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Biomedical subjects

U Schuler

Publications and source records attributed to U Schuler.

At least 37 records · Page 2Linked to original sources
PubMed1997

Sensitivity of combined DNA/immunophenotype flow cytometry for the detection of low levels of aneuploid lymphoblastic leukemia cells in bone marrow.

By simultaneous DNA staining and immunophenotyping, the aneuploid blasts of acute lymphoblastic leukemia (ALL) can be quantitated by flow cytometry. The present study evaluates the application of this method for the detection of minimal residual disease (MRD). For this purpose leukemia cells with known aneuploidy were serially diluted with diploid bone marrow cells obtained after chemotherapy. These mixed samples were immunophenotyped using antibodies CD34, CD10, or CD19 and processed for DNA staining with propidium iodide. Fifty thousand cells were measured for each experiment and the results were compared with the analysis of control sample without added aneuploid cells. Aneuploid cells diluted to 1% were not detectable in 6/15 cases when DNA content analysis was used alone, and in dilutions of < 1%, these cells were not detectable. When DNA content and immunophenotype were simultaneously measured, aneuploidy was detectable in 15/15 cases at 1.00%, 6/6 at 0.50%, 16/16 at 0.10%, and 16/17 at 0.05%. Therefore this method may be useful for the detection of minimal residual disease in cases of aneuploid lymphoblastic leukemia.

Aneuploidy↗
PubMed1997

A novel method for direct and fluorescence independent determination of drug efflux out of leukemic blast cells.

Multi drug resistance (MDR) is often due to an increased efflux of anti cancer drugs out of leukemic blast cells. Efflux assays are used to get an impression of functional resistance in those cells. Dyes like rhodamine 123 or 3'3'-diethyloxocarbocyanine iodide are commonly used for this purpose. A major known disadvantage is that dyes do not behave like cytotoxic drugs in efflux experiments. Assays using the self fluorescence of drugs like anthracyclines can not reveal a real impression of intracellular or effluxed drug due to quenching of the drug fluorescence in the nuclei of the cells. We have developed a reproducible and sensitive assay for direct and quantitative determination of drug efflux out of blast cells. This was done by a novel double radioactive labelling using a 3H-labelled drug and 14C-labelled sucrose as extracellular marker. So this assay can be applied to every drug of interest. Quenching of fluorescence is also by-passed with this technique as well as protracting washing or silicon oil procedures. As a model system we used the T-lymphoblastoid cell line CCRF CEM and its resistant sublines vincristine 100 and adriamycin 5000. The results were also transferable to clinical specimens of leukemic patients. In conclusion our assay may be used for precise and direct efflux measurement of a broad range of anti-cancer drugs in clinical MDR evaluation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Rapid engraftment after allogeneic ABO-incompatible peripheral blood progenitor cell transplantation complicated by severe hemolysis.

A patient with CML in accelerated phase received G-CSF-mobilized PBPC from an unrelated HLA genotypically matched donor. The blood groups of the patient and donor were bidirectionally incompatible. Hematologic recovery was rapid with > 500 PMN/microliter on day +9. Starting on day +5 bilirubin levels increased from 1.3 mg/dl up to a maximum of 18 mg/dl on day +14. Clinical signs and laboratory tests supported major hemolysis. Blood typing on day +16 revealed early blood-group change, consistent with donor-derived antibodies produced by passenger-lymphocytes which may have mediated severe hemolysis. The early onset and strong intensity of the hyperbilirubinemia could be a specific feature of ABO-incompatible allogeneic PBPC transplantation which would be difficult to differentiate from GVHD or VOD.

ABO Blood-Group System↗
PubMed1996

Evaluation of procollagen-III peptide as a marker for veno-occlusive disease after bone marrow transplantation.

Procollagen-III peptide (PIIIP) has been suggested as a marker for hepatic veno-occlusive disease (VOD) after bone marrow transplantation (BMT). Using the RIA-gnost PIIIP assay, we examined frozen plasma samples from three groups of patients. The groups included (A) four patients with clinically proven VOD, (B) nine patients with remarkably uneventful post-BMT courses, and (C) patients with either early complications other than VOD or pulmonary fibrosis in their later course. In group A, PIIIP levels increased parallel to the clinical course, with maximum values of 2.7-5.5 units/ml. In group B, values did not exceed 1.4 units/ml. In group C, higher values were occasionally observed. In one patient with early relapse of a lymphoma PIIIP peaks correlated with episodes of fever and graft versus host disease (GVHD). In another patient mild VOD seems possible retrospectively. The highest levels ( > 15 units/ml) occurred in one patient with ileus. Several patients with interstitial pneumonia (IP), adult respiratory distress syndrome (ARDS), or lung fibrosis showed increases in PIIIP levels corresponding to the clinical course; most of these events occurred later than day 30 after BMT. One patient with severe GVHD of the liver showed a maximum of only 1.4 units/ml. PIIIP elevation correlated with clinical VOD and may help to differentiate it from hepatic GVHD. In the presence of other complications (pulmonary, gastrointestinal), some caution in interpreting the results may be advisable.

Adult↗
PubMed1996

Complex cytogenetic and immunophenotypic aberrations in a patient with Sezary syndrome.

Sezary syndrome is defined as the leukemic variation of cutaneous T-cell lymphomas. Here we describe the cytogenetic pattern of peripheral T-cells of a 50-year-old male patient suffering from this disease. We used Giemsa-banding (G-banding) technique and a fluorescence in situ hybridization (FISH) assay to determine cytogenetic changes affecting 15 different chromosomes. The cells displayed an abnormal hypodiploid karyotype with a prominent insertion located at the short arm of chromosome 1. Unbalanced translocations were observed involving chromosomes 4 and 14. Besides other abnormalities we detected a 6q- deletion. These multiple genetic changes may reflect the high aggressivity of the neoplastically transformed T-cell population and the poor response to chemotherapeutic treatment.

Aneuploidy↗
PubMed1996

[Disseminated aspergillosis and mucormycosis. A case report].

This paper reports a simultaneous pulmonary infection due to Aspergillus fumigatus and Rhizomucor pusillus which evolved to disseminated aspergillosis and mucormycosis in a leukaemic and neutropenic 40-year-old woman. Both fungi were cultured ante mortem from bronchial secretion. Although high doses of intravenous amphotericin B were administered, the course of the infection was fatal. At autopsy, aspergilli were demonstrated by histology in lungs and brain, and zygomycetes were found to have invaded liver and kidneys.

Adult↗
PubMed1995

Polymerase chain reaction monitoring reduces the incidence of cytomegalovirus disease and the duration and side effects of antiviral therapy after bone marrow transplantation.

Culture-based preemptive therapy with ganciclovir was shown to reduce the incidence of cytomegalovirus (CMV) disease after bone marrow transplantation (BMT). Culture techniques did not detect CMV in 12% to 13% of patients before the onset of CMV disease. In a prospective study, 71 patients either received preemptive therapy based on polymerase chain reaction (PCR) technique (37 patients) or on culture assays (34 patients). In both groups, therapy was continued until clinical signs disappeared and PCR negativity was documented. Twenty-two patients in the PCR group and 15 patients in the culture group received antiviral therapy. PCR allowed detection of the virus (median day, +32 v day +49; P = .006) and introduction of antiviral therapy (median day, +44 v day +54; P = .02) earlier than did culture assays. The incidences of CMV disease (2 of 37 v 8 of 34 in PCR group v culture group, respectively; P = .02) and CMV-associated mortality (0 of 37 v 5 of 34 in PCR group v culture group, respectively; P = .02) were decreased, and the duration of ganciclovir therapy (P < .001) was shorter in the PCR-monitored group. Incidence and median duration of severe neutropenia (less than 500/microL) were lower in the PCR group (two v eight episodes, P = .02; median duration, 1.5 v 5 days, P = .04), as was the incidence of nonviral infections during/after antiviral therapy (2 of 37 v 9 of 34; P = .012). Thus, preemptive therapy based on more sensitive detection methods such as the PCR assay reduces the incidence of CMV disease and CMV-related mortality. Additionally, stopping and withholding antiviral therapy in a PCR-negative patient is safe and allows reduction of the duration and side effects of antiviral therapy.

Adolescent↗
PubMed1995

Use of a water-soluble busulfan formulation--pharmacokinetic studies in a canine model.

In a canine model we investigated the toxicity and pharmacokinetics of a water soluble busulfan preparation. Busulfan was dissolved in dimethylsulfoxide (DMSO) and administered either orally or intravenously in a single dose of 1 mg/kg. The application in either preparation was well tolerated. In seven dogs, peak levels in the range of 730 ng/mL to 1,000 ng/mL were measured after intravenous injection with an area under curve (AUC) of 75 ng.h/kg.mL to 146 ng.h/kg.mL. It was of note that even the oral administration of the same busulfan preparation resulted in AUC values in the same range as observed after parenteral application. The absorption rate of busulfan tablets in our model was as unpredictable as documented in clinical trials. On the basis of the present study, clinical trials using busulfan dissolved in DMSO given either intravenously or orally appear warranted. This approach should lead to predictable blood levels, reduced toxicity, and increased efficacy of busulfan-containing regimens.

Administration, Oral↗
PubMed1995

[Prophylaxis and therapy of fungal infections in oncology].

The observation of a considerable incidence of fungal infections in oncology patients has promoted a large number of studies both on prophylaxis and treatment in this patient group. Trials using triazoles, especially fluconazole, have shown effect in preventing fungal infections. In neutropenic patients, their role in therapy still remains less clear. Amphotericin B is the drug of choice for most life-threatening infections. With this drug, efforts concentrate upon the amelioration of side effects by sodium loading, administration in lipid emulsions or liposomes. The use of AMB as low-dose systemic prophylaxis or by inhalation needs further study.

Amphotericin B↗
PubMed1995

Thalidomide: rationale for renewed use in immunological disorders.

Despite its inherent teratogenic risk, thalidomide has over the years proven to be of clinical use in a small number of mainly immunological diseases (e.g. erythema nodosum leprosum, Behçet's syndrome and rheumatoid arthritis). The mode of action of thalidomide is still poorly understood. Recent research has shown a decrease in tumour necrosis factor-alpha (TNF alpha) during thalidomide treatment in several settings. Others have found altered expression of adhesion molecules. Currently, the most interesting new fields of application are the prevention and treatment of graft-versus-host disease in allogeneic bone marrow transplantation and the treatment of aphthous ulceration in HIV-positive patients. Contraceptive measures must be instituted in women receiving thalidomide, and careful monitoring for neurological adverse effects is required in all patients.

Bone Marrow Transplantation↗
PubMed1994

New approaches to the prophylaxis and treatment of bacterial and fungal infections in allogeneic marrow transplant recipients.

Bacterial and fungal infections continue to be a major threat to bone marrow transplant recipients. While standardized approaches to empiric therapy with early inclusion of antibiotics active against Gram-positive organisms and against fungi may have improved the outcome of these patients during the past decade, other developments (e.g. increasing number of patients in older age groups, unrelated donors, mismatch transplants) may even have increased the problem. Current approaches to the prophylaxis and treatment of these infections are discussed. Concerning fungal infections especially the new azoles and new approaches of amphotericin B administration are of interest.

Anti-Infective Agents↗
PubMed1994

Busulfan pharmacokinetics in bone marrow transplant patients: is drug monitoring warranted?

Pharmacokinetics were studied in relation to hepatic side-effects in 20 patients (19 adults aged 18-53 years and one child of 11 years) undergoing BMT after conditioning with 1 mg/kg busulfan (every 6 hours for 16 doses). Busulfan was quantitated in plasma samples at 10 time points within the 6 h dosing interval using HPLC before and after dose numbers 1, 2, 5, 13 and 14. For 13 patients data on all five doses are available; for the remaining seven patients three to four doses were studied. Mean maximum concentrations were 1512 ng/ml; mean trough levels for second and subsequent doses were 615 ng/ml. Maxima (Cmax) tended to be lower and times of maxima (Tmax) were later when busulfan was taken with a meal. Correlation of the area under the concentration versus time curve (AUC0-6h) between different doses was low within patients. In several patients problems with compartmental fitting of concentration data were observed mainly caused by the short dosing interval, which made estimates of T1/2 and model derived AUCs unstable. Three patients experienced hepatic veno-occlusive disease; kinetic parameters were not helpful in describing a particulate risk constellation for this subgroup. In our experience, the role of drug monitoring in this setting needs to be defined more clearly.

Adolescent↗
PubMed1993

Thalidomide--the need for a new clinical evaluation of an old drug.

Thalidomide shows activity in refractory chronic graft-versus-host disease. Best responses were seen in mucocutaneous disease. The studies vary in inclusion criteria (e.g. pretreatment), time of onset of GVHD and dose given. The optimal schedule of thalidomide treatment is not defined. The role of thalidomide must be assessed in large controlled trials for treatment and prophylaxis of GvHD. Due to the variable absorption rate there is a need for an intravenous formulation of thalidomide, and in addition the search for more active and possibly less teratogenic derivatives must be intensified.

Graft vs Host Disease↗