycles failed to mobilize adequate numbers of CD34+ cells. PB stem cells (PBSC) were purged using a cocktail of CD10, CD19, and AB4 monoclonal antibodies (mAbs) coupled to immunomagnetic beads (IMB). The median recoveries of total nucleated cells (TNC) and CD34+ cells after mAb/IMB purging were 84 and 81%. The peak numbers of CD34+ cells collected in a single leukapheresis were median 8.6 x 10(6)/kg pre- and 5.2 x 10(6)/kg postpurge (n = 4). The absolute prepurge CD19+ cells were as low as median 2.7 (range 1.4-19) x 10(6) per leukapheresis. Residual BCR-ABL+ cells in unpurged leukapheresis products were assessed by limiting-log10-dilution nested reverse-transcriptase polymerase chain reaction (RT-PCR) as one in 10(5) to one in 10(6) normal cells and were consistently undetectable in all purged PBSC autografts. We conclude that sufficient numbers of CD34+ cells for PBSCT can be collected after phase II but not at later stages of the GMALL 05/93 high risk protocol; PBSC grafts are 3 log less contaminated with residual BCR-ABL+ cells compared to an historical series of 13 autologous BM grafts; and purging of PBSC with mAb/IMB is feasible with minor loss of CD34+ cells and abolished BCR-ABL signals in the grafts.

Adult↗

PubMed1986

The use of a compact protable microcomputer system (EPSON HX 20) to measure on-line the contractile activity of the digestive tract from eight channels. Application to pharmacological tests.

The chronically prepared gut with strain-gauge transducers is a useful model to evaluate the effects of drugs affecting the digestive motility in fed and fasted animals. This paper describes a rapid and reproducible on-line microcomputerized technique to evaluate continuously, 23 hr per day, the level of gut motility using a portable compact microcomputer (EPSON HX 20). The gastric, intestinal, and colonic motility indexes were automatically determined from the surface of the contractile waves from eight different sites over periods of time varying from 1 to 120 min. This system has been successfully used to investigate the motor effects of spasmolytic or antidiarrheal drugs inravenously (N-butyl-hyoscine, trospium, secoverine, and prifinium) or orally (trimebutine, loperamide) administered in conscious, fed dogs.

Animals↗